Surface Inspection

Extensive use of interferometry is used to measure Laser Optics components and
assemblies. We use Zygo phase measuring interferometers (GPI-XP/D with 18" aperture, Mark-II with 12" aperture, and Mark IV-XP with 6" aperture) to characterize transmitted and reflected wavefront distortion and surface flatness. Changes to wavefront and surfaces are monitored throughout the manufacturing cycle at critical processing steps.

In addition to spherical shapes, we are experienced in using interferometry to measure the surface figure of ellipsoidal, toroidal, and aspheric surfaces.

Scratch-Dig visual comparators are used in accordance with MIL-PRF-13830 to measure the surface quality of optics. In some cases, the same standard is used to quantify optical scatter in bulk material. Lighting and magnification conditions used during inspection can be adjusted per customer requirements. When examining optics to be used under high laser power conditions, we use a high intensity quartz-halogen source.
 

Interferometric Quality Optics Measured reflected wavefront error @ 633 nm for a Laser Optics toroidal X-RAY mirror -- 10 mm x 36 mm. Profile at left represents the surface of the backing support. Profile in the center represents the same region of the support after a thin, semiconductor x-ray Bragg reflector was affixed to the backing. One can see that the semiconductor mirror primarily takes on the surface profile of the backing support. Scale at  the right shows deviation from a perfect surface, measured in wavelengths of light at 633 nm, is less than λ/10. Measured radii for the toroid are 496.63 mm and 441.75 mm +/- 0.05 mm.