Can a Laser Pointer Damage an LCD Screen?

[JB]

I am interested in using a Class2 or 3a laser pointer on an LCD screen which
is not covered by glass. The power output would be <5mw. I would be
standing behind the computer user operator and aiming over her shoulder.

She is unlikely to turn and face the laser as it would not be easy for her.

Is there any danger of damage to the screen from the direct beam or to the
eye from the reflected beam?

Thank you.

Mike

[Sam Goldwasser]

Post by JB
I am interested in using a Class2 or 3a laser pointer on an LCD screen which
is not covered by glass. The power output would be <5mw. I would be
standing behind the computer user operator and aiming over her shoulder.
She is unlikely to turn and face the laser as it would not be easy for her.
Is there any danger of damage to the screen from the direct beam or to the
eye from the reflected beam?

No damage to the screen.

But the reflected beam could be unpleasant in the eye, though not dangerous
if your pointer is indeed less than 5 mW.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
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[JB]

Post by Sam Goldwasser

Post by JB
I am interested in using a Class2 or 3a laser pointer on an LCD screen which
is not covered by glass. The power output would be <5mw. I would be
standing behind the computer user operator and aiming over her shoulder.
She is unlikely to turn and face the laser as it would not be easy for her.
Is there any danger of damage to the screen from the direct beam or to the
eye from the reflected beam?

No damage to the screen.
But the reflected beam could be unpleasant in the eye, though not dangerous
if your pointer is indeed less than 5 mW.
--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html
Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.

Thanks Sam. Interesting website you have.

I did not realize the reflected beam would be that intense. After browsing
your comments on laser safety I think I will forget the idea. We don't need
any more vision problems than we already have.

[Sam Goldwasser]

Post by JB

Post by Sam Goldwasser

Post by JB
I am interested in using a Class2 or 3a laser pointer on an LCD screen which
is not covered by glass. The power output would be <5mw. I would be
standing behind the computer user operator and aiming over her shoulder.
She is unlikely to turn and face the laser as it would not be easy for her.
Is there any danger of damage to the screen from the direct beam or to the
eye from the reflected beam?

No damage to the screen.
But the reflected beam could be unpleasant in the eye, though not dangerous
if your pointer is indeed less than 5 mW.
--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/

Thanks Sam. Interesting website you have.
I did not realize the reflected beam would be that intense. After browsing
your comments on laser safety I think I will forget the idea. We don't need
any more vision problems than we already have.

Only potentially from a shiny screen, and even then, it's not going to
be dangerous. However, with all the litigation today, it really isn't
worth the risk should someone claim they were injured.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.

[Lostgallifreyan]

Post by Sam Goldwasser

Post by JB

Post by Sam Goldwasser

Post by JB
I am interested in using a Class2 or 3a laser pointer on an LCD screen which
is not covered by glass. The power output would be <5mw. I would
be standing behind the computer user operator and aiming over her
shoulder.
She is unlikely to turn and face the laser as it would not be easy for her.
Is there any danger of damage to the screen from the direct beam or to the
eye from the reflected beam?

No damage to the screen.
But the reflected beam could be unpleasant in the eye, though not dangerous
if your pointer is indeed less than 5 mW.
--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/

Thanks Sam. Interesting website you have.
I did not realize the reflected beam would be that intense. After
browsing your comments on laser safety I think I will forget the
idea. We don't need any more vision problems than we already have.

Only potentially from a shiny screen, and even then, it's not going to
be dangerous. However, with all the litigation today, it really isn't
worth the risk should someone claim they were injured.

Litigation aside, there might still be a way.

There are restrictions to within 1 mW, even 0.5 mW, that are so safe that
if you can prove the laser is at this low level it might be legally safe no
matter what is claimed against it.

If you use very limited levels at 650 or better, 635 nm, you could focus
the laser to a fine point at around two feet beyond the output. This way
you might get a good visibility from 100 microwatts or less, on a screen
that can easily be seen, as the ambient light will be low enough. The
sharpness of the spot makes it easier to resolve, and it will be closer to
pixel size. Any reflection will be more spread because the incident light
isn't collimated, so it will be far less likely to be uncomfortable. You
can always minimise that anyway, by pointing from over or well aside from
the head so that reflections are not anywhere near the face.

The cheapest and safest way to do it in practise might be a cheap 1mW 650
nm focussable pointer, and an ND1 neutral density filter. If that's firmly
glued across the output to seal it, and tested by throwing on a hard floor
to make sure it survives, you can probably demonstrate a degree of safety
that will be legally hard to challenge.

[Kai-Martin]

tested by throwing on a hard floor to make sure it survives,
you can probably demonstrate a degree of safety that will be
legally hard to challenge.

I'd rather not through my lasers on the floor. They might prove totally eye
safe afterwards by not emitting any coherent light at all ;-)

Seriously: If you are worried about safety, but need good visibility, a
green laser might be an option. The human eye is much more sensitive to
500nm than 670nm. So you need less power for your application.

---<(kaimartin)>---

[Lostgallifreyan]

Post by Kai-Martin

tested by throwing on a hard floor to make sure it survives,
you can probably demonstrate a degree of safety that will be
legally hard to challenge.

I'd rather not through my lasers on the floor. They might prove
totally eye safe afterwards by not emitting any coherent light at all
;-)
Seriously: If you are worried about safety, but need good visibility,
a green laser might be an option. The human eye is much more sensitive
to 500nm than 670nm. So you need less power for your application.

And an awful lot more money and reduced reliability. But yes, not losing as
much as if thrown on the floor. :)

[Joshua Halpern]

Post by JB
I am interested in using a Class2 or 3a laser pointer on an LCD screen which
is not covered by glass. The power output would be <5mw. I would be
standing behind the computer user operator and aiming over her shoulder.
She is unlikely to turn and face the laser as it would not be easy for her.
Is there any danger of damage to the screen from the direct beam or to the
eye from the reflected beam?

Why not just use the mouse pointer on the computer screen.

Josh Halpern

[STEVE ROBERTS]

why not use one of teh old Lightbulb (or led) based pointers designed
for education. they show up on ebay once in a while and are probably
still made if you have a teacher friend with a sargent welch catalog or
other teaching supplies catalog

Steve Roberts