flashlight

One of those flashlights with about a dozen leds will cast a pretty even light, you'll find.

The bright spot is produced by the parabolic reflector focusing the point light source (the filament) into a collimated beam, the width of the reflector. The surrounding glow is the light from the filament that misses the front of the reflector and just fans out uniformly from the front of the filament.

You can defuse the reflector collimated beam by adding a layer of frosted Scotch Magic tape to the front of the glass. But the flashlight will no longer throw a long distance beam. Leave a little of the glass uncovered if you want to keep a little of the long distance beam (hot spot).

I have several CCFL lights (cold cathode fluorescent lamp) that use four AA batteries. They produce an even light and are very reliable. The tubes have a life of something like 5000-25,000 hours depending upon who you ask. I've been using mine daily for a few years. Most of them also have a spotlight (halogen) bulb but heck, you could always take out the bulb if it bothers you. They go for a few hours on NiMh batteries and longer on alkaline.

Here's an example on ebay that also has LEDs in it. Mine don't.

I only paid about $8 each for mine a few years ago. BTW ccfl tubes are also used in many laptops to illuminate the screen.

Someone has already mentioned flashlights with multiple LEDs in them. Some time ago, from Costco, I purchased some single-LED flashlights with bodies made entierly out of aluminum. The single LED is quite bright and they use a reflector (as already mentioned) in order to help form a narrower beam for further reach. However, at night (very late, say midnight?) when I'm walking along my driveway (1/4 mile long, in the woods), I will often just take the reflector cover off of the light, exposing the LED die in the center of a flat circle. It casts out a very nice and even distribution of light (almost lambertian) that is very good at night out to 50 feet or so and covers the entire 180 degrees in front of me in just the optimal way for night walking and seeing everything around you nearly at once.

I have done the same thing with traditional flashlights using incandescent bulbs with results that were very much inferior for that purpose. So I greatly prefer the unfocused LED light, walking my driveway from time to time. It provides all the right distributions of intensities at all the right angles away from center-line and without uniformity weaknesses. The incandescents I've tried have been kind of wan, by comparison. Admittedly, they don't have a backing flat reflector, so some of the light doesn't go forward when the reflector is removed, though. But even defocusing them doesn't really get nearly as good a result, so I still prefer that one LED light I found for this purpose.

Another approach for flashlights where possible, is to defocus the beam a bit by unscrewing the cap somewhat until you get something close to what you are looking for. Try that, too.

Jon

Maglite(tm) makes a number of adjustible ones, expect to pay for quality.

Bye. Jasen