Night vision in the context of "Digital image sensor"

An image sensor or imager is a device that detects and conveys information used to form an image. It does so by converting the variable attenuation of light waves (as they pass through or reflect off objects) into signals, small bursts of current that convey the information. The waves can be light or other electromagnetic radiation. Image sensors are used in electronic imaging devices of both analog and digital types, which include digital cameras, camera modules, camera phones, optical mouse devices, medical imaging equipment, night vision equipment such as thermal imaging devices, radar, sonar, and others. As technology changes, electronic and digital imaging tends to replace chemical and analog imaging.

The two main types of electronic image sensors are the charge-coupled device (CCD) and the active-pixel sensor (CMOS sensor). Both CCD and CMOS sensors are based on metal–oxide–semiconductor (MOS) technology, with CCDs based on MOS capacitors and CMOS sensors based on MOSFET (MOS field-effect transistor) amplifiers. Analog sensors for invisible radiation tend to involve vacuum tubes of various kinds, while digital sensors include flat-panel detectors.

Night, or nighttime, is the period of darkness when the Sun is below the horizon. Daylight illuminates one side of the Earth, leaving the other in darkness. The opposite of nighttime is daytime. Earth's rotation causes the appearance of sunrise and sunset. Moonlight, airglow, starlight, and light pollution dimly illuminate night. The duration of day, night, and twilight varies depending on the time of year and the latitude. Night on other celestial bodies is affected by their rotation and orbital periods. The planets Mercury and Venus have much longer nights than Earth. On Venus, night lasts about 58 Earth days. The Moon's rotation is tidally locked, rotating so that one of the sides of the Moon always faces Earth. Nightfall across portions of the near side of the Moon results in lunar phases visible from Earth.

Organisms respond to the changes brought by nightfall: darkness, increased humidity, and lower temperatures. Their responses include direct reactions and adjustments to circadian rhythms governed by an internal biological clock. These circadian rhythms, regulated by exposure to light and darkness, affect an organism's behavior and physiology. Animals more active at night are called nocturnal and have adaptations for low light, including different forms of night vision and the heightening of other senses. Diurnal animals are active during the day and sleep at night; mammals, birds, and some others dream while asleep. Fungi respond directly to nightfall and increase their biomass. With some exceptions, fungi do not rely on a biological clock. Plants store energy produced through photosynthesis as starch granules to consume at night. Algae engage in a similar process, and cyanobacteria transition from photosynthesis to nitrogen fixation after sunset. In arid environments like deserts, plants evolved to be more active at night, with many gathering carbon dioxide overnight for daytime photosynthesis. Night-blooming cacti rely on nocturnal pollinators such as bats and moths for reproduction. Light pollution disrupts the patterns in ecosystems and is especially harmful to night-flying insects.

The cat (Felis catus), also referred to as the domestic cat, is a small carnivorous mammal. It is an obligate carnivore, requiring a predominantly meat-based diet. Its retractable claws are adapted to killing small prey species such as mice and rats. It has a strong, flexible body, quick reflexes, and sharp teeth, and its night vision and sense of smell are well developed. It is a social species, but a solitary hunter and a crepuscular predator.Cat communication includes meowing, purring, trilling, hissing, growling, grunting, and body language. It can hear sounds too faint or too high in frequency for human ears, such as those made by small mammals. It secretes and perceives pheromones. Cat intelligence is evident in its ability to adapt, learn through observation, and solve problems. Female domestic cats can have kittens from spring to late autumn in temperate zones and throughout the year in equatorial regions, with litter sizes often ranging from two to five kittens.

The domestic cat is the only domesticated species of the family Felidae. Advances in archaeology and genetics have shown that the domestication of the cat started in the Near East around 7500 BCE. Today, the domestic cat occurs across the globe and is valued by humans for companionship and its ability to kill vermin. It is commonly kept as a pet, working cat, and pedigreed cat shown at cat fancy events. Out of the estimated 600 million domestic cats worldwide, 400 million reside in Asia, including 58 million in China. The United States leads in cat ownership with 73.8 million cats, followed by the United Kingdom with approximately 10.9 million cats. It also ranges freely as a feral cat, avoiding human contact. Pet abandonment contributes to increasing of the global feral cat population, which has driven the decline of bird, mammal, and reptile species. Population control includes spaying and neutering.

The Leopard 2 is a third generation German main battle tank (MBT). Developed by Krauss-Maffei in the 1970s, the tank entered service in 1979 and replaced the earlier Leopard 1 as the main battle tank of the West German army. Various iterations of the Leopard 2 continue to be operated by the armed forces of Germany, as well as 13 other European countries, and several non-European countries, including Canada, Chile, Indonesia, and Singapore. Some operating countries have licensed the Leopard 2 design for local production and domestic development.

There are two main development tranches of the Leopard 2. The first encompasses tanks produced up to the Leopard 2A4 standard and are characterised by their vertically faced turret armour. The second tranche, from Leopard 2A5 onwards, has an angled, arrow-shaped, turret appliqué armour, together with other improvements. The main armament of all Leopard 2 tanks is a smoothbore 120 mm cannon made by Rheinmetall. This is operated with a digital fire control system, laser rangefinder, and advanced night vision and sighting equipment. The tank is powered by a V12 twin-turbo diesel engine made by MTU Friedrichshafen.

Ghost hunting is the process of investigating locations that are purportedly haunted by ghosts. The practice has been heavily criticized for its dismissal of the scientific method. No scientific study has confirmed the existence of ghosts. Ghost hunting is considered a pseudoscience by the vast majority of educators, academics, science writers and skeptics. Science historian Brian Regal described ghost hunting as "an unorganized exercise in futility".

Typically, a ghost-hunting team will attempt to collect "evidence" supporting the existence of paranormal activity. Ghost hunters also refer to themselves as paranormal investigators. Ghost hunters use a variety of electronic devices, including EMF meters, digital thermometers, both handheld and static digital video cameras, including thermographic and night vision cameras, night vision goggles, and digital audio recorders. Other more traditional techniques are also used, such as conducting interviews and researching the history of allegedly haunted sites. Dowsing and Ouija boards are other traditional techniques.

Rod cells are photoreceptor cells in the retina of the eye that can function in lower light better than the other type of visual photoreceptor, cone cells. Rods are usually found concentrated at the outer edges of the retina and are used in peripheral vision. On average, there are approximately 92 million rod cells (vs ~4.6 million cones) in the human retina. Rod cells are more sensitive than cone cells and are almost entirely responsible for night vision. However, rods have little role in color vision, which is the main reason why colors are much less apparent in dim light.

A night-vision device (NVD), also known as a night optical/observation device (NOD) or night-vision goggle (NVG), is an optoelectronic device that allows visualization of images in low levels of light, improving the user's night vision.

The device enhances ambient visible light and converts near-infrared light into visible light which can then be seen by humans; this is known as I (image intensification). By comparison, viewing of infrared thermal radiation is referred to as thermal imaging and operates in a different section of the infrared spectrum.

The tapetum lucidum (Latin for 'bright tapestry, coverlet'; /təˈpiːtəm ˈluːsɪdəm/ tə-PEE-təm LOO-sih-dəm; pl.: tapeta lucida) is a layer of tissue in the eye of many vertebrates and some other animals. Lying immediately behind the retina, it is a retroreflector. It reflects visible light back through the retina, increasing the light available to the photoreceptors (although slightly blurring the image).

The tapetum lucidum contributes to the superior night vision of some animals. Many of these animals are nocturnal, especially carnivores, while others are deep-sea animals. Similar adaptations occur in some species of spiders. Haplorhine primates, including humans, are diurnal and lack a tapetum lucidum.