Opple Light Master 4 discussion thread (new 2023 model)

[ebastler (Moritz)]

My last comment in here regarding this - I created a new thread for the Little Garden:

Little Garden spectrometer - Impressions, opinions, discussion

Introducction As you all know, professional spectrometers with high resolution are really, really expensive. There has been a rather active scene of people building DIY spectrometers for cheap, but they all suffer from the same issues: good quality diffraction gratings are expensive, monochrome CMOS/CCD sensors are unaffordable, and RGB CMOS sensors have bad spectral response as the pixels are limited to R, G and B. Recently a Chinese hobbyist going by the name Lao Kang introduced his “Little…

@stevechang

why can’t the seller do calibration, why let the users do the calibration?

I think mainly price. These are made and sold by a single hobbyist who probably does not have the resources to calibrate all. The fluorescent lamp is used to calibrate the wavelength, that is fast and easy. The hard part is calibrating the spectral response curve of the CMOS sensor. This where I am struggling right now.

Basically the opposite issue of LM4. I got a spectrum with ~0.6nm resolution (digitally, not quite as high optically), but the intensities of all bands relative to one another are all weird and uncalibrated since CMOS have very different sensitivities for different wavelengths. Opple has few wide bands, so it is difficult to reconstruct a spectrum, but at least every single band is calibrated in its intensity.