Configurable spectrometer

For a long time I wondered whether it was possible to have a system that would allow to acquire spectral information only at some wavelengths.

Something like this can be achieved with a filter wheel and several band-pass filters (this is the NanoQNT approach). An AOTF could improve speed (and elegance) but it comes at implementation costs, since it would require some galvos to be added to the system.

Another approach is what appeared on [[@gentner2023Compressive Raman microspectroscopy parallelized by single-photon avalanche diode arrays]], where a DMD is pre-programmed to direct specific wavelengths into a point (or a series of) detector. Switching ON/OFF spectral bands becomes only a matter of selecting which pixels of the DMD are "ON" or "OFF".

I think this approach is very elegant, since it removes the requirement of "panel design" common to flow cytometer. In essence, a tunable spectrometer can have "infinite resolution", in the sense that is only optically limited and not filter-limited. Moreover, the arrangement of mirrors can be tuned based no optimal selection for discrimination without additional costs.

At hundreds of pixels in SPAD-Arrays, they would be a massive improvement on current channel-limited, camera-based, multi-spectral flow cytometers.