Looking for suggestions for somewhat technical situation


Newly Enlightened
Jul 20, 2002
Greetings from an old member…

I know I haven’t posted for a long time. Doesn’t mean that I’m not around; I still check the forum once in a while. So glad that this forum is continuously thriving.

I have a bit of technical situation and I like to get some recommendations from CPF members and their collective knowledges.

I am looking for a flashlight (head mostly, later on this) or some light source which will not be used as a conventional flash light. I limited the choice to an LED light source; since this forum. (Mod – feel free to relocate if this is not the best location)

I (our company to be precise) have a photometric test setup that measures various parameters for a product that goes into a cockpit of a commercial aircraft. One part of the test requires that the test surface illuminated at 7,500 fL with the light source located at 45-degrees off axis. Currently, we do this with a medium power Xenon light source which is getting old and in need of replacement (especially related electronics). Since the illumination target area is very small (about 0.5” diameter) and existing optical collimation setup is not that efficient, much of the light output is wasted, and worse yet, hinders other tests.

I figured that an efficient LED light source such as an LED flash light could do the job and save a lot of space, electricity, and replacement parts cost. I did a preliminary test to verify the feasibility with a couple of flashlight I have. Lupin Pico TL with 1,200 lumens published spec actually worked pretty close (generated well over 8,000 fL, however at a working distant that is a little too short) but main issue is that its brightness is not continuously variable. Being a relatively flood beam did not help either.

It really needs to be a continuously variable brightness because the setup needs to be calibrated with a tight tolerance. Also, the control could work better if it is not software based (accessing through multi-click or such) but rather hardware based (something like Sunwayman’s V-series rings). I am planning to power the light with a DC power supply, not with batteries. That means I will be doing a simple mod such as removing battery compartment and permanently attaching some wires, and because of that, the brightness control needs to be in the head or near the light engine.

The target beam size is 0.5” at 12” to 18” of working distant; and within that diameter, it would be desirable that the beam is really uniform. I could place a mild diffuser to even out beam artifacts, but that will have an effect on both the beam size and brightness. Anything beyond the target area will be spill light and too much of it will have to be blocked; not a big problem other than the efficiency of the whole setup will suffer.

The setup will be operating continuously several hours at a time. The light will definitely need to be rated for that, not those turbo mod that dims after a few minutes.

I think I described everything; please send me some pointers / suggestions / recommendations. If I missed anything, send me a question as well.

Thank you very much.