Thursday, February 4, 2010

First fringes off M2!

We don't yet have all the hardware we need for the M2 test, but we can do a rough-&-ready trial run to check that it'll work as planned...


Here's the test frame carrying the interferometer, fold mirror & null lens.  A laser beam's sent out by the interferometer & bounced off the fold mirror that directs it through the plano-concave null lens, up to M2.  There the beam's reflected back through the system & returned to the interferometer where, if all goes well, fringes ought to be produced.


A flat paddle mirror on the back of M2 (the same one used to align M5 way back when, although now with a hole added to its centre) is used to get M2 squared up in tip & tilt & aligned in decentre with the optics onboard the test frame.


After making rough measurements of the axial spacings & adjusting the null lens & interferometer to get the despaces right - success!!  The first fringes from M2 :)  It's too soon to interpret the interferogram as nothing was aligned to anywhere near the proper tolerances - this was, afterall, just the "let's see if we can do this" week...


Great job guys!

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