You can get a 1nm resolution "science grade" spectrometer for under £1k - I used to design them [1]. You can also buy used ocean optics kit for very reasonable

You can get a 1nm resolution "science grade" spectrometer for under £1k - I used to design them [1]. You can also buy used ocean optics kit for very reasonable prices on eBay (a few hundred for a USB2000 if you wait). Or make your own? It'll probably be good enough https://publiclab.org/w/spectrometry https://publiclab.org/w/spectrometry ThorLabs also sell cheaper spectrometers by the way. You don't need a spectrum analyser with seven significant figures! https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=3482 https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=34... You can also get light testing devices used for film/industrial illumination https://www.sekonic.com/color-meter/c700 https://www.sekonic.com/color-meter/c700 (about 1.5-2k) Or even single chip spectrometers with broad 20nm resolution from Hamamatsu (about £400 on group gets). https://groupgets.com/manufacturers/hamamatsu-photonics/products/c12880ma-micro-spectrometer https://groupgets.com/manufacturers/hamamatsu-photonics/prod... [1] https://is-instruments.com/products/miniature-spectrometer/ https://is-instruments.com/products/miniature-spectrometer/