In this section we explain how we built a basic optical spectrometer using a webcam to adapt to our telescopes to determine the spectrum of the planets, stars and nebulae we normally observe.
Fortunately, some had done part of it as shown by Ben at the Electron Exchange.
To use its app you need to download and install Wolfram CDF player from here. We were going to use commercial PVC piping and their elbows do not come at special angles, only 90° or 45°. Playing with the app, I found that to get a second order spectra the grating must be installed at approximately 32 to 36°.
Most of this process has been already described in our other section Adapting an HD webcam to a telescope with a few exceptions.
Disassemble the camera as explained before all the way to taking out the lens fixture.
The general process of building spectrometers using CDs or DVDs is explained very well by others, see for example Popular Mechanics Magazine.
There is even an open-source kit you can buy Public We went a bit further making one for our amateur telescope without breaking the budget (there are sophisticated optical spectrometer for Amateur Astronomers with deep pockets by Shelyak Instruments). This illustrations shows what we wanted to accomplish: We will use PVC piping to fit the spectrometer to the eyepiece adapter and to house the camera, all in one case. Before any assembly, we need to figure out how the main parts will be mounted: grating and camera.
Astrospectroscopy with a webcam We use again our well-know Microsoft Life Cam HD-3000, because it is small enough, not too complex to disassemble and cheap (remains below street price, online), and is CMOS HD with a video frame of 1280xx 720pixels.
We use a commonly accessible diffraction grating, a DVD-R blank disk, to separate the colors of the spectrum.
In the transmission mode there will be diffraction up and down the grating.
We chose down, which is considered negative orders of diffractions (below the horizontal).
If one can find a HD focusing Webcam, it will be better to optimize the image of the spectrum lines.