Lasers in light show can damage sensor

[bob_prichard]

<p>Thought this might be helpful as a warning to some.<br /><br />http://blog.planet5d.com/2010/07/lasers-can-damage-your-canon-hdslr-cameras-cmos-sensor/</p>

[JDMvW]

<p>Here's the link live <a href="http://blog.planet5d.com/2010/07/lasers-can-damage-your-canon-hdslr-cameras-cmos-sensor/">link</a><br>

Note that the laser has to be pointed right in the sensor to do damage, it's not just taking pictures at a laser concert or such/</p>

[bobatkins]

<p>They can also burn out your eyeball and (if powerful enough) cut through steel!</p>

<p>Laser light shows use fairly high power gas lasers. I'm guessing 10-20W Argon and Krypton lasers (I used to work with them in an optics lab). They'll burn you, blind you and set wood on fire.</p>

<p>I'm not in the least surprised they can damage a sensor if directed at it.</p>

[faysal]

<p>I'm thinking all that glass in front of it messes with it.<br>

edit: I meant, doesnt help.</p>

[steve m smith]

<p>It helps a lot. By focusing it into a spot on the sensor. Same with pointing it at the sun.</p>

[jim_krupnik]

<p>The blog offers an interesting warning, but I suspect an "urban legend" in the making... My (prior to semiconductor solid state) laser experience is limited to experimenting with holography and communications techniques with relatively low powered gas devices, and working with early models of IBM high speed, high volume mainframe printers of the 1980's that used pretty hot (for a helium/neon laser) SpectraPhysics units at their core.</p>

<p>I'd be interested in reading opinions from people with direct laser/CMOS sensor lab experience, but some parts of the story just don't sit well with me. I'm only writing about visible light lasers above class II here, as CO2 and other invisible beam devices likely fall under additional regulations. Also, there are are a slew of near infra red visible light lasers that can deliver Buck Rodgers levels of heat energy, like some of the ruby lasers, and many others, but you won't find them at a laser show....</p>

<p>First, lasers are (unless things have recently changed) regulated by the FDA in the United States as radiation sources. They are regulated by class, and also by their application. Class I, and class II lasers are pretty benign in terms of health risk, are used in most consumer devices, and devices where people may be exposed to laser radiation without advanced warning, or taking special precautions. Even then, exposed class I and II devices are required to have some built in means of preventing accidental long term uninterrupted eyeball exposure to the poor slob who wanders by.</p>

<p>Grocery store checkout scanners are a fine example. You can see the laser beam in operation, but it is always moving, and appears as a fixed pattern. Even if you stand there for awhile and stare at the source, your retina will never be exposed to enough power over time to cause damage.</p>

<p>Beyond that, there are class III lasers, of which I have had a few since 1980. That level has the potential to cause tissue damage under certain circumstances of beam focus and duration, and their commercial applications are regulated to avoid those situations. Still, in practice, class III lasers are not particularly dangerous to people experiencing casual exposure. Even the higher end of the class (it is divided into two power levels, with the top level covering up to 1/2 Watt of power), are unlikely to cause tissue damage in a short enough period of time that a person would not turn away or move first. That is not to say that they are perfectly safe, but in a practical sense, a person would likely have to either be targeted by a bad guy, have a desire to hurt themselves, or a combination of both in order to get the job done with a class III laser producing visible light.</p>

<p>Laser shows in smaller areas, dance halls, big parties, etc, usually top out by class IIIA, and sometimes class IIIB. I have a class III self contained commercial light show device for large wedding sized rooms and parties that is modulated by either ambient music, or sound wired from the DJ booth. It's source laser delivers green light at class III levels, but before the beam exits the case, it is divided into 14 (as I recall) separate beams that are individually computer modulated to provide a visual match the sound input. Even when there is no sound source, the beams continue to slowly move at idle.</p>

<p>That creates two important conditions. One, no single beam contains more than a class II energy level, and two, it would be nearly impossible for any person to maintain continuous exposure to any single beam long enough for tissue damage to occur. That is why such devices are are not (were not) subject to further regulation at the user level. They are effectively idiot proof.</p>

<p>Large laser show productions still often use multiple class III lasers for single beam effects, which are amazingly bright, even when modified with lenses for wider beam width. Now that costs have gone down, and options have gone up, class IV lasers (over 1/2 Watt) are popping up everywhere in complex laser shows, and a single device beam can be used intact, or broken into an amazing array of distinct modulated light patterns to suit a show. Most high end commercial laser show devices for even stadium sized venues are in the 1-3 Watt range, and top out at about 5 Watts (not too long ago). For fixed illumination and mobile signage, I have seen commercial visible light lasers with outputs as high as 90 Watts, but they are not in the IR heat producing wavelengths that can melt matter, nor are they in the UV end of the spectrum where they can deliver "cold" energy capable of ripping molecules apart at the atomic level.</p>

<p>Also, I can't imagine where anything over a couple of Watts would be used in any situation where it would be possible for anyone to be exposed to damaging levels of laser radiation without donning proper protection beforehand, no matter if they were members of the public, staff, or special access guests like event photographers. Granted, technology has made it possible to modulate very high powered RGB laser arrays to produce titanic sized full color still and video presentations with a bright, true to life color gamut on nearly any surface, from buildings, to mountain faces, to clouds. In those cases, the zone reaching from the projector to the "screen" where direct viewing of the projector source would result in excessive exposure is carefully protected to prevent accidents.</p>

<p>At that level of power, strict geographic venue limits on potential exposure, maximum absolute intensity of possible direct exposure, and maximum possible duration of direct exposure to significant radiation at laser shows have all been regulated since at least the 1980's. Violations were subject to criminal proceedings, as well as civil fines of nearly a half million Dollars each way back then. I doubt it has become any easier today..... That's not to mention the flood of lawsuits that would follow, no matter how much "we are not responsible" fine print was included in the ticket price to the show. I would bet that various permits, inspections, and minimum insurance coverage is now the order of the day.</p>

<p>As a side note, outdoor US laser displays/shows that use even relatively harmless class II and III power level devices require prior approval from the FAA if there is any chance that they might be painting air traffic with their laser beams. My recollection is based on the way things were 25 years ago, but I'd bet they have become even tighter, and not easier since then.</p>

<p>OK, the last bit that leads me to think that the entire "CMOS camera dies at laser show" story is bunk may well hang me, as I only have anecdotal evidence to support it. As anyone who has left an SLR on the seat of a car with the lens looking at the sun knows, it is very possible for a lens with an oblique view of the sun the cause an "off the lens axis" spot of sharp focus to form somewhere in the mirror box, and within a few minutes, that spot can melt the mirror box into a useless gob of goo. I even recall some posts on other sites where the hapless camera owner who left her/his camera on the car seat with the lens pointing up bitterly complained that Canon or Nikon refused to offer free warranty service for their dead expensive cameras, as a solar meltdown isn't really a factory defect. Tsk tsk, imagine that?</p>

<p>The sun delivers an enormous volume of energy across a wide slice of spectrum to the earth, and plenty of it is in the form of infra red heat energy. Even with a small lens attached, it is quite possible for the sun to enter from an angle that causes the projected image of the solar disk to become focused to a point somewhere behind the lens, and rather than create a large image circle that will make a nice film or sensor capture if you tripped the shutter, it becomes an intense energy spot beam that delivers so much more heat energy to the target point than the target can get rid of that the target is pretty much gone in 60 seconds....</p>

<p>Light show lasers, on the other hand, are very precise in wavelength. There is a great deal of waste heat produced in creating a laser beam due to process inefficiency, but unless your laser is designed to deliver coherent infra red heat energy like a carbon dioxide laser (old school) that can punch holes in diamonds and steel plate, the beam is pretty cold. Show lasers do not cut steel, nor do they set stage props on fire. Even if they did have that ability, I doubt the power levels used at a laser show could do any harm at all in the span of one second. Or even three seconds..... You can't burn a hole in a sheet of black toilet paper with a direct beam from a high powered show laser!</p>

<p>So here is the catch. I'm not aware of any special sensitivity to permanent damage by laser light in CMOS devices. I know that there are biological issues that can place living tissue at risk from intense laser radiation, even when heat is not a factor, especially in the bio stuff that forms a retina, but those conditions simply do not exist at a laser light show. If they did, they would not be tolerated, nor would they be excused by an "enter at your own risk" contract.</p>

<p>Unless there is a risk of permanent damage to a CMOS sensor by human-safe levels and durations of visible laser exposure that I am not aware of, how can it be possible that a Canon CMOS sensor was "destroyed" by a show laser at a public event in less than on second, while no humans were ever harmed? How can that be?</p>

<p>I gave the background info so everyone can understand what I base my observations upon, and even though it's old info, it should still be sound info. I would love to read a new perspective that can explain the destroyed sensor in context with the event, but until that time, I just don't see how it can be possible. I have been using Canon DSLR's since the 20D days, and many of them have looked directly into unmodulated class II and III HeNe, and various solid state lasers over time when I was tinkering with holography. I recently bought a Microvision ShowWX pico projector that employs a trio of 1 mw RGB lasers to deliver focus free full color video projection at a 1:1 projector distance vs image size ratio. It can project a dime sized image, or a 100" image without focusing. Pretty awesome..</p>

<p>A few weeks ago, I butchered my old junk 500 mm mirror lens ash tray to use it's EOS T-mount, rear body plate with screw in ND filters, and added lots of duct tape and cardboard to play around with pointing my ShowWX laser projector into my 7D in video live mode to see how it plays out. So far, the copies of the projector images look like high-def crap, and clearly show the ShowWX scan line structure, but the CMOS sensor in the 7D has not suffered a bit from having a seriously bright class II tri-color laser lighting it up for several minutes at a time. That's just a fact, and that said, how can a hand held camera possibly be subjected to sensor destroying time/intensity levels of light at a laser show without a ray gun wielding Martian being present?</p>

<p>If I'm missing something in my understanding, please let me know. If not, beware of possible urban legends, even if they sound Internet worthy at first....</p>

[robin_sibson1]

<p>Jim, that's fascinating, thank you very much for taking the trouble to provide such a full explanation.</p>

<p>One question. What's the story with laser pointers as used in presentations? There have been a number of pretty well-attested reports of these being pointed at pilots, particularly of helicopters, causing a serious hazard by temporarily blinding the pilot. Could this sort of laser be a problem for a camera, or is the power level too low to harm anything but a retina, and that only temporarily?</p>

[matthias_meixner2]

<p>I can only think of one possibility that could explain such a damage: Laser shows are set up so that there should be no damage to the human eye considering the maximum pupil size of around 8mm. However, when using a fast telephoto lens we are talking about apertures of up to and above 80mm. So if you had a widened laser beam that was safe for the human eye a camera would receive 100 times of the power due to the larger aperture. This represents a very special case which is very unlikely to happen.<br>

On the other hand I consider a CMOS sensor to be much more robust than the human eye. It should survive temperatures above 100°C without taking damage since making this sensor also involves high temperatures.<br>

Overall I do not think that there is a real risk of damaging a camera. Before a laser damages your camera it will damage your eye.</p>

[nicolasraddatz]

<p>Not Urban legend at all. I had a both a Canon S2IS and a Canon HV20 that got some pixels burned at a disco with laser beams. And I'm not talking about a gigantic disco with out-of-this-world laser beams. I'm talking about a rather small venue. Both cameras were hit by lasers while taking pictures/filming, and both got some nasty pixels burned, they looked like traces or like having a "hair" in the sensor (it obviously wasn't).</p>

[bill_johnson17]

<p>This whole thing doesn't sit well with me.......Shure sounds like the making of an urban legend but who knows.......... That being said, is the damage that's supposedly occuring damaging the actual sensor or is it damaging the amplifier for the pixels buy supplying much higher than normal voltages to the amplifiers due to the pixels being exposed to extreemly higher than normal brighness levels........ I'd love to here Canon comment on this......</p>

[nicolasraddatz]

<p>Bill, you can think whatever you want...all I know is that I have 2 (yes, two) Canon cameras fail on me in the same fashion after being exposed to laser beams...I know I won't be exposing my cameras to similar situations any more...</p>

[matthias_meixner2]

<p>If a laser damaged my camera I would be very afraid that it would also damage my eyes. Maybe the laser was operating beyond safe limits?</p>

[david_z3]

<p>http://www.reuters.com/article/idUSL1452972520080714</p>

[uttam]

<p>Yesterday My 2 (yes, two) SONY HVR Z-7P cameras' CMOS burnt while shooting in a musical evening in a hall in which lasers were heavily used. Now there comes always a vertical line.</p>