Monday, August 16, 2010

Laser pointer IR hazard

There is a recent technical note from NIST out describing potential IR hazards from off-the-shelf green laser pointers. It makes use of the CD spectrometer that I blogged about years ago, but is far more quantitative. It also shows a cool trick for detecting IR leakage from household lasers: evidently cheap webcams can see IR, while good digital cameras do not, so the images can be compared, to detect IR.

More importantly, I think it is awesome that the federal government is encouraging people to set up physics experiments at home using paper cups, old music, and other stuff lying around the house. Take that, lawyers and stuffy nay-sayers!
The technical note, "A green laser pointer hazard" is here.
The experimental setup is shown below:

And a comparison of visual-only and visual+infrared diffraction image is below. The bright white dots are 808 nm IR leakage from the laser. This constitutes an eye hazard.


perfectlasers said...

it is quite a serious thing about laser pointer IR hazard. thank you anyway for your kind remind. just take care!

EliRabett said...

The expensive camera could see the IR, but they put in a blocking filter (which the brave can remove) and then see through clothing to an extent. The band gap for silicon (and thus the CCD camera is about 1.1 eV which is somewhere out around 1100 nm.

In the case of the cheap webcam there is no filter, so if you use an IR long wavelength pass filter you have something like a night scope.