gajinoz said:
I'd like to slide slightly away from the topic here for a moment and ask a question.
It seems that you can now get a light in every colour of the visible spectrum and, for all I know, a few outside of it. What is the purpose of the different colours? If you have different coloured lights could you tell me what you use them for. Thanks.
Here's my collection of colors:
Blue/green or turquoise: This shade is compatible with night vision devices/goggles (NVD/Gs). The NVDs can not detect this color spectum, so an enemy equiped with NVDs will not be able to pluck out your light like a 2 million candle power search light. Also, as a pilot who routinly flies Nap of the Earth in the dead of night with the aid of NVGs, a small light in this spectrum is neccessary for in-cockpit illumination of maps, charts, freq cards, etc. It will not overpower and shut down your goggles.
Blue and Green: Same as above, but not as good. Also, blood shows up well with blue spectrum lights. This is popular with hunters for tracking wounded prey at night.
Red: This spectrum is least damaging to "scotopic vision" or "night vision." There are two types of light recepters in the eye: Rods and Cones. Cones are used for "photopic vision" (day time) and have the best resolution. Rods are used during low light, and at night. They produce the chemical
rhodopsin, which is wash out by full spectrum light. Rod cells are least sensitive to red spectrum light, thus it presevers night vision. With the exception of NVD use, red light is also the most difficult spectrum for the naked eye to "lock on too", making it desirable for avoiding detection at night. There are no rod cells in the center of the retina, so a red light is virtually invisible at night when directly looked at. Red light at any appreciable range is only detectable at night with "off-center" viewing techniques.
Infa Red, Red and Orange also has the detrimental effect of wiping out night vision decives. NVDs are most sensitive to red light. Even more so than white light. A man smoking a cigarette looks like a bon fire from miles away under NVDs. Infra Red is also used to illuminate things for night vision devices. The "Night Shot" feature of your Sony handycam included a small IR light for illumination (Look close, and you will find the little IR LED). The Helicopter I fly has an IR spotlight that will illuminate HUGE chunks of terrain that I can see with the aid of NVDs, but the light is invisible to an unaided observer.