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My monochromator

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Apr 26, 2010
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So it's been requested that I make a thread about this, so here I go!

Mechanically, it includes an entrance slit, that slit went to a bounce mirror, then to a grating. This grating splits the incoming light, and forwards it to it's place in the spectrum. So now after that grating, two more bounce mirrors, and then the exit slit.

After that slit comes it's only electrical component, the PMT. For the purpose of explanation, this is a glorified photodiode. When the grating is tuned via a micrometer on the side, to the right wavelength going in, the light will hit the PMT, and this will send a signal to an outside voltmeter.

This voltmeter is wired to a 6 terminal switch. The switch includes power to the meter, or the PMT, pending switch position.

A potentiometer is turned that applies more or less power to the PMT, I can just this to change the sensitivity.

In the second switch position, the power is going directly to the meter, and I can use this to monitor the power that I am applying to the PMT, pending position of the potentiometer.

Feeling pretty lazy, so it may be a bit before I get images up. Also going to do an instructional video on external cavities sometime this weekend. So get ready to learn!
 



Blord

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Thank you for the explanation. I am anxious waiting for the pictures. I am always curious about the working of the machine.
 

SKeeZ

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Thanks bloom. I'm subbed so ill see it. and i think its a great setup with the PMT, so you know where it peaks.
 
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Before I go do some sparing, I figured I would get some pics up of my wonderful tool :)

Keep in mind, the PSU is totally external, and was not meant for the Verity. It simply provides all of the requirements, so it is perfect.

I am looking for someone with custom enclosure building abilities to make a custom plastic home for this. It will need 4 openings for the pot, switch, voltmeter, and power to the Verity itself. I would like to have this be a modular unit, similar to an argon where the PSU and Head are separate, and the umbilical cord connects the two.

If anyone has experience with this, PM your quote! I am really looking to get this done!!

Pics!

Here is the overview of both meter, and PSU. Ignore the shotty wiring job.. It looks awful.



Verity open and to the world. The razor blade was there to limit the slit width. Wasn't until the next test that I realized it had settled into position blocking the light fully. It was removed :p



All the doodads that do all the work :p



Test with a 532nm laser, and a white card blocking the PMT. Micrometer tuned to about 630nm.



Test with micrometer tuned to 530nm (it runs 1.5-2nm low). Again, white card to block the light.



In these pictures you can only really see the first bounce mirror, grating, and then second bounce mirror. Right outside of the exit slit, is the third bounce mirror. It sends the light from the previous mirror, directly into the exit slit and PMT element (pending tuning of micrometer of course).

Hope that cleared up a few things :)
 




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