Laser burn

[norty303]

In case anyone is in any doubt as to the danger of lasers, or the fragility of camera and projector sensors, take a look at these...

That happened at ~25m range, using max 3.5W RGB laser and thats a very knackered £2.5k LCD part!

What I find interesting is the concentration of damage down the very sides of the large image. I wonder if the nature of the projector lens working as a reverse telescope causes beams to concentrate more in these areas when they enter the lens on the periphery.

[Bradfo69]

Is that the one from the festival you were concerned about and they blamed you for?

[Picasso]

I've only ever seen damage to cameras so this is the first ive seen of projector damage. It sure looks nothing like the burns on a camera.

[danielbriggs]

Sure it's not just ants?

[norty303]

I thought it looked like Nokia Snake personally.

[norty303]

Yes Brad it's that one, although your post does seem to suggest they tried to pin it on me I'm not sure I have that impression in my first thread.

Although I won't be able to, in the interests of science, it would be great to actually wilfully scan the broken LCD with a projector and actually monitor the damage and how it occurs in real time, using different scan patterns, etc to see exactly how the damage manifests itself.

[Bradfo69]

Sorry if I misinterpreted this:

http://www.photonlexicon.com/forums/...autionary-tale

But, it seemed to me you're intial reaction was they were going after you.

I agree that would be interesting to see exactly what a direct hit does. I just know it's something I've learned to be cautious about. I did a show the other night and while their two projectors were facing out 90 degrees in relation to the stage, I didn't see ANY cameras and discovered during the show they were obviously broadcasting the band on stage through one of the projectors. I worried a touch about that one since I know it took some direct hits.

We have a big $6,500 Panasonic projector in our ballroom on a lift that lowers down out of the ceiling when needed and I always make sure that it's retracted before running lasers.

[The_Doctor]

In case anyone is in any doubt as to the danger of lasers, or the fragility of camera and projector sensors, take a look at these...

That happened at ~25m range, using max 3.5W RGB laser and thats a very knackered £2.5k LCD part!

What I find interesting is the concentration of damage down the very sides of the large image. I wonder if the nature of the projector lens working as a reverse telescope causes beams to concentrate more in these areas when they enter the lens on the periphery.

That's a 'gotcha' of the First Order. Nasty.. I remember wondering about stopping retroreflection in diode lasers, which never got far because cost wasn't worth it, cheaper to get another diode, but in this case, is it possible for you to set laser polarisation plane (PBS cubes likely bork your chances of doing this) such that a polarisation filter over the projector output can stop the beam getting in while allowing strong light out?

[norty303]

But, it seemed to me you're intial reaction was they were going after you.

I think this may be a language barrier thing. Yes, they are pursuing me to rectify the situation (as is right and correct - and things are afoot in that respect) but 'pinning' it on someone over here usually refers to an innocent party being stitched up, rather than simply being asked to take responsibility for the situation caused.


Anyhow, given how infrequently these things seems to come to light, especially with pictures, I thought it would be interesting for people to see the nature of the damage. The only other pics I could find were from the laserist.org and concerned DLP projectors and tests done a number of years ago. Interestingly, some of the details there talk of damage in a very similar scenario - ~25m range, long throw lens on the projector, similar sized lasers, etc

[Soulstorm]

Fantastic shot, thanks for sharing. Reminds me of a Lichtenberg figure. Once a mate forgot to cover up a DLP projector that was in close proximity while testing. Brief exposure of a 2W yag at lower power setting, didn't end so well. Completely killed it, not dead pixels like a CMOS.

Have some ancient 3M long throw projectors laying around, they had 5k worth of lens on each, bet a little hene could take them out!