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Night Vision

Reducing light pollution, conserving energy and homeland security target hardening is making it more important than ever to achieve high quality video surveillance with minimal illumination. Intensified, IR and thermal imaging technology are ready to meet the challenge.

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Welcome to the fourth and final chapter in the 2010 run of SECURITY SALES & INTEGRATION’s acclaimed “D.U.M.I.E.S.” series: “Advanced Video for D.U.M.I.E.S.” Brought to you by Pelco, this four-part course has been designed to educate readers about recent advances in technology and systems that are likely to shape this decade’s progression of the video surveillance industry. “D.U.M.I.E.S.” stands for dealers, users, managers, installers, engineers and salespeople.

Part 1 of this year’s series (see “Redefining High Definition” in the March issue) covered alternate methods of achieving high quality HD video surveillance, including HDcctv and its ability to do so without the need for IP and/or megapixel networked cameras. The article looked at the technology, the organization championing it, how it compares to megapixel, its pros and cons, and its potential in the marketplace.

Part 2 (see June’s “Sensible Surveillance Management”) then explored the brains that tie together and facilitate control of today’s sophisticated networked video surveillance systems — video management systems/software (VMS). The piece discussed how VMS platforms relate to scalability, hybrid solutions, analytics, remote capabilities, integration, troubleshooting, return on investment (ROI) and total cost of ownership (TCO) metrics.

Part 3(“Pushing Video to the Cutting Edge”; August issue) investigated the advent of so-called “edge” devices, in which more processing power, storage and other capabilities are located within surveillance cameras themselves. The article addressed the pros and cons of edge topology, and its effect on system design, selection and deployment.

To wrap up this year’s series, we’ll look at technologies that allow cameras to capture images in dimly lit or nighttime surveillance applications. Not only are such capabilities useful for security and safety but, increasingly, new regulations are targeting the reduction of “light pollution” such as the types of lighting traditionally necessary to render useable video footage.

In fact, many states have enacted laws to regulate the use of exterior lighting in order to prevent it from shining skyward or onto neighboring properties. The objective is to eliminate the lighting altogether or at least shield it so direct light from outdoor fixtures shines only on the property where the fixtures are located.

Another reason for elevated interest in low-light surveillance is the Department of Homeland Security (DHS) urges it for facility hardening of America’s critical infrastructure. To help prevent and protect against attacks, DHS recommends the reduction of very well-lit facilities such as nuclear power plants, water treatment plants and fuel storage depots.

Thus, understanding how to deliver quality images regardless of illumination is a very attractive proposition right now for your end-user customers. The surveillance technologies enabling image capture in little to no lighting are intensified, infrared (IR) and thermal imagery. Let’s take a closer look.

Intensified Amplifies Existing LightTechnology advances in the past 20 years have resulted in great improvements to the performance of how well intensified CCDs pick up images in low light.

The first area of low-light systems open for discussion is known as the intensified charge-coupled device (ICCD).

This method of night vision amplifies the existing light. It focuses the existing light on the photocathode of an intensifier. The light causes electrons to be released. These electrons are then accelerated by a high voltage (about 15,000 times); the accelerated electrons are focused onto a phosphorous screen. The energy of the electrons makes the screen glow, which in turn is received by a CCD sensor producing a video image.

Technology advances during the past 20 years have resulted in great improvements to the performance of intensified devices. Their ability to identify people and objects at very low light is its major advantage. ICCDs also offer high resolution or detailed images in extreme lighting environments. However, ICCDs do require some existing light in order to function. Intensified CCD cameras also produce a poor daytime image when compared to day-only cameras.

So what do we do if there is no existing light available? IR lighting is one possible solution.

IR Works With No Visible Light

IR lighting is a light source designed for black-and-white cameras or the new day/night switchover surveillance cameras. It is incorporated for extremely low- or no-light applications. This light source has little or no effect on the spectrum of light that the human eye uses to produce an image. Therefore, applications where video is required but the use of visible light is prohibited are cases in which IR light is extremely helpful.

IIR light can be split into three categories:

Near-infrared (near-IR) — Closest to visible light, near-IR has wavelengths that range from 0.7 to 1.3 microns, or 700 billionths to 1,300 billionths of a meter.

Light Spectrum Chart: IR light has little or no effect on the spectrum of light the human eye uses to produce an image. It’s well suited for applications where video is required but the use of visible light is prohibited.Mid-infrared (mid-IR) — Mid-IR has wavelengths ranging from 1.3 to 3 microns. Both near-IR and mid-IR are used by a variety of electronic devices, including remote controls.

Thermal-infrared (thermal-IR)— Occupying the largest part of the infrared spectrum, thermal-IR has wavelengths ranging from 3 microns to in excess of 30 microns.

The key difference between thermal-IR and the other two is that thermal-IR is emitted by an object instead of reflected off it. The near-IR range is by far the most popular. The main reason is the cost of the equipment. Unlike intensified and thermal cameras, near-IR emits a light source in order to illuminate an area.

The other methods rely on existing light or energy to produce an image. Therefore, many more factors must be taken into account when selecting near-IR equipment. They include the wavelength of the emitted light, and power and degree of coverage.

Wavelengths, Power and Coverage

Near-IR can have an 850 nanometer (nm), 880nm or 940nm wavelength light source. The selection is based on distance and the covertness of the application. A camera incorporating an 850nm light source can be detected by the human eye. Thus the covertness of the unit is very low; however, the operating distance can be more than 600 feet.

As the light source increases in nanometers, the ability to view the source becomes less. At 940nm, the source can only be viewed by another IR-sensitive device and not by the human eye. The drawback is that the overall operating distance has also been reduced.

When you need to see in the dark, you get a flashlight ... well, IR operates as a flashlight to IR-sensitive cameras (black/white or true day/night cameras). The greater the distance requirements, the greater the power (wattage) requirements will be.

Additionally, the angle of coverage must also be factored when planning for distance requirements.  In most cases, to achieve extreme distances the angle of illumination is reduced. The angle of the lens on the cameras should closely match the angle of the IR unit. A mismatch may produce images that are unacceptable for video surveillance.

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Article Topics
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About the Author
Bob Wimmer
Bob Wimmer is president of Video Security Consultants and has more than 35 years of experience in CCTV. Known as “CCTV Bob,” this well-respected technical guru focuses on providing unbiased CCTV education. He has been a training consultant for several of the industry’s leading CCTV manufacturers and other organizations, including Pelco, the Department of Justice, Sony and Vicon. He has also written numerous articles on CCTV applications and advancing equipment technology, including SSI’s popular “D.U.M.I.E.S.” series of technical how-to articles. Wimmer was named in 2006 to the Security Sales & Integration Hall of Fame.
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