Doug Ferrell's interferogram

Mark Suchting (masuch@dap.CSIRO.AU)
Wed, 29 Mar 1995 11:04:41 +1200 (EST)

On Tue, 28 Mar 1995, Doug Ferrell wrote:

> > Was this mirror test data indicating P-V on the surface or on the
>wavefront?
> >
> I'm not sure. I got the mirror from Crazy Ed Optical (local guy) who
> buys them from PAP (see ad in latest S&T). They come with a a copy of
> the laser interferogram, number of sample points, P-V error, and RMS
> error. I would assume wavefront, but I'm far from an expert on this
> subject. The interferogram looked quite good (not as nice as some of
> the 2.14" secondaries, though).
>
> > How do they say it was tested?
> >
> You could call PAP and ask--now I'm curious too!
>
> Doug

I love to, but it may be a bit expensive from Australia :-)

As far as I can work out, if the interferogram was taken using a null lens, the interferogram will indicate surface shape ( 0.5 waves per fringe) and if by autocollimation against a flat it will be wavefront ( 0.25 waves per fringe ). It's certainly great to see companies supplying interferograms with their optics.

Mark