Optics vs. Reflector who wins in terms of Lumen output

If you compare a reflector and an acrylic optics (that are about a similar size) and measure the LUMENs they put out, using the same LED (LuxIII)- which one puts out more lumens, when you DON'T factor in the light that spills out on the side of an optics (so the optics would have to be in a cylinder).

Don is probably the only one who could answer that question empiricly - unless this question is obvious or has been discussed before.

I think there is some loss with a reflector as well. Or maybe you know the answer without doing any tests.

My GatLight Foto here is probably the first light that shows how much side spill optics have. I am wondering whether reflectors would be better. On the other hand I noticed that optics seem to produce better hotspots then reflectors (when being the seme size).

Reflectors will win if it comes down to forward lumen output.

Reflectors are first surface mirrors with no light passing through therefore losing little, and lenses, even thin polycarbonate lenses which are worse in transmission than glass can lose 11% of available light (reference Flashlightlens.com website). Same reference states changing to a glass lens can increase output to 98% of available light. Different types of glass have individual characteristics each with their own abberations. Multiple mm's of media in the light path begin to take it's toll. Ar coatings can reduce output slightly, but are an acceptable tradeoff.

One of the largest losses of light are from air / optical surface interface reflections, which is the main point of AR coated materials.

The advantage of optics, is that for the same diameter, the fundamentals of TIR force the beam into more of a hot spot kind of configuration. As you have seen, there are light "leaks" from the side of the optic as the TIR effect is usually not 100%. It actually could be improved by applying the concepts used in optical fibers.

Optical acrylic is actually quite clear, but there are losses.

For your specific question, which has better total Lumens out the front, it is interesting that SF has optics in so many of its lights, despite the low cost of molded reflectors.

My understanding of optics is that they're more efficient than reflectors. A typical inexpensive reflector will lose about 15%. Chop another 10% off of that for a cheap lens and you're down to 76.5% of the original source - assuming no other losses.

Exceptionally high-quality reflectors will lose 2-5%, and good AR glass will lose 1-2% - combine those and you'll lose less than 8%.

Optics are often quoted as being more efficient - I've seen 85% & 95% tossed around. Of course, sometimes these figures are tricky - they claim high efficiecy based on intensity readings at a distance rather than lumens in vs lumens out. A combination of refraction and reflection allows optics to work, so they can be smaller than reflectors.

Some optics don't produce results as satisfactory as reflectors - by concentrating the light so well, they eliminate the spill that is so useful for close-up work.