How to ZAP a Camera:
Using Lasers to Temporarily Neutralize
draft - not
©2002 Michael Naimark
Cameras are ubiquitous today, and, from a technology perspective, the
revolution is just beginning. Video cameras are becoming smaller and cheaper
while the Internet is enabling unlimited live webcasting. Web camera usage
has grown from one
in 1991 to hundreds in the mid-1990s to hundreds of thousands today.
Video cameras the size of
postage stamps can be procured for under $100, and will certainly
become even smaller and cheaper.
To many, this is good news. Public webcams enable remote users to see
what they would otherwise need to visit, and empower local subjects to
have a voice and a face to the outside world. Private webcams empower
friends and family to see each other remotely, and to check up on the
safety of their homes and their loved ones.
But there is a dark side. While hidden cameras are clearly an invasion
of privacy, visible public cameras can be as well. A camera placed in
a legally valid site can peer into otherwise private spaces. Their connections
to the Internet enable arbitrary numbers of users to watch anonymously.
And telephoto lenses enable cameras far greater vision than that of the
human eye. Imagine looking out your window and seeing someone on top of
a building with a large telescope looking down at you. Now imagine the
nightmarish vision of seeing thousands of people on top of the building
with telescopes looking down at you. Laws and conventions acceptable for
a single live gaze do not scale for remote multiple ones.
image from robotic webcam near Paris aimed by anonymous web user
On a personal note, I'm a camera-guy. For over twenty years I've worked
as an artist and researcher exploring new ways to represent place, work
which often involved custom-designed cameras for 3D, immersion, and interactivity.
Last fall I moved to a small town in Japan for an artist residency, ostensibly
to continue my work with VR and webcams. But the dark times caught up
with me and I felt compelled to ask some deeper questions, like, when
cameras are everywhere, is it possible to become invisible from them?
The more I learned, the more I realized the answer is, well, yes and no.
I began by aiming an inexpensive laser pointer directly into the lens
of a video camera. The results were striking. The tiny beam neutralized
regions of the camera sensor far larger than the actual size of the beam.
Properly aimed, it could block a far-away camera from seeing anything
inside of a large window.
Then I looked around the Web. Relevant articles existed but were highly
scattered. Not surprisingly, a lot of data exists in the military literature
(much of which appears to be getting "re-classified" and disappearing
from the Web day by day). I realized that I could more or less cover everything
there is to know about camera zapping during my residency, both in terms
of practical information and of larger metaphors.
I have some artistic and ethical discomfort with this work. It's divided
my artist colleagues into those who see a new activist tool and those
who liken it to burning canvasses. Indeed, is an anti-tool a tool? Then
there's the question of releasing potentially useful information to criminals
and terrorists. Perhaps, but anyone who really wanted to knock out a camera
wouldn't waste their time with harmless, temporary techniques.
My interest and motivation is to provide the creative community with some
stimulating and provoking stuff. These are stimulating and provoking times.
This is a report of my findings.
Camera zapping is possible because cameras are not perfect machines. Two
such imperfections are blooming and lens flare. Blooming is the technical
term for when a portion of the camera's sensor is overloaded, resulting
in "leakage" to neighboring regions. For example, a candle in
an otherwise dark setting may cause blobs or "comet tails" around
the flame. Many video cameras today advertise "anti-blooming"
capabilities, but it's ultimately a matter of degree. Most can indeed
handle a candle light without blooming but almost certainly not direct
The other relevant imperfection is lens flare, caused by unwanted light
bouncing around the glass and metal inside the camera. Multi-coated optics
and good design can minimize lens flare but not completely eliminate it.
For example, it is virtually impossible to eliminate the multi-facet reflection
of the lens' diaphragm blades in today's cameras when they're aimed at
Another imperfection common in digital cameras occurs in the electronics
downstream from the camera sensor. Often, when one small portion of an
image is unnaturally brighter than its immediate surroundings, the electronics
get confused. The result may be large digital "blocky" artifacts
in the image.
In addition to these imperfections, cameras' strengths can also contribute
to their weakness, for example with long, or telephoto, lenses. These
lenses act as telescopes, allowing the camera to fill its frame with a
magnified image. Since the field of view is small, the amount of light
needed by the sensor is proportionally larger. Consequently, telephoto
lenses are typically large, making concealment more difficult and detection
Further, telephoto lenses exhibit a strong retro-reflective effect, the
bright reflection caused when viewing such things more or less on-axis
with a light source. Examples include animal eyes viewed with a flashlight
(held close to the observer's eyes), "red eye" in flash photography,
and the reflection of car headlights from retro-reflective material common
on today's running shoes. When a telephoto lens is aimed at you, you will
see a "glint" in the lens if you are shining a light in its
Lasers are near-perfect monochromatic light sources, in that they emit
a single narrow wavelength, one pure color (actually some lasers emit
several pure colors). The first lasers were made of glass tubes with polished
mirror ends and had the additional feature of emitting collimated light,
a parallel beam so precise that it could be extremely narrow (and therefore
concentrated) or could converge to a microscopic point.
It is important to understand that a parallel beam of collimated light
does not lose any of its brightness travelling through empty space. Here
on earth, the atmosphere has enough density to diffuse and weaken a collimated
beam. But on a clear day or at night, a small bright spot from a well-collimated
laser will remain a small bright spot for distances of hundreds of meters.
The solid-state revolution that replaced vacuum tubes with silicon chips
had a similar effect on lasers. Solid-state technology allowed lasers
to become smaller, more efficient, and much cheaper. Useful new industries
emerged, such as laser printers and laser-scanning at supermarket checkout
counters. Useless ones appeared as well, such as cheap home laser light
shows and laser pointers.
Laser pointer like
this can be found for $1 on the Web
Laser pointers represent a case study of what happens when technological
advancement and high volume production reduce costs so much that a product
simply happens, regardless of need or utility. Laser and other light-based
pointing devices were originally made to help a lecturer highlight something
on an accompanying projection screen. So in theory, there need not be
more pointers in the world than lecterns or projection screens (or lecturers).
But because laser pointers could be made and sold for a few dollars, they
found a market as a novelty item. Red laser pointers can be bought on
the Web today for $1 or $2 each, while green ones are much more expensive
($200-$400) and blue ones are still in commercial development.
Today lasers come in extremely wide varieties of type, wavelength, and
power. (Everything one would ever want to know about lasers can be found
on the Web at Sam's
Laser FAQ.) They range from
lasers capable of destroying missiles to tiny
lasers that create images directly on the human retina.
Though lasers are often associated with danger (think Goldfinger), their
hazard level is related to power, wavelength, and concentration, but primarily
to power. Lasers are classified into four classes (two of which have sub-classes).
These range from "Class I" lasers which are deemed never harmful
(e.g., laser printers), to "Class IV" lasers that can blind,
burn, and sometimes cut through steel. The big dividing line lies between
Class IIIa and Class IIIb lasers, with the major criteria being whether
or not the laser emits more or less than 5 milliwatts. Class IIIb and
Class IV lasers must be registered in many countries, though a casual
Web search suggests it's pretty easy to buy serious Class IV lasers if
All off-the-shelf laser pointers are Class IIIa lasers, emitting light
from 1 - 5 milliwatts. The official view is that they cannot burn or damage
skin, but can produce "spot blindness" under the right conditions
and should have a "danger" label attached. Spot, or temporary,
blindness can indeed be hazardous, for example, while driving a vehicle.
But, contrary to the popular belief, not
a single instance of permanent eye damage from laser pointers has been
recorded anywhere, according to a report published in the Industrial
Safety and Hygiene News in May 2000.
In addition to spot blindness, laser pointers can get people into other
kinds of trouble. Today, many sports arenas and concert halls ban laser
pointers. Various direct and indirect laws can be used to cite irresponsible
use of laser pointers as a misdemeanor. And since the beam from a laser
pointer looks the same as the beam from a laser-sighted firearm, you don't
want to aim your laser pointer at someone carrying a weapon. In June 2000,
an unarmed juvenile, who aimed a laser pointer at an officer's torso,
for "602 WIC 417.26 (c) P.C., (Laser Scope Pointed at a Police Officer)."
Art and Activism
Using bright light as an aggressive tool goes back to ancient Greek mathematician
Archimedes and the legend that he burned invading Roman ships with large
mirrors and reflected sunlight. The activist art group,
Rtmark (pronounced "arteemark"), inspired by the Archimedes
legend, distributed 1,000 hand-held
mirrors to protesters at the 2001 G8 summit in Genoa, to use against
the police by spot blinding them with sunlight.
The proliferation of surveillance cameras has increasingly become a topic
of concern in the arts and activist communities. Rtmark has a Web guide
to closed circuit television destruction. (Though the guide includes
laser pointers as a method, it is not recommended, in part because it
doesn't leave any visible sign of inoperability. They prefer plastic bags,
paint guns, axes, and rocks to make their point.)
Community-made maps showing the locations of surveillance cameras in public
spaces are appearing on the Web. For example, the NYC
Surveillance Camera Project has mapped over 2,000 surveillance cameras
in Manhattan through a network of volunteers. The artist/activist group
Institute for Applied Autonomy
created a web-based application allowing New Yorkers to find walking
routes to avoid surveillance cameras.
Other forms of artist activism against surveillance cameras are more light-hearted.
The Surveillance Camera
Players, a New York based group, perform unannounced street theater
"for the entertainment, amusement and moral edification of the surveilling
members of the law enforcement community." The SCP organized a protest
against surveillance held on September 7, 2001, with 22 participating
organizations in 6 countries. Currently the SCP has several satellite
groups, including in Italy, Sweden, and Lithuania.
Detecting and stopping cameras turns out to be fundamentally difficult.
Cameras don't emit anything (e.g., the way cellular phones do). With a
great deal of surveillance and anti-surveillance products on the Web,
virtually none could be found to simply detect and stop cameras. (Cameras
connected to transmitters, perhaps, but cameras alone, no.) [October 2002
update: see Laser Dissuader below.]
A Google search of "anti
paparazzi device" yielded two hits, both about near-identical
devices called "Eagle Eye" and "Backflash" (and both
unfindable as actual products). These devices apparently couple a light
sensor to a flash unit: when a flash of light is detected, the devices
instantaneously flash back. They're both small, made to be worn, and claim
to obscure a portion of the photographic image near them whenever a flash
is used (ostensibly as protection against intruding photographers). If
these devices work, they obviously would only work for still, flash photography.
The gold vein of camera zapping material can (or could) be found in the
military literature. Indeed, the race to build the first laser (built
in 1960) was fueled by DARPA funding. During the Cold War, both the Pentagon
and the Kremlin spent billions of dollars developing high-power laser
weapons, which continued during Reagan's "Star Wars" initiative
in the 1980s and continues today. But as the silicon revolution made lasers
smaller and more efficient, the international military community looked
into additional opportunities. Two such opportunities were "antisensor"
and "antipersonnel" weapons.
Antisensor lasers are capable of scanning a region looking for "glints"
of reflected light coming from lenses aimed at them, then switching to
a high energy laser capable of overloading or destroying the sensor (or
whatever) behind the lens. The U.S. developed such a system called the
and deployed two tank-based prototypes in Saudi Arabia during the Gulf
War (they allegedly were not used). The Stingray's range of operation
is claimed to be several kilometers. It's not clear if (or how) the Stingray
could discriminate between lenses and eyeballs, or between sensors behind
a lens and human eyeballs behind a lens.
Antipersonnel lasers are made to "dazzle" (the technical term
for spot-blindness plus its effects, such as disorientation and delay).
One such system developed by the U.S. Air Force is the Saber
203. It's designed to fit in the grenade launcher of an M-16 rifle
and emits a beam in-line with the rifle's scope, with an effective range
of 300 meters. Its 28 milliwatt laser is considerably more powerful than
the 5 mw laser pointers, but it is claimed to be below the threshold of
The line between antisensor and antipersonnel lasers is vague, since there
is nothing preventing a soldier from using a Stingray to permanently blind
soldiers in the battlefield. The Human
Rights Watch and the
International Committee of the Red Cross led a campaign for a United
Nations ban on blinding laser weapons, which was adopted in 1996.
Some believe this only drove such development further into secrecy. Rumors
persist that Israel
acquired U.S. Stingrays after the ban, and that China
has been making a cheap version of the Stingray called the ZM-87 that
can blind soldiers 2 miles away and disable soldiers 7 miles away.
At the same time, at least two companies are marketing commercial versions
of the laser dazzler developed for the U.S. Military. The "Laser
Dissuader" and the "Laser
Dazzler" both claim to be safe, and better alternatives than
bullets. [October 2002 update: The Laser Dissuader link has changed since
last summer to include "SpyFinder," a new product that appears
to detect cameras by aiming a small laser and detecting the retro-reflection
from the lens.]
It remains uncertain whether any 100% successful antisensor detecting
system actually exists.
TESTS AND PROTOTYPES
First field tests were conducted simply with an inexpensive laser pointer
aimed into the lens of a video camera. At close range (1 - 5 meters),
the beam was easy to aim by hand. The laser beam almost completely obliterated
the image, covering it with a red starburst.The effect completely disappeared
when the laser was aimed away, leaving no trace of any permanent damage.
Inexpensive laser pointer
(1 mw, 650 nm red)
Laser pointer aimed at video camera from 3 meters away.
This cheap laser pointer emitted an oval-shaped beam (as is often the
case) that was about 2mm by 4mm in diameter at very short distances, and
expanded to over 5cm by 10cm at 100 meters (due to cheap collimating optics).
In medium and bright light, it was difficult to see with an unaided eye.
The obvious solution was to couple the laser to an optical scope and pre-calibrate
Telescopes and binoculars generally do not have cross-hair reticules built
in, but rifle scopes do. Rifle scopes are available at prices upwards
of $2,000, but like handguns, most of the market appears targeted at lower-income
customers, and cheap rifle scopes can be found for under $10. All rifle
scopes have built-in reticules with some form of cross-hair or dot at
the center, which are internally adjustable with set screws. The only
problem is that, unlike telescopes, rifle scopes are made to be viewed
with the eye several centimeters from the rear optics, since they are
mounted in front of the operator's face. (This distance is specified as
"eye relief," and is typically 2 - 5 inches but is never zero.)
A simple prototype system was built with a $30 mail order 5mw red laser
(635 nm wavelength, which appears much brighter than 670 or 690 nm red)
and a $10 rifle scope with a 4X magnification (Tasco Rimfire, made for
small game hunting). The laser and scope were secured together and the
cross-hair adjusted to center on the laser beam at 100 meters.
Simple laser / rifle
Telephoto view from 100 meters, cloudy day (video)
Wide angle view from
100 meters (video)
Through the rifle scope, the glint reflected from the lens was indeed
apparent, particularly when the camera lens was zoomed in. It was easy
to intermittently hit the lens but difficult to maintain aim by hand.
A second prototype expanded in several directions. First, it is tripod-based,
with a precision head allowing independent adjustment of its 3 axes (Bogen/Manfrotto
"Junior Geared Head," complete system costs around $200). Then,
a larger rifle scope was used for a bigger, brighter image (Tasco World
Class 3-9x zoom, $70). Finally, the cheap laser pointer was replaced with
a laser gun sight, which has the same Class IIIa power rating but much
better optics, resulting in a more circular and collimated beam (Beamshot
1001 for $110). These gun sights also have adjustment screws to align
the beam, durable metal cases, and many options of mounting hardware.
So, for under $400, a rather serious camera zapper can be assembled.
Laser gun sight, zoom
rifle scope, 3-axis adjustable tripod head
Camera Zapper in window approx. 200 meters from camera, early evening
Telephoto view (video)
system was portable and could be quickly deployed. Aiming was extremely
critical, and at long distances, very careful fine tuning was necessary.
But when the camera was aimed in the direction of the zapper and zoomed
in, the glint reflected from the lens was very obvious. This system can
work well for cameras which are visible and stationary.
the camera, or target, is moving, then some form of aiming and dynamic
tracking is required. One solution is to do it ourselves. A third prototype
was built to be small and hand-held for near and medium range moving cameras.
Hand-held unit with
laser gun sight and golf scope
The result was made with a Beamshot 1001 laser gun sight and a small monocular
made for golf range finding (Tasco Golf Scope, $20), basically a small
telescope with a grid-like reticule inside. Unlike a rifle scope, its
eye relief distance is zero, which makes it comfortable to use hand-held.
This new system could fit in a pocket and was very easy to use. It turns
out that precise calibration was not necessary, since the beam is easily
visible in the scope at near and medium range distances. If one wanted
to scare away a news cameraperson, this system would be ideal.
It would indeed be a achievement to be able to wear a small device that
prevents your image from ever being seen by a camera. (I once recklessly
such a device myself.) And though it may be possible, it would not be
One limitation of using lasers to zap cameras is due to their purity of
color, which makes it possible to filter out. Filtering can be done either
optically (e.g., using a special green filter to filter a red laser) or
electronically, downstream from the camera sensors. Neither are perfect
solutions, and at best, filtering may provide a recognizable image but
without full color.
Original image, zapped,
and filtered (and readjusted by hand) to show green channel only
Filtering can also be counter-measured. The best method is to use 3 lasers
(e.g., red, green, and blue). The next best method is to use a green laser,
since most of the signal coming from a color camera sensor is from the
green element, the color to which our eyes are most sensitive. The military
solution is to use "wavelength-agile" lasers that can randomly
change color, rendering any filtering useless.
Another limitation is how to track a moving camera automatically. In the
long term, this is (arguably) solvable using computer vision techniques.
The problem is more solvable if a human operator first constrains the
range and an automated system does the fine tuning.
The biggest limitation - and this is where things ultimately get depressing
- is detection. Look out any window and ponder that cameras can be the
size of buttons. Cameras don't even need lenses; they can use "pinholes."
It's my conclusion that the problem of detecting cameras is ultimately
unsolvable: if someone wants to hide a camera, they can hide a camera.
There is good news. Long, telephoto lenses, whose powers are greater than
human vision and therefore of special concern, are detectable. At least
for the foreseeable future, cameras that see far away can also be seen.
So in the end,
two applications of camera zapping are immediately possible. If a camera's
location is known, and can be seen, and is stationary, a tripod/rifle
scope/gun sight laser system can successfully zap it, even at distances
greater than 100 meters. If a camera is roving, a golf scope/gun sight
laser can intermittently zap it by hand with little effort.
The umbrella issue, on top of camera zapping, is perhaps most provocative
of all: how does one stop, or at least gain control of, representation
of oneself? Suppose, for example, you wanted to eliminate every instance
of your name that appears in a Google search. You could, in theory, contact
each website and demand they remove your name (though it's not clear what,
if any, leverage you might have). And of course, it would be naïve
to assume that every database with your name in it will be found with
a Google search.
One approach is simply to not care about one's representation.
Another approach is to go through life avoiding cameras, never submitting
your name on any form, and only using cash. (I know of at least two people
Whatever alternative or optimal approaches may exist, it's clear that
"de-presentation" is as fundamental a force as re-presentation
as we approach the brave new world of massive databases and cameras everywhere.
Some new and difficult issues need to be addressed. Camera zapping may
provide a robust metaphor for these deeper issues and help to stimulate
and provoke solutions.
gratefully acknowledges support from the Institute
of Advanced Media Arts and Sciences, Ogaki, Japan, and the IAMAS community,
particularly President Itsuo Sakane and Professor Hiroshi Yoshioka. Special
thanks to researcher Arnaud Pilpre of the Human and Object Interaction Processing
Group, Softopia Center, Ogaki, Japan, and a very special thanks to artist