Re: 3D printed UVEX spectrograph
Posted: Thu Jun 22, 2017 1:40 pm
If this spectrograph is a simple design, on the other hand, the exploitation and the processing of data is non standard. It would be a bit long in a simple message to describe all these aspects - I prefer to write a specific Web page when the second prototype will be realized, I think in about 10 days. I suggest you wait for a more advanced opinion.
There are three main difficulties:
- The presence of an optical aberration called field astigmatism, which means that the spectrum does not have the same width (spatial axis) as a function of the wavelength.
- There is also a horizontal distortion (deformation of the lines).
- Finally, there is no slit in normal work (only large hole), which makes it impossible to calibrate with a spectral lamp. I used the Balmer lines to find the calibration law (and now also the ozone lines for the far UV). But I recall, one can also realize visible and IR spectra. Currently, stellar lines must be used to calibrate.
The approach is that of a StarAnalyser, but here an improved StarAnalyser, a little more powerful (and complex of course). Remember, we are in the experimental and the exploration phase.
I would describe it in detail. Also, plans and 3D print files will be free to use, of course. But patience, I do not have too much time for me.
Concerning the cylindrical lens, a quart/fused silica version would clearly be better (achromat to be analyzed in the same way). The problem also arises for the windows of the camera and the detector. I was surprised of the present result despite these difficulties.
The detector's response is also a serious limit in the UV. But remember, the UV is only one of the possible uses of this spectrograph. We can also exploit it in the visible, the infrared, and I think I will change the name of the project!
We can not adapt a guidance system like the Aply system because for accessibility questions of the focal point. Changes are probably possible ... But this spectrograph can not compete a model like the Alpy. I insist, it is intended for only small telescope and refractor (because the small size of stars images ate the focus and small difficulties with sidereal time tracking), and for the pleasure of experimentation only. Suggestions are welcome as well.
But, "at the same time" (the French readers will understand, this with related to our new Republic President Macron , one can do a little science with a little care...
Christian
(sorry for rough English)
There are three main difficulties:
- The presence of an optical aberration called field astigmatism, which means that the spectrum does not have the same width (spatial axis) as a function of the wavelength.
- There is also a horizontal distortion (deformation of the lines).
- Finally, there is no slit in normal work (only large hole), which makes it impossible to calibrate with a spectral lamp. I used the Balmer lines to find the calibration law (and now also the ozone lines for the far UV). But I recall, one can also realize visible and IR spectra. Currently, stellar lines must be used to calibrate.
The approach is that of a StarAnalyser, but here an improved StarAnalyser, a little more powerful (and complex of course). Remember, we are in the experimental and the exploration phase.
I would describe it in detail. Also, plans and 3D print files will be free to use, of course. But patience, I do not have too much time for me.
Concerning the cylindrical lens, a quart/fused silica version would clearly be better (achromat to be analyzed in the same way). The problem also arises for the windows of the camera and the detector. I was surprised of the present result despite these difficulties.
The detector's response is also a serious limit in the UV. But remember, the UV is only one of the possible uses of this spectrograph. We can also exploit it in the visible, the infrared, and I think I will change the name of the project!
We can not adapt a guidance system like the Aply system because for accessibility questions of the focal point. Changes are probably possible ... But this spectrograph can not compete a model like the Alpy. I insist, it is intended for only small telescope and refractor (because the small size of stars images ate the focus and small difficulties with sidereal time tracking), and for the pleasure of experimentation only. Suggestions are welcome as well.
But, "at the same time" (the French readers will understand, this with related to our new Republic President Macron , one can do a little science with a little care...
Christian
(sorry for rough English)