Laser Starfinder




Introduction: Laser Starfinder

I've always been interested in astronomy, and often thought I'd like to get a telescope.  Last year was the International Year of Astronomy, marking the 400th anniversary since Galileo first pointed a telescope at the heavens, and learned that there was so much more to discover there.  There were a lot of astronomy related events going on, and it spurred me to delve into the subject again.

By fortunate happenstance, I managed to acquire a somewhat dirty and disused, but quite serviceable 10" newtonian telescope.  Since then I've had great fun finding nebulae, examining planets, and gazing in awe at the detail that can be seen on the moon.

I've had some trouble finding things though.  Using a finder scope (the small telescope mounted on the side of your larger one) is a big pain in the rear.  At one of the monthly star parties hosted by our local astronomical society I saw that someone had a green laser mounted to the side of his telescope in place of a finder scope.  It was amazing!  He didn't have to mess around with anything, he just turned on the laser, pointed it where he wanted to look, and there it was!

I of course thought to myself, "I can make one of those!"  So here I'll show you how you can as well, and save a few bucks off the cost of buying one of them new.  This is a very simple and cheap fix that will definitely make amateur astronomy a lot more fun!

If you should decide to make one of these yourself, make sure to post a picture in the comments section below, and I'll send you a digital patch!

Step 1: Supplies

For this project you'll need:
  • a cheap green laser (less than 10 bucks at
  • some stiff speaker wire
  • a 2xAA battery holder
  • a flashlight type clicky switch (pack of five for less than 2 bucks at dealextreme)
  • some sugru
  • a strap or some electrical tape
  • something to mount it all on.

For the "Something to mount it all on," you can use pretty much anything that is straight, relatively stiff, has two level sides, and is about 6-8 inches long.  No innuendo intended.  The idea is that if you place something along these lines on the side of a telescope, it will naturally center and straighten itself along the telescope tube.  My original plan was to saw a piece of 1 1/4" PVC pipe in half, but I found this plastic case lid in my stuff drawers, and figured since it was already level and had a flat top it would probably work better.  All I had to do was slice off the ends!

As to tools, you'll need:
  • a dremel
  • soldering iron
  • a hot glue gun   
  • a pair of pliers
  • a small flat head screwdriver
  • a ruler

Finally, you'll want to have some strong epoxy on hand, and some sugru to cover everything up.

Step 2: Prep the Laser Pointer

Just a word of advice, if you live in the US, don't try to buy anything stronger than 5mw.  Even if you can get DX to ship it, it WILL be confiscated in customs!  Besides, you really don't need anything more than 5 for this application.  Your eyes are well tuned to see green light, and even in a badly light polluted region, these lasers have an easily visible beam when you're standing at the base.

Here you just need to dismantle everything and keep only the laser diode, the lens, and the driver board.  If you get one of these laser pens, you'll find that while the back actually screws off, everything else takes a little elbow great to pull apart.

Once you've separated the parts you want to keep, make some modifications.  First, attach the clicky switch to about 2 inches of stiff speaker wire, and solder each end of that wire across the momentary switch on the laser's driver board. 

Also, attach the battery pack to the laser.  Negative goes to the spring on the back of the board, positive goes to the bronze looking metal around the top.  It's hard to solder to the bronze metal, I recomend just getting it to stick and then epoxying it in place.  Leave enough wire between the laser and the batteries so you can put one at each end of the base.

Step 3: Aligning the Laser

This is a tricky part, but don't worry too much about it--you won't get it exactly right, and it doesn't really matter too much anyway!

Hot glue the battery pack to the back of the base.  Use hot glue to tack the laser pointer to the other end, but only use a little bit.  Keep the glue gun hot and close by!

Place the laser on a flat surface and turn it on.  Using the ruler, check the height of the beam close to the unit, and far from the unit.  Are they close?  Using a bit of paper, shim one end of the laser until it is as close to level as possible. 

Next, put the unit up against something flat and even (preferably a wall), still on a level surface.  Use the ruler to see how far away from the wall the beam is up close, and then far.  Have the hot glue gun ready.  Use one hand to hold the ruler and the other to move the laser left and right until the beam is even with the wall.  Hold the laser in that position, put down the ruler, and use the hot glue gun to tack it more firmly in place.  Make sure you hold it there until the glue is completely cool!

Step 4: Seal Everything Up!

Use epoxy to hold everything down.  Use plenty of epoxy to tack the battery pack and laser firmly to the base, and also to hold the wires down.  Bend the wire holding the switch up so that it sticks up and away from the electronics.  With the switch in this position, it will be easier for you to turn the laser on and off without jiggling the telescope.

Once that has hardened, cover all the electronics up with sugru to protect them.  This will make it look nicer, as well as reduce your chances of damaging anything while you're fumbling around in the dark.  I chose green for most of it, and orange for the switch, as that will be more visible in low light conditions.

Step 5: Stargaze!

Strap or tape the laser securely to your telescope.  Using your widest field lens, look in the scope and point it at something obvious and stationary, like a distant treetop.  Turn on the laser and move it around until it's pointing at the same treetop. 

Look in your scope.  Can you see the beam?  In my telescope it looks like a hazy green triangle coming from one side of the field of view and pointing at the center of the field.  Move it around until it is pointing at the center.  You may still need to put a paper shim under the front or back of the unit to get it just right.

Once you're satisfied, try something harder, like a planet or obvious star.  Turn on the laser, and move the telescope until the beam is pointing at your target.  Turn off the laser and check the scope.  If all went well, you should see your target dead center or close to it!

Step 6: Final Thoughts

Ever since I built this, stargazing has gotten SO MUCH better!  It really makes finding even difficult to spot objects easier when you don't have to keep switching between the finder scope and the main scope.  It's been especially useful for me in my light polluted backyard, and I've been able to find a few of the more prominent Messier objects I couldn't with just the finder scope.  I highly recommend this to anyone with an interest in astronomy and a telescope!

Thanks for checking this out!  I'd love to hear from you, so please comment, and don't forget to rate and subscribe!

If you should decide to make one of these yourself, make sure to post a picture in the comments section below, and I'll send you a digital patch!





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    19 Discussions

    neat! but I would find out if its legal in your area to fire green lasers skyward. some people especially near airports might get onto trouble

    1 reply

    I'm pretty sure it's okay as long as you're not actively pointing them at airplanes, but you're right--people should definitely check their local laws.

    everyone don't do that. at least the laws in the area I live clearly state even if there is no air traffic you can still be finned the minimum fine of $10,000 and a 5 year sentence in jail. and secondly the only civilian laser able to be purchased that can enter our atmosphere is stupid expensive and can only truly be seen on the moon.

    I use a regular green laser for that, it has enogh power to see the beam and it costs about 15€ ($10~).

    Looks really easy to knock the laser out of alignment, don't you have to keep recalibrating it? Like the use of sugru though!

    1 reply

    It's not really for precision work, just to get you pointed at the right area. It IS really easy to knock out of alignment!

    I don't quite get this? It's a great idea for improving your telescope but.....Seems like you have just taken apart a laser pointer you had to buy then reassembled it exactly the same but in a less neat/compact format. Have I missed something here? Would be more useful if you had started from more basic components perhaps.

    1 reply
    Whoops, sorry looks like I missed your comment! I usually try to get back to people the same day when they've got questions, but I guess this one slipped under my radar.

    It is true that the new assembly is less, as you say, neat and compact, but it has been reconfigured for a different purpose. There are several advantages to the new design:
    1. The new shape allows it to be conveniently strapped to the telescope
    2. The new shape also is aligned so that it will be immediately useful when attached to said telescope
    3. It now has a click on, click off switch (like a flashlight) rather than a momentary switch.  This allows you to turn on the laser and then use both hands to point the telescope, rather than keeping on hand on the laser to keep it on
    4. It now uses AA batteries instead of AAA's.  This allows for much longer battery life.
    I hope that answers your questions.  Also, what do you mean by it being more useful if I'd started from more basic components?  I don't understand what you're saying there.

    Wow I'd never heard of this before, but I've always been fascinated by the way a laser goes off forever into space and wanted to do something with it. Just using the parallax to help your perception of stars is genius.

    Don't annoy the little green men too much.

    5 replies

    Hi Cefn, thanks for the comment!

    Unfortunately, this little greenie laser probably doesn't keep going up to space, it's weak enough that the atmosphere would absorb it before it got that far. You should check out how observatories use yellow lasers in their work, they actually use them to create an "Artificial star" to help their telescopes compensate for air currents and temperature gradients.

    I'll try not to annoy the LGM's, I don't want to get the dreaded anal probe!

    If you've got a moment, I'd love a vote in the Sugru and Gorilla Glue contests!

    'Tis done. Crazy to vote against myself but I need new insights like this once in a while. Also I've been collecting high-powered lasers for no visible reason for some time, and I should damn well do something with them.

    Ah, but collecting high-powered lasers is its own reason! I only collect low power lasers, just in a variety of colors, because I'm too cheap for protective eyewear and I'm scared for the integrity of my eyeballs.

    By the way, I cast a vote your way for the calendar, it's a great project and a great write up! Don't forget to vote for yourself as well, I saw I was the first vote on it!

    You can vote for yourself. Yuk, I feel dirty. But I did it anyway. Thanks for the advice.

    I just got featured! Had to tell someone who'd know what it means to me. My family and colleagues will just look at me blankly. I was almost hoping I wouldn't get featured, as it makes me think I'll have to do something even bigger and better next time to make the grade - maybe no bad thing.

    Out of interest do you have access to a laser cutter? Do you know who I should recommend to people stateside?

    I got lucky and found someone in the next village (Suffolk, UK) who has one and isn't too busy so I get a pretty good service - same day often.

    The first proto of the tacticalendar I went through Ponoko UK which was a truckload of cash and they took more than three weeks! Can't speak for the other Ponoko making centres around the world though.

    Yeah, I used to feel bad about voting for myself until I realized I could vote as many times as I wanted, so I make it a point to vote for lots of people as well as myself.

    Congrats on the feature! I remember the first time I got featured and I told my girlfriend about it. Her reaction was, "Oh, that's nice."

    Unfortunately I don't have access to a laser cutter. I'm kind of poor and haven't really looked into the options available in the US. Of course, I've not yet had a project where I felt like I really needed one, but if I had easy access I'm sure I'd come up with some sort of excuse!

    I know a guy through work who runs a plant where they have a 4 kilowatt laser that cuts 3/4" plate steel. I got a tour once, which was awesome. As cool as the giant laser was, the super duper high pressure water jet cutter was actually more impressive. They cut a 2" diameter slug out of a solid steel gear 5" thick with that thing!