What do those UCL lenses do, anyway?

I've noticed that people are buying these UCL replacement lenses that flashlightlenses.com sells (I think). Why? Do they give better output? Is it noticeable? I have a G2 that I might install one in, but only if its worth it. Someone care to explain?

they have better output than normal glass or plastic. noticable to the eye? depends but usualy not. ucl's usualy give an extra 8 percent boost in output

Look here for the results of some testing I did on the UCL lens some time back.

The main reason I like them is they do not scratch at all. Nothing looks worse than a scratched-up poly lens. AA-MM's are weak as it is, and a UCL lens is visibly better than a poly lens that has been through the ringer.

I think the quality of light is (slightly) perceptivley better; clearer and more intense.

My favorite lens is the UCL-LDF in a AA Mag with a TerraLux Ministar1. It is the perfect bedroom, reading in the car or tent at night light (short on an L-1 of course).

There is a great potential for transmission loss whenever light must travel through different density media on it's way to the target. In a lens there are two of these air barriers, one where the light must enter the lens and one where it must exit the lens. IIRC these two barriers represent the greatest potential transmission loss. UCL's have special anti-reflective coatings which greatly reduce losses at both of these barriers.

The third potential transmission loss in the lens has to do the clarity of the base material that the lens itself is made of, and while this is not nearly as big a factor in the efficiency of the lens as reducing the air barrier losses, it is noteable.

Also, whatever forming process is used initially in making the lens will have an impact on the quality of it's surfaces all the way down the line.

I'm sure I'll be corrected if I've messed any of this up. /ubbthreads/images/graemlins/grin.gif

What about heat?

If you have, say, 10% loss through a plastic lens, that lost energy has to go somewhere -- heat? If you cut your transmission loss from 10% to 5%, it would seem like things would run a little cooler. (You'd still have the normal losses to heat before emission, though.)

Scott

the lost energy is reflected back to the reflector. the ucl has a anti reflective coating so less light is reflected. this coating is simaler to the ones used on camera lenses and other optics

IMO, the UCL lens is a good investment. HOWEVER, if you plan to use one on a G2, need to first check to be sure the "factory" lens can be removed for replacement. While I accomplished this with several of my older G2's, I recently acquired several of the new "tan" models, and was not able to remove the OE lens. Checked with Surefire and was advised that the lens on these could not be removed/replaced.

How about some hints as to how to change the G2 lens?

I used a watch case back opener, but you could get some piliers that open that wide, or a spanner wrench

Hmmm, so you do notice a difference. I think I might get one, after I determine if I can replace my G2 lense. Could you replace the lens in a 6P as well?

how much lost is there in a pyrex lens?

[ QUOTE ]
Theo said:
AA-MM's are weak as it is, and a UCL lens is visibly better than a poly lens that has been through the ringer.



[/ QUOTE ]

What exactly does "UCL" stand for...tis not in the
Acronyms above. How does it differ (or does it?) from
"mineral glass"?

Thanks

MB

About four percent (3-4%) on the entrance side and 3-4% on the exit side. 6-8% overall, with waterwhite glass types.

Glass lenses

Another info thread

AR coating info

Another benefit I haven't seen mentioned is that these lenses really add to the aesthetic quality of any light they are used in. They are virtually invisible when installed, and really are a great way to "dress up" a light while also adding functionality.

Peter

mykall,

UCL = Ultra Clear Lens