Print the spectrograph
- Download the spectrograph scad files.
- If you're using a different grating modify the angle "1st" in both files. If you use different lenses modify the parameter "ff" in both files.
- Make sure the screw-holes match the TCD1304 PCB you have (there are two SMD versions of the PCB).
- Print the spectrograph and the lid.
NB: It takes around 18h to print the spectrograph, so go get drunk or something in the meantime.
The linear CCD module
- Goto https://hackaday.io/project/9829-linear-ccd-module
- Populate the TCD1304 PCB. However you may want to put T1 on the same side as the CCD and solder the cable directly onto the PCB. There's not a lot of space inside the OtterVis LGL box.
- Insert the PCB in the spectrograph. NB: Hex-screws will be much easier to deal with than philips head screws.
Stripping the lenses:
While the Pentax SMC-A 50mm f/2 are small, they need to be stripped from all their extra weight.
- Unscrew and remove the bayonett.
- Unscrew and remove the aperture coupling together with any screws you find.
- Unscrew front ring.
- Again remove any screws you come by.
- Remove the front lens group.
- Remove the aperture iris.
- Remove the lens barrel from the focusing helicoid.
- Reassemble the front and back lens groups, and you should have something like the picture above.
You can also watch this video (not mine) on youtube: Pentax SMC-A 50/2 disassembly. Be advised that for this project you won't need any spanner wrenches, so if you find yourself in need of that, you're going too far..
Download and print the lens holders. Insert the lenses in the lens holders and secure them using the left-over screws. Finally insert the lenses in the spectrograph.
Assemble the slit:
Find a small ring magnet from somewhere. Try and find one that's not taller than 3mm. Download the scad-file for the slit holder and modify the insert, so the magnet fits.
Insert the magnet. Cut a razor blade - scissors are fine for this - and fit them over the magnet.
- Insert two 10mm M3 screws in the two lower screw-holes of the spectrograph (the holes will be inaccessible later).
- Mount the slit-holder with two 16mm M3 screws and two pieces of ballpoint-pen-spring.
- Place a small mirror after the focusing lens and a flashlight in front of the slit:
Use the reflection of the slit onto itself to focus.