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A LED illuminated collimator

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My telescope requires re-collimation sometimes and this is a bit tricky when you are out in the dark. Instead of buying one of those expensive laser collimators that probably draws lots of current, I wanted to build something much cheaper and simpler. This turned out to be a perfect oppurtunity as I now had a small power supply with me for the heaters.

I used two plastic pipes, one of diameter 1.25" (same as the focuser diameter) and one of about 1.8". I glued these together with two middle rings of wood. At the end of the widest pipe I glued a round plate and made a very small peep hole in its center. Inside the pipes are three red light diodes (LED's) that illuminates the lower side of the plate.

Before you can start to use this tool, make sure you have a small black spot (a piece of tape for example) fastened on the surface of the primary mirror, exactly in the center. This will not affect the overall performance of the telescope, if you were afraid of that.

If you supply the LED's with electricity and look into the small peep hole in the collimator, you will through reflections in the mirrors, see the little black spot on the mirror projected against the illuminated round plate of the collimator. This will work even if it is totally dark since the LED's provide the only light that is needed.

Remember that this will not automatically collimate the telescope for you but it will allow you see how the tweeking of the collimation screw affects the collimation. Try to make this little tool if you need to collimate your telescope out in the dark and don't have a laser collimator or any other collimation tool that works.

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Text and photographs copyleft Olle Eriksson unless otherwise noted. All rights reversed.

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