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Recommend a pointer to defy laws of physics

mmabc

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Apr 29, 2014
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I have an odd job this week. My job assignment is to select a laser pointer than can defy the laws of physics. I have until Friday. Have you seen the youtube video about the technical expert who is assigned the job of drawing 7 red lines? If you haven't, you should. It's hilarious. Essentially, that is my assignment.

I support a large conference room. It has a large glass projector screen. Long before me I believe it was installed backwards in the room with the matte side facing into the projector room and the glass side into the conference room.

There is a long standing issue getting laser pointers to work on this screen. Most pointers show up very dimly on the screen, barely visible. The screen is also highly reflective, and even pointers that show up dimly reflect the laser into the room and the audience.

We have found one green laser that generates a bright wide circle on the screen, but it reflects so strongly into the room that people complain. It seems to me that every laser is going to do exactly the same thing, either too dim to see well or too reflective to not get complaints.

So, help me solve this problem. Don't drag me down with all your technical mumbo jumbo negativity! It's just a laser pointer. If I need Harry Potter's magic wand, just make it happen! By Friday! Or else!

Seriously though, if there is some specific laser pointer characteristics that could help with this problem, let me know and perhaps recommend a product and a source where I can get one. Thanks.
 





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Have the glass scoured so that it becomes ever so slightly rough and hence less reflective. Or, install the screen the right way round.
 
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You may not get a "perfect pointer solution" however, green or yellow are the colors the eye sees best, and therefore you can use relatively lower mW output and "see it" (no more than 3-4 mW s/b good. I think yellow may be near as visible as green, also, try to hold the pointer low so the reflection goes high, if this works the reflection will go over the observers' heads. the only thing more ideal, is to somehow have the pointer behind or reflect to behind the screen... good luck!
 
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Video for reference:


So you want a pointer to reflect diffusely off of a reflective surface. I got nothin'.
 
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Like Cyp said, it's a reflective surface. It means it'll reflect light and that's it, there is just literally no other way around it.

You can try 405nm pointer maybe, they are dirt cheap on eBay. Perhaps you're lucky enough they'll produce some sort of flourescence on the glass, as I've seen it happen a few times - violet laser passing through glass sometimes produces green or orange-colored beams that glow more brightly than the percieved brightness of the laser.

Otherwise, I sincerely hope you are in an adequate enough of a position to instruct politely any presenter to, feel free to quote, "Get off their lazy fat ass and use their hands to point out things", solving about 19 problems at once.

Or just write up presentations in such a way that they don't neccessitate specific things pointed out among large number of them. In my entire academic life, I have seen a laser pointer being used at a presentation only about handful of times, out of which precisely 0 times the laser was actually neccessary to convey the information.
 

djQUAN

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select a laser pointer than can defy the laws of physics.

I was going to suggest you get those 10,000MW laser pointers from China that are powered off of 18650 batteries. :)
 
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Like Trencheel said. Go to the local hardware shop, get a few sheets of 1200 wet and dry paper, go back to the board with a bucket of water, divide your wet and dry paper into smaller rectangles wet them and keep them wet and lightly and evenly go over the whole glass.
A quick fix could also be some chalk dust or talcum powder dusted lightly over the board!
 
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Teej

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Are images projected onto it from the rear, towards the audience, or, at it, from the audience side?

If from the audience side, just get a regular projector screen, and drop it down in front of the glass, and project onto that.
 
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mmabc

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Thanks folks for your responses. Actually, the screen may not be glass. It may be some sort of plastic. As far as sanding the screen, I'll mention that as a possibility, but I'll let management take the responsibility for that one given the cost of this screen and the visibility of the meetings they hold in this room.

We have a Logitech presenter tool with a green laser that says: <5mw @ 522-542nm. That is barely visible, and it also reflects into the room. They have another pointer made by TechLaser. I can't find any stats on that. It is obviously much more powerful. It shows up clearly but the reflection is so powerful someone has written a safety report about it.

So, given my engineering experience with physics over 25 years ago, I'm still holding my position that any laser will have the same problems. Either it will be too dim to see, or you will have a reflection at likely higher than 5mw hitting the audience. It's my understanding that this is potentially a safety issue for the audience. Would you all agree?
 

mmabc

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Are images projected onto it from the rear, towards the audience, or, at it, from the audience side?

If from the audience side, just get a regular projector screen, and drop it down in front of the glass, and project onto that.

This is a very high dollar room with a brand new 4K projector that was well over $100K. It is projected from behind the screen. I'm getting a quote on replacing the 16ft screen with a similarly high dollar top of the line screen. That will likely be rejected by management over cost. It's been deemed so much more effective for me to just buy a different laser pointer. How hard could it be? I am the technical expert after all.
 
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Oh and I also thought that you were a financially challenged organisation. But instead it is an institution full of educated but brain dead people which always, no matter the country deserves the name "Government" attached to it! Change it the way it is supposed to be installed you Troll.
 
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Easy Bus, no need to get testy. It's not his fault he's brain dead. It's the institution....
 

Teej

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Easy Bus, no need to get testy. It's not his fault he's brain dead. It's the institution....

I agree, there's no time to waste on things like being angry at stupid....to be angry at ALL the stupid would simply mean no time for anything else...there's a lot of it out there.


The thing is, they don't KNOW they're stupid....its like that Bruce Willis Movie...


Its like the kid says to him "I see stupid people", and, Bruce doesn't know he means HIM.

:D




I_see_dumb_people.jpg



:D





Of course, to be fair, I see smart people who DO say to their bosses stuff like "Um, lets turn the glass around the way it was supposed to be (Or get the contractor who did it wrong to come back and correct it, etc...)", and, for whatever corporate/governmental mental internia that can't be overcome, they say, "No, YOU come up with a creative way of making it work w/o us actually fixing anything"

And the smart guy is stuck with a pointy haired boss figure, etc...and, ends up doing a cockamammy work around.
 
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