Interferometer First light - WooHoo!

Cheers Phil, thanks for the tips and link.

Thats some going there Phil,
Could I put my scope mirror in there and see how it fairs??

Ok, here are a couple of pics of the Bath Interferometer as promised...

Plan view of Bath Interferometer:


Side view, showing three-axis (X,Y,Z) stage for aligning the beams and wavefronts:


Close inspection of the second pic reveals some of the hi-tech solutions I employed to hold the optics in place... i.e. Blue-Tac! Hay, it works. I had to grind down the edge of the beam expanding lens to allow the return beam to re-enter the beamsplitter without being vignetted. The two beams have to be made parallel and are only 5mm apart. The lens is 12mm in diameter - so it had to go on an enforced diet!

Phil.

Thats some going there Phil,
Could I put my scope mirror in there and see how it fairs??

Certainly can... but you'll have to wait until I get home before I can analyse the I-grams... assuming I can get usable images in Galway

Phil.

Sorry to harp in on something i completely am oblivious to but i'm a curious kinda person. Does this contraption measure/analyze the purity/size/curve of mirrors?

Sorry to harp in on something i completely am oblivious to but i'm a curious kinda person. Does this contraption measure/analyze the purity/size/curve of mirrors?

An interferometer is a tool for measuring the surface errors on precision optics (telescope mirrors and lenses) to a very high degree. It is capable of measuring the lumps and bumps on the surface of the optic smaller than 1/20th of a wavelength of light. In this case I am using a laser with a wavelength of 532nm, so it can measure surface deviations as small as 25nm or smaller. That's pretty hot snot!! Where the interferometer wins out over other methods like the Foucault knife-edge test is that it is entirely objective and not prone to the very subjective interpretation by the operator of vague shadows created in the Foucault test. Bottom line: with the Foucault test you can unconciously fudge the readings. An interferogram doesn't pull any punches - it tells you exactly how crap your mirror is... and doesn't even say sorry!

Phil.