Bath Interferometer for testing telescope mirrors - Assembled

Description

This specific bath interferometer has been shown to be as accurate as a ,000 PSI Zygo for testing telescope mirrors.  I can provide more info.  Measurements were made of a reference mirror which has calibration traceability to a reference which was calibrated by many experts.  In other words each Interferometer is tested thoroughly.  All measurements were within 1/30th wave agreement with reference.
Your parabolic mirror must be above the red line in the graph (see images).  Additionally this bath only covers mirrors to about F/3.7 (e.g. not F/2.5 - contact me for alternate diverging lenses if you need to test faster than F/3.7 or slower than F/7).
Includes laser with fat 2.6mm wide beam (calibrated wavelength is supplied), XYZ stage with standard tripod mount, optical parts, hex driver.  Includes 13mm focal length diverging lens for mirrors as fast as F/3.7.
You will need:
standard USB 5V power source (e.g. an old iphone charger or a laptop)
A 4 megapixel (or higher) DSLR camera with live view and a lens of fixed focal length (between 50mm and 100mm works great) (zoom lenses won't work)
2 tripods (one for bath, one for camera)
A mirror holder to hold your mirror on edge with proper support (either sling support or 2 90 degree center of mass supports)
A windows PC computer to run the free software DFTFringe
Plastic parts are 3d printed. Colors may differ from photo. Parts may not be as beautiful as expected but it will function perfectly.
Instructional videos - consider to maybe watch before buying:
On youtube search "dftfringe quickstart version 2"
and in that same channel watch "setting up and using a bath interferometer"