Night vision devices in surveillance
Night vision devices are specialized equipment that enables users to see in low-light conditions without emitting visible light, making them crucial tools in surveillance, particularly for law enforcement. These devices are significant as they allow officers to monitor activities discreetly during nighttime or in dark environments, effectively countering the concealment that darkness provides to potential criminal acts. Originating for military applications during World War II, the use of night vision technology expanded significantly during the Vietnam War and has since been adapted for civilian purposes, notably in policing.
Night vision devices can be categorized primarily into two types: image intensification and thermal imaging. Image intensification works by amplifying available light through a series of processes involving an image-intensifier tube, with advancements leading to devices that can function under minimal light conditions, such as bright starlight. In contrast, thermal imaging detects infrared radiation emitted by objects, allowing it to work in complete darkness, although these systems tend to be more expensive.
In recent years, the emergence of Internet of Things (IoT) technologies has further enhanced surveillance capabilities, enabling continuous data exchange and monitoring. For instance, IoT cameras have been utilized in criminal investigations, demonstrating their growing role in both daytime and nighttime surveillance efforts.
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Night vision devices in surveillance
DEFINITION: Devices designed to allow operators to see in low light conditions without shining visible lights.
SIGNIFICANCE: Using night vision devices, law-enforcement personnel can conduct surveillance at night or in dark indoor spaces without those who are being watched knowing that they are under surveillance. Such devices also benefit police in that they effectively remove the cover of darkness often used to hide criminal activities.
Night vision devices were first developed for military use during World War II, but they were not used extensively until the Vietnam War. Like many other military technologies, night vision equipment eventually found its way into civilian uses, including law enforcement.
Night vision equipment falls into two different technology categories: image intensification and thermal imaging. Image-intensification systems use low levels of visual light or infrared light just beyond the visual range. The heart of this kind of system is an image-intensifier tube. When light enters the tube, it strikes a material that releases electrons. The electrons are then accelerated down the tube, where they run into atoms releasing other electrons in a cascade effect, amplifying the effect of the initial light. The electrons then strike a phosphor screen, causing it to glow. Typically, a green phosphor screen is used because the human eye can differentiate many different levels of green light intensity. Image-intensifier tube technology has improved since it was introduced; light amplification has been increased from a factor of one thousand or less to a factor of more than fifty thousand.
Different types of night vision devices are often classified according to when they were developed and the types of technology they use. Early devices, or Generation 1 devices, amplified light by only a factor of one thousand or so and often required powerful infrared illuminators to light the targets. Generation 2 devices could operate under only moonlight, whereas Generation 3 devices can often operate using only bright starlight. No image-intensification system can operate in complete darkness, however, so many night vision devices come with small infrared illuminators for use when the ambient light level is too low. Most police departments in the United States are equipped with Generation 3 night vision devices.
A separate type of night vision technology uses thermal imaging. In these devices, thermal imaging cameras detect long wavelength infrared radiation. All living creatures give off thermal radiation. The warmer an object is, the more radiation it emits and the shorter the wavelength of the most intense radiation. Because thermal imaging night vision systems use light emitted by objects, they can operate in total darkness. Fire departments sometimes use such systems to find people in smoke-filled rooms or to find smoldering hot spots after a fire has been brought under control. However, thermal imaging systems are far more expensive than image-intensification night vision devices, so they are less frequently used by police departments.
The Internet of Things (IoT) refers to devices with sensors that can process information and exchange data with other devices and systems via the Internet. In the 2020s, forensic experts began using IoT cameras, which could be used in surveillance during the day and night. According to the Brennan Center for Justice, a California man was charged with the murder of his stepdaughter after her Fitbit showed that her heart rate had spiked, dropped, and then stopped. This occurred when a neighbor's IoT surveillance camera showed the man's car parked at her house.
Bibliography
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