If you want to see and record activity after dark, you can choose from three common technology options which don’t involve adding more visible light to the scene. People commonly confuse and mistake one for another. These options are night vision, infra-red lighting and thermal imaging. Each has their advantages. Perhaps this post can help with that confusion.
The U.S military uses night vision very often. It has been available to our military members for about 50 years. The image from a night vision device is typically a grainy-green glowing image that you would recognize from watching movies and the news.
Night vision uses the light that is already available on the scene. Night vision amplifies the light electronically inside the device to show light contrast where before there may have been very little. There is no need to add light to the scene but, there are real limits to the available image detail.
The next technology we mention here is near infra-red, or IR. This light lies just outside the range of our white-light spectrum (the light we use to see with our eyes). There are two ranges of infra-red that are used widely in security: semi-covert (about 850nm) and fully covert (about 940nm). Semi-covert illuminators can usually be seen by humans because of the faint, dull red glow produced by the light emitting diodes (LEDs). However, the fully covert LEDs produce a practically non-visible light to all humans.
IR off IR on
Most modern security cameras are sensitive to IR light. IR light comes from stars and from IR illuminators (light producing panels). IR is very good at giving detailed images with good contrast. It is generally inexpensive when compared to the other two technologies mentioned here, which probably contributes to its popularity.
According to the new ‘Global Infrared Light-emitting Diode Market 2017-2021’ report by Technavio, the infrared LED market is projected to reach $475.3 million by 2021, at a CAGR of close to 13 percent during the forecast period.
The top three revenue-generating application segments are surveillance, consumer electronics, and automotive The surveillance segment generates over 40 percent of the overall revenue. These light sources are used for low light levels and night vision applications in CCTV cameras. “The healthy growth of the CCTV camera market will result in constant demand for infrared LEDs,” says Navin Rajendra, one of the lead analysts at Technavio for lighting research.
The third technology is thermal imaging. No light is needed with thermal imaging. All things emit heat, (some things more than others). A warm body viewed in a cooler environment will produce high contrast. This contrast is what makes thermal imaging so useful for detection. The image details are not refined but the high contrast allows for excellent detection.
Thermal can be used in both day and night operations. It requires no additional lighting, can detect heat through fog or smoke, and is excellent for defending perimeters. Critical infrastructure security benefits from thermal detection.
Night vision is not very popular in security surveillance applications. Infra-red is very popular and is very effective when optimized. Thermal imaging is superb for detection, but it has been traditionally price prohibitive. Lately, pricing for thermal products has become more attractive. In addition, there are several new thermal options available to the commercial end-user which provide the same advantages in detection enjoyed by government entities.
There are hybrid systems available which use both IR and thermal. These are becoming more popular in the hunting and military arenas, but have yet to make a big splash in surveillance.
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