High-precision imaging interferometer for short gauge blocks

Interferometric image-analyzing comparator for short gauge blocks is reported. Sophisticated image acquisition and processing software that supports 0.1 nm (/spl lambda//6000) resolution in central length and 1 nm in 3D measurements is developed. Best stability achieved is about 10/sup -9/. Inclination error is minimized and can be measured at 8/spl times/10/sup -9/ uncertainty or better.