erics@bucsb.UUCP (Michael L. Ardai) (01/09/90)
(This is posted for a friend with read-only news access) I was in the supermarket today, and while walking past the checkout counter, I got zapped in the face with the laser. Does anyone know if this is unsafe? The first thing that I learned about lasers was never to shine one in someones eyes. (The second was that laser tubes retain a charge after they are unplugged, but that is a different story :-} The tube looked like it was about a 5 mW unit. Any idea what to do about this (other than wearing blue sunglasses) /mike Michael L. Ardai Teradyne EDA ...!sun!teraida!maven.decnet!ardai -- ooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo o Eric Schneider o This is only where I get my mail. o o The Terminal Beach o My opinions are in no way related to my compilers. o o erics@bucsb.BU.EDU o And how many DEC repairmen does it take to... o ooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo
siegman@sierra.Stanford.EDU (Anthony E. Siegman) (01/09/90)
I'd be very surprised if a supermarket laser scanner were hazardous. The manufacturers must be very knowledgable about the safety issues -- including the knowledge that they have deep pockets, lasers have a death ray image, and a supermarket checkout stand is a very public place, all of which would make them very vulnerable to damage claims, real or spurious. I'd expect their concern for safety (including every possible form of fail-safe design) to be very extreme. In addition, a few milliwatt cw visible laser is really not that hazardous. It certainly can't burn skin or the outer surface of an eye, and even if optimally focused within an eye on a continuous basis my guess is it would still not do real physical damage (burning or phase transformation) to the retina. In addition, your natural blink reflex will close the eyelid very rapidly. And, the actual output beam from a supermarket scanner unit may be more in the 10 to 100 microwatt range. I've never heard of eye damage (or any other kind of damage) from a milliwatt-level He-Ne laser. It's the multi-watt cw ion lasers, or the high energy pulsed lasers, that you really have to be careful with. In general, injuries from laser beams have been very, very few. But, several people (including at least two students I know of) have been electrocuted by laser power supplies in laboratory accidents.
king@dciem.dciem.dnd.ca (Stephen King) (01/09/90)
In article <446@sierra.stanford.edu> siegman@sierra.UUCP (Anthony E. Siegman) writes: >I'd be very surprised if a supermarket laser scanner were hazardous. They aren't. The output of the laser tube is VERY carefully controlled. The scanning is done via a rotating mirror, so the beam never lingers on one spot, but is always in motion. There are numerous safety features which shut the laser off should emmission exceed a certain amount, or should the scanning motor fail. Nevertheless, it's still not a good idea to look directly into one when it is operating.
seibert@XN.LL.MIT.EDU (seibert) (01/09/90)
You ask if they're dangerous? Ever wonder why the clerks ring fresh fruits and vegetables by hand...? ((I see melted bananas, sprouts catching fire, boiled oranges...)) I can't believe OSHA lets the clerks stand so close to the laser units or that innocent customers, like yourself, can be zapped accidentally! You're lucky you weren't maimed. _MS ((winking smiley with glasses)) -- Michael Seibert seibert@xn.ll.mit.edu ll-xn!seibert
mikemc@mustang.ncr-fc.FtCollins.NCR.com (Mike McManus) (01/10/90)
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mikemc@mustang.ncr-fc.FtCollins.NCR.com (Mike McManus) (01/10/90)
In article <446@sierra.stanford.edu> siegman@sierra.Stanford.EDU (Anthony E. Siegman) writes: > In addition, a few milliwatt cw visible laser is really not that > hazardous. It certainly can't burn skin or the outer surface of an > eye, and even if optimally focused within an eye on a continuous basis > my guess is it would still not do real physical damage (burning or > phase transformation) to the retina. In addition, your natural blink > reflex will close the eyelid very rapidly. And, the actual output > beam from a supermarket scanner unit may be more in the 10 to 100 > microwatt range. Also, the laser scanners found in check-out lanes have beams which are being rapidly projected across the surface of the package (or in this case, your face :-) by a series of spinning mirrors. The amount of time that the laser is focused on any one spot, most notably your eyes, is minimal. The same thing is true, incidently, with those hand-held laser "guns" that some retail stores use. A guy I used to work with tried shooting one in his eyes ones, "just to see what it would do..." He said that it was a sensation similar to having a flash bulb go off in your eyes, but recovered after several minutes, and there was no permanent damage (burns on the eye or retina). -- Disclaimer: All spelling and/or grammer in this document are guaranteed to be correct; any exseptions is the is wurk uv intter-net deemuns. Mike McManus (mikemc@ncr-fc.FtCollins.ncr.com) NCR Microelectronics 2001 Danfield Ct. mikemc@ncr-fc@ncr-sd.sandiego.ncr.com, or Ft. Collins, Colorado mikemc@ncr-fc@ccncsu.colostate.edu (303) 223-5100 Ext. 360 (they're ugly, but they work!)
jharkins@sagpd1.UUCP (Jim Harkins) (01/10/90)
In article <189@bucsb.UUCP> erics@bucsb.UUCP (Michael L. Ardai) writes: >(This is posted for a friend with read-only news access) > >I was in the supermarket today, and while walking past the checkout >counter, I got zapped in the face with the laser. Does anyone know >if this is unsafe? I doubt they are directly unsafe, but indirectly I'm not sure. Whats going to happen when Sue Supermarket Checker gets used to her laser zapping her and her customers in the eyes with no ill effects, then meets Larry the laser wiz? I think most people see lasers as a "badanddangerous thing" and this is a good attitude for most people to have. I know that when I had my 5 mW he-ne laser most people got upset if I shined it on them, and when I put my hand in the path of the beam their eyes got wide as the proverbial saucers. jim "Only dead fish go with the flow"
whit@milton.acs.washington.edu (John Whitmore) (01/10/90)
The lasers are hazardous, because the spectral purity and focus of a laser allow eye damage (not irreversible eye damage) at energies of one microwatt-second. This energy, reflected off a curved surface into a researcher's eye from a pulsed laser, actually caused a temporary blind spot. The checkout counters are NOT hazardous, however, because the typical laser scanner, rather than using a spinning mirror, uses a rotating hologram for its scanning (this allows a very complex scan pattern with a simple rotating hologram as the only moving part). The hologram's accuracy is sufficient for scanning, and sloppy enough that the deflected beam does NOT have the uniform wavefront that makes laser light focusable to a pinpoint. OSHA, I am sure, approves. I am known for my brilliance, John Whitmore by those who do not know me well.
thomas@mvac23.UUCP (Thomas Lapp) (01/10/90)
I looked at the label on the one in the supermarket that I frequent. I
was surprized to see it read something to the effect that one "should
not look into the window for a prolonged period of time", rather than
the usual warning about not looking at it at all.
- tom
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The UUCP Mailerdoug@letni.UUCP (Doug Davis) (01/10/90)
In article <2826@dciem.dciem.dnd.ca> king@dretor.dciem.dnd.ca (Stephen King) writes: >In article <446@sierra.stanford.edu> siegman@sierra.UUCP (Anthony E. Siegman) writes: >>I'd be very surprised if a supermarket laser scanner were hazardous. > >They aren't. The output of the laser tube is VERY carefully controlled. >The scanning is done via a rotating mirror, so the beam never lingers on >one spot, but is always in motion. There are numerous safety features which >shut the laser off should emmission exceed a certain amount, or should the >scanning motor fail. Nevertheless, it's still not a good idea to look >directly into one when it is operating. Actually they aren't even as sophisticated as a spinning mirror, I have several surplus NCR laser scanners, the way these are set up the laser light goes into a beam splitter which splits the light into two directions the both light beams strike separate mirrors that vibrate at 60hz making up the x-y axis of the scanning beam. The separate beams are recombined and sent upwards at several angles based on yet another vibrating mirror. The reflected light from the scanned barcode is then directed back into a photo-multiplier producing the electrical pulses used the figure out what just passed over the scanner. The vibrating mirrors are great, hook one thru a transformer to each channel of your stereo and you have an instant laser light show. Of course you could always tape mirrors to the cones of the speakers ;-) Oh yeah, the lasers are .9mw output power (Class II - Non harmful.) BTW, Class III lasers are >= 1mw and are classified as slightly harmful. Read the food and drug adminstration book 21CFR section 93.(somthing) for all the regulations concerning lasers. And if you want to BUY a laser I have several .9mw He-Ne lasers and 24vdc power supplies left from a project I was working on, email me for details. doug __ Doug Davis/1030 Pleasant Valley Lane/Arlington/Texas/76015/817-467-3740 {texsun, motown!sys1, uiucuxc!sys1 lawnet, attctc, texbell} letni!doug
jad@dayton.UUCP (J. Deters) (01/11/90)
> Article <189@bucsb.UUCP> From: erics@bucsb.UUCP (Michael L. Ardai) >I was in the supermarket today, and while walking past the checkout >counter, I got zapped in the face with the laser. Does anyone know >if this is unsafe? The first thing that I learned about lasers was >never to shine one in someones eyes. (The second was that laser tubes >retain a charge after they are unplugged, but that is a different >story :-} The tube looked like it was about a 5 mW unit. Any idea >what to do about this (other than wearing blue sunglasses) > >Michael L. Ardai Teradyne EDA ...!sun!teraida!maven.decnet!ardai I've been working with various scanner manufacturers for a couple of years now, and I've found that all the lasers used in all of the different types of scanners used in a retail environment (hand-held, flat bed, etc.) are "Class II". This means that they are safe within normal eye reaction time. They have a 1.0 mW max output, and health-wise do not constitute a threat when used as directed. The directions (and various warning stickers) all say "DO NOT STARE INTO BEAM." So of course, I stare into the beams :-). Normal blink reflex closes your eyelids after maybe 1/4 second. By forcing myself to consciously stare into the beam, my blink reflex takes over after about 1/2 second. The beams are painful, but do not cause any permanent damage in limited amounts. You may be interested in knowing about the safety circuits built into the different scanners. All "checkout" laser scanners use a "moving beam" -- a beam that is constantly deflected by a moving mirror of some sort. This insures that you, the user, will not have the opportunity to stare into a straight beam. Consider the fan-out of the beam vs. the diameter of the pupil. Worst case is if you take the hand-held type and hold it as close to your eye as possible. The fan-out is already at 2", and your pupil is probably about 1/8". This means you will never see more than 6% of the total beam, and that takes a lot of effort. The typical grocery store flatbed scanner has between 16 and 64 scan beams (although some grocery store flatbeds operate at 5.0 mw, as you guessed). If you are of average height you probably stand 30" above the scanner face. At that distance, the fan-out of any one beam is approximately 30". Assuming 16 scan beams, your pupil received .02% of the output of a 5mw laser, or 1.3 microwatts. Not exactly enough to run off to OSHA about (but maybe enough for a lawyer?? :-) There is also control circuitry that either shuts off the laser or closes an aperture if the mirror motion is prevented or if the mirror motor fails. I jammed a mirror against the side of the case to try to get a straight beam out of a hand-held unit, and the laser would not stay on, so their circuit must have been functioning properly. I certainly wouldn't worry about occasional eye contact with the beams used in any retail application. DISCLAIMER: This letter does *NOT* reflect any opinion whatsoever of the Dayton-Hudson Department Store Co. It's just stuff I've learned from the various vendors I deal with, and the occasional shining we get playing with them. I'm not trying to defend our use of lasers, it's just that I don't want to hear a panic like they are starting with VDTs. -j -- J. Deters INTERNET: jad@dayton.DHDSC.MN.ORG .\ /. "Smile -- Cthulu loathes you!" UUCP: ...!bungia!dayton!jad \_____/ ICBM: 44^58'36"N by 93^16'12"W
sean@ms.uky.edu (Sean Casey) (01/20/90)
Two people posted that scanners do not use spinning mirrors. One claimed holograms, and the other claimed vibrating mirrors. I believe it, but I used to work at a store that used spinning mirror type scanners. The mirrors were highly polished faceted blocks of metal. Sean -- *** Sean Casey sean@ms.uky.edu, sean@ukma.bitnet, ukma!sean *** Copyright 1990 by Sean Casey. Only non-profit redistribution permitted. *** "You see before you two identical Tiamats." "Uh oh."