DSLR all-sky spectrometer
Hi all,
I want to build a diffraction grating spectrometer that I can use to observe a large portion of the sky, if not the entire sky.
The main purpose of this setup is to detect whether an aurora is present. I already use an HSV-based detection algorithm, but it isn't very reliable because of ambient light sources such as the Moon, light pollution, and twilight.
I currently have an APS camera, an APS-C camera body, and the following lenses available for this project:
- 50mm f/1.4
- 11–16mm f/2.8
- 70–200mm
Here's where I'm stuck:
Many people seem to have built spectrometers like this, but almost all of them are designed to observe relatively small or localized light sources rather than a large section of the sky. In nearly every design I've found, the optical path starts with a narrow slit, followed by a collimating lens, then a diffraction grating (or even a stripped DVD), followed by another lens and finally the camera sensor.
Would it be possible to use an ultra-wide-angle lens to gather light from a large area of the sky and then feed that light through the slit and the rest of the optical system? Or would the slit simply defeat the purpose of using a wide-angle lens?
For someone with a solid background in optics, this is probably a trivial question. For me, not so much. I'd really appreciate any advice or pointers.
Thanks in advance! I can't wait to have my hopes crushed.
Picture from Google search. This device takes an optical fiber.
