Inside a laser
Scan fail card
Laser diode blocks
Dichroic mirrors are coated with a wavelength specific reflective coating, so other wavelengths will pass through unaffected
Scanners
US requires a laser to have 30 second delay after power on before emission. The aperture LED flashes during the 30 second time period.
Brass and copper are used for heatsinking because they are better thermally, less size change when heated. Aluminium base plate because it is thick and aluminium is cheaper.
Scanning
“Visible points” – have position and colour data
“Blank points” – have just position data
PPS – Points per second – Scan rate
20-120kpps in theory, in practice you tend to use 20-30kpps
Setting a lower scan rate than galvos max (e.g. running 30kpps @ 22kpps)
Galvos max specification will be for a smaller angle of the operating area, often you want to use more than that so you need to derate.
A slower moving beam can appear brighter so can be visually more pleasing
Physical scan area
Using the edge of the max scan area is really good as the galvos can’t go past it (they have physical stops) and you get a really nice clean edge.
Physical shutter or some rosco black foil (gaffa taped to housing) can be used, it works but its less good as it gives a fade out edge which effectively means a not nice to use bit of scan area.
Reflective items in the scan area, or cameras?
Use rosco black foil on them to shield them (best = physical stop)
In software you can define them out using the beam attenuation map.
Stage mounted lasers
Always mark their positioning using tape markers, so you can see on a pre-show check if they’ve been moved.
Do this for floor stands holding lasers too – what if someone crashed into the stand without you knowing?
Setting up a projection zone
Brightness: 1%
Size: Make smallish, but not so small that too much energy is concentrated into a point
Position: To the top, unless riggers are up there. Somewhere safe
EStop enabled
Turn on the test pattern, once on increase the brightness until you can see it.
Beam attenuation zone – used to define blank areas
This is a software control, so consideration should be given to safety.
Use to avoid reflective areas, performer, camera positions<<<<Very important, lasers can destroy camera sensors!
It is NOT acceptable to use this for audience protection.
PASS – Professional audience scanning system
This is a requirement in the USA for audience scanning. It took 7 years for it to go through FDA approvals!
Diffraction effects
The zero order beam is the original beam. It will be there in the same place on the diffracted beam too, but with lower power.
The next ring of dots is the 1st order beams, the next is the 2nd, etc. The intensity drops off rapidly as you move away from the zero order beam.
The zero order beam always projects into the safe zone (3m above) because:
Its still has lots of power
It might be outputted as a single static beam if the diffraction effect isn’t selected correctly due to a fault.
When effect rotates (so beams moving) it remains static.
