Thinking about flashlight got me thinking about what I want in a flashlight. About the various flashlight I own and have used. About what features and designs I like and which ones I don't. About what I really want.

Form-factor: I want a flashlight that rides like a thick pen. Thin enough to slip into a pocket unobtrusively. If I have it in my pocket and fall on it it should be flat and rounded enough so it doesn't leave a painful bruise. On the other hand I don't want it so thin that I'm afraid of it folding if I fall on it and not so long that it won't ride in a shirt pocket. Four to five inches long and not more than 5/8" diameter, if round in cross section, is about right. It can be an oval or a well rounded rectangle in cross-section. But widest cross-section shouldn't be more than about 1-1/4".

Weight: The unit should be as light as possible with just enough weight to lend confidence. It should be light enough not to sag or pound when jogging. Less than, but certainly not much more than, a quarter pound (about 114g) with standard Alkaline batteries would be ideal. Standard AA alkaline batteries run about 23g each, lithium about 15g each.

Alternate holding: The materials and dimensions should allow use while held in the mouth without risk of freezing your lips to the metal, chipping teeth, lousy plastic taste, or fatiguing the jaws. The design should allow easy mounting on a headband. The clip might pivot ninety degrees to accommodate this. The flashlight should have provision so it does not roll off an incline.

Retention: I want a sturdy clip so it will ride in a shirt pocket, pants pocket or on the belt. The clip should be located well above the center of mass so that the light doesn't tip-out' when riding in a shirt pocket or tend to shake or vibrate out of a pocket. Only enough of the unit need be exposed when clipped onto pocket to allow an easy grip for pulling out. The clip should grip quite firmly and might incorporate an exposed tab that has to be depressed to release it so the unit can be slipped out easily.

A clip that can be removed, bent back into shape or adjusted and reattached would be good. One of the flex metals, possibly one that will reform itself if heated, would be great. If a screw is used it should be retained if the clip is removed so there is not danger of it being lost. Head design should allow use of a coin or knife blade to tighten in addition to a normal tool.

Light quality: Good quality light that shows colors accurately. Such that reading faded wire color codes and detecting skin flushing or a red tone is easy. Daylight white is best for color rendering.

Controls: All controls should be operable while wearing heavy mittens. Ideally with one hand. The surfaces of the unit's body and controls should be textured, or faceted such that gripping is easy and controls are readily operable even when both hands and the unit are wet and greasy.

Settings should be limited to (OFF-ON) on one control and (High-Low) on a separate control. Controls should have a positive mechanisms such that they will not be effected by anything but the purposeful actions of the operator. The OFF setting should be particularly resistant to being changed inadvertently but should remain easily operable.

Light output: On low output should be high enough to perform simple mechanical tasks within arms reach, read a standard trade paperback without excessive eyestrain, orient oneself within a space, and easily recognize a face at 20'. That doesn't take a whole lot of light.

On high it should provide enough light to find a dropped button compass in leaves, examine a wound closely, and enough reach, about 40' is fine, to read a street sign from a car with the car stopped and window rolled down. A wide enough beam to maintain situational awareness and avoid walking into a brier patch or off a cliff. A strong and concentrated enough beam to tell at 40' what a person has in their hands. Handy to have but not a requirement: Being able to differentiate between gun, wallet, knife, and cell phone at 40' would be ideal as long as it doesn't require violation of other specifications.

Batteries: Uses standard AA alkaline or lithium batteries.

Battery life: Eight hours on high and twenty-four hours on low using a single set of standard alkaline batteries would be a good minimum to shoot for. Twelve hours on high and forty-eight on low would be ideal. Anything beyond that is gravy. You can't have to much battery life as long as other requirements are met.

Water resistance: Proof against rain, mud and ice. Submersible to a depth of at least 50' or better. It needn't be a diver flashlight but that would be a good thing.

Flammable atmospheres: Should be certified, or at least be designed to be certifiable, for division I and II, and MSHA.

Resistance to impact: withstands without permanent damage or impairment of function from a 25' drop onto concrete.

Exterior materials: Majority non-conductive, highly resistant to corrosion, and all common chemicals. Can be sterilized by chemical means or flash autoclaved without damage or loss of function.

Interior materials: Case interior and all electrical components can sustain repeated and prolonged exposure to leaking alkaline batteries, alkali, and common chemicals without significant damage. Returning the unit to functionality after a set of batteries leaks should require no more than removal of the old batteries, washing the interior with a mild detergent, and installing new batteries. Washing, even if the interior retains significant amounts of water and detergent, should cause no significant damage.

Cost: Ideally the unit would retail for less than $25. If all other specifications can be met I think I would pay up to $60. Perhaps a bit more. After all, it would be the worlds best flashlight.

Now if I can just blackmail a team of German scientists and designers to come up with my perfect flashlight. I'm sure with a well rounded team and an investment of two or three million dollars I can get my light. On the other hand, perhaps, a team of engineers will read this and take it as a challenge... right. Like that is going to happen. A guy can dream.

What do you think?
What did I get right/wrong?
What changes in the specifications would you make to get your perfect flashlight?
Is this flashlight even possible given current technology?