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1000 ln/mm Holographic Diffraction Grating Sheet Results...

A project log for DAV5 V3.01 Raman Spectrometer

The only thing worth doing, is the thing worth doing right!

david-h-haffner-srDavid H Haffner Sr 01/25/2017 at 10:424 Comments

This is the temporary diffraction grating that I have set up as a replacement for the DVD piece. Even at 1000 ln/mm I really didn't think it would work but I was wrong, it works beautifully! So...next month I will have my second mirror (concave focusing mirror) and my 1800 ln/mm Holographic diffraction grating for the Czerny-Turner configuration.

No more DVD piece...it's time has expired...

Discussions

David H Haffner Sr wrote 01/28/2017 at 09:14 point

Yes...yes and yes Thomas! I exhausted all possibilities with the DVD grating and there are just too many imperfections and no blaze angle. The Holographic grating provides the perfect incident blaze angle of 39 degrees and at 1800 ln/mm, it is perfect also for Raman spectroscopy.

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Thomas wrote 01/28/2017 at 06:26 point

A regular pattern with a spacing close to lambda of visible light is a thing of beauty!

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David H Haffner Sr wrote 01/28/2017 at 07:28 point

Hey Thomas, yes it is! I didn't think this type of grating would work but I needed to try it out before getting the 1800 ln/mm grating from Thorlabs next month :)

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Thomas wrote 01/28/2017 at 07:45 point

This is about harmonics, isn't it? The question is whether the distance of different bands of diffraction merge or not. The grating with its 1µm spacing is at 1λ for near IR, 2λ of green light, and 3λ for near UV. I guess that whether it's usable or not depends on angle, optical transmission (filtering) and spectral sensitivity of the CCD.

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