Optical applications are broad and varied. Testing at design wavelength is critical for final alignment and system qualification. Lithographic, DVD, and Infrared imaging lenses all require testing at design wavelength and represent broadly-varying wavelength requirements. ZYGO, long recognized as the world leader in interferometric testing, has designed and built many specially-equipped interferometer systems, including those meeting the most demanding requirements, from the deep ultraviolet to the far infrared. ZYGO offers complete solutions including interferometer mainframes, transmission flats and spheres, mounts and accessories to support numerous wavelengths and testing applications.