A recent innovation in the field of personal flashlights is the use of high output LEDs (Light Emitting Diodes) in place of conventional bulbs. These are available in a wide range of colours, including infra-red wavelengths. It should be feasible to construct a small flashlight with a rotating head section so the user can select light from a choice of six colours. Such a torch would resemble as small right-angle torch powered by an AA battery.
It would have an on-off switch and squeeze button.
The head would be hexagonal and each face would be marked with the appropriate colour and letter in Braille. (..and before anyone asks, the side with the Infrared diode would be black!).
There would be a clip for attaching the torch to clothing or webbing and a finger loop for a more secure grip.
A good mix of colours would be white, red, green, blue, orange and infra-red.
Such a small but versatile flashlight would find numerous uses, including signaling between units.
UPDATE Recently I brought a Photon II LED light. This fits on my keyring virtually unnoticed, and resembles a car key with the shank broken off. It occurs to me that such a mechanism could be built into something the size of a signet ring. This would give a soldier a descrete light "readily to hand" that could be used for checking maps, signalling etc.
Further UPDATE Mike Sparks reminds us that when using a lightsource it is tactical prudent to cover it and the item you are examining with a poncho.
NSN: 62630-01-357-2175 is the stock number of a small green light that can be attached to the finger by a velcro strap. This lightsource is NVG compatible.
The latest model of Photon Micro Light, the Photon III includes various levels of brightness and strobe modes.
Tactical flashlights with multiple LEDs are now available, some also incorporating a conventional Xenon or Hallogen bulb. By varying the number of LEDs used the light level and battery life can be varied. A lens allows the beam to be changed from flood to spot. Such a flashlight would be compatible with the idea suggested above by using several white LEDs and one each of blue, orange, green and infra-red. The Flashlight would have a flip-up transparent filter that would convert the output to red light for tactical illumination. An alternate fliter (stored on the flashlight's butt?) would convert the output to infra-red illumination. Just behind the head of the flashlight would be a diagonal swivel that would allow the configuration to be varied from right-angle to in-line. A trick used by some Soldiers is to use a flashlight in the barrel of an M203 to create a very directional lightsource for signaling at night. The head of our tactical flashlight should be dimensioned to allow such use. The torch would use one or more AA batteries. It is high time that the diverse electronic items used by Soldiers standardized on a single type. It is quite possible to build a small LED flashlight that is powered by clockwork, but I see this option being more popular with survivalists than the military.
Another recent purchase has been an Inova 24/7 LED light. This offers various light options including low and high intensity white light, night vision friendly red light and various strobe options, including one that flashes "SOS" in morse. By adding a programmable element this could be the basis of a Code Strobe.
RED or GREEN? In some circles there seems to be considerable confusion about what coloured light should be used if night vision is to be preserved. The current vogue is to advocate green light for everything and some writers imply that the last hundred years or so of using red light was an error. What these advocates are in fact displaying is a lack of fundamental understanding of how the eyes work. As a professional physiologist that teaches medical students about vision, I'll set the record straight.
Vision is the product of two types of cell in the eye. The "Cones" are responsible for colour vision but also the perception of fine detail such as reading a map. "Rods" only see black and white but are sensitive to lower light levels so are used for night vision. The catch is that the Cones need a minimum level of the light to work and the Rods are deactivated by high levels of light. If the Rods get bleached it will take 30-40mins for you to recover your night vision.
As a generic group the Cones are most sensitive to green light (c540nm). Using green light lets the Cones see detail at low light levels unlikely to bleach the Rods. Rods detect very little light of more than 600nm so Red light (620nm+) lets the Cones work with little stimulation of the Rods.
Green light is best used when you have some control over the light intensity and can set it as dim as possible. In practice, green light is used for transmitted light sources such as compass needles and instrument displays, while red light is best used for reflected light from sources such as torches or interior lighting.
Fit a red filter to your torch but be aware that some map features will appear different under red light.
Another consideration is that green light at night is visible over a far greater distance than red light so anyone misguided enough to use a green light at night is far more likely to be seen and targeted by an enemy.
