https://web.archive.org/web/20230914035459/https://caoyuan.s...
A $500 DIY near-IR spectrometer that would sell for $10,000, Yuan Cao
>The placement of the cylindrical lens (position & angle) affects the focal point for different wavelength. I did not do a rigorous calculation here —— I simply resorted to a trial-and-error method to figure out the optimal placement.
elikoga•8h ago
https://victorpoughon.github.io/torchlensmaker/