Night vision

Night vision is the ability to see in low light conditions. Whether by biological or technological means, night vision is made possible by a combination of two approaches: sufficient spectral range, and sufficient intensity range. Humans have poor night vision compared to many animals, in part because the human eye lacks a tapetum lucidum.

Types of ranges

Spectral range

Night-useful spectral range techniques can sense radiation that is invisible to a human observer. Human vision is confined to a small portion of the electromagnetic spectrum called visible light. Enhanced spectral range allows the viewer to take advantage of non-visible sources of electromagnetic radiation (such as near-infrared or ultraviolet radiation). Some animals such as the mantis shrimp can see using much more of the infrared and/or ultraviolet spectrum than humans.

Intensity range

Sufficient intensity range is simply the ability to see with very small quantities of light.

Many animals have better night vision than humans do, the result of one or more differences in the morphology and anatomy of their eyes. These include having a larger eyeball, a larger lens, a larger optical aperture (the pupils may expand to the physical limit of the eyelids), more rods than cones (or rods exclusively) in the retina, and a tapetum lucidum.

Night

Night or nighttime (sp. night-time or night time) is the period of time between the sunset and the sunrise when the Sun is below the horizon.

This occurs after dusk. The opposite of night is day (or "daytime" to distinguish it from "day" as used for a 24-hour period). The start and end points of time of a night vary based on factors such as season, latitude, longitude and timezone.

At any given time, one side of the planet Earth is bathed in light from the Sun (the daytime) and the other side of the Earth is in the shadow caused by the Earth blocking the light of the sun. This shadow is called the umbra. Natural illumination is still provided by a combination of moonlight, planetary light, starlight, diffuse zodiacal light, gegenschein, and airglow. In some circumstances, bioluminescence, aurorae, and lightning can provide some illumination. The glow provided by artificial illumination is sometimes referred to as light pollution because it can interfere with observational astronomy and ecosystems.

Vision

Vision or The Vision may refer to:

Perception

Film and TV

Rihanna discography

Barbadian singer Rihanna has released eight studio albums, one soundtrack album, two compilation albums, two remix albums, one reissue, and 58 singles (including thirteen as a featured artist). Since the beginning of her career in 2005, Rihanna has sold over 200 million records, making her one of the best-selling artists of all time. She has released seven Recording Industry Association of America (RIAA) certified platinum and multi-platinum albums in the United States, that have totalled sales of over 10 million copies in the country. Thirteen of Rihanna's singles have reached number one on the US Billboard Hot 100, tying her with Michael Jackson for having the third most number one songs on the chart.

Rihanna made her chart debut in June 2005 with "Pon de Replay", which reached the top five in twelve countries. It was followed by the release of her debut studio album, Music of the Sun (2005), which reached the top ten in Canada and on the US Billboard 200. Rihanna's second studio album A Girl like Me (2006) produced four singles including the chart-toppers "SOS" and "Unfaithful". The former became Rihanna's first number one single on the US Billboard Hot 100 and earned a platinum RIAA certification.Good Girl Gone Bad (2007), Rihanna's third studio album, peaked at number two on the Billboard 200 and was certified two-times platinum in the United States and five-times platinum in the United Kingdom. The album's lead single "Umbrella", became a massive commercial success, peaking at number one in fifteen countries, including on the Billboard Hot 100 where it stayed atop the chart for seven consecutive weeks. Seven further singles were released from the album and its reissued version, including the international hits "Don't Stop the Music", "Take a Bow" and "Disturbia".

Night vision device

A night vision device (NVD) is an optoelectronic device that allows images to be produced in levels of light approaching total darkness. The image may be a conversion to visible light of both visible light and near-infrared, while by convention detection of thermal infrared is denoted thermal imaging. The image produced is typically monochrome, e.g. shades of green. NVDs are most often used by the military and law enforcement agencies, but are available to civilian users. The term usually refers to a complete unit, including an image intensifier tube, a protective and generally water-resistant housing, and some type of mounting system. Many NVDs also include optical components such as a sacrificial lens, or telescopic lenses or mirrors. An NVD may have an IR illuminator, making it an active as opposed to passive night vision device.

Night vision devices were first used in World War II, and came into wide use during the Vietnam War. The technology has evolved greatly since their introduction, leading to several "generations" of night vision equipment with performance increasing and price decreasing. Consequently, they are available for a wide range of applications, e.g. for gunners, drivers and aviators. Another term is "night optical/observation device" or NOD.