From RBOSE
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Light spectrum intensity analyser
Purpose
The purpose of this project is to make a device that can detect which wavelenght that a light source emmits and the intensity. This will be widely used for the OSF project where then members can be able to measure the exact intensity and wavelenght that their device emmits and therefore be able to get better feedback on the equipment needed for optimal results.
A spreadsheet testing the concept of using an array of photodiodes to detect amplitudes of different wavelenghts [1]
Existing devices
HOWTO
- Use a prism to seperate light into different wavelengths.
- Then use several (or one movable) photoresistor, phototransistor or solar cell to detect the intensity of the light. Please note that these elements will not respond the same way to every light color, so find one that responds to all visible colors at least. The difference in sensitivity will affect the resolution of the device, but will be corrected for during calibration.
- This sensor will have to be in complete darkness, other than the light from the prism, therefore design and build a suitable casing.
- After the device has been assembled, you will have to calibrate the detector against a known light frequency/intensity source. This means you have to take the intensity measurement at every wavelength and record the multiplication factor required for the device output to match the levels that you should be getting. The resulting document is called a calibration table.
- Whenever taking a measurement, for each wavelength, apply the factor from the calibration table.