Laser Hidden Camera Finder Thingy
I'm not exactly sure how this $350 "Laser Hidden Camera Finder Professional" works. For one, the "laser" doesn't seem to be a proper laser, but instead "dual high power laser frequency LEDs." (Emphasis added.) It seems to be able to detect hidden cameras but flashing the LEDs out and catching the light reflected from the camera lens, but that wouldn't seem to address false positives are thoroughly as they claim.
Anybody have a clue how this might work?
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I am just guessing, but I imagine it could flash the beams around, see what reflects and how large the reflection is. If it is a small point, it could decide it is a camera, as opposed to a large reflection, which would be a window.
Not sure either. They have other less expensive ones there. Perhaps this one just has less false positives than those? Not sure. I would like to look through it to see if it really looks like that.
Cats eye effect.
When you have a lens focusing on a reflective surface it becomes a retroreflector. I.E. It bounces light back along the same path as it came from (as per joggers vests, and bike reflectors). This is why cats eyes light up when you photograph them with a flash near the camera lens.
If you illuminate a scene with a modulated light source next to the lens flipping the light on and off on every other frame and subtract the alternating frames (and threshold the results) you pull out the retroreflections. These may be eyes or cameras. If you peak the illumination at points where silicon peaks in reflection but not retinas you have a pretty good camera detector.
Of course this is still crude, otherwise snipers wouldn't be able to ply their trade.
This is probably a spinoff of MPAA anti camcorder tech.
There is a video showing one in use here: http://www.spyops.net (Camera Finder video demonstration).
Monopole is spot on. A ring of LEDs are mounted around the eyepiece. A bandpass filter lets through the LED colour, but no other. Lenses appear as a bright spot against a dull background.
just as a point of tech, most lasers are leds now a days. I believe need a high quality led that produces light in a very small spectrum and a narrow aperture so the light comes out in a beam and tada, laser.
Does this work with infrared? because then you would turn into one giant bright spot to the camera as well...
but....why?
Yeah, I'm with you, Danceasaurusrex; maybe I'm misinterpreting its purpose, but it seems like this would only be useful for spies, private eyes, and criminals. No?
In the future, Goose Bandit, we'll all be spies, private eyes, and criminals. At the asme time!
Dance, Goose: also useful for people who are paranoid, or whose creepy uncle seems a little too knowledgeable about the state of their lingerie when they stay over in Uncle's well-lit guest room.
Might detect old-fashioned honkin' big cameras. Modern cameras with much smaller lenses, never mind the pinhole/lipstick cameras that the real paranoids ought to be worrying about? Not much surface, not much reflection, not easy to find even when you're looking straight at 'em...
Anonymous @5
Not Quite.
Light Emitting Diodes simply emit light from energy transitions from higher energy state to a lower one. The excitation mechanism is the drop in energy states at the junction between appropriately doped crystals.
Light Emission by Stimulated Emmission of Radiation (LASER) devices on the other hand have material that is in a higher energy state which does not immediately transition down by emmiting a photon but rather is an inverted population of more elevated states than lower states. Occasionally a photon is emmitted and when it strikes an atom in the higher energy state two photons are emmited of the same wavelength and direction. This leads to a chain reaction producing a coherent monochromatic beam which may be collimated by the appropriate optics. But in order to continuously do this it is generally necessary to have a resonant cavity with parallel reflective faces.
If stimulated emission occurs but does not predominate you get a superluminescent diode.
Generally, laser diodes and LEDs are made out of similar semiconductor structures, but a laser is much tougher to make than an LED.
(obviously glossed over a lot of tech here but you get the idea)
DealExtreme sells a camera detecting gadget that seems to work in the manner except it's only $73:
http://www.dealextreme.com/details.dx/sku.3617
I'm not paranoid enough to try it out.
Science!
UsefulCat @13
Yep thats the basic setup, the LEDs and the filter are the primary components needed.
Actually I just remembered that I have a security cam sitting on my table with an IR pass filter and IR ring light(my desk has many wondrous things). Grabbing a few cameras I tested it out. Definite cat's eye detection.
Take an extremely sensitive CCD (say ISO 32000). Put it in a camera without any lens. Just a pin hole. Can it defeat this device, and MPAA anti-camcorder devices, thereby enabling you to record movies in the cinema. As an additional benefit, this also eliminates all focussing problems and you have infinite depth of view.
How it works:
http://www.pat2pdf.org/patents/pat6665079.pdf
--Mike
I hope there are no cats looking over at the same time you're trying to detect cameras!
Marisa is onto something: If this can be modified into a *Cat Detector* a lot of people would buy it. People care a lot more about cats than they do about spy stuff. Besides, are you on camera? More and more the answer is *yes* - and what are you going to do about it? More and more the answer is *nothing* - but finding a lost cat? Priceless.
I wouldn't mind having a jacket with a few of these mounted around and designed in such a way that they would blind the cameras. They should certainly be small, stylish and not too expensive. A dream? A hope!
Perhaps one day we can deal a severe blow to the ever expanding surveillance society in which we live.