Re: ATM Laser Artifical Star

[Hugues_Laroche@ses-astra.com]

>> Since some of us-- even large organizations like NASA and Perkin-Elmer--
>> are not affluent enough to have a 150 foot optical testing tunnel, you
may
>> now better understand why the null test was invented and appreciate its
>> contribution to our art!
>>
>> . . . Richard
>
>I believe the original posting was about using a laser and a lens. With
the lens you can convert the >spherical wavefront exiting from the laser
into a parallel one, thus imitating an artificial star at >infinity. There
would be no need for a 150 foot tunnel, somewhere in the order of the FL
would suffice.
>
>Did i miss something?
>
> ... Arjan te Marvelde

True, but stricly speaking you need a lens of high quality and of
the same size as or larger than the mirror to be tested...
BTW, I wonder how they tested optics like those of the Kecks
or the VLT... Must be monstruous!

Hugues





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