Photon Control Inc. — M&A Activity 2021

Jun 1, 2021

IMPORTANT NOTICE TO SHAREHOLDERS

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Dear Shareholder

We are writing to you today to thank you for your support over the last 20 years. As you are aware, the Photon Control Board of Directors has unanimously recommended that securityholders vote in favor of the arrangement with MKS Instruments Inc.

Your Board of Directors regularly evaluates business and strategic opportunities with the objective of maximizing shareholder value, including assessing potential risks and benefits of a variety of possible alternatives. The Board considers strategic alternatives available to Photon Control considering our size, growth opportunities, our employees and key supplier and customer relationships.

The following includes key reasons why the Board has recommended the transaction:

Certainty of Value and Immediate Liquidity: Photon Control shareholders to receive $3.60 per share in cash, representing an aggregate transaction value of approximately $387 million.

Strong Premium: The purchase price represents a premium of 26% to the 30-day volume weighted price of $2.87 per Photon Control common share (as at the trading day before announcement).

Fairness Opinion: The Board of Directors received an opinion from Echelon Wealth Partners Inc.to the effect that, subject to certain assumptions, limitations, and qualifications, the consideration to be received by Photon Control’s shareholders is fair, from a financial point of view to such shareholders.

Attractive Valuation in an Increasingly Competitive Market: The competitive landscape and market volatility creates uncertainty as to what growth may be achieved by Photon Control in the future. Photon Control operates in an intensely competitive market. Photon Control’s competitors are increasingly larger and better capitalized with broad product portfolios, while Photon Control’s business is focused on developing and manufacturing a single category of product, optical sensors, for sale to its three largest customers. The Board of Directors and management view the competitive landscape and market volatility as significant challenges to growth, while the proposed Arrangement with MKS delivers certainty and immediate cash consideration to shareholders at a valuation which may not be achievable by Photon Control on a stand-alone basis in the future, or at all.

Yours faithfully,

D. Neil McDonnell (Chair) and Nigel Hunton (CEO)

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BOARD RECOMMENDATION

The Board unanimously recommends that the Photon Control Securityholders vote IN FAVOUR OF the Arrangement Resolution.

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THE MEETING

You are cordially invited to participate in the annual general and special meeting of the Securityholders of Photon Control Inc. which will be held in a virtual-only format on June 29, 2021 at 9:00 a.m. (Pacific Time).

Join the Photon Control meeting on June 29, 2021, via live audio webcast by going to https://web.lumiagm.com/264239665

password: “photon2021”

ARRANGEMENT RESOLUTION

Your VOTE is Important

Whether or not you expect to participate in the Meeting virtually, please submit your vote as soon as possible. Please take the time to vote today by using the proxy or voting instruction form provided to you with these materials.

Regardless of how many shares you own, your vote is important.

Voting Instructions and Questions on Voting

For voting instructions, please refer to your proxy or voting instruction form.

If you have any questions or require assistance with voting, please contact our proxy solicitation agent:

Laurel Hill Advisory Group

North America Toll-Free: +1.877.452.7184 Outside North America: +1.416.304.0211 Email: assistance@laurelhill.com