This person making and selling this stuff is a member of an interferometry group that I subscribe to (interferometry@groups.io)
You can build an entire bath interferometer for about $150, a good deal I think. My opinion is a great way to analyze smoothness and figure of your mirror if you are into
Dale Eason has written some good software to analyze the igram data that this set up will generate. Its freeware too... DFTFringe version 4.0 .. I have used it, its very good.
Here is a list of tips and tricks, and best practices for bath interferometry.
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Dale Eason’s DFTFringe software for the Bath interferometer, developed with input from several technical contributors, has given ATMs a very powerful tool for testing mirrors. Dale has published a number of videos on use of DFTFringe and general setup and use of the Bath, including:
Setting up a Bath Interferometer to measure a telescope mirror:
Bath Interferometer optics alignment:
DFTFringe Quickstart Guide:
DFTFringe displays:
DFTFringe igram outlining helper:
DFTFringe 3D surface display:
DFTFringe color maps:
DFTFringe Interferogram Intensity Analysis Tools:
Tilt and defocus in DFTFringe simulated interferograms:
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which is located here:
https://groups.io/g/Interferometry/wiki ... -Practices
Best,
Ian