copper vapour audience Scanning

Discussion in 'Laser Safety' started by Laser Envy, Mar 31, 2003.

  1. Laser Envy

    Laser Envy Member

    Are copper vapour lasers safe for audience scanning?

    I was told no because the are pulsed , but while I was in vancouver BC, there was a Laser company that was scanning the Audience with one.

    they also had rotating difraction effects, are these safer for the audience?

  2. Pangolin

    Pangolin Staff Member

    These are generally unsafe, unless the beam diameter and beam divergence are such that the irradiance is so low that it would be "safe" for some duration.

    I may know of the laser and projector that you are talking about. Greg Makhov and I saw a similar one (or maybe the same one) in Rimini several years ago. We computed the Nominal Occular Hazard Distance (NOHD) at somewhere far enough that it was "outside the building", so I doubt that this would really be a safe exposure.

    And keep in mind that diffraction gratings have one notable danger and that is the "zero order beam".

  3. lasrgreg

    lasrgreg Member

    CVLs are inherently pulsed lasers that have very short pulse durations of generally less than 20 nanoseconds. Pulse repetition rates vary from about 6000 to 15000 pulses per second. For an example, let's use a 5 W average power CVL. Divide the 5 watts by say, 10,000 pulses per second, and we have an energy per pulse of 0.5 millijoules per pulse. Now we can take that energy and divide it by the time of the pulse, 20 nanoseconds. This laser pulse has a peak power of 25000 watts!!! In other words, during the time of the pulse, the output is a "slice" of a 25 kW laser. good for vaporizing things.