Old 01-12-2010, 10:21 PM #1
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Default What laser pointer TRULY works with LCDs

Hello to all.

I have searched to no avail, online, this forum, locally, everywhere. Here is my situation. I have a videowall that is 2 42" monitors high, and 6 42" monitors wide. I will have someone about 7-12 feet away from that wall at most. He wants a device to be able to point and highlight/bring to people's attention specific sections. He asked for the dot to be the size of a golf ball or a little wider.

i have been looking for pointer that project items, like circles, crosses, etc. I found one from staples which does exactly what I want. It does a circle which is about 4 inches wide, and has a dot in the middle. The problem is....it only shows if I am pointing it to the monitor that is directly infront of me. If I go at an angle or point to a monitor that is about 2 monitors down, the circle fades or disappears. When I switch to the normal dot, it is alot brighter, but the same thing occurs.

My inference is that the LCD panels are simply absorbing the light (idk how, but its the only thing that makes sense, the slightest angle shift and you can see the difference).

So I want to know what are my options to be able to achieve my goal. How can I be sure it wont damage my screens?

*my laser was red
Staples Laser Pointer, Solid Brass, 5 Light Patterns | StaplesŪ


Thanks for your time, and sorry for wasting my first post on this question


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Old 01-12-2010, 10:31 PM #2
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Default Re: What laser pointer TRULY works with LCDs

Welcome to the forums.

Personally I think it is a matter of power, though your link does not show a laser, I am assuming it is a rather weak red laser (~1mw). Problem no. 1.

Add to this the rather poor quality of the diffraction gratings you are using, which not only have sub-par transmission but disperse the lasers photons, resulting in a low energy density...this is why you are having quite a hard time.

My personal suggestion would be a 5mw 532nm focusable pen laser. Though none comes to mind, maybe another member can help you out on that part.

This should be bright enough for the designated use. But it will be a good idea to never focus the laser to a tight dot while it is pointed at the LCD screen, as in the past members have managed to fry the pixels on their screen with lasers (though much higher powered), but still better to be safe IMO.
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Old 01-13-2010, 03:59 PM #3
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Default Re: What laser pointer TRULY works with LCDs

The black-and-white LCDs have a polarizing filter on them. Maybe the color ones do as well? That may account for some of the loss of brightness. I would suggest a 5mW green pointer with a small lens taped or glued to the front. The focal point of the lens would need to be pretty long to make something as small as a golf ball at 7 feet.
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Old 01-13-2010, 09:58 PM #4
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Default Re: What laser pointer TRULY works with LCDs

hmm. very helpful, and it does make more sense to me. Any recommendations for an adjustable green laser?

It is just weird that when i am 2 feet away and shine the laser at an angle, it just seems to get lost in the screen somewhere never to be found again.

I am def. going to spend some time researching some green lasers that will let me adjust the dot.

Thanks to you two guys, and anyone who is going to contribute.
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Old 01-14-2010, 03:33 AM #5
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Default Re: What laser pointer TRULY works with LCDs

Sorry, it is unlikely that any laser will work on an LCD screen. It doesn't matter how much power you use or how you focus the beam.

This question is like "Why can't I see the laser beams dot when I point it at a mirror?"
All of the light is being reflected. (That's why the dot is very strong when you point it straight towards the monitor - the light is being reflected into your eyes)

LCD screens (even ones with anti-glare coatings) have very specular reflections as they are panes of glass. A glossy monitor will reflect your laser pointer near-perfectly. What you describe as the light "getting lost in the screen" is just the light reflecting away. If you point the laser down towards a screen you might be able to see the laser reflected onto the floor/table.

And there lies the problem, any laser powerful enough to project a visible dot at all angles will be powerful enough to be very uncomfortable to whomever gets hit by the reflection (and even worse if someone is unfortunate enough to get the direct beam).

You might be able to play tricks by defocusing perhaps 20mW of green, but you are looking at a custom job that might work on a non-glossy screen.
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Old 01-14-2010, 04:36 AM #6
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Lightbulb Re: What laser pointer TRULY works with LCDs

Quote:
Originally Posted by sblerouge View Post
I have a videowall that is 2 42" monitors high, and 6 42" monitors wide. I will have someone about 7-12 feet away from that wall at most. He wants a device to be able to point and highlight/bring to people's attention specific sections. He asked for the dot to be the size of a golf ball or a little wider.

i have been looking for pointer that project items, like circles, crosses, etc.
Hmmm... Were you involved in installing / maintaining the wall or back end feeding the wall? Could I have a bit more info about the back end for your video wall? You could get the back end computer to display a circle or any shape for that matter. As for the pointer, a Wii remote can fulfill that role nicely. Software is available for windows & linux that allows a Wii remote to act as a mouse by pointing it at your screen & works via bluetooth.
Now it would be a bit more work then a laser pointer but it would work & a laser might not work or cause unavoidable dangerous reflections. Tho if your video wall is mounted high enough all reflections might be directed at the celling & not be a problem.

Let me know what you think.

Last edited by HaloBlu; 01-14-2010 at 06:05 AM. Reason: typo
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Old 01-14-2010, 12:47 PM #7
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Default Re: What laser pointer TRULY works with LCDs

Thanks to the previous two posts. I really appreciate your time and knowledge. That is what I feared, a laser probably wont do the job.

The back end is somewhat...weird...we are using 2 thin clients connected to servers in colocation. There are 3 guys that will be using the wall, but only 2 that will be controlling it. The guy that is not directly controlling it will be the one directing the other two on where to look or what to focus on. So there is technically two separate computers controlling the 12 monitors, I guess I can look into something where he can have two wii like remotes or a handheld programmable presenter with a 360 mouse on it......this is just an idea we had so you guys are really helping me with new ideas.

lol, all this research and im not even a member of the IT team...
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Old 01-14-2010, 12:50 PM #8
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Default Re: What laser pointer TRULY works with LCDs

Quote:
Originally Posted by HaloBlu View Post
Hmmm... Were you involved in installing / maintaining the wall or back end feeding the wall? Could I have a bit more info about the back end for your video wall? You could get the back end computer to display a circle or any shape for that matter. As for the pointer, a Wii remote can fulfill that role nicely. Software is available for windows & linux that allows a Wii remote to act as a mouse by pointing it at your screen & works via bluetooth.
Now it would be a bit more work then a laser pointer but it would work & a laser might not work or cause unavoidable dangerous reflections. Tho if your video wall is mounted high enough all reflections might be directed at the celling & not be a problem.

Let me know what you think.
do you have anymore info on the wii and the software for it that can make it work via bluetooth or other connections
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Old 01-14-2010, 04:44 PM #9
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Default Re: What laser pointer TRULY works with LCDs

I can grab more info on a wii setup when I get home but since your not on IT they will most likely want to go with the much more traditional solution of a 360 air mouse. The wii remote is controlled more like a laser pointer but there is no commercially available wii setup so I doubt IT will want to go that way.

Last edited by HaloBlu; 01-14-2010 at 04:47 PM.
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Old 01-15-2010, 03:20 AM #10
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Default Re: What laser pointer TRULY works with LCDs

understood. thank you for your time.
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