I bought today a Logitech MX1000 mouse. The first thing I realised when I plugged it in, was that the mouse emmits no visible light.
According to the manual, the laser wavelength is in the 832-852nm range and the peak output is 716μW.
Is 716μW powerful enough to cause any permament damage to the eye? Also, how can I avoid staring at the laser beam since the laser is invisible? Wouldn’t a laser in the visible spectrum be a better choice for a mouse?
I would guess that a laser is dangerous because it overstimulates and burns out the rods and cones in the eye. If the laser is of a wavelength that can’t be seen, then they’re not stimulating the rods and cones at all and harmless.
This is pure speculation; corrections welcome.
I have the same model - cool, isn’t it? A bit overpriced probably, but who cares.
The mouse does emit a very faint red glow, if you stare down the beam at it. The effect is similar to that produced by a grocery store UPC scanner.
No worries, though - the documentation and sticker on the bottom classifies the laser as a class 1 device, which means (quoted from here):
My slightly more educated pure speculation is that that’s wrong - it’s the energy carried by the laser beam (or really, composing the laser beam) that burns out the rods and cones in the eye, not their overstimulation. And all wavelengths of light have energy.
Infrared lasers are more dangerous, as the OP alludes, because you can’t see where the beam is, making it harder to take precautions to avoid it.
Also, there is this, from CNET:
Argh, I swear I’m not trying to hasten the coming of my 400th post, but I keep thinking of stuff I forgot.
The big part of the danger with infrared lasers is that, being invisible, they don’t trigger your eye’s blink reflex, and so even at output wattages that would be safe in a red laser, they can pose a threat. I believe, although this is completely a WAG, that some visible-spectrum class 2 lasers, even though not technically safe to look at, actually aren’t harmful because your eye will blink fast enough to avert any damage.
Wheter the laser light is within the visible spectrum or not doesn´t get into it; it´s the power output of the laser that matters. I used to work with a laser engraver/cutter, it used an invisible infrared CO2 laser, you couldn´t see it, but it sliced through 1cm thick acrylic like hot butter, I resisted the pinch to try it on my cornea.
Errr… I mean, the hunch to try it on my cornea… :smack:
I have a quarrel or two with this. This definition is for pure lasers, as used in science labs or wherever else you’d need laser light. An optical mouse isn’t a “pure” laser and the design use for it is flat against your desk. In normal operation, you’d never see the laser (visible light or not).
Obviously, if you turn the mouse over and trigger the laser, it kicks up to full power and as this one’s IR, you don’t really have a clue how strong it is until your eye hurts. As the old joke sign in science labs says “Don’t look at laser beam with your remaining eye.”
I’ve got a visible-light optical mouse and when it’s actively moving, its light is really, really bright, and is painful to look at. The way I managed to do this is I had it upside down with the intent of preventing accidental movement, and when I flipped it, the light was at full strength. It was painful and I did see spots for a while afterward.
What it all comes to is don’t try to look at the light coming out of the mouse, and you’ll be OK.
Actually, all I can see is a faint green glow. I think it comes from the green battery indicator LEDs.
As a physicist who works with invisible lasers regularly, I would say that 700 microWatts is probably not enough to damage your retina even after sustained viewing. Furthermore, since the divergence angle of a mouse-beam is large (meaning the beam is already quite spread out even close to the source), you’d really have to put the thing right up to your eye to even have a hope of damaging anything.
Ale, Absolute, thanks for the correction.
Ah. They’re not 1920’s style “death rays”.
(Ow! Stop hitting me!)
I thought that most (if not all) visible light optical mice used LED’s, not lasers?
They do. The Logitech one we’re talking about is the only optical mouse that uses a laser, visible light or not.
However, some of the LEDs that are used in optical mice are Pretty Freaking Bright. I think that’s what gotpasswords is referring to.
Different frequencies of lasers affect different parts of the eye for many of the same reasons as non-laser versions of the same frequency will damage your eye – just a lot quicker. Think of what happens when you expose your eye to non-laser IR, or non-laser UV.
It depends on whether the beam is collimated (made into a thin parallel beam, like a laser pointer). A bare laser diode emits a wide, divergent beam which is relatively safe to look at. If it’s collimated, that means the full output of the laser diode is focused into a narrow beam, which can all go into your eye.
My WAG is that this optical mouse does not contain any collimating optics, just a bare laser diode. Does anyone know for sure? For that matter, does anyone understand why this model uses a laser diode and not a plain infrared LED?
Of course someone understands. The marketing people always understand. See:
“Featuring the Logitech MX™ Laser Engine, the MX1000 delivers a new pinnacle of performance no optical mouse can match. With an incredible 20x more sensitivity to surface detail—or tracking power—than optical, laser can track reliably even on tricky polished or wood-grain surfaces. And the MX1000 offers even more advanced features that will make you more productive and more comfortable”
I believe CD drives contain class 2 lasers which can damage your eye if you stare at them for a prolonged period of time.
OK, so can someone here explain why they use a laser diode instead of an LED? I’d read the marketing blurb (the one you quoted) and it doesn’t explain why a simillar wavelength LED wouldn’t do the job.