Veeco Instruments Inc. of Plainview, N.Y., has signed a letter of intent to purchase Tucson, Ariz.-based WYKO Corp., currently a privately owned company, for 3 million shares of stock. Veeco officials say their hard drive and semiconductor customers would benefit from the acquisition of WYKO's noncontact, optical measurement and surface metrology products. A spokesperson said that Veeco would make decisions on name, site and personnel changes pending closure of the deal. The agreement is subject to approvals by the board of directors, shareholders and the government.