Night Vision refers to one’s ability to vision in night or total dark. Animals are biologically empowered with night vision ability whereas humans profusely lack the ability to see objects in the night. This is because animal eyes contain tapetum lucidum which is absent in human eyes, which defies night vision. Technically night vision is possible by combination of specific spectral range and intensity range.
Human eyes detect light and send impulse to neurons in the brain cells in the form of electro chemicals. Human eyes can sense only visible light and not the radiations that come out in the dark. This when technology is interfered to increase spectral ranges of radiations that are otherwise not visible to human eyes, especially infrared radiations. Increasing spectral range of infrared radiations allows human eyes to detect objects. Animals are capable of using these infrared rations to view objects. This is the reason they can view in the dark while humans cannot.
Intensity range allows one to view objects that emit very less light. Theoretically humans can identify as low as one photon however in realty neurons responds in presence of some multiples of tens photons. Animal eyes on other hand have bigger eyeballs, lens and optical aperture, more number of rods and lesser cons in addition to tapetum lucidum which allows vision even in the night.
Humans have developed technologies to empower themselves with night vision for night driving, wild life studies, night safari, night flying and many more.
There are two common methods of night vision technology.
a) Low light Imaging:
Above works on the technology of enhancing available light from natural sources such as moonlight or start light or any other object. They are mostly used in goggles for night vision and night scopes. These are cheaper and very effective technology for night vision but they fail in places where there is no light. Image intensifiers and on-chip gain multiplication cameras are two well known methods of low light imaging.
b) Thermal Imaging:
Thermal Imaging also known as infrared thermography detects infrared radiations and generates images of specific radiations. The fact that infrared radiations are emitted by all objects around room temperature other than black bodies it is possible to view anything that suffices above conditions. Moreover as temperature of objects increase so does the radiations, warmer objects are seen clearer than colder objects. They come in extremely handy in viewing humans, animals in warm blood category for military and security purposes.
