RTEC Rudolph Technologies Inc

ABOUT THIS JOINT PROXY STATEMENT/PROSPECTUS

This document, which forms part of a registration statement on Form S-4 filed with the SEC by Nanometrics, constitutes a prospectus of Nanometrics under Section 5 of the Securities Act of 1933, as amended, which is referred to as the Securities Act, with respect to the shares of common stock of Nanometrics to be issued to Rudolph stockholders pursuant to the Agreement and Plan of Merger, dated as of June 23, 2019 (as it may be amended from time to time), by and among Nanometrics, Rudolph and Merger Sub, which is referred to as the merger agreement. This document also constitutes a joint proxy statement of Nanometrics and Rudolph under Section 14(a) of the Securities Exchange Act of 1934, as amended, which is referred to as the Exchange Act. It also constitutes a notice of meeting with respect to the Nanometrics special meeting and a notice of meeting with respect to the Rudolph special meeting.

Nanometrics has supplied all information contained or incorporated by reference into this joint proxy statement/prospectus relating to Nanometrics, and Rudolph has supplied all such information relating to Rudolph. Nanometrics and Rudolph have both contributed to the information related to the merger contained in this joint proxy statement/prospectus.

You should rely only on the information contained in or incorporated by reference into this joint proxy statement/prospectus. Nanometrics and Rudolph have not authorized anyone to provide you with information that is different from that contained in or incorporated by reference into this joint proxy statement/prospectus. This joint proxy statement/prospectus is dated September 10, 2019, and you should not assume that the information contained in this joint proxy statement/prospectus is accurate as of any date other than such date unless otherwise specifically provided herein.

Further, you should not assume that the information incorporated by reference into this joint proxy statement/prospectus is accurate as of any date other than the date of the incorporated document. Neither the mailing of this joint proxy statement/prospectus to Nanometrics stockholders or Rudolph stockholders nor the issuance by Nanometrics of shares of its common stock pursuant to the merger agreement will create any implication to the contrary.

This joint proxy statement/prospectus does not constitute an offer to sell, or a solicitation of an offer to buy, any securities, or the solicitation of a proxy, in any jurisdiction to or from any person to whom it is unlawful to make any such offer or solicitation in such jurisdiction.

All references in this joint proxy statement/prospectus to “Nanometrics” refer to Nanometrics Incorporated, a Delaware corporation. All references in this joint proxy statement/prospectus to “Rudolph” refer to Rudolph Technologies, Inc., a Delaware corporation. All references in this joint proxy statement/prospectus to “Merger Sub” refer to PV Equipment Inc., a Delaware corporation and wholly-owned subsidiary of Nanometrics. All references in this joint proxy statement/prospectus to the “combined company” refer to Nanometrics immediately following completion of the merger and the other transactions contemplated by the merger agreement. All references in this joint proxy statement/prospectus to “Nanometrics common stock” refer to the common stock of Nanometrics, par value $0.001 per share, and all references in this joint proxy statement/prospectus to “Rudolph common stock” refer to the common stock of Rudolph, par value $0.001 per share.

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QUESTIONS AND ANSWERS

The following are some questions that you, as a stockholder of Nanometrics or a stockholder of Rudolph, may have regarding the merger and the other matters being considered at the special meetings of each company’s stockholders, and brief answers to those questions. You are urged to carefully read this joint proxy statement/prospectus and the other documents referred to in this joint proxy statement/prospectus in their entirety because this section may not provide all the information that is important to you regarding these matters. Additional important information is contained in the annexes to, and the documents incorporated by reference into, this joint proxy statement/prospectus. You may obtain the information incorporated by reference in this joint proxy statement/prospectus, without charge, by following the instructions under the section entitled “Where You Can Find More Information” beginning on page 229 of this joint proxy statement/prospectus.

In order to complete the merger, among other things:

Nanometrics is holding a special meeting of its stockholders, which is referred to as the Nanometrics special meeting, to obtain approval of the Nanometrics share issuance proposal, the Nanometrics charter proposal #1 and the Nanometrics charter proposal #2. Nanometrics stockholders will also be asked to approve the proposal to adjourn the Nanometrics special meeting to solicit additional proxies if there are not sufficient votes at the time of the Nanometrics special meeting to approve the Nanometrics share issuance proposal, the Nanometrics charter proposal #1 and the Nanometrics charter proposal #2 or to ensure that any supplement or amendment to this joint proxy statement/prospectus is timely provided to Nanometrics stockholders, which proposal is referred to as the Nanometrics adjournment proposal.

Rudolph is holding a special meeting of its stockholders, which is referred to as the Rudolph special meeting, to obtain approval of the Rudolph merger agreement proposal. Rudolph stockholders will also be asked to approve, on an advisory (non-binding) basis, the compensation that will or may be paid to

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Rudolph’s named executive officers that is based on or otherwise relates to the transactions contemplated by the merger agreement, which proposal is referred to as the Rudolph advisory compensation proposal; to approve, on an advisory (non- binding) basis, the proposed increase of authorized shares of Nanometrics common stock under the Nanometrics certificate of incorporation from 47,000,000 shares of common stock to 97,000,000 shares of common stock, which proposal is referred to as the Rudolph advisory share authorization proposal; and to approve the proposal to adjourn the Rudolph special meeting to solicit additional proxies if there are not sufficient votes at the time of the Rudolph special meeting to approve the Rudolph merger agreement proposal or to ensure that any supplement or amendment to this joint proxy statement/prospectus is timely provided to Rudolph stockholders, which proposal is referred to as the Rudolph adjournment proposal.

Your vote is very important, regardless of the number of shares that you own. The approval of the Nanometrics share issuance proposal, the Nanometrics charter proposal #1, and the Nanometrics charter proposal #2 and the approval of the Rudolph merger agreement proposal are conditions to the obligations of Nanometrics and Rudolph to complete the merger. None of the approvals of the Rudolph advisory compensation proposal, the Rudolph advisory share authorization proposal, the Nanometrics adjournment proposal or the Rudolph adjournment proposal are conditions to the obligations of Nanometrics or Rudolph to complete the merger.

The Rudolph special meeting will be held at the offices of Wilmer Cutler Pickering Hale and Dorr LLP, 60 State Street, Boston, Massachusetts, 02109, on October 24, 2019, beginning at 12 p.m., Eastern Time.

If you choose to vote your shares in person at your respective company’s special meeting, please bring required documentation in accordance with the section entitled “The Nanometrics Special Meeting—Attending the Nanometrics Special Meeting” beginning on page 63 of this joint proxy statement/prospectus, with respect to the Nanometrics special meeting, and the section entitled “The Rudolph Special Meeting—Attending the Rudolph Special Meeting” beginning on page 76 of this joint proxy statement/prospectus, with respect to the Rudolph special meeting. The use of video, still photography or audio recording at either the Nanometrics special meeting or the Rudolph special meeting is not permitted. For the safety of attendees, all bags, packages and briefcases are subject to inspection.

Even if you plan to attend your company’s special meeting, Nanometrics and Rudolph recommend that you vote your shares in advance as described below so that your vote will be counted if you later decide not to or become unable to attend the applicable special meeting. Shares held in “street name” may be voted in person by you only if you obtain a signed legal proxy from your bank, broker or other nominee giving you the right to vote the shares.

For Nanometrics stockholders, if you do not return or submit your proxy or vote at the special meeting as provided in this joint proxy statement/prospectus, it will have no effect on the Nanometrics share issuance proposal or the Nanometrics adjournment proposal, but the effect will be the same as a vote “AGAINST”

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the Nanometrics charter proposal #1 and the Nanometrics charter proposal #2. The board of directors of Nanometrics, which is referred to as the Nanometrics board of directors, unanimously recommends that you vote “FOR” the Nanometrics share issuance proposal, “FOR” the Nanometrics charter proposal #1, “FOR” the Nanometrics charter proposal #2 and “FOR” the Nanometrics adjournment proposal.

For Rudolph stockholders, if you do not return or submit your proxy or vote at the special meeting as provided in this joint proxy statement/prospectus, the effect will be the same as a vote “AGAINST” the Rudolph merger agreement proposal, and will have no effect on the Rudolph advisory compensation proposal, the Rudolph advisory share authorization proposal, or the Rudolph adjournment proposal. The board of directors of Rudolph, which is referred to as the Rudolph board of directors, unanimously recommends that you vote “FOR” the Rudolph merger agreement proposal, “FOR” the Rudolph advisory compensation proposal, “FOR” the Rudolph advisory share authorization proposal and “FOR” the Rudolph adjournment proposal.

If the merger is completed, Nanometrics stockholders’ shares of Nanometrics common stock will, after the effective time, constitute shares of the combined company. Because Nanometrics will issue a fixed number of shares of Nanometrics common stock in exchange for each outstanding share of Rudolph common stock, the value of the merger consideration that Rudolph stockholders will receive in the merger will depend on the market price of shares of Nanometrics common stock at the effective time. The market price of shares of Nanometrics common stock that Rudolph stockholders receive after the merger is completed could be greater than, less than or the same as the market price of shares of Nanometrics common stock on the date of this joint proxy statement/prospectus or at the time of the special meetings. Accordingly, you should obtain current market quotations for Nanometrics common stock and Rudolph common stock before deciding how to vote with respect to the adoption of the merger agreement. Nanometrics common stock is traded on Nasdaq, and Rudolph common stock is traded on the New York Stock Exchange, which is referred to as the NYSE, under the symbols “NANO” and “RTEC,” respectively. Shares of common stock of the combined company are expected to trade on the NYSE or, if approval for listing on the NYSE is not received prior to the effective time, then on Nasdaq, under a symbol to be agreed upon by the parties prior to the completion of the merger. Stockholders will be informed in conjunction with the closing on which exchange the shares will trade.

For more information regarding the merger consideration to be received by Rudolph stockholders if the merger is completed, see the section entitled “The Merger Agreement—Merger Consideration” beginning on page 138 of this joint proxy statement/prospectus.

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At the effective time, each Rudolph time-based restricted stock unit and performance-based restricted stock unit, each of which we refer to as a Rudolph RSU award, that is outstanding immediately prior to the effective time and that is not then vested will be assumed by Nanometrics and will be converted into a Nanometrics RSU award to acquire shares of Nanometrics common stock. The number of shares of Nanometrics common stock subject to each such assumed Nanometrics RSU award will be equal to the product of (i) the number of shares of Rudolph common stock subject to the Rudolph RSU award immediately prior to the effective time multiplied by (ii) the exchange ratio, with the resulting number of Nanometrics shares rounded up or down to the nearest whole share. Except as noted in the immediately preceding sentence, each assumed and converted Nanometrics RSU award will continue to have, and will be subject to, substantially the same terms and conditions as applied to the applicable Rudolph RSU award

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immediately prior to the effective time (including the vesting and settlement schedule(s) as were applicable to the corresponding Rudolph RSU award immediately before the effective time).

Any share of Rudolph common stock underlying a Rudolph RSU award that is vested and so is not assumed by Nanometrics, but as to which such underlying share of Rudolph common stock has not been issued by the effective time (including any performance-based Rudolph RSU awards, which we refer to as Rudolph PSU awards, which will be treated, in accordance with their terms, as vesting as of the effective time based on the target performance under such award, with any portion of the Rudolph PSU award that would have been issued at above target performance being forfeited), will be issued as of immediately prior to the effective time (at target, to the extent they are performance-based awards) and will be treated as a share of Rudolph common stock issued and outstanding immediately prior to the effective time and will receive the same consideration provided to holders of Rudolph common stock, subject to the terms and conditions of the merger agreement. Any Rudolph directors who remain in service until the closing but will not join the board of directors of the combined company upon completion of the merger will have their Rudolph RSU awards fully vested (under the treatment for resignations when not being asked to remain after a change in control) and be treated as described in the preceding sentence.

Nanometrics and Rudolph may mutually agree in writing to treat equity compensation held by Rudolph employees subject to non-U.S. law in another manner to take into account applicable non-U.S. law or tax or employment considerations; provided that the parties shall use commercially reasonable efforts to ensure such treatment corresponds as closely as permitted by applicable law to treatment of equity compensation held by Rudolph employees subject to U.S. law.

The merger will be treated as a “change in control” or term of similar meaning for purposes of the Rudolph compensation and benefit plans, including Rudolph equity awards, which determination will result in certain “single trigger” benefits at the effective time and certain “double trigger” benefits under such plans upon a qualifying termination of employment by certain executives subsequent to the effective time. For more information, see the information provided in the section entitled “Interests of Rudolph’s Directors and Executive Officers in the Merger” beginning on page 192 of this joint proxy statement/prospectus.

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In considering the recommendations of the Nanometrics board of directors, Nanometrics stockholders should be aware that Nanometrics directors and executive officers have interests in the merger that are different from, or in addition to, their interests as Nanometrics stockholders. These interests may include, among others, the payment of severance benefits and acceleration of outstanding Nanometrics equity awards upon a qualifying termination of employment, determination of achievement of performance under Nanometrics PRSU awards at closing (which Nanometrics may deem to be at the target level by amending the Nanometrics PRSU awards), the acceleration of a pro-rated portion of annual bonus payments in the year of the closing, and the combined company’s agreement to indemnify Nanometrics directors and officers against certain claims and liabilities. For a more complete description of these interests, see the information provided in the section entitled “Interests of Nanometrics’ Directors and Executive Officers in the Merger” beginning on page 185 of this joint proxy statement/prospectus.

In considering the recommendations of the Rudolph board of directors, Rudolph stockholders should be aware that Rudolph directors and executive officers have interests in the merger that are different from, or in addition to, their interests as Rudolph stockholders. These interests may include, among others, the payment of severance benefits and acceleration of outstanding Rudolph equity awards upon certain terminations of employment or service, acceleration and settlement, in accordance with their terms, of Rudolph PSU awards at closing, pursuant to the terms of the key executive compensation plans for the period ending December 31, 2019, pay out of key executive annual incentives in cash at target in connection with the closing, and the combined company’s agreement to indemnify Rudolph directors and officers against certain claims and liabilities. For a more complete description of these interests, see the information provided in the section entitled “Interests of Rudolph’s Directors and Executive Officers in the Merger” beginning on page 192 of this joint proxy statement/prospectus.

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A “broker non-vote” occurs on an item when (a) a bank, broker or other nominee has discretionary authority to vote on one or more proposals to be voted on at a meeting of stockholders, but is not permitted to vote on other proposals without instructions from the beneficial owner of the shares and (b) the beneficial owner fails to provide the bank, broker or other nominee with such instructions. Because none of the proposals currently scheduled to be voted on at either the Nanometrics special meeting or the Rudolph special meeting are routine matters for which brokers may have discretionary authority to vote, Nanometrics and Rudolph do not expect there to be any broker non-votes at the Nanometrics special meeting or the Rudolph special meeting.

Nanometrics Proposal # 2: Nanometrics charter proposal #1. Assuming a quorum is present at the Nanometrics special meeting, the adoption of the amended and restated certificate of incorporation of Nanometrics to increase the authorized shares of Nanometrics common stock from 47,000,000 shares of common stock to 97,000,000 shares of common stock by Nanometrics stockholders requires the affirmative vote of the holders of a majority of the outstanding shares of Nanometrics common stock entitled to vote on such proposal. Accordingly, a Nanometrics stockholder’s abstention from voting, a broker non-vote or the failure of a Nanometrics stockholder to vote (including the failure of a Nanometrics stockholder who holds shares in “street name” through a bank, broker or other nominee to give voting instructions to that bank, broker or other nominee) will have the same effect as a vote “AGAINST” the Nanometrics charter proposal #1.

Nanometrics Proposal # 3: Nanometrics charter proposal #2. Assuming a quorum is present at the Nanometrics special meeting, the adoption of the amended and restated certificate of incorporation of Nanometrics to provide that a director of Nanometrics will not be liable for monetary damages to Nanometrics or Nanometrics stockholders for a breach of fiduciary duties as a director, subject to any

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limitations under the DGCL, by Nanometrics stockholders requires the affirmative vote of the holders of a majority of the outstanding shares of Nanometrics common stock entitled to vote on such proposal. Accordingly, a Nanometrics stockholder’s abstention from voting, a broker non-vote or the failure of a Nanometrics stockholder to vote (including the failure of a Nanometrics stockholder who holds shares in “street name” through a bank, broker or other nominee to give voting instructions to that bank, broker or other nominee) will have the same effect as a vote “AGAINST” the Nanometrics charter proposal #2.

Nanometrics Proposal # 4: Nanometrics adjournment proposal. The Nanometrics special meeting may be adjourned to solicit additional proxies if there are not sufficient votes at the time of the Nanometrics special meeting to approve the Nanometrics share issuance proposal, the Nanometrics charter proposal #1, the Nanometrics charter proposal #2 or to ensure that any supplement or amendment to this joint proxy statement/prospectus is timely provided to Nanometrics stockholders. Whether or not a quorum is present, the affirmative vote of the holders of a majority of the shares of Nanometrics common stock present or represented at the Nanometrics special meeting and entitled to vote thereat is required to adjourn the Nanometrics special meeting. A Nanometrics stockholder’s abstention from voting will have the same effect as a vote “AGAINST” the Nanometrics adjournment proposal, while a broker non-vote or the failure of a Nanometrics stockholder not present at the meeting to vote (including the failure of a Nanometrics stockholder who holds shares in “street name” through a bank, broker or other nominee to give voting instructions to that bank, broker or other nominee) will have no effect on the Nanometrics adjournment proposal.

Rudolph Proposal 2: Rudolph advisory compensation proposal. Assuming a quorum is present at the Rudolph special meeting, approval of the Rudolph advisory compensation proposal requires the affirmative vote of the holders of a majority of the shares present in person or by proxy and entitled to vote at the Rudolph special meeting on this proposal. A Rudolph stockholder’s abstention from voting will have the same effect as a vote “AGAINST” the Rudolph advisory compensation proposal, while a broker non-vote or the failure of a Rudolph stockholder not present at the meeting to vote (including the failure of a Rudolph stockholder who holds shares in “street name” through a bank, broker or other nominee to give voting instructions to that bank, broker or other nominee) will have no effect on the outcome of the Rudolph advisory compensation proposal.

Rudolph Proposal 3: Rudolph advisory share authorization proposal. Assuming a quorum is present at the Rudolph special meeting, approval of the Rudolph advisory share authorization proposal requires the affirmative vote of the holders of a majority of the shares present in person or by proxy and entitled to vote at the Rudolph special meeting on this proposal. A Rudolph stockholder’s abstention from voting will have the same effect as a vote “AGAINST” the Rudolph advisory share authorization proposal, while a broker non-vote or the failure of a Rudolph stockholder not present at the meeting to vote (including the failure of a Rudolph stockholder who holds shares in “street name” through a bank, broker or other nominee to give voting instructions to that bank, broker or other nominee) will have no effect on the outcome of the Rudolph advisory share authorization proposal.

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Rudolph Proposal 4: Rudolph adjournment proposal. The Rudolph special meeting may be adjourned to solicit additional proxies if there are not sufficient votes at the time of the Rudolph special meeting to approve the Rudolph merger agreement proposal or to ensure that any supplement or amendment to this joint proxy statement/prospectus is timely provided to Rudolph stockholders. Whether or not a quorum is present, the approval of the holders of a majority of the shares of Rudolph common stock present and entitled to vote at the Rudolph special meeting is required to adjourn the Rudolph special meeting. A Rudolph stockholder’s abstention from voting will have the same effect as a vote “AGAINST” the Rudolph adjournment proposal, while a broker non-vote or the failure of a Rudolph stockholder not present at the meeting to vote (including the failure of a Rudolph stockholder who holds shares in “street name” through a bank, broker or other nominee to give voting instructions to that bank, broker or other nominee) will have no effect on the outcome of the Rudolph adjournment proposal.

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Shares in “street name.” Shares held in “street name” may be voted in person by you only if you obtain a signed legal proxy from your bank, broker or other nominee giving you the right to vote the shares and bring the signed legal proxy to the meeting. If you choose to vote your shares in person at the Nanometrics special meeting or Rudolph special meeting, as applicable, please bring required documentation in accordance with the section entitled “The Nanometrics Special Meeting—Attending the Nanometrics Special Meeting” beginning on page 63 of this joint proxy statement/prospectus, with respect to the Nanometrics special meeting, and the section entitled “The Rudolph Special Meeting—Attending the Rudolph Special Meeting” beginning on page 76 of this joint proxy statement/prospectus, with respect to the Rudolph special meeting.

Even if you plan to attend the Nanometrics special meeting or the Rudolph special meeting, as applicable, Nanometrics and Rudolph recommend that you submit a proxy to vote your shares in advance as described below so that your vote will be counted if you later decide not to or become unable to attend the respective special meeting. The use of video, still photography or audio recording is not permitted at either the Nanometrics special meeting or the Rudolph special meeting and, for the safety of attendees, all bags, packages and briefcases are subject to inspection.

Additional information on attending the special meetings can be found in the section entitled “The Nanometrics Special Meeting” on page 58 of this joint proxy statement/prospectus and in the section entitled “The Rudolph Special Meeting” on page 71 of this joint proxy statement/prospectus.

Additional information on voting procedures can be found under the section entitled “The Nanometrics Special Meeting” on page 58 of this joint proxy statement/prospectus and under the section entitled “The Rudolph Special Meeting” on page 71 of this joint proxy statement/prospectus.

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If your shares of common stock in Nanometrics or Rudolph are held by a bank, broker or other nominee, you are considered the beneficial owner of shares held in “street name,” and your bank, broker or other nominee is considered the stockholder of record with respect to those shares. Your bank, broker or other nominee will provide you, as the beneficial owner, a package describing the procedure for voting your shares. You should follow the instructions provided by them to vote your shares. You are invited to attend the Nanometrics special meeting or the Rudolph special meeting, as applicable; however, you may not vote these shares in person at the respective special meeting unless you obtain a signed legal proxy, executed in your favor, from your bank, broker or other nominee that holds your shares, giving you the right to vote the shares in person at the applicable special meeting.

For Nanometrics stockholders, the effect of not instructing your bank, broker or other nominee how you wish to vote your shares will be the same as a vote “AGAINST” the Nanometrics charter proposal #1 and the Nanometrics charter proposal #2, but will not be counted as “FOR” or “AGAINST” and, assuming a quorum is present at the Nanometrics special meeting, will have no effect on the Nanometrics share issuance proposal or the Nanometrics adjournment proposal.

For Rudolph stockholders, the effect of not instructing your bank, broker or other nominee how you wish to vote your shares will be the same as a vote “AGAINST” the Rudolph merger agreement proposal, but will not be counted as “FOR” or “AGAINST” and, assuming a quorum is present at the Rudolph special meeting, will have no effect on, the Rudolph advisory compensation proposal, Rudolph advisory share authorization proposal or the Rudolph adjournment proposal.

Record Holders. For shares held directly, please complete, sign, date and return each proxy card (or submit a proxy to cast your vote over the Internet, or by telephone, as provided on each proxy card) or otherwise

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follow the voting instructions provided in this joint proxy statement/prospectus in order to ensure that all of your shares of Nanometrics common stock or Rudolph common stock are voted.

Shares in “street name.” For shares held in “street name” through a bank, broker or other nominee, you should follow the procedures provided by your bank, broker or other nominee to vote your shares.

Execution or revocation of a proxy will not in any way affect your right to attend the applicable special meeting and vote in person. Attending the applicable special meeting will not, by itself, revoke a proxy. Written notices of revocation and other communications with respect to the revocation of proxies should be addressed:

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For more information, see the section entitled “The Nanometrics Special Meeting—Revocability of Proxies” beginning on page 62 of this joint proxy statement/prospectus and the section entitled “The Rudolph Special Meeting—Revocability of Proxies” beginning on page 75 of this joint proxy statement/prospectus, as applicable.

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For further information, see the section entitled “Material U.S. Federal Income Tax Consequences” beginning on page 200 of this joint proxy statement/prospectus.

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CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS

This registration statement on Form S-4, of which this joint proxy statement/prospectus forms a part, and the documents to which Nanometrics and Rudolph refer you to in this registration statement, as well as oral statements made or to be made by Nanometrics and Rudolph, include certain “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995 that are subject to risks and uncertainties and are made pursuant to the safe harbor provisions of Section 27A of the Securities Act, and Section 21E of the Exchange Act. The words “believe,” “continue,” “could,” “expect,” “anticipate,” “intends,” “estimate,” “forecast,” “project,” “should,” “may,” “will,” “would” or the negative thereof and similar expressions are intended to identify such forward-looking statements. These forward-looking statements are only predictions and involve known and unknown risks and uncertainties, many of which are beyond the control of Nanometrics and Rudolph. Statements in or incorporated by reference into this registration statement regarding Nanometrics, Rudolph, or the proposed business combination between Nanometrics and Rudolph, referred to as the proposed transaction, that are forward-looking, including statements regarding the anticipated benefits of the proposed transaction, the impact of the proposed transaction on Nanometrics’ and Rudolph’s employees, business and future financial and operating results, the amount and timing of synergies from the proposed transaction, and the closing date for the proposed transaction, are based on Nanometrics’ and Rudolph’s management’s estimates, assumptions and projections, and are subject to significant uncertainties and other factors, many of which are beyond Nanometrics’ and Rudolph’s control. These factors and risks include, but are not limited to:

In addition, material risks that could cause actual results to differ from forward-looking statements include: the inherent uncertainty associated with financial or other projections; the ability of the companies to integrate their respective businesses promptly and effectively and to achieve the anticipated synergies and value-creation contemplated by the proposed transaction; the companies’ ability to obtain the approval of the proposed transaction by their respective stockholders and the timing of the closing of the proposed transaction, including the risk that the conditions to the transaction are not satisfied on a timely basis or at all and the failure of the proposed transaction to close for any other reason; the risk that a consent or authorization that may be required

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for the proposed transaction is not obtained or is obtained subject to conditions that are not anticipated; unanticipated difficulties or expenditures relating to the transaction, the response of business partners and retention as a result of the announcement and pendency of the proposed transaction; and the diversion of management time in connection with the proposed transaction.

For further discussion of these and other risks, contingencies and uncertainties applicable to Nanometrics and Rudolph, see the section entitled “Risk Factors” beginning on page 47 of this joint proxy statement/prospectus and in Nanometrics’ and Rudolph’s other filings with the SEC incorporated by reference into this joint proxy statement/prospectus. See also the section entitled “Where You Can Find More Information” beginning on page 229 of this joint proxy statement/prospectus for more information about the SEC filings incorporated by reference into this joint proxy statement/prospectus.

All subsequent written or oral forward-looking statements attributable to Nanometrics or Rudolph or any person acting on its or their behalf are expressly qualified in their entirety by the cautionary statements contained or referred to in this section. Neither Nanometrics nor Rudolph is under any obligation, and each expressly disclaims any obligation, to update, alter, or otherwise revise any forward-looking statements, whether written or oral, that may be made from time to time, whether as a result of new information, future events or otherwise, except as may be required by law.

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RISK FACTORS

In deciding whether to vote for the Nanometrics share issuance proposal, the Nanometrics charter proposal #1, and the Nanometrics charter proposal #2 in the case of Nanometrics stockholders, or the adoption of the merger agreement, in the case of Rudolph stockholders, you are urged to carefully consider all of the information included or incorporated by reference in this joint proxy statement/prospectus, which is listed in the section entitled “Where You Can Find More Information” beginning on page 229 of this joint proxy statement/prospectus. You should also read and consider the risks associated with each of the businesses of Nanometrics and Rudolph because these risks will also affect the combined company. The risks associated with the business of Nanometrics can be found in Nanometrics’ Annual Report on Form 10-K for the fiscal year ended December 29, 2018 and the risks associated with the business of Rudolph can be found in Rudolph’s Annual Report on Form 10-K for the fiscal year ended December 31, 2018, as such risks may be updated or supplemented in each company’s subsequently filed Quarterly Reports on Form 10-Q or Current Reports on Form 8-K (excluding any information and exhibits furnished under Item 2.02 or 7.01 thereof), each of which are incorporated by reference into this joint proxy statement/prospectus. In addition, you are urged to carefully consider the following material risks relating to the merger, the business of the combined company, the business of Nanometrics, and the business of Rudolph.

Risks Relating to the Merger

The exchange ratio is fixed and will not be adjusted in the event of any change in either Nanometrics’ or Rudolph’s stock price.

Upon completion of the merger, each share of Rudolph common stock outstanding immediately prior to the merger (other than Rudolph excluded shares) will be converted into and become exchangeable for 0.8042 shares of Nanometrics common stock. This exchange ratio is fixed in the merger agreement and will not be adjusted for changes in the market price of either Nanometrics common stock or Rudolph common stock. The market prices of Nanometrics common stock and Rudolph common stock have fluctuated prior to and after the date of the announcement of the merger agreement and may continue to fluctuate from the date of this joint proxy statement/prospectus to the date of the Nanometrics special meeting and the Rudolph special meeting, respectively, and the date the merger is consummated, and the market price of the common stock of the combined company may continue to fluctuate thereafter.

Because the value of the merger consideration will depend on the market price of Nanometrics common stock at the time the merger is completed, Rudolph stockholders will not know or be able to determine at the time of the Rudolph special meeting the market value of the merger consideration they would receive upon completion of the merger. Similarly, Nanometrics stockholders will not know or be able to determine at the time of the Nanometrics special meeting the market value of the shares of Nanometrics common stock to be issued pursuant to the merger agreement compared to the market value of the shares of Rudolph common stock that are being exchanged in the merger.

Stock price changes may result from a variety of factors, including, among others, general market and economic conditions, changes in Nanometrics’ or Rudolph’s respective businesses, operations and prospects, reductions or changes in U.S. government spending or budgetary policies, market assessments of the likelihood that the merger will be completed, interest rates, general market, industry and economic conditions and other factors generally affecting the respective prices of Nanometrics’ or Rudolph’s common stock, federal, state and local legislation, governmental regulation and legal developments in the industry segments in which Nanometrics or Rudolph operate, and the timing of the merger.

Many of these factors are beyond Nanometrics’ and Rudolph’s control, and neither Nanometrics nor Rudolph are permitted to terminate the merger agreement solely due to a decline in the market price of the common stock of the other party. You are urged to obtain current market quotations for Nanometrics common stock and Rudolph

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common stock in determining whether to vote for the Nanometrics share issuance proposal, the Nanometrics charter proposal #1 and the Nanometrics charter proposal #2 in the case of Nanometrics stockholders or for the adoption of the merger agreement in the case of Rudolph stockholders. In addition, see the section entitled “Comparison of Nanometrics and Rudolph Market Prices and Implied Value of Merger Consideration” beginning on page 44 of this joint proxy statement/prospectus.

The merger may be delayed or may not be completed and the merger agreement may be terminated in accordance with its terms, which could negatively impact Nanometrics and/or Rudolph.

The merger is subject to a number of conditions that must be satisfied, some of which are beyond the control of Nanometrics and Rudolph, may not be satisfied or waived in a timely manner or at all, and, accordingly, the merger may be delayed or not completed. These conditions include: the approval by Nanometrics stockholders of the Nanometrics share issuance proposal, the Nanometrics charter proposal #1 and, unless waived by Rudolph, the Nanometrics charter proposal #2 and approval by Rudolph stockholders of the Rudolph merger agreement proposal, approval for listing on the NYSE of the shares of Nanometrics common stock (including those to be issued pursuant to the merger agreement) (subject to limited exceptions, in which case such shares must be listed on Nasdaq), the expiration or earlier termination of any applicable waiting period under U.S. antitrust and competition laws, the absence of governmental restraints or prohibitions preventing the consummation of the merger, the effectiveness of the registration statement on Form S-4 registering the Nanometrics common stock issuable pursuant to the merger agreement and the absence of any stop order or proceedings by the SEC with respect thereto. The obligation of each of Nanometrics and Rudolph to consummate the merger is also conditioned on, among other things, the receipt by such party of a written opinion from counsel, to the effect that for U.S. federal income tax purposes the merger will qualify as a “reorganization” within the meaning of Section 368(a) of the Code, the absence of a material adverse effect on the other party, the truth and correctness of the representations and warranties made by the other party on the date of the merger agreement and on the closing date (subject to certain materiality qualifiers), and the performance by the other party in all material respects of its obligations under the merger agreement. No assurance can be given that the required consents and approvals will be obtained or that the required conditions to closing will be satisfied, and, if all required consents and approvals are obtained and the conditions are satisfied, no assurance can be given as to the terms, conditions and timing of such consents and approvals. Any delay in completing the merger could cause the combined company not to realize, or to be delayed in realizing, some or all of the benefits that Nanometrics and Rudolph expect to achieve if the merger is successfully completed within its expected time frame. For a more complete summary of the conditions that must be satisfied or waived prior to completion of the merger, see the section entitled “The Merger Agreement—Conditions to the Completion of the Merger” beginning on page 161 of this joint proxy statement/prospectus.

Additionally, either Nanometrics or Rudolph may terminate the merger agreement under certain circumstances, including, among other reasons, if the merger is not completed by December 23, 2019 (which date may be extended by three months under certain circumstances if certain regulatory approvals are not obtained by December 23, 2019). In addition, if the merger agreement is terminated under certain circumstances specified in the merger agreement, either party may be required to pay the other party a termination fee of $26,000,000. See the section entitled “The Merger Agreement—Termination of the Merger Agreement” beginning on page 162 of this joint proxy statement/prospectus and the section entitled “The Merger Agreement—Termination Fees” beginning on page 163 of this joint proxy statement/prospectus for a more complete discussion of the circumstances under which the merger agreement could be terminated and when a termination fee may be payable by Nanometrics or Rudolph.

If the merger is not completed for any reason, including as a result of a failure to obtain the required Nanometrics vote or the required Rudolph vote, the ongoing businesses of Nanometrics and Rudolph may be adversely affected and, without realizing any of the benefits of having completed the merger, Nanometrics and Rudolph would be subject to a number of risks, including the following:

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The market price for shares of common stock of the combined company following the completion of the merger may be affected by factors different from, or in addition to, those that historically have affected or currently affect the market prices of shares of Nanometrics common stock and Rudolph common stock.

Upon consummation of the merger, Nanometrics stockholders and Rudolph stockholders will both hold shares of common stock in the combined company. The businesses of Nanometrics and Rudolph differ from each other, and, accordingly, the results of operations of the combined company will be affected by some factors that are different from those currently or historically affecting the results of operations of Nanometrics and Rudolph. For a discussion of the businesses of each of Nanometrics and Rudolph and some important factors to consider in connection with those businesses, please see the section entitled “The Parties to the Merger” beginning on page 56 of this joint proxy statement/prospectus and the documents and information included elsewhere in this joint proxy statement/prospectus or incorporated by reference into this joint proxy statement/prospectus and listed under the section entitled “Where You Can Find More Information” beginning on page 229 of this joint proxy statement/prospectus.

The shares of common stock of the combined company held by Nanometrics stockholders and to be received by Rudolph stockholders as a result of the merger will have rights different from the current shares of Nanometrics common stock and the shares of Rudolph common stock.

Upon consummation of the merger, the rights of Rudolph stockholders, who will become stockholders of the combined company, will be governed by the amended and restated certificate of incorporation and bylaws of the combined company. The rights associated with Nanometrics common stock and Rudolph common stock are different from the rights which will be associated with the common stock of the combined company. See the section entitled “Comparison of Stockholders’ Rights” beginning on page 204 of this joint proxy statement/prospectus for a discussion of these rights.

Nanometrics stockholders and Rudolph stockholders will each have reduced ownership and voting interest in the combined company as compared to ownership and voting interest in each of Nanometrics and Rudolph on a standalone basis.

Upon consummation of the merger, each Nanometrics stockholder and each Rudolph stockholder will become a stockholder of the combined company with a percentage ownership of the combined company that is smaller than such stockholder’s percentage ownership of Nanometrics or Rudolph, as applicable, immediately prior to the merger. As of the date of this joint proxy statement/prospectus, based on the exchange ratio and the estimated number of shares of common stock of Nanometrics and Rudolph that will be outstanding immediately prior to the completion of the merger, including exercisable options, Nanometrics and Rudolph estimate that holders of shares of Nanometrics common stock as of immediately prior to the completion of the merger will hold, in the aggregate, approximately 50% of the issued and outstanding shares of common stock of the combined company (based on fully diluted shares outstanding of the combined company including equity awards (using the treasury stock method)) immediately following the completion of the merger, and holders of shares of Rudolph common stock as of immediately prior to the completion of the merger will hold, in the aggregate, approximately 50% of the issued and outstanding shares of common stock of the combined company (based on fully diluted shares

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outstanding of the combined company including equity awards (using the treasury stock method)) immediately following the completion of the merger. Because of this, each share of Nanometrics common stock and each share of Rudolph common stock will represent a smaller percentage ownership of the combined company than it represented in Nanometrics or Rudolph, respectively.

Until the completion of the merger or the termination of the merger agreement in accordance with its terms, Nanometrics and Rudolph are each prohibited from entering into certain transactions and taking certain actions that might otherwise be beneficial to Nanometrics or Rudolph and their respective stockholders.

From and after the date of the merger agreement and prior to completion of the merger, the merger agreement restricts Nanometrics and Rudolph from taking specified actions without the consent of the other party and requires that the business of each company and its respective subsidiaries be conducted in all material respects in the ordinary course of business consistent with past practice. These restrictions may prevent Nanometrics or Rudolph from making appropriate changes to their respective businesses or organizational structures or from pursuing attractive business opportunities that may arise prior to the completion of the merger, and could have the effect of delaying or preventing other strategic transactions. Adverse effects arising from the pendency of the merger could be exacerbated by any delays in consummation of the merger or termination of the merger agreement. See the section entitled “The Merger Agreement—Conduct of Business Prior to the Effective Time” beginning on page 145 of this joint proxy statement/prospectus.

Failure to attract, motivate and retain executives and other key employees could diminish the anticipated benefits of the merger.

The success of the merger will depend in part on the retention of personnel critical to the business and operations of the combined company due to, for example, their technical skills or management expertise. Current and prospective employees of Nanometrics and Rudolph may experience uncertainty about their future role with Nanometrics and Rudolph until strategies with regard to these employees’ roles in the combined company are announced or executed, which may impair Nanometrics’ and Rudolph’s ability to attract, retain and motivate key management, sales, marketing, technical and other personnel prior to and following the merger. If Nanometrics and Rudolph are unable to retain personnel, including Nanometrics’ and Rudolph’s key management, who are critical to the successful integration and future operations of the companies, Nanometrics and Rudolph could face disruptions in their operations, loss of existing customers or loss of sales to existing customers, loss of key information, expertise or know-how, and unanticipated additional recruitment and training costs. In addition, the loss of key personnel could diminish the anticipated benefits of the merger.

If key employees of Nanometrics or Rudolph depart, the integration of the companies may be more difficult and the combined company’s business following the merger may be harmed. Furthermore, the combined company may have to incur significant costs in identifying, hiring and retaining replacements for departing employees and may lose significant expertise and talent relating to the business of each of Nanometrics or Rudolph, and the combined company’s ability to realize the anticipated benefits of the merger may be adversely affected. In addition, there could be disruptions to or distractions for the workforce and management associated with activities of labor unions or integrating employees into the combined company. No assurance can be given that the combined company will be able to attract or retain key employees of Nanometrics and Rudolph to the same extent that those companies have been able to attract or retain their own employees in the past.

The merger, and uncertainty regarding the merger, may cause customers, suppliers or strategic partners to delay or defer decisions concerning Nanometrics and Rudolph and adversely affect each company’s ability to effectively manage their respective businesses.

The merger will happen only if the stated conditions are met, including the relevant stockholder approvals, among other conditions. Many of the conditions are outside the control of Nanometrics and Rudolph, and both parties also have certain rights to terminate the merger agreement. Accordingly, there may be uncertainty

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regarding the completion of the merger. This uncertainty may cause customers, suppliers, vendors, strategic partners or others that deal with Nanometrics or Rudolph to delay or defer entering into contracts with Nanometrics or Rudolph or making other decisions concerning Nanometrics or Rudolph or seek to change or cancel existing business relationships with Nanometrics or Rudolph, which could negatively affect their respective businesses. Any delay or deferral of those decisions or changes in existing agreements could have an adverse impact on the respective businesses of Nanometrics and Rudolph, regardless of whether the merger is ultimately completed.

Whether or not the merger is completed, the announcement and pendency of the merger will divert significant management resources to complete the merger, which could have an adverse effect on their respective businesses, financial results, and/or market prices.

Whether or not the merger is completed, the announcement and pendency of the merger could cause disruptions in the businesses of Nanometrics and Rudolph by directing the attention of management of each of Nanometrics and Rudolph toward the completion of the merger. Nanometrics and Rudolph have each diverted significant management resources in an effort to complete the merger and are each subject to restrictions contained in the merger agreement on the conduct of their respective businesses. If the merger is not completed, Nanometrics and Rudolph will have incurred significant costs, including the diversion of management resources, for which they will have received little or no benefit.

The directors and executive officers of Nanometrics and Rudolph have interests and arrangements that may be different from, or in addition to, those of Nanometrics and Rudolph stockholders generally.

When considering the recommendations of the boards of directors of Nanometrics or Rudolph, as applicable, with respect to the proposals described in this joint proxy statement/prospectus, stockholders should be aware that the directors and executive officers of each of Nanometrics and Rudolph have interests in the merger that are different from, or in addition to, those of Nanometrics stockholders and Rudolph stockholders generally. These interests include the continued employment of certain executive officers of Nanometrics and Rudolph by the combined company, the continued service of certain directors of Nanometrics and Rudolph as directors of the combined company, the treatment in the merger of outstanding equity, equity-based and incentive awards, severance arrangements, and other compensation and benefit arrangements, and the right to continued indemnification of former Nanometrics and Rudolph directors and officers by the combined company.

Nanometrics stockholders and Rudolph stockholders should be aware of these interests when they consider the recommendations of the respective Nanometrics and Rudolph boards of directors that they vote in favor of the Nanometrics share issuance proposal, the Nanometrics charter proposal #1, and the Nanometrics charter proposal #2, in the case of Nanometrics, or that they adopt the merger agreement, in the case of Rudolph. The interests of Nanometrics directors and executive officers are described in more detail in the section entitled “Interests of Nanometrics’ Directors and Executive Officers in the Merger” beginning on page 185 of this joint proxy statement/prospectus, and the interests of Rudolph directors and executive officers are described in more detail in the section entitled “Interests of Rudolph’s Directors and Executive Officers in the Merger” beginning on page 192 of this joint proxy statement/prospectus.

Nanometrics or Rudolph may waive one or more of the closing conditions without re-soliciting stockholder approval.

Nanometrics or Rudolph may determine to waive, in whole or part, one or more of the conditions of its obligations to consummate the merger. Among other things, Rudolph may waive the approval of Nanometrics charter proposal #2. Nanometrics and Rudolph currently expect to evaluate the materiality of any waiver and its effect on Nanometrics and Rudolph stockholders, as applicable, in light of the facts and circumstances at the time to determine whether any amendment of this joint proxy statement/prospectus or any re-solicitation of proxies or voting cards is required in light of such waiver. Any determination whether to waive any condition to the merger

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or as to re-soliciting stockholder approval or amending this joint proxy statement/prospectus as a result of a waiver will be made by Nanometrics and Rudolph, as applicable, at the time of such waiver based on the facts and circumstances as they exist at that time.

Each of Nanometrics and Rudolph will incur significant transaction, merger-related and restructuring costs in connection with the merger.

Nanometrics and Rudolph have incurred and expect to incur a number of non-recurring costs associated with combining the operations of the two companies, as well as transaction fees and other costs related to the merger. These costs and expenses include fees paid to financial, legal and accounting advisors, facilities and systems consolidation costs, severance and other potential employment-related costs, including retention and severance payments that may be made to certain Nanometrics employees and Rudolph employees, filing fees, printing expenses and other related charges. Some of these costs are payable by Nanometrics or Rudolph regardless of whether the merger is completed.

The combined company will also incur restructuring and integration costs in connection with the merger. The costs related to restructuring will be expensed as a cost of the ongoing results of operations of either Nanometrics or Rudolph or the combined company. There are a large number of processes, policies, procedures, operations, technologies and systems that must be integrated in connection with the merger and the integration of the two companies’ businesses. Although Nanometrics and Rudolph expect that the elimination of duplicative costs, strategic benefits, additional income as well as the realization of other efficiencies related to the integration of the businesses, may offset incremental transaction, merger-related and restructuring costs over time, any net benefit may not be achieved in the near term or at all. Many of these costs will be borne by Nanometrics or Rudolph even if the merger is not completed. While both Nanometrics and Rudolph have assumed that certain expenses would be incurred in connection with the merger and the other transactions contemplated by the merger agreement, there are many factors beyond their control that could affect the total amount or the timing of the integration and implementation expenses.

Nanometrics stockholders and Rudolph stockholders will not be entitled to appraisal rights in the merger.

Appraisal rights are statutory rights that, if applicable under law, enable stockholders of a corporation to dissent from an extraordinary transaction, such as a merger, and to demand that such corporation pay the fair value for their shares as determined by a court in a judicial proceeding instead of receiving the consideration offered to such stockholders in connection with the transaction. Under the DGCL, stockholders do not have appraisal rights if the shares of stock they hold are either listed on a national securities exchange or held of record by more than 2,000 holders. Notwithstanding the foregoing, appraisal rights are available if stockholders are required by the terms of the merger agreement to accept for their shares anything other than (a) shares of stock of the surviving corporation, (b) shares of stock of another corporation that will either be listed on a national securities exchange or held of record by more than 2,000 holders, (c) cash in lieu of fractional shares or (d) any combination of the foregoing.

Because the merger is of Merger Sub with and into Rudolph and holders of Nanometrics common stock may continue to hold their shares following completion of the merger, holders of Nanometrics common stock are not entitled to appraisal rights in the merger.

Because shares of Nanometrics common stock are listed on Nasdaq, a national securities exchange, and are expected to be listed on the NYSE, a national securities exchange, in connection with the merger, and because Rudolph stockholders hold shares that will be listed on the NYSE, a national securities exchange, immediately prior to the completion of the merger and are not required by the terms of the merger agreement to accept for their shares anything other than shares of Nanometrics common stock and cash in lieu of fractional shares, holders of Rudolph common stock will not be entitled to appraisal rights in the merger. See the section entitled “No Appraisal Rights” beginning on page 220 of this joint proxy statement/prospectus.

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Risks Relating to the Combined Company

Combining the businesses of Nanometrics and Rudolph may be more difficult, costly or time-consuming than expected and the combined company may fail to realize the anticipated benefits of the merger, which may adversely affect the combined company’s business results and negatively affect the value of the common stock of the combined company following the merger.

The success of the merger will depend on, among other things, the ability of Nanometrics and Rudolph to combine their businesses in a manner that realizes cost savings and facilitates growth opportunities.

Nanometrics and Rudolph must successfully combine their respective businesses in a manner that permits these benefits to be realized. In addition, the combined company must achieve the anticipated growth and cost savings without adversely affecting current revenues and investments in future growth. If the combined company is not able to successfully achieve these objectives, the anticipated benefits of the merger may not be realized fully, or at all, or may take longer to realize than expected.

An inability to realize the full extent of the anticipated benefits of the merger and the other transactions contemplated by the merger agreement, as well as any delays encountered in the integration process, could have an adverse effect upon the revenues, level of expenses and operating results of the combined company, which may adversely affect the value of the common stock of the combined company after the completion of the merger.

In addition, the actual integration may result in additional and unforeseen expenses, and the anticipated benefits of the integration plan may not be realized. Actual growth and cost savings, if achieved, may be lower than what Nanometrics and Rudolph expect and may take longer to achieve than anticipated. If Nanometrics and Rudolph are not able to adequately address integration challenges, they may be unable to realize the anticipated benefits of the integration of the two companies.

The failure to successfully integrate the businesses and operations of Nanometrics and Rudolph in the expected time frame may adversely affect the combined company’s future results.

Nanometrics and Rudolph have operated and, until the completion of the merger, will continue to operate independently. There can be no assurances that their businesses can be integrated successfully. It is possible that the integration process could result in the loss of key Nanometrics employees or key Rudolph employees, the loss of customers, the disruption of either company’s or both companies’ ongoing businesses, inconsistencies in standards, controls, procedures and policies, unexpected integration issues, higher than expected integration costs and an overall post-completion integration process that takes longer than originally anticipated. Specifically, the following issues, among others, must be addressed in integrating the operations of Nanometrics and Rudolph in order to realize the anticipated benefits of the merger so the combined company performs as expected:

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In addition, at times the attention of certain members of either company’s or both companies’ management and resources may be focused on completion of the merger and the integration of the businesses of the two companies and diverted from day-to-day business operations or other opportunities that may have been beneficial to such company, which may disrupt each company’s ongoing business and the business of the combined company.

The combined company may not be able to retain customers or suppliers or customers or suppliers may seek to modify contractual obligations with the combined company, which could have an adverse effect on the combined company’s business and operations. Third parties may terminate or alter existing contracts or relationships with Nanometrics or Rudolph.

As a result of the merger, the combined company may experience impacts on relationships with customers and suppliers that may harm the combined company’s business and results of operations. Certain customers, licensors, business partners or suppliers may seek to terminate or modify contractual obligations following the merger whether or not contractual rights are triggered as a result of the merger. There can be no guarantee that customers and suppliers will remain with or continue to have a relationship with the combined company or do so on the same or similar contractual terms following the merger. If any customers or suppliers seek to terminate or modify contractual obligations or discontinue the relationship with the combined company, then the combined company’s business and results of operations may be harmed. Furthermore, the combined company will not have long-term arrangements with many of its significant suppliers. If the combined company’s suppliers were to seek to terminate or modify an arrangement with the combined company, then the combined company may be unable to procure necessary supplies from other suppliers in a timely and efficient manner and on acceptable terms, or at all. Any of the aforementioned disruptions could limit the combined company’s ability to achieve the anticipated benefits of the merger. The adverse effect of any such disruptions could also be exacerbated by a delay in the completion of the merger or by a termination of the merger agreement.

The combined company may be exposed to increased litigation, which could have an adverse effect on the combined company’s business and operations.

The combined company may be exposed to increased litigation from stockholders, customers, suppliers, consumers and other third parties due to the combination of Nanometrics’ business and Rudolph’s business following the merger. Such litigation may have an adverse impact on the combined company’s business and results of operations or may cause disruptions to the combined company’s operations.

The unaudited pro forma condensed combined financial information included in this joint proxy statement/prospectus may not be indicative of what the combined company’s actual financial position or results of operations would have been.

The unaudited pro forma condensed combined financial information included in this joint proxy statement/prospectus is presented solely for illustrative purposes and is not necessarily indicative of what the combined company’s actual financial position or results of operations would have been had the merger been completed on the dates indicated. This unaudited pro forma condensed combined financial information reflects adjustments that were developed using preliminary estimates based on available information and various assumptions, and may be revised as additional information becomes available. Accordingly, the final acquisition accounting adjustments may differ materially from the pro forma adjustments reflected in this joint proxy statement/prospectus.

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The combined company may be unable to retain Nanometrics and Rudolph personnel successfully after the merger is completed.

The success of the merger will depend in part on the combined company’s ability to retain the talents and dedication of the professionals currently employed by Nanometrics and Rudolph. It is possible that these employees may decide not to remain with Nanometrics or Rudolph, as applicable, while the merger is pending, or with the combined company after the merger is consummated. If key employees terminate their employment, or if an insufficient number of employees are retained to maintain effective operations, the combined company’s business activities may be adversely affected and management’s attention may be diverted from successfully integrating Nanometrics and Rudolph to hiring suitable replacements, all of which may cause the combined company’s business to suffer. In addition, Nanometrics and Rudolph may not be able to locate suitable replacements for any key employees that leave either company or offer employment to potential replacements on reasonable terms.

Risks Relating to Nanometrics’ Business

Nanometrics’ business will continue to be subject to the risks described in the sections entitled “Risk Factors” in Nanometrics’ Annual Report on Form 10-K for the fiscal year ended December 29, 2018, in Nanometrics’ Quarterly Report on Form 10-Q for the quarterly period ended June 29, 2019, and in other documents incorporated by reference into this joint proxy statement/prospectus. See the section entitled “Where You Can Find More Information” beginning on page 229 of this joint proxy statement/prospectus for the location of information incorporated by reference into this joint proxy statement/prospectus.

Risks Relating to Rudolph’s Business

Rudolph’s business will continue to be subject to the risks described in the sections entitled “Risk Factors” in Rudolph’s Annual Report on Form 10-K for the fiscal year ended December 31, 2018, in Rudolph’s Quarterly Report on Form 10-Q for the quarterly period ended June 30, 2019 and in other documents incorporated by reference into this joint proxy statement/prospectus. See the section entitled “Where You Can Find More Information” beginning on page 229 of this joint proxy statement/prospectus for the location of information incorporated by reference into this joint proxy statement/prospectus.

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THE PARTIES TO THE MERGER

Nanometrics Incorporated

1550 Buckeye Drive

Milpitas, California 95035

(408) 545-6000

Nanometrics is a leading provider of advanced, high-performance process control metrology and inspection solutions used primarily in the semiconductor manufacturing industry, as well as in the fabrication of other solid-state devices and components in the optoelectronic, LED and storage industries, and more recently in the industrial, aerospace and scientific research markets. Nanometrics’ principal executive offices are located at 1550 Buckeye Drive, Milpitas, California 95035 and its telephone number is (408) 545-6000.

Nanometrics common stock is listed on Nasdaq under the ticker symbol “NANO.”

For more information about Nanometrics, please visit Nanometrics’ website at https://www.nanometrics.com. The information contained on Nanometrics’ website or accessible through it (other than the documents incorporated by reference herein) does not constitute a part of this joint proxy statement/prospectus or any other report or document on file with or furnished to the SEC. Additional information about Nanometrics is included in the documents incorporated by reference into this joint proxy statement/prospectus. See the section entitled “Where You Can Find More Information” beginning on page 229 of this joint proxy statement/prospectus.

PV Equipment Inc.

1550 Buckeye Drive

Milpitas, California 95035

(408) 545-6000

PV Equipment Inc., a newly formed and a wholly-owned subsidiary of Nanometrics, is a Delaware corporation that was formed on June 20, 2019, for the sole purpose of effecting the merger. Under the merger agreement, PV Equipment Inc. will merge with and into Rudolph as of the effective time of the merger, and Rudolph will continue as the surviving corporation and a wholly-owned subsidiary of Nanometrics.

Rudolph Technologies, Inc.

16 Jonspin Road

Wilmington, Massachusetts 01887

(978) 253-6200

Rudolph is a worldwide leader in the design, development, manufacture and support of process control tools that perform macro-defect inspections and metrology, lithography systems, and process control analytical software used by semiconductor and advanced packaging device manufacturers. Rudolph delivers comprehensive solutions throughout the semiconductor fabrication process with its families of proprietary products that provide critical yield-enhancing information, enabling microelectronic device manufacturers to drive down costs and time to market of their devices. Rudolph provides process and yield management solutions used in both wafer processing facilities, often referred to as “front-end” and device packaging and test facilities, or “back-end” manufacturing, through a portfolio of standalone systems for macro-defect inspection, lithography, probe card test and analysis, and transparent and opaque thin film measurements. All of Rudolph’s systems feature sophisticated software and production-worthy automation. In addition, Rudolph’s advanced process control software portfolio includes powerful solutions for standalone tools, groups of tools, or factory-wide suites to enhance productivity and achieve significant cost savings. Rudolph’s systems are backed by worldwide customer service and applications support.

Rudolph common stock is listed on the NYSE under the ticker symbol “RTEC.”

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For more information about Rudolph, please visit Rudolph’s website at https://www.rudolphtech.com. The information contained on Rudolph’s website or accessible through it (other than the documents incorporated by reference herein) does not constitute a part of this joint proxy statement/prospectus or any other report or document on file with or furnished to the Securities and Exchange Commission. Additional information about Rudolph is included in the documents incorporated by reference into this joint proxy statement/prospectus. See the section entitled “Where You Can Find More Information” beginning on page 229 of this joint proxy statement/prospectus.

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THE NANOMETRICS SPECIAL MEETING

This joint proxy statement/prospectus is being mailed on or about September 12, 2019 to holders of record of Nanometrics common stock as of the close of business on September 3, 2019 and constitutes notice of the Nanometrics special meeting in conformity with the requirements of the DGCL and the bylaws of Nanometrics, which are referred to as the Nanometrics bylaws.

This joint proxy statement/prospectus is being provided to Nanometrics stockholders as part of a solicitation of proxies by the Nanometrics board of directors for use at the Nanometrics special meeting and at any adjournments or postponements of the Nanometrics special meeting. Nanometrics stockholders are encouraged to read the entire document carefully, including the annexes to and documents incorporated by reference into this document, for more detailed information regarding the merger agreement and the transactions contemplated by the merger agreement.

Date, Time and Place of the Nanometrics Special Meeting

The Nanometrics special meeting is scheduled to be held at 1550 Buckeye Drive, Milpitas, California 95035, on October 24, 2019, beginning at 9 a.m., Pacific Time, unless adjourned or postponed to a later date and/or time.

Matters to be Considered at the Nanometrics Special Meeting

The purposes of the Nanometrics special meeting are as follows, each as further described in this joint proxy statement/prospectus:

Recommendation of the Nanometrics Board of Directors

The Nanometrics board of directors unanimously recommends that Nanometrics stockholders vote:

After careful consideration, the Nanometrics board of directors unanimously (1) determined that the merger agreement and the transactions contemplated by the merger agreement, including but not limited to the merger, the share issuance and the adoption of the amended and restated certificate of incorporation on the terms set forth in the merger agreement are fair to, and in the best interests of, Nanometrics and the holders of shares of Nanometrics common stock; (2) approved and declared advisable the merger agreement and the transactions contemplated by the merger agreement, including the share issuance and the adoption of the amended and restated certificate of incorporation, on the terms and subject to the conditions set forth in the merger agreement; (3) directed that the share issuance and the amended and restated certificate of incorporation be submitted to the

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holders of shares of Nanometrics common stock for their adoption; and (4) resolved to recommend that the holders of shares of Nanometrics common stock approve the share issuance, and the adoption of the amended and restated certificate of incorporation.

See also the section entitled “The Merger—Recommendation of the Nanometrics Board of Directors; Nanometrics’ Reasons for the Merger” beginning on page 92 of this joint proxy statement/prospectus.

Record Date for the Nanometrics Special Meeting and Voting Rights

The record date to determine who is entitled to receive notice of and to vote at the Nanometrics special meeting is September 3, 2019. As of the close of business on the Nanometrics record date, there were 24,829,935 shares of Nanometrics common stock issued and outstanding, each entitled to vote at the Nanometrics special meeting. Each Nanometrics stockholder will have one vote for any matter properly brought before the Nanometrics special meeting for each share of Nanometrics common stock such holder held at the close of business on the Nanometrics record date. Only Nanometrics stockholders of record at the close of business on the Nanometrics record date are entitled to receive notice of and to vote at the Nanometrics special meeting.

Quorum; Abstentions and Broker Non-Votes

A quorum of stockholders is necessary to conduct the Nanometrics special meeting. The holders of a majority of the shares of Nanometrics common stock issued and outstanding and entitled to vote at the meeting must be represented at the Nanometrics special meeting in person or by proxy in order to constitute a quorum. Abstentions will be counted for purposes of determining whether a quorum exists. Shares held by a bank, broker or other nominee who holds shares in “steet name” for a beneficial owner of those shares who does not submit voting instructions for such shares will not count towards the presence of a quorum. If a quorum is not present, the Nanometrics special meeting will be adjourned until the holders of the number of shares of Nanometrics common stock required to constitute a quorum attend.

Under NYSE rules, banks, brokers or other nominees who hold shares in “street name” for a beneficial owner of those shares typically have the authority to vote in their discretion on “routine” proposals when they have not received instructions from beneficial owners. However, banks, brokers or other nominees are not allowed to exercise their voting discretion with respect to the approval of matters that NYSE determines to be “non-routine.” Generally, a broker non-vote occurs on an item when (a) a bank, broker or other nominee has discretionary authority to vote on one or more “routine” proposals to be voted on at a meeting of stockholders, but is not permitted to vote on other “non-routine” proposals without instructions from the beneficial owner of the shares and (b) the beneficial owner fails to provide the bank, broker or other nominee with such instructions. Under NYSE rules, “non-routine” matters include the Nanometrics share issuance proposal (Nanometrics Proposal #1), the Nanometrics charter proposal #1 (Nanometrics Proposal #2), the Nanometrics charter proposal #2 (Nanometrics Proposal #3) and the Nanometrics adjournment proposal (Nanometrics Proposal #4). Because none of the proposals to be voted on at the Nanometrics special meeting are routine matters for which brokers may have discretionary authority to vote, Nanometrics does not expect any broker non-votes at the Nanometrics special meeting. As a result, if you hold your shares of Nanometrics common stock in “street name,” your shares will not be represented and will not be voted on any matter or count towards a quorum unless you affirmatively instruct your bank, broker or other nominee how to vote your shares in one of the ways indicated by your bank, broker or other nominee. It is therefore critical that you cast your vote by instructing your bank, broker or other nominee on how to vote. The NYSE rules governing brokers’ discretionary authority will not permit brokers to exercise discretionary authority regarding any of the proposals to be voted on at the Nanometrics special meeting. These NYSE rules are applicable to the votes to be held at the Nanometrics special meeting even though the Nanometrics common stock is currently listed on Nasdaq.

If you submit a properly executed proxy card, even if you abstain from voting or vote against the adoption of the share issuance or the amended and restated certificate of incorporation, your shares of Nanometrics common

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stock will be counted for purposes of calculating whether a quorum is present at the Nanometrics special meeting. Executed but unvoted proxies will be voted in accordance with the recommendations of the Nanometrics board of directors. If additional votes must be solicited to adopt the share issuance and the amended and restated certificate of incorporation, it is expected that the meeting will be adjourned to solicit additional proxies.

As of the Nanometrics record date, Nanometrics directors and executive officers, and their affiliates, as a group, owned and were entitled to vote 1,315,006 shares of Nanometrics common stock, or approximately 5.30% of the total outstanding shares of Nanometrics common stock. Although none of them has entered into any agreement obligating them to do so, Nanometrics currently expects that all of its directors and executive officers will vote their shares “FOR” the Nanometrics share issuance proposal, “FOR” the Nanometrics charter proposal #1, “FOR” the Nanometrics charter proposal #2 and “FOR” the Nanometrics adjournment proposal. See also the section entitled “Interests of Nanometrics’ Directors and Executive Officers in the Merger” beginning on

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page 185 of this joint proxy statement/prospectus and the arrangements described in Part III of Nanometrics’ Annual Report on Form 10-K for the fiscal year ended on December 29, 2018, as well as the information specifically incorporated by reference in Part III of Nanometrics’ Annual Report on Form 10-K for the fiscal year ended on December 29, 2018, from Nanometrics’ Definitive Proxy Statement on Schedule 14A for Nanometrics’ annual meeting filed with the SEC on April 3, 2019, which information is incorporated into this joint proxy statement/prospectus by reference.

Methods of Voting

If you are a stockholder of record as of the record date for the Nanometrics special meeting, you may vote by proxy through the Internet, by telephone, or by mail, or by voting in person at the Nanometrics special meeting. For shares held through a bank, broker or other nominee in “street name” instead of as a registered holder, you may vote by submitting your voting instructions to your bank, broker or other nominee. In most instances, you will be able to do this over the Internet, by telephone or by mail as indicated below. Please refer to the information from your bank, broker or other nominee on how to submit voting instructions. If you do not provide voting instructions to your bank, broker or other nominee, your shares of Nanometrics common stock will not be voted on any proposal as your bank, broker or other nominee does not have discretionary authority to vote on any of the proposals to be voted on at the Nanometrics special meeting; see the section entitled “—Quorum; Abstentions and Broker Non-Votes” beginning on page 59 of this joint proxy statement/prospectus.

If you are a stockholder of record, proxies submitted over the Internet, by telephone or by mail as described above must be received by 11:59 p.m., Eastern Time, on October 23, 2019. To reduce administrative costs and help the environment by conserving natural resources, Nanometrics asks that you submit a proxy to vote through the Internet, which is available 24 hours a day.

Notwithstanding the above, if your shares are held in “street name” by a bank, broker or other nominee, you should follow the instructions you receive from your bank, broker or other nominee on how to vote your shares. Registered stockholders who attend the Nanometrics special meeting may vote their shares personally even if they previously have voted their shares.

If you deliver a proxy pursuant to this joint proxy statement/prospectus, but do not specify a choice with respect to any proposal set forth in this joint proxy statement/prospectus, your underlying shares of Nanometrics common stock will be voted on such uninstructed proposal in accordance with the recommendation of the

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Nanometrics board of directors. No matters other than the proposals listed above will be brought before the Nanometrics special meeting and Nanometrics bylaws provide that the only business that may be conducted at the Nanometrics special meeting are those proposals brought before the meeting pursuant to this joint proxy statement/prospectus.

Revocability of Proxies

Any stockholder giving a proxy has the right to revoke it before the proxy is voted at the Nanometrics special meeting by:

Execution or revocation of a proxy will not in any way affect the stockholder’s right to attend the special meeting and vote in person.

Written notices of revocation and other communications with respect to the revocation of proxies should be addressed to:

Nanometrics Incorporated

Attn: Corporate Secretary

1550 Buckeye Drive

Milpitas, CA 95035

If your shares are held in “street name” and you previously provided voting instructions to your broker, bank or other nominee, you should follow the instructions provided by your broker, bank or other nominee to revoke or change your voting instructions.

Proxy Solicitation Costs