Crude Raman Spectrometer

Also see a further refinement.

It works only well enough to demonstrate the principle for a strong Raman emitter like polystyrene. I will have to fiddle with it to improve the sensitivity.
Be careful assembling the parts with glass components - overtightening will break the glass.
* The spectrometer is from [GroupGets](https://store.groupgets.com/collections/hamamatsu-sensors-accessories/products/hamamatsu-c12880ma-mems-u-spectrometer-and-breakout-board)
* Laser is from [ThorLabs](https://www.thorlabs.com/thorproduct.cfm?partnumber=CPS532). Important to get one that has a narrow range of wavelength.
* The filter is from Omega Filters. Just use an optical notch filter (or a longpass filter) to match the laser wave length. And adjust that mount to hold it. You can get a smaller filter - that was what was available on eBats at the time.
* 5x infinity microscope objective
* The square mirror was a half silvered mirror, Not critical.
* i didn't really need the fan.