Ametek, an American manufacturer of electronic instruments and electromechanic devises with annual sales of $3 billion, has paid $150 million to acquire Reichert Technologies, the maker of ophthalmic instruments. Reichert was previously owned by Beecken Petty O'Keefe & Company, a private equity firm. The U.S. company, which has a European service center in Germany, makes analytical instruments and diagnostic devices for the eye care market, bringing in about $55 million a year in revenues. Ametek said the purchase would help it get a foothold in the ophthalmic equipment market, and that it planned to keep the Reichert name, co-branded with its own. Reichert invented the industry-standard phoroptor.