Some people use them for burning or etching things, some for doing physics measurements of semiconductor wafers, or use them as infrared illuminators for night photography using your nightscope or infrared-sensitive camera. The combination of this laser module (built into an IR illuminator, see link below) and an IR camera can be a powerful night vision device with considerable range. It can turn what appears to be total darkness to the unaided eye into a well lit scene. The infrared output is not visible to the unaided eye.
Instructions (with schematics, performance data, & photos) for building this diode into such an illuminator are here: Infrared Illuminator Build Instructions. The instructions also include a comparison of various other IR illumination devices, such as the multiple-IR-LED illuminators so often for sale.
Specs:
• These have a short multimode fiber optic cable with an SMA connector that attaches to a simple collimating lens.
• Fiber core diameter is 100um.
• Center wavelength: 870 nm
• Spectral width: 5-6 nm at 0.5 W output
• Spectral shape: Highly multimode with a half dozen peaks between 865-871 nm
Lasing threshold: 236 mA
• Optical Power out at 0.54 A: 0.2 W
• Optical Power out at 1.0 A: 0.56 W
• Optical Power out at 1.5 A: 0.91 W
• Optical Power out at 2.0 A: 1.18 W 
Slope efficiency between threshold and 1.5 A: about 0.7 W/A, drops off above that. However, I'm not actively cooling so could be a thermal effect. No damage detected in going back down to lower currents.
The beam out of the collimating lens diverges at roughly a 35-degree angle. To get a narrow beam, you'll need to add an additional lens, and otherwise know what you're doing.
Tests done with ILX3900 laser diode driver, Ando optical spectrum analyzer, and Newport power meter.
The diode in this auction is not the same serial number that was tested for the specs above, but should be very similar. The label says "PRESSTEK, INC.", but the actual manufacturer is unknown.
The serial number of the diode in this auction is _________, and one of the photos shows a different serial number (same model) burning some dark paper.
I will guarantee for seven days that if you put 1 amp through this diode, you will get approx 0.5w optical output. Improper operation can burn out this diode instantly, so know what you're doing (see link to instructions above). I don't know the max power this diode can handle (it is probably intended to be a 1.2W diode), so please exercise caution.
Caution: This item may hold a potential danger and hazard to life and/or goods when misused or by unqualified handling. By bidding on this item you agree, accept and confirm to take full responsibility for the use or misuse of this product, not to hold seller nor ebay liable for any injury or damage whatsoever caused by this item, and that you are over 18 and qualified to use and handle this item. Bid only if you know how to use this diode safely.
Buyer to pay $5.00 shipping/handling.