Hey! This thing is still a Work in Progress. Files, instructions, and other stuff might change!
Spectrograph / Spectroscope (LOWSPEC)
by PJHGerlach, published
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A spectrograph lets you analyse light. Attaching it to a telescope enables you to discover all sorts of things about the stars. In fact, almost all we know about the universe has been obtained through spectroscopy!
This field of science is becoming more and more popular amongst amateur astronomers. A commercial spectrograph however will set you back € 2000 or more!
That’s why I decided to build one with a 3D printer. Of course, you’ll have to buy the optical components (slit, lenses, mirrors and grating) . But that will ‘only’ cost you about € 500. Which is a huge difference compared with a commercial spectrograph. This spectrograph is designed for telecopes which are f/8 or slower.
This is still a work-in-process project. I’ve included a STEP file of the whole design so you can change or improve upon it. Later on I will include more information on how to assemble the instrument. This will be done as a series of images that I will add in the coming days.
I do not have in-depth knowledge of optics. So if you can improve this design, please let me know. Even better, share it with the rest of the world!
It is possible that I will make slite alterations to the design. So be sure to always download the latest STL files before you start printing.
Felix Pro 2
The main body can be printed at 200-250 micron (infill >= 50%).
Print smaller part a 100 micron with 80% infill.
Some parts require support.
Print the main body at 200 micron with >=50% infill. Use support (max overhang 60 degrees).
Remove support after printing.
Check that the two threads fit the main body before you glue them in place using two component Epoxy glue.
You can use a 3/8" nut so you can eventually attach the instrument to a photo tripod. Glue the plug in place.
Screw in the threaded M4 insert.
Use a M4 threading tool to thread the four locations indicated.
Next screw Allen Grub Screws (M4) into these threaded holes.
Insert the round coupling nut M5 x 25mm (mine had a diameter of 7.9mm) into the center hole of the focus slider. It should be a tight fit and you may have to resort to some brute force...
Push the M3 nuts into the slots (two in both rail holders).
Cut two pieces of aluminum pipe (length 55mm, diameter 6mm) and slide them into the two other holes of the focus slider. Make sure that they can slide smoothly.
Cut two coilsprings to size (aprox. 22mm) and slide them over the aluminum tubes. Assemble this part by sliding both rail holders over the tube ends.
Make sure the whole focus part fits in the designated slots underneath the main body. If it does not then make sure that both sliding tubes are pressed far enough into the rail holders.
Still no fit? Than you’ll have to shorten both sliding tubes a bit.
Screw it in place with four M3 cylinder screws.
Check that the focus slider can travel the whole length!
If not, unscrew it and change the coil springs.
Take a M5 threaded rod (length 75mm) and screw a M5 locking nut on one end. Make sure it’s tight.
Screw the rod in place. Screw it all the way in.
Screw the Knurled nut onto the other end of the rod.
If every thing looks ok, place a drop of superglue into the top opening of the nut.
Test the focus-unit by turning the knurled nut.
Press the mirror into the main mirror holder. Wear gloves so you will not damage the mirror!
Also insert a M3 nut in the slot on the backside of the mirror holder.
Make sure the Allen Grub Screws do not protrude before placing the mirror holder.
Place the mirror holder and secure it with a M3x10mm Philips screw. Take care not to over tighten the screw. The three Allen Grub Screws will be used later to change the tilt of the mirror.
Cut a aluminum pipe (dia. 6mm) to length (16mm) and secure it in place with some glue into the hole of the focus slider.
Use a M4 threading tool for the small hole and screw in a 6mm Allen Grub Screw.
Press the camera lens into the holder (should be a tight fit). Be aware of the correct orientation of the lens.
Slide the camera lens holder over the protruding piece of aluminum pipe and tighten the Grub Screw. Make sure the biggest bulging side is facing as illustrated.
Press the collimator lens into its holder. Wear gloves to protect the surface of the lens. Note the position of the parts. Insert a M3 nut all the way into its slot.
Place the collimator holder in the slot at the bottom of the main body. Take note of the orientation.
Use a M3x12mm philips cylinder screw to keep the collimator in place.
By loosening this screw a bit you are able to slide the collimator back and forth.
Use a 4M wire tap to tap the two holes on top of the rotary section of the grating holder.
Screw in two M4x6mm Allen Grub Screws.
Carefully slide in the reflective grating. Take great care not to touch the surface of the grating as it can easily be damaged!
Also, notice the arrow that is drawn on one of the sides of the grating (the 'blaze direction'). It should be pointing in the direction as is indicated in the illustration above.
Gently tighten the two Allen Grub Screws so that they hold the grating in place. Be careful! Over tightening them could break the glass grating!
Place the whole rotary section onto the base plate and put the cap on top.
Check that the rotary section can move freely. If needed you can glue the cap to the base.
Insert two M3x12mm Cylinder Philips screws and install the spring.
Take care not to damage the grating!
Insert two M3 nuts into the indicated positions above.
Gently screw the grating holder in position. Again, take great care not to damage the surface of the grating. To access the screw under the coil spring you may need to push it aside a bit with you screwdriver. Take care not to touch the grating!. The other screw can be accessed by rotating the grating.
Use a 4M wire tap to tap the hole of the guide platform and screw in a Allen Grub Screw.
Place the APLY slit and secure it by gently tightening the Allen Grub Screw.
Insert the 12.7mm Thorlabs mirror into it's socket. Use gloves and make sure it's pushed in all the way.
Next, insert the mirror holder into it's socket.
UPDATE 10/29/2017: the mirror holder has been redesigned a bit so it looks different than in the image above.
Slide the autoguide/slit platform into the main body.
Insert the autoguide lens into it's holder (08_guidelens_holder). Make sure that themore curved surface is facing the guide mirror...
...and push this into the socket at the back of the autoguide port.
Make sure it's firmly in place. If in doubt use some glue to keep it in place.
Place the micrometer and secure it with the Allen Grub Screw.
The micrometer used has a mounting diameter of 9.5mm and a travel of 1-13mm.
Insert the five M4 locking nuts.
Place the lid and secure it with five hexagon socket head cap screws (M4 x60mm).
Also screw in the knurled Screw (M4 x 20mm).
The assembly is now complete!
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Spectrograph / Spectroscope (LOWSPEC) by PJHGerlach is licensed under the Creative Commons - Attribution - Non-Commercial - Share Alike license.
What does this mean?
- You must attribute (give credit) to the creator of this Thing.
- You must distribute Remixes under the same license as the original.
- Remixing or Changing this Thing is allowed.
- Commercial use is not allowed.
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