Laser burn

[dsli_jon]

Ok, few points....so I have no reason to mistrust what is being said, and the idea of a ruse is a bit distasteful to say the least.

Well, totally-ignorant supposition, retracted.. I certainly did not / could not have known such 'context', so.. No offense, m8..

Hope ya can suss it out and save yerself a few K-£'s

cheers..
j

[White-Light]

How about this as a test subject Norty?

http://www.ebay.co.uk/itm/Optoma-ES5...item3cd3eca251

[dnar]

Looks like a fracture to me. I have seen those patterns before, its leakage. Hard to say what caused the failure with out some science! So As mentioned above, its no good so repeat the damage if you can or cant.

At the end of the day you may be better off sorting this out of good will. Put it down as a lesson learnt and tax deduction. Good will is more valuable than upset friends.

The reverse telescope effect is similar to what occurs with lasers and the human eye right?

[norty303]

The reverse telescope effect is similar to what occurs with lasers and the human eye right?

Correct.

Here are the links to articles I've been able to find so far about laser damage, take a read if you haven't already and see what you think about the relative powers and distances involved.
http://www.laserist.org/forums/showthread.php?t=156

http://www.laserist.org/camera-and-DLP-damage.htm

[Pangolin]

HI Norty,

I have to say, I've never seen damage like this before in my life. Normally what happens is that when a laser hits a projector, it knocks out a whole row or column (or row and column like a cross) of pixels. I've seen that quite a bit and to me, that's the signature look. But what you're showing in those pictures is really strange.

I agree with James that you could try shining a laser back into the projector (preferably of the same type and from the same distance) to see if you can cause more damage and see if any new damage looks similar.

Also, I've not seen rather ordinary laser projectors knock out a video projector. So far every instance I've ever heard of (or seen with my own eyes) has been instances where the laser has a very good M2, such as Coherent OPSL.

Best regards,

William Benner

[Things]

That's definitely not _directly_ caused by a laser, those patterns are the LCD leaking for sure. Crack a LCD computer monitor and you'll get the same effect, and it'll slowly spread over time. It's possible maybe the laser caused some thermal shock, but the leaking around the edges definitely doesn't look laser related.

[JStewart]

Adam,

I can fully understand where you are coming from with not wanting to potentially cause further damage to the projector by conducting more experiments. And sometimes it’s just better to bite the bullet and move on.

Although we have all commented about how strange the damage pattern appears, and it looking like mechanical shock, that doesn’t rule out that a laser could have been the cause.

Not many people are willing to post pictures, (or even admit to possibly causing damage to a projector), so we don’t have much to compare your pictures with. We are all more used to seeing the damage caused by laser beams being more clinical and localised; whether it be on skin, plastic, wood or even some other harder appearing materials. But in each case the damage is usually something that shows a good degree of correlation to the profile of the beam that hits the material.

The LCD on the other hand will have been a thin brittle combination of materials, which when subject to a very high and localised radiant exposure, would not have been able to accommodate rapid expansion and dissipation as with other more tolerant materials. The result being a changing of the tensile stresses in the brittle material, setting off a chain reaction of fractures appearing.

Hopefully the projector is repairable and can be put into service again without too much fuss for everyone concerned.

[norty303]

One of the reasons the damage pattern may not be typical could be due to the mounting of the projector, which was on a hangman's type scaffold (upside down L shape) which had some flex in it. So a static beam would track out from a central point as the projector moved in certain axis and combinations, diagonals particularly given the rotation points inherent in the structure.
That still doesn't explain the side damage though.

I'm curious, of the people who have commented on this thread, aside from Jon who has stated his lack of experience in the matter, what experience/credentials do you have in this specific area to make the comments more than broad conjecture? This to help me determine what is objective/subjective.

As I said earlier in the thread, I would love to take the opportunity to shoot the crap out of that LCD with a video camera to capture the results, because as James says, we simply don't get the chance to do this very often

[norty303]

I wonder if I could find a visuals/projector forum to post it on, and see if their evaluations matched those here. It would provide an interesting counterpoint (or not!) to the views here.

[JStewart]

Adam,

I wasn’t ruling in or out the cause of the damage, as I haven’t seen the results of laser encounter with an LCD based projector. The second post was simply to suggest that because it does not look like familiar laser induced damage, doesn’t necessarily mean it isn’t.

Think taking a hot blowtorch to a sheet of aluminium or wood, and a hole will appear. Do the same to a sheet of brittle glass, and you are more likely to fracture it. A similar process could have taken place at a much smaller level on the substrate of the LCD, which would explain the fracturing.

James