DIY Spectroscope with USB Webcam and Grating

thingiverse

I uploaded a revised version as requested in the comments on Feb06 2020. 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 used with an optical grating (i.e. 1000 lines grating). It works with free software like the 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. The first figure shows the calibration based on an energy-saving lamp and its Hg-lines (436nm, 546nm calibration lines), while 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's easy to disassemble (only four 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 five 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 - Grating foil (1000 or 500 lines) - Two blades or similar for the slit - Two M3 20mm screws with nuts and washers I attached the camera PCB and the grating foil to their respective holders using superglue. The two M3 20mm screws with nuts and washers fix the camera and the grating holder to the base. The grating holder should be adjusted to the 140° marking, while the camera is set to the 150° marking. Other ratios are possible for increased resolution but might be harder to adjust to.