How do IR, night vision gogglles work? I'll guess, much like digital cameras - lenses, sensor, viewscreen, amplifiers and necessary electronics. My question is, could a unit be designed to operate completely passively, just lenses and filters, i.e. no battery required, like hand held binoculars?
I had assumed these devices were regulated, limited to Big Brother's storm troopers, can't let the peons have access to dangerous toys! But then I saw an ad for one at a sporting goods shop (aimed at hunters) (deer, not man hunters, presumably). This is a case where I'm glad to be wrong.
Night vision and IR are different. Night vision uses light amplification. It will also work with IR illumination, but spewing out IR gives away your location. NV is not passive, but it is actually more efficient power wise to use NV goggles than a flashlight. Cost wise, well.....
Note that CCDs also respond to IR, or more correctly near IR, say 800n to 1.2um] That is why some so called night vision gear is just a CCD with IR illuminator.
There is plenty of Russian NV out there. It is hardly regulated. The better US stuff is regulated, but gear just as good, say EMCCD, is sold without regulation.
I have a Russian nv. It uses a vacuum tube and a high voltage source. The tube is all in one. Light enters the front, and the light is amplified inside by electron collision, and hits the back screen illuminating it in a green color.
I also have an older Sony camcorder. It has a night vision mode, and super night vision which appears to slow the scan speed down to get further enhancement.
Why is it always the official "crackpot" who needs to "go read a freshman textbook" who has to answer everyone's practical questions? I take it you and Freddi are not experimentalists.
You are talking about two different devices here. An IR viewer sees in the "dark" only because to you (or deer) IR is invisible. So the area appears dark, but through the "viewer" the scene is actually brightly lit (usually with an IR LED these days). Many standard camera devices have response into the IR. Silicon chips often do as do many vidicon tubes. unless steps were taken to block IR. Here we are talking NEAR IR which is just out of visible range. Longer wavelengths (like military FLIR) are usually scanners. Many video cams today have built- in IR LEDS for "night vision".
A "real" IR viewer (like say used by a "real" physicist in a "real" lab) is built a bit differently. It is similar in many ways to an electron microscope. Except the front of the tube has a photoelectric coating on a window where IR shakes loose electrons. The electrons are then focused on a fluorescent screen with electron optics. Hence one can "see" the IR light.
True "night vision" is different. It is similar to the IR viewer, only the principles of a photomultiplier tube are incorporated so that when even a single electron (one photon) is kicked out it gets amplified enough you can see the spot. Obviously these cannot see in NO light, but can see in VERY low light. They are regulated only by PRICE! :-) For military use you can see the disadvantage of IR LEDS on your viewer. Makes you light up into a dandy target!
Whew! OK, finally can you see IR with only optics? Yes you can! You have to use something known as a "doubling crystal" GREAT physics there. Go look it up! Hence one can input an IR laser and it doubles the frequency to green light that comes out the other end. I do not recommend doing this for a viewer, however, as light intensity must be VERY high.
I now return you to the folks "smarter than Einstein"....
Say, wait a minute! Why am I explaining all this when I can just rip a page out of Wormley's playbook?
I believe that the night vision goggles employ a microchannel plate. This is analogous to a photomultiplier - actually LOTS of photomultipliers in parallel. Lens focuses light on the front photocathode of the MCP, generating electrons which are amplified in the channels and then hit a phosphor screen (instead of the traditional Anode of the photomultiplier).
And I want a ray gun and a Beano Annual and a cowboy outfit and a clockwork train set and a pony and a phone I can play "Angry Birds" on, and NO batteries on any of them.
Land and See: Infrared and 3-D Vision Systems Combine to Help Pilots Avoid Crash Landings [Video]
flight (see video below), actually combines and leapfrogs two earlier technologies only recently being installed on smaller commercial craft. Synthetic vision systems (SVSs) use terrain data culled from actual flights and stored in a database to create a 3-D graphical interface (think Windows or Mac OS) on a screen in front of the pilot and co-pilot, enabling them to see a digital model of their surroundings even when their vision is obscured by darkness or clouds. SVSs also include information about the location of airports and runways, to help guide pilots until they can establish visual contact with their landing destination.
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.