Wikia

Psychology Wiki

Changes: Night vision

Edit

Back to page

 
(tidied leaving only biologically relevent content)
 
Line 1: Line 1:
 
{{BioPsy}}
 
{{BioPsy}}
[[image:nightvision.jpg|thumb|right|Two [[United States|American]] soldiers pictured during the [[2003 Iraq War]] seen through an Image Intensifier]]
+
'''Night vision''' is the ability to see, whether through biological or technological means, in a [[dark]] environment. Most instances, whether biological or technological, use a combination of two approaches: enhanced spectral range, and enhanced intensity range.
+
'''Night vision''' is the ability to see in a dark environment. Most instances, whether biological or technological, use a combination of two approaches: enhanced spectral range, and enhanced intensity range.
   
 
==Enhanced spectral range==
 
==Enhanced spectral range==
Line 15: Line 15:
 
In biological night vision, molecules of [[rhodopsin]] in the rods of the [[eye]] undergo a change in shape as light is absorbed by them. The peak [[rhodopsin]] build-up time for optimal night vision in humans is 30 minutes. Rhodopsin in the human rods is insensitive to the longer red [[wavelengths]] of light, so many people use red light to preserve night vision as it will not deplete the eye's rhodopsin stores in the [[rod cell|rod]]s and instead is viewed by the [[cone cell|cone]]s.
 
In biological night vision, molecules of [[rhodopsin]] in the rods of the [[eye]] undergo a change in shape as light is absorbed by them. The peak [[rhodopsin]] build-up time for optimal night vision in humans is 30 minutes. Rhodopsin in the human rods is insensitive to the longer red [[wavelengths]] of light, so many people use red light to preserve night vision as it will not deplete the eye's rhodopsin stores in the [[rod cell|rod]]s and instead is viewed by the [[cone cell|cone]]s.
   
Some animals, such as [[cat]]s, [[dog]]s, and [[deer]], have a structure called the [[tapetum]] in the back of the [[eye]] that reflects light for even better night vision than humans, in which only 10% of the light that enters the eye falls on photosensitive parts of the [[retina]]. Their night vision likely falls between a Generation 1 and Generation 2 [[image intensifier]].
+
Some animals, such as [[cat]]s, [[dog]]s, and [[deer]], have a structure called the [[tapetum]] in the back of the [[eye]] that reflects light for even better night vision than humans, in which only 10% of the light that enters the eye falls on photosensitive parts of the [[retina]].== Thermal vision ==
   
== Night glasses ==
+
Far [[infrared]], or thermal, sensing is generally not considered night vision because it is constructed with mechanisms substantially different from the methods used to sense visible light.
   
Night glasses are [[telescope|telescopes]] or [[binoculars]] with a large diameter objective. Large lenses can gather and concentrate light, thus intensifying light with purely optical means and enabling the user to see better in the dark than with naked eye alone. Often night glasses also have a fairly large [[exit pupil]] of 7 mm or more to let all gathered light into the user's eye. However, many people can't take advantage of this because of the limited dilation of the human [[pupil]]. To overcome this, soldiers were sometimes issued [[atropine]] eyedrops to dilate pupils. Before the introduction of image intensifiers, night glasses were the only method of night vision, and thus were widely utilised, especially at sea. Second World War era night glasses usually had a lens diameter of 56 mm or more with magnification of seven or eight. Major drawbacks of night glasses are their large size and weight.
+
Some organisms have the ability to sense far infrared energy which we perceive as heat. This is prevalent in some [[snakes]] such as [[Crotalinae|pit viper]]s and [[Boa constrictor|boa]]s. However, this is not actual "vision", but more of a system of thermosensitive pits in the face that can detect the amount of heat and the distance to the heat source. There is still some debate as to what degree this information is perceived as "feeling" heat, and to what degree it is processed as an image by the snake's [[brain]]. Since these sense structures lack imaging optics for [[Focus (optics)|focus]], the spatial resolution of such sensing is necessarily very poor.
   
== Thermal vision ==
 
   
Far [[infrared]], or thermal, sensing is generally not considered night vision because it is constructed with mechanisms substantially different from the methods used to sense visible light. It is possible to construct an imaging device with [[microwave]] energy, [[sound]], or any other signal that is reflected or radiated by objects and can be focused and sensed, but these are also not generally considered night-vision.
 
   
Some organisms have the ability to sense far infrared energy which we perceive as heat. This is prevalent in some [[snakes]] such as [[Crotalinae|pit viper]]s and [[Boa constrictor|boa]]s. However, this is not actual "vision", but more of a system of thermosensitive pits in the face that can detect the amount of heat and the distance to the heat source. There is still some debate as to what degree this information is perceived as "feeling" heat, and to what degree it is processed as an image by the snake's [[brain]]. Since these sense structures lack imaging optics for [[Focus (optics)|focus]], the spatial resolution of such sensing is necessarily very poor.
 
   
[[Cadillac (automobile)|Cadillac]] introduced a far-infrared night vision as an option on the [[2000]] [[Cadillac Deville|Deville]]. It sold well initially, but sales fell and the option was dropped early in the [[2005]] model year. [[Toyota Motor Company]]'s [[Lexus]] marque was next with a night vision system in their [[Lexus LX|LX470]] [[SUV]]. The 2007 [[BMW 5 Series]] will also offer night vision as an option.
 
   
See [[Thermographic camera]].
+
== See also ==
   
==Image intensifier==
 
{{main|image intensifier}}
 
The image intensifier is a vacuum-tube based device that amplifies visible light from an image so that a dimly lit scene can be viewed by a camera or by eye.
 
   
==Night vision goggles==
 
{{main|night vision goggles}}
 
 
Night vision goggles typically use an image intensifier to convert weak light from the visible and near-infrared spectrum to visible light. Most night vision goggles display a green image, because the peak sensitivity of human color vision is around 530 nm.
 
 
== See also ==
 
* [[Car safety]]: [[BMW]] night vision. [http://www.bmw.co.uk/bmwuk/about/news/0,5126,1156___co-160134112,00.html] [http://www.carpages.co.uk/bmw/bmw-night-vision-22-07-05.asp]
 
* [[Thermographic camera]]
 
* [[Image intensifier]]
 
 
* [[Scotopic vision]]
 
* [[Scotopic vision]]
 
* [[Night vision goggles]]
 
* [[Night vision goggles]]
   
== Patents ==
 
 
* [[US D248860]] - Night vision Pocketscope
 
* [[US 4707595]] - Invisible light beam projector and night vision system
 
* [[US 4991183]] - Target illuminators and systems employing same
 
* [[US 6075644]] - Panoramic night vision [[goggles]]
 
   
 
== External links ==
 
== External links ==
* [http://www.badacetechshow.com/nvc.htm How To Build Your Own Night Vision Camera]
+
* [http://www.nvl.army.mil/ Night Vision & Electronic Sensors Directorate] - Fort Belvoir, [[Virginia]]
 
* [http://bookstore.spie.org/index.cfm?fuseaction=DetailVolume&productid=612862&CFID=2928271&CFTOKEN=1398491618th 18th International Conference on Photoelectronics and Night Vision Devices] international conference in Russia published by [[SPIE]].
 
   
   

Latest revision as of 10:05, October 8, 2006

Assessment | Biopsychology | Comparative | Cognitive | Developmental | Language | Individual differences | Personality | Philosophy | Social |
Methods | Statistics | Clinical | Educational | Industrial | Professional items | World psychology |

Biological: Behavioural genetics · Evolutionary psychology · Neuroanatomy · Neurochemistry · Neuroendocrinology · Neuroscience · Psychoneuroimmunology · Physiological Psychology · Psychopharmacology (Index, Outline)


Night vision is the ability to see in a dark environment. Most instances, whether biological or technological, use a combination of two approaches: enhanced spectral range, and enhanced intensity range.

Enhanced spectral rangeEdit

Enhanced spectral range techniques make the viewer sensitive to types of light that would be 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 UV radiation).

Enhanced intensity rangeEdit

Enhanced intensity range is simply the ability to see with very small quantities of light. Although the human visual system can, in theory, detect single photons under ideal conditions, the neurological noise filters limit sensitivity to a few tens of photons, even in ideal conditions [1]. Some animals have evolved better night vision through the use of a larger optical aperture, improved retina composition that can detect weaker light over a larger spectral range, more photoefficient optics in the eye, and improved neurological filtering which is more tolerant of noise. Enhanced intensity range is achieved via technological means through the use of an image intensifier, gain multiplication CCD, or other very low-noise and high-sensitivity array of photodetectors.

Biological night vision Edit

In biological night vision, molecules of rhodopsin in the rods of the eye undergo a change in shape as light is absorbed by them. The peak rhodopsin build-up time for optimal night vision in humans is 30 minutes. Rhodopsin in the human rods is insensitive to the longer red wavelengths of light, so many people use red light to preserve night vision as it will not deplete the eye's rhodopsin stores in the rods and instead is viewed by the cones.

Some animals, such as cats, dogs, and deer, have a structure called the tapetum in the back of the eye that reflects light for even better night vision than humans, in which only 10% of the light that enters the eye falls on photosensitive parts of the retina.== Thermal vision ==

Far infrared, or thermal, sensing is generally not considered night vision because it is constructed with mechanisms substantially different from the methods used to sense visible light.

Some organisms have the ability to sense far infrared energy which we perceive as heat. This is prevalent in some snakes such as pit vipers and boas. However, this is not actual "vision", but more of a system of thermosensitive pits in the face that can detect the amount of heat and the distance to the heat source. There is still some debate as to what degree this information is perceived as "feeling" heat, and to what degree it is processed as an image by the snake's brain. Since these sense structures lack imaging optics for focus, the spatial resolution of such sensing is necessarily very poor.



See also Edit


External links Edit

da:Nattesyn

es:Visión nocturna fr:Nyctalopie he:ראיית לילה id:Penglihatan malamnl:Nachtzichtapparatuurno:Nattsyn pt:Visão noturna

This page uses Creative Commons Licensed content from Wikipedia (view authors).

Around Wikia's network

Random Wiki