for testing focal optical systems such as large concave telescope mirrors and lens systems, and for multi-segment mirror alignment. It can also be adapted for testing small aperture afocal components such as flat mirrors and collimators. A stabilized HeNe laser (632.8 nm) provides excellent stability, while the high speed, 1K x 1K phase sensor makes it is easy to measure moving or complex components, even in challenging environments. Numerous accessories and options are available including different operating wavelengths and a 4 mega-pixel phase sensor.