I have seen several videos on the Bath interferometer and not one has defined which beam is the reference beam and which is the test beam. After watching this video MANY times, it looks like the reference beam is coming through the beam splitter and the test beam is coming off the side mirror. Also, I am assuming the lens is used to compensate for the parabolic curve of the mirror. If so, there is no mention of the diameter or focal length of the lens.
When testing at the radius of curvature it is limited not by size but by how many fringes of asphericity the mirror has and the resolution of the camera used. There was a thread on Cloudy Nights where this is discussed.
I have seen several videos on the Bath interferometer and not one has defined which beam is the reference beam and which is the test beam. After watching this video MANY times, it looks like the reference beam is coming through the beam splitter and the test beam is coming off the side mirror.
Also, I am assuming the lens is used to compensate for the parabolic curve of the mirror. If so, there is no mention of the diameter or focal length of the lens.
Who plays the Banjo?
Ed how large of a mirror can this equipment test?
doc
When testing at the radius of curvature it is limited not by size but by how many fringes of asphericity the mirror has and the resolution of the camera used. There was a thread on Cloudy Nights where this is discussed.