Night vision

Night vision refers to the ability to see in low-light conditions. This can be achieved either biologically through special physical structures and adaptations, or technologically through the use of special equipment and devices.

Biological Night Vision

Many animals, including certain species of birds, mammals, and reptiles, have evolved to have superior night vision compared to humans. This is often due to the presence of a layer of cells in their eyes called the tapetum lucidum, which reflects light back through the retina and increases the amount of light available for the photoreceptors.

Technological Night Vision

Technological night vision can be achieved through a variety of methods, including image intensification, thermal imaging, and active illumination.

Image Intensification

Image intensification works by amplifying the available light, such as moonlight or starlight, to levels that can be detected by the human eye. This is often achieved through the use of an image intensifier tube, which uses a photocathode to convert the light into electrons, which are then amplified and converted back into light by a phosphor screen.

Thermal Imaging

Thermal imaging works by detecting the differences in temperature between objects and their surroundings. This is often achieved through the use of a microbolometer, which measures the changes in electrical resistance caused by changes in temperature.

Active Illumination

Active illumination works by projecting a beam of infrared light, which is invisible to the human eye but can be detected by special sensors. This is often used in conjunction with image intensification or thermal imaging to improve visibility in very low-light conditions.

See Also

• Infrared vision
• Night vision device
• Thermographic camera

References

Night vision Resources
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