Sinusoidal phase-modulating Fizeau interferometer using phase-conjugate wave

Interferometry 6 : techniques and analysis : Conference : Jul 1993, San Diego, CAWe propose a sinusoidal phase-modulating Fizeau interferometer using self-pumped conjugate wave for surface profile measurements. The interferometer is self-referencing and free from the effects of the axial movements of object surfaces. The characteristics of the interferometer are made clear through the surface measurement of a diamond-turned aluminum disk. For large-size objects, the size of the plate glass can be much smaller than that of the object. The small-size plate glass provides the accurate sinusoidal phase modulation easily. We also propose the method of absolute measurement to eliminate the undesirable phase distribution caused by aberration of the lenses. It is shown through the surface profile measurements of a mirror that the interferometer and the method of absolute measurement are useful for large- size objects