A laser collimator seemed like a really easy way to align my Dobsonian (Newtonian reflector) telescope, but the cost of commercial units was out of my budget. What you see below is the design I came up with. Total cost was about $20.00 with the laser pointer being about $17.00 of the total.
Ideally the collimator would be made from 1.25" od tube. Mine is made from 1.25" id tube, I just replace the focusers draw tube with the collimator when I use it. The tube has a .75" tall window cut into it for the viewing screen. The viewing screen is made from a plastic milk carton. The screen is a 1.25" disk with a .25" hole punched in the center. It is glued into the main tube below the window.
There are eight screws which hold the laser pointer centered in the tube. The eight screws are installed in Rivnuts. Rivnuts, also called Nutserts, and other brand names which I don't know, are a combination of a pop rivet and a nut. You drill a hole the size of the Rivnut, insert the Rivnut in the hole, and expand the Rivnut with a special tool. Its a great way to put threads in thin material. Harbor Freight and Tools has a kit including the tool and Rivnuts for about $15.00. The ninth screw is located over the laser pointers power switch. I just tighten this screw to turn on the collimator, and loosen it to turn it off.
The black ring is a rubber O-ring to prevent me from inserting it to far into the focuser.
Aligning the Collimator
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