DIY Spectroscope with USB Webcam and Grating

Update Feb06 2020
I uploaded a shorter version as requested in the comments.
If someone tests this shorter design, please let me know, if it works as expected.

This is an optical spectroscope for near-UV to near-IR spectroscopy based on a CMOS webcam in conjunction with an optical grating (i.e. 1000 lines grating).
It works with free software (for non-commercial use), like the very sophisticated SpectraGryph and the less complex Theremino Spectrometer v2.7 or with Public Lab online via spectralworkbench.org.

https://www.effemm2.de/spectragryph/
http://www.theremino.com/en/downloads/automation#spectrometer

I added two reference measurement figures of my setup with a 1000 lines/mm grating.
First figure shows the calibration based on an energy saving lamp and its Hg-lines (436nm, 546nm calibration lines) and the other figure is a proof measurement of a green laser (532nm). Accuracy is quite good and completely sufficient for my needs.

A fitting webcam for this purpose is the AUSDOM 1080p Full HD PRo Webcam. It is easy to disassemble (only 4 screws) and the IR filter in the objective can be removed (tip: attach a strip of Tesa on the filter first in case it cracks). Of course, any LED of the webcam has to be cut off as well.

The whole assembly consists of 5 parts:
- case base for mounting and adjusting everything
- camera fixture (for AUSDOM 1080p PCB here)
- Grating frame holder
- Slit holder
- case top lid

For the assembly you will also need
- one bare webcam (without housing) like an AUSDOM 1080p Pro
- graiting foil (1000 or 500 lines)
- 2 blades or similar for the slit
- 2x M3 20mm screw + nuts + washers

I attached the camera pcb and the grating foil with superglue to the respective holders.
2x M3 20mm with nuts and washers fix the camera and the grating holder to the base.
The grating holder should be adjusted to the 140° marking and the camera to the 150° marking. Other ratios are possible for increased resolution but might be harder to adjust to.

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