Interferometer Test Reports.
We do not test with Interferometers ourselves as we do not believe they are as accurate as the Double Pass Null test that we do use. But below are some third party Interferometer test reports on Oldham Optical optics and mirrors that we have been given permission to show.
Note that an important criterion with Interferometer testing is Strehl:-
A mirror with a PV of a quarter of a wave (measured on the wavefront), is equal to a Strehl of 0.82, providing it has a smooth conic shape.
PV of a sixth wave mirror would be equal to Strehl of 0.9.
PV of a tenth wave mirror would be equal to a Strehl of 0.95, which in most cases is diffraction limited.
In some cases the reports show a central obstruction that is not explained by the interferometer test setup. The central obstruction has been deliberately placed to cover the central portion of the mirror.
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