Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Advice on making laser ray box for teaching

  1. Jan 15, 2008 #1
    Next month I am going to be teaching my 9th grade "Physics First" classes about optics, and I'd like to use a set of lasers to show them how rays diverge and converge in various situations.

    Students will literally be able to see things like this:

    Frey Scientific sells what looks to be a wonderful device: It has 5 side-by-side, 1 mW diode lasers, all lined up next to each other. It makes five parallel lines that do not diverge (at least not to a significant degree over the length of a lab table!)

    These are great to aim at lenses or mirrors for ray tracing, optics experiments, etc. The only problem is that each device costs $380, which is total garbage. These low power laser diodes only cost them $10 each at most, probably less.

    Laser Ray Box Item #: 1552737821
    https://www.schoolspecialtyonline.net/ECommerce;jsessionid=BE4D8356EAF9023000B9CC88941A1F8B [Broken]

    It occurs to me that I should be able to build a useful device with cheaper, lower power, pointer lasers. These can be purchased for $5 to $20 each. But the trick is finding cheap lasers with a useful on/off switch. All the cheap lasers I see have no real switch. You have to constantly put your thumb down on the switch to turn it on, and the moment you let go it turns off. Not convenient. Do you know of any affordable, small lasers, that can be turned on - and stay on until they are switched off?

    I've never done this before, but I am thinking of picking up cheap laser diodes, and soldering them together to a battery, or some power source, but I don't quite know how to do this. Its supposed to be easy, but not having done this before, I need some sort of instruction. Any idea on where I might find good instructions, including photos?

    Take a look at these cheap laser components: I was thinking of picking some up here, but I am open to any suggestions!

    http://www.wholesaleforeveryone.com/Merchant2/merchant.mv?Store_Code=WFE&Screen=CTGY&Category_Code=lasermod [Broken]

    Thanks much for your time,

    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Jan 15, 2008 #2


    User Avatar
    Science Advisor
    Homework Helper

    You can't really beat the keyring laser diodes for price, the performance is pretty good as well.
    I would take a few, drill holes in a block to hold the barrels so that it also holds down the on switch. You might have to rotate them to get them beams parallel, the diode isn't very well aligned to the outer case.
    Then remove the end caps and the internal little watch batteries, solder a wire to the spring at the end of the battery compartment and another to either the case or the wire to the tailcap. You can then run them all from either a couple of AA cells (most are 4.5V) you can also switch them on and off easily with a switch to the new batteries.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook