View Full Version : laser module use?

10-22-2008, 09:01 PM
I scrapped out a HP LaserJet 4 printer today, and saved the laser module: housing, motor/mirror, laser. Did not save any of the electronics.

Is it of any use? The label says "invisible", so I assume that it's in the UV band and would be useless for anything where you'd want to see the beam. What voltages might be required for the motor and laser? Or do they require something other than simple DC for power?

TIA: <<Jim>>

10-22-2008, 11:06 PM
One wavelength used is 790nm. How the laser is driven depends on whether you are looking at a laser module or the laser diode itself. Typically, a laser diode requires a drive current which is controlled by feedback from a "back facet" monitor, a photodiode that sits right behind the laser die. You could test drive the laser with a simple voltage supply and a limiting resistor but unless you have spec's on the diode, it would be easy to toast.

If it's a module, it will most likely have power connections, on/off control and modulation input for pulsing.

The easiest way to see the laser (or your TV remotes) is to aim a digital camera or camcorder at it. It will appear brightly as the wavelength is within the range of silicon imaging chips. As drive current is increased, it will go from dim (LED-like) and hit a point where it begins to lase ... and appear like it entered warp drive.

I'm not familiar with the laser printer optics but would be very careful with the IR source. If it is collimated (narrow, straight beam) it can do damage to your eyes from some distance). The short wavelength is also in a region that will do damage more quickly than long wavelengths used in communications (optical fiber).


10-23-2008, 06:42 AM
It's an infrared laser. It is powerful enough to do serious eye damage and is particularly dangerous because you can't see the beam. If you feel compelled to play with it then wear gas welding goggles when you do. They will stop the IR radiation.

Off topic, I haven't been able to get on this site most of the time for the last several days. I get DNS failure when I try.

10-23-2008, 07:55 AM
Thanks for the feedback, fellas, I'll throw the thing in the trash.

10-23-2008, 09:40 AM
Toss the IR laser, unless you have a use for it.

You can have a lot of fun with a cheap laser pointer and the Foucault mirror though :D

That's the polygon 1st surface mirror, mounted on a motor ;)