A green laser is very useful for pointing out objects in the night sky. But how do you know what you're pointing at? If if you want to find something specific in the sky, how do you find it?
A lot of people have telescopes without computerized go-to systems. It can be difficult to find specific objects in the sky for observation.
This system combines the usefulness of a green laser pointer with the computerized astronomical magic of sky mapping software available for most smartphones. It is a family of four, 3D printable parts I designed for astronomical use. There is a handle with a trigger, a tube to hold a laser pointer, a bracket to hold a cell phone, and a rail to mount on a telescope or tripod.
The idea is to use Google Skymap or SkEye in combination with a laser pointer to locate and point out objects in the night sky. It can be used hand-held for educational lectures or casual observation, or the handle can be removed and the laser and phone slid onto a rail mounted on a telescope tube to aim the scope. You simply tell the sky mapping app on the phone what you'd like to see, then follow the on-screen arrow until the laser is pointing at it.
The laser mount for the telescope can be used for pointing the scope for terrestrial observation, too.
Step 1: The Telescope Rail
I wanted to make it easy to mount the laser/phone on a handle or a telescope or binoculars so I decided that a sliding mount would be easiest and most secure. I looked up dimensions of a standard gunsight rail and copied it. The rail piece that mounts on the telescope or binocular tube attaches with two screws. It can also mount on a tripod by adding a 1/4-20 nut.
Step 2: The Phone Mount
I spent a long time trying to design a printable, universal phone mount but could not come up with anything that would really work for all phones. I eventually settled on providing a flat surface to which one could attach velcro tape to hold the phone. It means you'll have to put a piece of velcro tape on the back of your phone. The phone bracket slides into the top side of the laser tube and uses a single screw to secure it.
Step 3: The Handle
The handle is shaped to fit in your hand comfortably and slides into the laser tube. The fit is tight and secure, but I added a screw hole in case you don't trust it. The original handle was just a handle and the system had to be operated with two hands- one on the handle and the other to push the button on the laser. I redesigned it with a trigger for one-handed operation.
Step 4: The Laser Tube
The laser tube has slots that fit standard gunsight rails on its top and bottom. There are three screws at each end of the tube that allow fine adjustment of the laser direction for accurate alignment for use on a telescope or large binoculars. The tube can accommodate laser pointers up to 1" in diameter.
I use a small rubber band to make sure the trigger shuts off the laser when you let go- the little springs inside the laser power buttons aren't very strong and can use the help. You have to position the laser in the tube so that the trigger ring will push the power button when the trigger is pulled.
If you mount the laser on a telescope or binoculars you can use a small, wide rubber band or a piece of tape on the laser tube to hold the laser on until you have finished aiming the scope.
Step 5: The Files
All the relevant CAD files and printable STLs can be downloaded from Thingiverse
I printed with ABS (PLA should be OK, too) using 0.2mm layer height, 20% infill, 2 bottom and top layers and shells. I recommend printing the objects separately because of the widely varying heights.