Fading Lasers without modulation, optically

[-bart-]

If the lasers are polarised you can easily dim them by inserting a polaroid filter into the beam and rotate it with a servo. If the energy is to high expand the beam.
A pbs takes higher powers but is more difficult to rotate.

[VDX]

... I've used polarizing goggles used in 3D-cinema for 'dimming' light by rotating one of the eyepieces against the other ...

Viktor

[White-Light]

How about a galvo with a wide mirror and a retro-reflector like in the old XY+blanking scanners?

Or how about an actuator of the type used as a beam shutter with the a flag of ND filter cut off the strip so that when activated it swings the flag into the path of the beam. By having several (if your optical table was big enough) could you not combine densities by having multiple actuators with different density flags on them and then combining a number in the beam as well as putting them in individually? Also, would this not open the possibility for programmed sequences allowing for many varied densities?

Just an idea and I guess it depends on how stiff the ND filter material is, but maybe it could work.

[Displaser]

Edmund's had a linear as well. I don't know if they still do. Seems like they were around $100

[absolom7691]

Just out of curiosity, why not modulate? Is it because of the cost? I am going to use modulation in mine with Dave's DMX boards for my 0~5V reference... http://lasershowparts.com/store/inde...&productId=285

I have already tested these and they work like a charm. I can queue my lumias via DMX.

[Photonbeam]

I have some of these 1/2 wave plates rotated by stepper motor. The parallel plates separate the two polarizations and the waveplate varies the ratio 0-100%. They are from Laserscopes - 532nm. Not sure how they would work for other wavelengths. Of course your beam must be polarized.

[WookieBoy]

Ummmm.... not sure if this would work but, find an old Martin MAC600 or MAC300 moving light on FleaBay.
They use an etched glass wheel on a stepper as a frost filter that runs from clear to pretty much fully opaic as the wheel turns.
Was a pretty crap effect as it dimmed more than softened the beam, hence think it might work here... but it might not give you a full blackout...

Might be worth a go if it's cheap enough

[Galvonaut]

I have a friend locally who produces high quality photographic filters (ND a speciality). I'll ask for some prices.

What sort of power are we talking here PolishedBall?

[polishedball]

1.5-2w

Thanks.....

I have a friend locally who produces high quality photographic filters (ND a speciality). I'll ask for some prices.

What sort of power are we talking here PolishedBall?

[Galvonaut]

Might have to do some experimenting as not sure what his dyes will take. Worth a blast though.