Infrared cameras

       Thermographic cameras which are sometimes called a FLIR or simply infrared camera, is an electronic device that can form images by detecting infrared radiation. It is similar to the common camera which forms an optical image using the visible light. Instead of sensing the 450–750 nanometer wavelength range of the visible light camera, infrared camera does operate in wavelengths which is as long as 14,000 nm (14 µm).

Cooled Infrared Detectors

       Cooled infrared detectors are typically housed in a vacuum-sealed casing or Dewar container and then it is cryogenically cooled. The cooling is needed for proper operation of the semiconductor materials used in this type of sensor. The usual operating temperatures can range from 4 K to just about below average room temperature, depending on the technology used in the detector. Many modern cooled detectors are operating in the 60 K to 100 K temperature range; this is dependent on the type and performance level of infrared detectors. Without the use of cooling, these infrared sensors (which can detect and converts light in the same way as the common digital camera, but are only made of different semiconductor materials) will be 'blinded' or flooded by the radiation coming from them.

Some of the materials used for cooled infrared detectors include photodetectors that are based on a wide selection of narrow gap semiconductors, they include:

• indium antimonide
• indium arsenide
• mercury cadmium telluride
• lead sulfide
• lead selenide

Infrared Detectors which are Uncooled

       Thermal imaging can also detect the elevated body temperature of an individual; this is one of the signs of the virus H1N1. Uncooled thermal cameras uses a semiconductor sensor that operates at ambient temperature, or it can also use a sensor stabilized at a temperature that is close to the ambient using tiny temperature control elements. Modern uncooled detectors usually use sensors that operate by means of the change of its resistance, voltage or current when they are heated by infrared radiation. These parametric changes are then measured and then compared to the values set at the operating temperature of the infrared sensor.

Some of the materials that are used for the sensor arrays are.:

• lead zinc niobate (PZN)
• lead strontium titanate (PSrT)
• barium strontium titanate (BST)
• barium titanate (BT)
• antimony sulfoiodide (SbSI)
• polyvinylidene difluoride (PVDF)
• lead zirconate titanate (PZT)
• lanthanum doped lead zirconate titanate (PLZT)
• lead scandium tantalate (PST)
• lead lanthanum titanate (PLT)
• lead titanate (PT)
• vanadium(V)
• lanthanum barium manganite (LBMO, metal insulator phase change material)
• amorphous silicon  

Infrared Security Camera ( Infrared Surveillance Cameras )

       An infrared security camera system will also work in full color as long as there is enough light, but after sunset, the images turn will be turned into black and white. The built-in sensors will turn on the LEDs and then the cameras can begin reading the light coming from the LEDS. The level of light that is required to shoot good quality photographs is called the camera's lux rating. To calculate this rating, usually the lower the lux, the better is that particular equipment in seeing in the dark. If the lux value is 0.0 , then no light is needed at all to take good quality photographs. The number of LEDs will determine how far the security camera can see in the dark. When you are purchasing a wireless infrared security camera, take note that the size of the lens will also determine the optical clarity of the pictures taken and the distance that it can see ahead. Unlike previous versions, at 940 nanometers, the hull of the machine will always become invisible to the human eye even if we are talking about total darkness. At 850 nanometers, a very slight reddish or weak pinkish glow will shine through the dark. An “nm” is called the wavelength in nanometers rating.

Digital Infrared Camera and Infrared Photography

       Another alternative method infrared photography using DSLR is by removing the infrared filter in front of the charge-coupled device and then replacing it with a filter that cuts visible light. This filter is placed behind the mirror, so that the camera can be used in a normal fashion. Light metering also works but it will not always be accurate because of the difference in intensity between visible and infrared reflection. When the IR filter is removed, many lenses which previously display hotspots will cease to do so, and they will become perfectly usable for digital infrared photography. Additionally, because the red, green and blue micro-filters in the sensor will remain and will also have transmissions not limited in their respective color but also in the infrared region, enhanced infrared color can be also recorded.

       Since the Bayer filter array in many digital cameras absorb a large fraction of the infrared light, these type of cameras are usually not very sensitive as compared to infrared cameras and they can sometimes give false colors in the images. An alternate approach is to employ a Foveon X3 sensor, since they do not have absorptive filters on it; the Sigma SD10 DSLR features removable IR blocking filter and a removable dust protector, these can be simply omitted or can be replaced by a deep red or complete visible light cutting filter. The Sigma SD14 has an IR and UV blocking filter that can be also removed and installed without tools. The end result is a very sensitive digital infrared camera.

Wireless Infrared Security Cameras

       Infrared cameras can be equipped with IR illuminators which can virtually see even in complete darkness, and they also provide excellent video performance even in the worst lighting conditions. An infrared camera will be perfect for night time applications or for applications with very poor illumination. Infrared security camera uses light that has wavelengths greater than 700 nanometers, these wavelengths are invisible to the human eye. Some IR cameras feature infrared illumination using photosensor activation, which automatically turns on and turns off the camera's illuminators depending on the lighting conditions.