How Night Vision Goggles Work
There are two types of night vision technology. The first, commonly called "night-vision devices" or "NVDs," uses a system of light amplification to bring out otherwise imperceptible detail in a dark scene. NVDs produce the iconic green night vision scene and are the most commonly available equipment.
NVDs take in ambient light through a regular optical lens and send it through image-intensifier tubes. In these tubes are a series of specialized discs that convert light into electricity, amplify it, and then revert it back to visible light energy. The first disc in the image-intensifier tube is a photocathode. The photocathode is a battery-powered device that converts photons, or light energy, into electrons, or electrical energy.
The electrons travel through the tube to the second disc, called the microchannel plate (MCP). MCPs are glass discs with millions of microscopic holes called microchannels in them and is flanked by two electrodes. When the electrons from the photocathode strike the first electrode, they are propelled into the MCP's microchannels. They bombard the sides of the channels, releasing thousands more electrons as they go. A few electrons go in, and thousands more come out the other side.
The channels keep the electrons in roughly the same location they entered, allowing them to maintain the same configuration they held as photons. This is what ensures the same picture comes out as went in, just amplified. The electrons then come to a phosphor screen, where the excited electrons trigger the release of photons, converting the image back to light energy. It is this phosphor screen that gives NVD images their green cast.
Finally, the image hits an ocular lens that focuses and magnifies the image for viewing. Because this process actually degrades the image-intensifier tube in order to function, NVDs have a limited life. Current NVD technology can amplify light 40,000 times and has a life span of about 10,000 operating hours.
The second type of night vision technology is thermal imaging. Thermal imaging captures infrared light, the wavelengths emitted by heat from objects like warm bodies and engines. Thermal imagining produces the multi-colored images in which purple or black areas are cool and bright white areas are hot spots.
Light travels in waves. The shorter the wavelength, the more energy the light contains. Our visible light spectrum is represented by a rainbow with red at the beginning and violet at the end. Violet contains the most energy, and just beyond it is the ultraviolet spectrum. Red contains the least energy, and just beyond it is the infrared spectrum.
Infrared is split into near-infrared (near-IR), which is closest to our visual spectrum, mid-IR and thermal-IR. Near- and mid-IR encompasses light reflected off of objects, like the light in our visual spectrum, while thermal-IR is emitted by objects as they produce heat. Even inanimate objects produce heat as the atoms in them move.
Thermal imaging technology captures thermal-IR. After a lens in a thermal imaging unit focuses the infrared light in the area, the infrared emissions are picked up by infrared-detector elements that creates a pattern called a thermogram. The thermogram is converted into electrical impulses that become the multi-colored image displayed.
Night vision technology is used by law enforcement, the military and hunters to do everything from detecting contraband to finding a deer in the bush. As the technology improves, even more incredible opportunities will open up for the use of night vision." > How Night Vision Works
Now matter how commonplace it becomes, night vision technology never stops being incredible to behold. From spy movies to the battlefield, night vision is science fiction turned reality.
There are two types of night vision technology. The first, commonly called "night-vision devices" or "NVDs," uses a system of light amplification to bring out otherwise imperceptible detail in a dark scene. NVDs produce the iconic green night vision scene and are the most commonly available equipment.
NVDs take in ambient light through a regular optical lens and send it through image-intensifier tubes. In these tubes are a series of specialized discs that convert light into electricity, amplify it, and then revert it back to visible light energy. The first disc in the image-intensifier tube is a photocathode. The photocathode is a battery-powered device that converts photons, or light energy, into electrons, or electrical energy.
The electrons travel through the tube to the second disc, called the microchannel plate (MCP). MCPs are glass discs with millions of microscopic holes called microchannels in them and is flanked by two electrodes. When the electrons from the photocathode strike the first electrode, they are propelled into the MCP's microchannels. They bombard the sides of the channels, releasing thousands more electrons as they go. A few electrons go in, and thousands more come out the other side.
The channels keep the electrons in roughly the same location they entered, allowing them to maintain the same configuration they held as photons. This is what ensures the same picture comes out as went in, just amplified. The electrons then come to a phosphor screen, where the excited electrons trigger the release of photons, converting the image back to light energy. It is this phosphor screen that gives NVD images their green cast.
Finally, the image hits an ocular lens that focuses and magnifies the image for viewing. Because this process actually degrades the image-intensifier tube in order to function, NVDs have a limited life. Current NVD technology can amplify light 40,000 times and has a life span of about 10,000 operating hours.
The second type of night vision technology is thermal imaging. Thermal imaging captures infrared light, the wavelengths emitted by heat from objects like warm bodies and engines. Thermal imagining produces the multi-colored images in which purple or black areas are cool and bright white areas are hot spots.
Light travels in waves. The shorter the wavelength, the more energy the light contains. Our visible light spectrum is represented by a rainbow with red at the beginning and violet at the end. Violet contains the most energy, and just beyond it is the ultraviolet spectrum. Red contains the least energy, and just beyond it is the infrared spectrum.
Infrared is split into near-infrared (near-IR), which is closest to our visual spectrum, mid-IR and thermal-IR. Near- and mid-IR encompasses light reflected off of objects, like the light in our visual spectrum, while thermal-IR is emitted by objects as they produce heat. Even inanimate objects produce heat as the atoms in them move.
Thermal imaging technology captures thermal-IR. After a lens in a thermal imaging unit focuses the infrared light in the area, the infrared emissions are picked up by infrared-detector elements that creates a pattern called a thermogram. The thermogram is converted into electrical impulses that become the multi-colored image displayed.
Night vision technology is used by law enforcement, the military and hunters to do everything from detecting contraband to finding a deer in the bush. As the technology improves, even more incredible opportunities will open up for the use of night vision.
To Buy Night Vision Goggles click here