Instantaneous phase-shift Fizeau interferometer utilizing asynchronous frequency shift mechanism

摘要

An on-axis, vibration insensitive, polarization Fizeau interferometer is realized through the use of apixelated polarization mask spatial carrier phase shifting technique in conjunction with a highcoherence source and a polarization frequency shift device. In this arrangement, differential motionbetween the test and reference surfaces, in conjunction with the polarization frequency shift device, isused to effectively separate the orthogonally polarized test and reference beam components forinterference. With both the test and the reference beams on-axis, the common path cancellationadvantages of the Fizeau interferometer are maintained. Additionally, the use of a high coherencesource eliminates the need to path match the test and reference arms of the interferometer. Using a 1mW HeNe source, the optimum camera shutter speed, used when measuring a 4% reflector, was 250usec, resulting in significantly reduced vibration sensitivity. Experimental results show theperformance of this new interferometer to be within the specifications of commercial phase shiftinginterferometers.