Zygo have been good at providing interferometers for measuring 4" and 6" diameter parts and up to 32" (for flats) with their current systems. To measure small optics/parts involved using a 4" aperture system and the 6x zoom facility. Further reduction could be made using a 4" to 1" aperture converter. This all works quite nicely but it does work out to be expensive to measure small optics.

The best solution would be to have a small Zygo to measure small optics. Zygo have now introduced such a system called the PTI 250. It is a 25 mm aperture Fizeau interferometer available as a visual only, phase and/or FlashPhase based system. It can be configured for vertical and horizontal use. As the PTI 250 is a Fizeau interferometer it directly correlates with the older, larger aperture systems.

The PTI 250 has a full range of accessories for measuring small optics and precision parts. The PTI 250 optical accessories are designed for high performance at economical prices. A 25 mm transmission flat, 25 mm to 6 mm aperture converter with integrated transmission flat are used for transmitted wavefront applications. Seven transmission spheres cover a wide range of surface diameters and radii. Also available is a radius measurement kit with 30 mm of travel and 2 micron resolution. All accessories mount with a simple positive-lock bayonet.

The ZYGO PTI 250 mounting accessories provide an excellent foundation for your test setups. Tip/tilt stages, XY translation stages, a self-centering element holder, and a lens nest kit provide all the functions to get you started. Custom fixturing for unique test setups can be mounted to access points in the PTI 250 base.