Ultra-Precision Grinding of Grazing Incidence X-Ray Mirrors by On-Machine Measurement

This paper deals with a machining method for making a large non-axisymmetric aspheric surface with a high accuracy. An electric micrometer has been set near a grinding head on 5-axis control ultra-precision grinding machine for measuring the shape error of ground surface in conformity with the machine movement due to the cutter location data. A series of the measured shape errors corrects the former cutter location data automatically and the next grinding operation will be performed by the new cutter location data. A large CVD-SiC sample 110 by 510 mm has been ground into a toroidal surface of 0.75 μm in shape accuracy by the fifth grinding operation with the fourth correction of cutter location data. The machine has been also installed in a constant temperature room of ±0.5K in variation.