!%Zygo Corp.%! of Middlefield, Conn., has received orders for metrology systems valued at more than $6 million from two Chinese optical research and manufacturing organizations. The orders were for large-aperture interferometers and associated reference optics that enable precise measurement of spherical optics greater than 12 in. in diameter. Zygo supplies optical metrology instruments, precision optics and electro-optical design and manufacturing services to biomedical, scientific and industrial markets.