A friend gave my a spectrometer kit (of unknown origin) and I'm trying to get it to work. I use DVD-RW grating at 65° (lines horizontally), camera at 45° and a distance to the slit of 200mm. I adjusted the distance camera <--> grating, so that the spectrum is in the middle of the captured image.
I'm getting a very narrow image as you can see below. I can get it even more narrow when I adjust the focus really carefully and adapt the exposure. This makes it hard to choose a good cross section. Light source here is a phone LED.
Things I noticed:
- When I adjust the focus, s.t. the image appears sharp, the focus is not around 200mm as suggested, but far beyond (more than infinity). When I adjust to 200mm, the image is blurry (e.g. the LED typical gap between blue and green gets blurred).
- For some reason the slit included in the kit is vertical. However, in a dark room with a point light source, I can reproduce the image above without _any _slit, so I don't think that's the reason. But why would they design it that way??
I will try to produce a CFL spectrum later today, to see whether I can still get a sharp spectrum. I'm glad about any suggestions, on what could be wrong with my setup.
Here's more pictures: