摘要 |
An improved system for testing a full reflectivity range of optical surfaces employs an improved Fizeau spherical or plano wavefront interferometer comprising a laser source (2) and an optical element (18) located in the wavefront (16) having a reference surface (20) everywhere normal to the wavefront (16) which has a partially reflective, partially absorbtive, and partially transmissive beamsplitting coating (19) applied to the plano or spherical reference surface (20) and having a transmittance such that there will be only two beam interference and the contrast of the two beam interference fringes between the reflected reference wavefront (25R) and the reflected test wavefront (25T) will be substantially equalized at the two extremes of the test surface (28) reflectivity.
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