DOUBLE-ENDED FIZEAU INTERFEROMETERS WITH PHASE-STEPPING EVALUATION FOR DIMENSIONAL MEASUREMENTS

Material standards of volume or length can be measured with highest ac curacy, when double-ended Fizeau interferometers with phase stepping e valuation are used. The technique is suitable for regular bodies with reflecting flat or spherical surfaces. For the measurements, the bodie s are included in the interferometer system, so that light waves of ap propriated wavefronts and known wavelengths can directly be used for p robing their surfaces. Interferometers for measurement of spheres and cubes including the necessary servo control units and data evaluation systems are described. Experimental material is presented to demontrat e the properties of a special Fizeau algorithm and the features of a p articular interferometer.