Safety Documentation And Requirements; Description Of The Laser Unit - MediaLas Spooky blue Bedienungsanleitung

Safety documentation and requirements

Spooky Blue laser Projector up to 10mW Green
Conception and verification March 2002.
The Spooky Blue laser projectors represent stand alone laser display units. All units comply with the
European Regulations, DIN and VDE 0837 Safety requirements of laser products only if the following
operation requirements are assured and fulfilled.
Description of laser unit
The laser source is mounted in a blue metal housing. The housing prevents any unintended and scattered laser
beam to leave the box at any other position than the square window of dimension 40mm x 40mm. The
Spooky Blue Laser projector requires an external Power supply. 255 animations are preprogrammed and can
be selected via 2 DMX channels in a 16 x 16 matrix (16 effect groups with 16 effects each)
The laser projector contains a frequency doubled Nd:YAG laser, with wavelength 532nm. The laser source is
cooled actively to increase the laser power stability fluctuation to less than 15% over 6 hours of continuous
laser emission. The laser diodes used are classified with a maximum laser power of 10mW, in CW emission.
Besides the laser source, the laser projector contains two linear motors (galvanometer scanners) to reflect and
scan the laser beam in two directions, referred to X for the horizontally axis and Y for the vertical axis
respectively.
The galvanometer control circuit has an integrated and independent running safety function. The safety
circuit continuously watches proper function of galvanometers and deactivates laser output if
1) at least one galvo motor fails or stops working
2) the actual scanning angle decreases below a minimum pre-adjusted scanning angle
3) average laser power increases above save levels due to low output angle or stopping beams.
In each case the laser power is shut off within a few milliseconds. Therefore, an independent control circuitry
measures the following signals:
X and Y of the Galvo-feedback signals
X and Y from the computer for unsafe signals
For this reason the signals are measured at 8-bit resolution independent of the onboard micro controller.
All signals have to track a pre-selected distance within the safety time of 50ms to switch on the laser beam.
This distance cannot be adjusted, so there is no user changeable signals or adjustments.
If one of the signals (computer input or feedback input) fails to track the pre-selected distance, the laser beam
will shut down. Since laser safety officers recommend to have at least 100ms detection time, the response
time was increased to 50ms to avoid any possible cases of unsafe operation.
The switching criteria are:
Movement X input AND feedback X OR movement Y AND feedback Y = Laser ON.
All other conditions: Laser off.
At least one axis has to be in safe condition.
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