Fabre Parot Etalon

[Binky Todd]

Hello, Does anyone know if a Spectra Physics FP etalon would determine
if a ruby laser with 20ns pulse was operating in single mode.
the driver is model 474 scanning interferometer driver
The heads are Model 421 for 630 nm and model 450 for blue and green
Freq.we would use it in combination with a storage scope.
Thanks in advance. Michael Page

[Samuel M. Goldwasser]

450 is useless due to the mirrors not have enough bandwidth. The 421 (never
heard of that but assume similar to others) might work at 694 nm though
the finesse would be lower, especially if it is spec'd with laser line
rather than broadband mirrors. Check the mirrors on a monochromator
or spectrometer.

But one problem is that the laser is pulsed. And 20 ns is short enough
that the pulse duration is short enough that there will be a limited
number of round trips in a confocal cavity. It sounds like the laser
is Q-switched so you may have to cut the power way down to avoid damage.
But then, you could repetitively pulse the laser while slowly ramping the FP.

Might be doable.

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