I intend to inspect hand soldered PCBs with fine very pitch SMD components to check for dry joints and any other possible defects.
I will use a stereo microscope with total magnifications from 5x to 80x. Fluorescent/LED ring lights and halogen/LED spot lights are available for it. RGB car headlight LED rings could also be easily adapted. Oddly, none have filters available. I would have thought different wavelengths of illumination would be particularly valuable? Perhaps also polarising filters?
Goals would be to, for example: exaggerate differences between: flux, solder, solder mask, PCB tracks, device leads (and more?). To see through flux reflections to what lies underneath. To differentiate solder states. Spot gaps (perhaps with shadows), weakened pins, lifted pads or broken tracks.
Are such techniques used? If so, what specific spectra or other filters etc are useful? Might variable RGB LED lights be helpful, or counterproductive? Do any other non-destructive techniques besides electrical continuity checking help achieve these goals?