Lateral shear interferometer for infrared and visible light.

An infrared wavefront is recorded holographically on a dynamic recording medium consisting of a thin oil film on a glass substrate. The phase hologram obtained may restore the information of the infrared wavefront or alternatively play the role of a diffraction grating for a visible reconstruction beam. On this basis, the principle of a lateral shear interferometer for the simultaneous testing of infrared or visible optical components is described and physically implemented. A theoretical discussion explains the operation of the interferometer and points out experimental restrictions due to recording medium nonuniformities, holographic aberrations, and the curvature of the reconstructed wavefronts. The interferometer is easy to set up and confirms its usefulness with experimental results that include collimation tests for both visible and infrared afocal assembly, as well as quality tests for visible components.