Analysis of Laser Light Threat to CCTV

Purpose

This paper investigates the level of threat that commercial and consumer lasers pose to CCTV cameras. None of the tests were conducted by the author, but several tests from various cited sources were compiled to determine what types of lasers can pose permanent damage, what are the power requirements, and considerations of the costs associated with deployment. Finally, problem mitigation and prevention is addressed.

Background

 

To establish a baseline for this investigation, we must first provide some background information.

Cameras (CCTV)

 

The three major parts of a CCTV camera that a laser can effect are:


       1. Lens

       2. Sensor

       3. CCD/CMOS image array

 

No test with a commercially available laser has ever caused damage to a lens, even cheap plastic lenses in webcams did not seem to be effected by any readily available lasers. This paper then, does not address the possibility of lens damage.

Some CCTV cameras (and all SLR cameras) have a sensor that determines the ambient light in order to provide auto-contrast and backlight adjustment. These sensors are generally easy to damage if a direct hit by a laser is performed. Their small size generally makes this a difficult task. The damage that results will mean that the camera brightness may not adjusted and the images will be dark or too bright. It would be possible in post-production of archived video to adjust the images to identify any laser- wielding person in the field of view. In general, the principles discussed regarding lasers damaging CCD/CMOS components apply to sensors as well.

 

There are many examples on YouTube of green lasers from a light show ruining a CMOS in an SLR:
Example: www.youtube.com/watch?feature=player_embedded&v=Ldh8nUs7pVE

The main concern regarding laser damage to CCTV cameras is with the imaging array. These arrays are either CCD (mostly analog cameras) or CMOS (IP-based cameras) chips. Damage from lasers includes temporary blinding, burned out pixels, and in extreme cases destruction of the silicon substrate over an extended area, rendering the camera non-functional.

 

Lasers

 

There are many different types of lasers, however, not all are readily available. They range from military-grade through industrial-grade, and finally commercial grade, which include inexpensive consumer-level lasers for about one dollar. Lasers come in three general colors of increasing wavelength: red; green; blue. These also correspond to increasing power, and cost. Note that red lasers also include Infra-Red (IR) lasers as well. Lasers also can be steady-beam (i.e. continuous) output, or pulsed output. Pulsed lasers have high power outputs, are non-portable, and not readily available to the general public; they are used in industrial environments to weld, cut, or melt materials. Pulsed lasers are not a consideration of this paper.

 

Laser Classifications

Lasers are usually labeled with a safety class number, which identifies how dangerous the laser is:

  • Class I/1 is inherently safe, usually because the light is contained in an enclosure, for example in CD players.
  • Class II/2 is safe during normal use; the blink reflex of the eye will prevent damage. Usually up to 1 mW power, this includes most laser pointers.
  • Class IIIa/3R lasers are usually up to 5 mW and involve a small risk of eye damage within the time of the blink reflex. Staring into such a beam for several seconds is likely to cause permanent damage to a spot on the retina.
  • Class IIIb/3B can cause immediate eye damage upon exposure.
  • Class IV/4 lasers can burn skin, and in some cases, even scattered light can cause eye and/or skin damage. Many industrial and scientific lasers are in this class.

 

Class IIIb and Class IV lasers must be registered in the United States. However, it should be noted that a casual web search suggests it may be easy to buy serious Class IV laser if one desires. The cost of Class 4 lasers is prohibitive to the general public and also there is no defense for a CCTV camera if a laser beam of such power is aimed through the lens.

 

Problem Statement: Disabling a CCTV using a laser

 

There are many crime shows on television where a perpetrator uses a laser pointer to disable a CCTV camera. As with most things on television, they are much more difficult to perform in real life. The two major advantages of using a laser to disable a CCTV camera are that it is silent (unlike a gunshot), and it has a long range (unlike a stick, rock, or paint gun).

 

There are, however more drawbacks and difficulties to using a laser to disable a CCTV then advantages. The biggest issue is aiming the beam. The laser is a very focused beam and to do any damage must be aimed exactly through the lens, typically from a relatively large distance; the farther one is from the lens, the more difficult it is to aim the beam to hit the image array. Since the laser ruins the image array by overheating the chip, the laser beam must aim must be held for some period of time (depending upon the power of the laser.) In addition, if a Class3 laser is operated, the user can unintentionally cause himself (or others) permanent eye damage. These lasers are meant to be operated with special safety goggles.

 

The other factor to consider is cost. Generally it is inexpensive to purchase the parts to create a laser that will temporarily blind a CCTV, but to create one that will permanently damage it will generally cost several hundred dollars. It is much cheaper and easier to use the typical methods of destroying a unreachable CCTV camera. These include paint guns, bags of paint or glue, or cable cutters. The other drawback compared to other methods is that you cannot be sure if you have disrupted the camera or not since there is no visible feedback of the cameras output in most cases. Someone whose intentions are simply vandalism, however, may not care if he was successful or not.

 

Here is a Class3B IR (invisible) light laser for about $700 that can reach up to 850mW!

http://www.laserglow.com/GSC

Here is a relatively inexpensive Class3B green 500mW laser for $300

http://www.wickedlasers.com/lasers/S3_Krypton_Series-113-63.html

 

Note: the above lasers require use of protected eyewear or permanent damage may occur.

 

Both of the above would be able to permantly damage a CCTV camera, for which the owner would have little recourse in preventing. However common and inexpensive lasers are capable of blinding a CCTV camera during the time that the beam was held directly into the lens. It should be noted that since lasers have very specific light frequencies, they can be readily masked out during post-processing, and thereby revealing the image behind it. So while this method is a nuisance, it would not be sufficient to blind a camera where a major crime is involved, such as a bank robbery.

 

Based on our preliminary research, no Class 2 laser was able to permanently destroy a CCTV camera since the wattage levels were too insignificant to cause widespread damage. There were some test reports of single pixel damage on the more sensitive CMOS arrays. Therefore, to be able to permanently disable a CCTV camera from a distance, a Class 3 laser would be required. It should be noted that green and blue lasers are more effective than red, however, IR cameras do not shield infrared or visible red light and as such, are more prone to the red light lasers.

 

Making a Laser CCTV Disrupter

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.

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 them. 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. 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. The 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. Again, no permanent damage to the CCTV camera occurred. This device was not aimed at a closer CCTV camera. These tests were done with a red light laser.

 

Test Results

 

Several tests conducted by both universities and individuals (references cited in appendix) have come to different conclusions, each of the tester’s results are listed below:

 

  • A Class2 laser of 1mW was never able to permanently disable a CCTV camera when at least 3m away from the lens
  • A green Class3A laser of 5mW was able to disable a CCD-based camera at 15 meters which resulted in a permanent white screen
  • A red Class3A laser of 5mW was not able to disable a CCD-based camera (see above) at 100m
  • Lasers in the Class3B power range (both red and green) are able to destroy the CCD/CMOS chip elements.

There are many factors involved that may change the above rule, including the quality of the laser (i.e. how tight the beam is); the distance the laser is placed from the image array, the image array manufacturer, and the focal length of the lens.

 

Prevention

 

If laser damage is a major concern there a few general guidelines for low-cost low-power lasers:

 

  • Keep the cameras high and/or away from anyone who might carry a laser, thereby making it difficult to aim and reducing the potential power of the beam
  • PTZ cameras (moving) are very difficult to track with a laser for any length of time
  • Use red light and IR filters on non-IR cameras to reduce laser light
  • Use blinding notification in CCTV software so that when a laser is used to obscure or damage a camera, notification can be sent to security personnel.
  • Deploy cameras such that there are multiple cameras lensed on common field of views. The probability of disrupting two cameras (or more) at the same time is greatly reduced for this type of countermeasure.

Filters can eliminate the effect of most of the cheaper low-watt lasers. Filter Lens of different lens sizes can be purchased to selectively guard against 400nm-750nm through 808nm-1064nm for about $5 each. This assumes that the camera is not an IR camera, otherwise the resultant image will be dark or black due to the filtering.

 

The other drawback of filters is that they are generally for specific frequencies or small ranges of laser light, as seen by one manufacturers catalog below, and if a different red laser frequency is used, the filter will have minimal effect.

 

 

Summary of Findings

In general, low wattage (class 2) lasers are not a concern to cameras regarding permanent damage. All lasers caused flash blinding when aimed directly into the lens.

Lasers over 100mw caused damage in some cameras, those over 200mw were able to “poke holes” and blow out pixels; and those over 400mw were able to blow out the CCD/CMOS image array. The latter of these lasers generally cost several hundred dollars retail.

Overall, there are much cheaper methods to destroying or disabling a CCTV camera and lasers are likely to be used mostly when other methods are not feasible, such as a camera in a bullet-proof housing mounted high up on a building.

MTS believes that deploying additional cameras such that no single camera is as vulnerable is a more cost effective solution then retrofitting cameras with filters, etc. Incorporating event alerts for blinding with multiple cameras allows you to identify the individual performing the disruption and notify security personnel such that the individual can be apprehended.

Outdoor applications would be realistically more vulnerable than indoors due to the simple nature of the risks associated with attempting to disrupt/damage a camera system.

 

 

Appendix – Citations

 

Camera Zapper

http://www.naimark.net/projects/zap/howto.html

Guide to Closed Circuit Television (CCTV) destruction.

http://www.schnews.org.uk/diyguide/guidetoclosedcircuittelevisioncctvdestruction.htm

Can an infared light or a powerful laser disable surveillence cameras? - Yahoo! Answers

http://answers.yahoo.com/question/index?qid=20090725041729AAnjAZm

Wattage required to destroy a cctv camera? - Page 2 - Laser Pointer Forums - Discuss Lasers & Laser Pointers

http://laserpointerforums.com/f44/wattage-required-destroy-cctv-camera-29752-2.html

How To Do Stuff: How to Blind a Camera Using a Laser

http://how2dostuff.blogspot.com/2008/05/how-to-blind-camera-using-laser.html

U.S. Laser corp: CCTV Components

http://www.uslasercorp.com/catalog/cctv.html

12mm Filter Lens for 400nm-750nm Laser Light

http://www.laserlands.net/400-750-filter-12-bl.html

Laser safety for cameras - International Laser Display Association

http://www.laserist.org/camera-sensor-damage.htm

 

http://www-ssrl.slac.stanford.edu/lcls/technotes/lcls-tn-02-1.pdf

 

Report: CMOS & CCD Cameras Damaged by Laser « HD Cam Team

http://www.hdcamteam.com/2011/07/10/report-cmos-ccd-cameras-damaged-by-laser

 

NASA ADS: Laser-induced functional damage to silicon CCD sensor arrays

http://adsabs.harvard.edu/abs/1992SPIE.1624...67B

 

http://misspiggy.gsfc.nasa.gov/tva/meldoc/photonicsdocs/LDthresholdstud y.pdf




 

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