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by PragmaticPulp
1500 days ago
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> Anyone know of active DIY higher-er resolution spectrometer projects using image sensors? Is it possible to create a sharp image of 940-1240nm 3000 pixels across with less then $3000 in parts? I want to learn how to make a broader(uv to ir) but crappy-er version of this: https://solarsystem.nasa.gov/resources/390/the-solar-spectru... The linked project uses a 4000px wide image sensor and the second example in the article is a solar spectrum like what you want. It's not as sharp, but it's remarkably good given that the diffraction grating was a fragment of a DVD and the opening was a 3D printed slit. 940-1240nm isn't "uv to ir" like you described, though. That's just pure deep infrared. You'd have to test to see if the camera's image sensor was sensitive in those regions with any filters removed, but I doubt you'd get much signal in the deep IR region. Good sensitivity that far outside of the visible range requires a specialized sensor. Some security cameras designed for "invisible IR" will have such a sensor inside, so you could start by looking there. |
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Photons of different wavelength are absorbed and converted at different depth in silicon sensors. Blue photons mostly convert at the surface, while red go much deeper into the sensor. The pixel electronics of a regular cmos image sensor however will only collect the resulting electrons in a certain region at the surface. If an electron is generated somewhere else, it will recombine and be 'lost', not contributing to the signal.
Depending on the sensor, at 1000nm only <10% of the photons will result in electrons that are captured by the pixel electronics. The sensor does not give you any signal any more.
Why? Silicon has a band gap of 1.12eV - photons with lower energy will not interact. This corresponds to ~1100nm - you will need sensors with different materials