For spherical lenses, 3D in-process metrology is rather simple. Surface form may be tested in reflection using a test plate or a tower
interferometer, and the polisher can rapidly assess the progress of the polishing process. For aspheric lenses 3D surface metrology is
not easy. It often requires expensive, long lead time holograms or diffractive optical elements, a powerful interferometer and labor
intensive setup by a skilled test technician. All of these factors combine into repeatability errors and suspect results. Looking deeper,
there are specific geometries where it may be advantageous to look THROUGH the lens rather than AT the lens. Testing and correcting
the aspheric lens as it is used, in transmission, addresses some of the shortcomings of traditional 3D surface metrology.
This presentation will compare and contrast transmission testing versus surface testing for aspheric lenses. It will list specific cases where Optimax Systems chose transmission testing over surface metrology and the reasons for the choice. Additionally it will touch on the techniques and results of this transmission testing.