nx05 improvement

This has probably been mentioned before but I'll ask anyway:
Anyone try painting the backside of an nx05? A lot of light is wasted which seems to be the biggest complaint about this lens. I painted the side with metal-flake silver enamel to act as a reflector, and now it'll focus an LS into a tight square beam. I would post before and after photos, but I only had the one nx05 and wasn't expecting that much improvement. Black enamel should work also. Frosting the side before painting would be interesting to test. Thoughts?

~ned

It has been discussed before, and the concensus was that adding anything directly on the optics will mess up the reflection pattern, thus resulting in lower output. /ubbthreads/images/graemlins/frown.gif

Hope this helps,

NX05 question

emitter,

You might try spacing your optic about .050" above your HD LS and note what happens to the "squarishness." To me it seemed to provide a much-improved beam, and in side-by-side comparisons with an otherwise identical light, actually seemed brighter. I to have wondered about adding to an -05s internal reflectivity, but by vacuum metallizing the rear of it. I did try one in a polished copper cone that matched the taper, along with some mineral oil to fill the slight gap. The output was definately decreased, not to mention copper-colored in the side spill /ubbthreads/images/graemlins/frown.gif .

Larry

Bart and tvodrd posted while I was composing but I think I'll still offer this:

From what I've read here that would defeat the physics that make a collimator work. It took me a while to understand it and I should say "kind of" understand it.

For the optic to work it must have a thin atmosphere around it. It is this membrane of air that allows the collimator to reflect and manage most of the photons out to a focal point making a beam. Anything applied to the surface defeats this. Notice when the tab is dremmeled off; when you look into the optic it appears as a foriegn substance.

Some folks have put a collar of reflective material in the head of a flashlight and reported increased brightness but they were careful not to let this touch the optic.

Slick has reported that a new Frean product should be available in a few months that replaces and outperforms the NX05 significantly. See his post.

Yep. The way the optics works, it's pretty much cardinal rule to leave the outsides/back of the optics free of clutter or anything reflective/coated... Otherwise, it'll just distort the beam...

Of course, I do wonder if you could "sputter" the NX05 by doing something like coating the sides...
/ubbthreads/images/graemlins/thinking.gif

/ubbthreads/images/graemlins/icon3.gif

Didn't someone report sometime back that they had noticed the that the optics seemed to be picking up the color of the inside of the head of the Minimag? The color of the sidespill seemed to match the color of the minimag. I have been thinking of painting the inside of Minimag head with flat white paint to see if it makes any difference.

Icebreak,

My "kind of" understanding differs from yours a little. I see the optic as a combined reflector and refractor. Photons which strike the ball lense are refracted forward through the acrylic and out. Those that "miss" the ball lense and those which are reflected from the outer edges of it enter the cylindrical section around the optic. From that point, it is internal reflection works to get them out the front. The internal reflection part is what doesn't seem to great, based on the amount of light that "leaks." When light goes from one transparent media to another (acrylic to air) with a different index of refraction, the light will be transmitted or reflected as a function of the angle at which it arrives. I'm really rusty here, but if the incident photons arrive at less than the critical angle for the difference in indices of refraction, it will be reflected. When the photons arrrive at an angle greater, they (or a portion) will be transmitted. I suspect that the design of an optic like that takes a bunch of computer time, of an enormous amount of trial and error. I wish someone could get one metallized (masking the lens cavity could be tricky) and see what the results are- beamshots and lightmeter.

Larry

Larry -

I'm not that great at explaining things I understand and am much less able to explain things I only have a little grasp on. The only part I'm pretty sure about is the envelope of air around the optic being intregal to the optic working correctly.

The description of how the ball and shaft work sounds right from my memory of how others have described the activities of the photons in the optic system.

I just did a little experiment with a very good MadMax in a Mini running on lithiums. I cut a piece of aluminum tape to fit the outside of the NX05 and applied it. When I look into the optic it definately seems more reflective. However, when the optic is installed in the Mini the beam is significantly reduced. It seems that the envelope of air is needed.

I'm thinking if you made a similarly shaped reflector that did not touch the optic then that would push the lost light back into the optic. I haven't a clue as to what angle they would exit the NX05.

- Jeff

Jeff,

I tried carefully-cut aluminum foil with exactly the same result you got. /ubbthreads/images/graemlins/grin.gif I suspect that we produced a "mixed" interface- many areas of air between the foil and optic. I have been polishing the conical-machined area outside (not touching) the optic in the hopes of bouncing a few more photons out of the lights I have been building. Whether this helps or hurts I honestly don't know. If I get the time, I may look into vacuum metallizing a couple. Probably a rude Lot minimum charge?

Larry

I see. I'll bet you're right.

I just tried something else that you probably have already tried. I put a circle of the aluminum tape inside the head adhering it to the head walls. My eyes don't see any difference but maybe a light meter would pick something up. Probably has to do with angles and I'm probably just letting the little photon critters live a little longer before they die. I would think your reflector would work to some degree.

Hopefully, some hard-core type with a light meter will polish the hell out of the inside of a minimag head, and do an A-B. /ubbthreads/images/graemlins/grin.gif On another note, looking into the installed optic (Disclaimer- remove batteries first /ubbthreads/images/graemlins/grin.gif) can be revealing? Placing an -05 on a HD reveals a large circular gap in the visable phosphor between the center lens and the outer diameter. When I space the (cut-down and shortened) optic .050" out from the LS, I see a whole lot more phosphor. It works in the flashlight but I can't hold things steady/square/concentric enough to do it by hand /ubbthreads/images/graemlins/icon3.gif Another interesting note is if you blow smoke across the front of mine in a dark room, there is a distinctly brighter emission in the very center about the diameter of the ball lense in the -05.

Larry

[ QUOTE ]
Icebreak said:
For the optic to work it must have a thin atmosphere around it...

[/ QUOTE ]

This is correct. The optic relies on total internal reflection at the cone surface to direct light forward. The angle of the cone relative to the location of the point source determines the performance but only if the design interface is maintained. I this case, it is the ratio of the indices of refraction of the acrylic and air at the interface.

This is the same effect you get when you look at a fish aquarium at an oblique angle. Beyond some angle, you will get total internal reflection inside the tank and you will not be able to see outside the tank but will see a reflection of the inside just as if there was a silvered glass mirror in place of the plate glass.

Wilkey

Wilkey,

It still seems to me that it is the lack of *perfect* internal reflection that results in the "leakage" of light out the side of the optics. I still believe- could be wrong- that the internal reflection would improve by plating the outside of the cone. I did find a local vacuum metalizing shop in the yellow pages, and learned how to spell metalizing in the process. /ubbthreads/images/graemlins/grin.gif

Larry

I think maybe the leak comes from too perpendicular angles of light, maybe especially at the bottom part, around and near the dome. If you metalize some -05's it would be interesting to see the effect of only partly metalizing on some as well (mask the upper part, for instance). Would it be easier to make a more perfect internal reflection if the surrounding matter were anything else than air?

[ QUOTE ]
You might try spacing your optic about .050" above your HD LS and note what happens to the "squarishness."

[/ QUOTE ]

tvodrd, you've mentioned this a couple of times and I've been meaning to ask you how the heck you are doing this? I'd like to try it. I was thinking about using a nylon washer if I can find the right size.

it depends on the light.

i a minimag, it's as simple as unscrewing the head. with other lights it might require some sort of spacer.

Roth,

In your MM (or MMM or MMMM /ubbthreads/images/graemlins/grin.gif ) the optic will "rattle around." Machine a small spacer and polish the I.D. (I haven't tried it yet, and try angling the I.d. to act as a "mini" reflector.) Once more, I think plating the outside of the optic should result in the internal reflection having no choice but to become total. This may have negative ramifications for the relative energy of the hot spot, corona, and side spill. Only one way to find out. /ubbthreads/images/graemlins/grin.gif

sflate, I am "supporting" my optics by a machined flange at their front- the optics are mechanically seperated from the LS by the surrounding hardware. I hope to do a "biggie" post in a few weeks.

Larry

actually, if you use an oring in front of the optic, it holds it in place he same way the mag reflector works.

as far as the optic system goes, i coated the inside with glowpowder /ubbthreads/images/graemlins/grin.gif the first time i turned the light off after coating it, i thought i killed the sandwhich! it was so darn bright, i thought i messed up the led and turned it green! /ubbthreads/images/graemlins/yellowlaugh.gif

[ QUOTE ]
tvodrd said:
Wilkey,

It still seems to me that it is the lack of *perfect* internal reflection that results in the "leakage" of light out the side of the optics. I still believe- could be wrong- that the internal reflection would improve by plating the outside of the cone. I did find a local vacuum metalizing shop in the yellow pages, and learned how to spell metalizing in the process. /ubbthreads/images/graemlins/grin.gif

Larry

[/ QUOTE ]

Larry,
Strictly speaking, from the perspective of total light reflected, this is true. After all, light will not penetrate a sufficiently thick layer of vacuum deposited aluminum. However, the critical factor is not simply total light captured, but total light directed where you want it to go. In other words, the angle of internal reflection changes as the ratio of the two indices of refraction change. So, in effect, what you are doing by plating the cone with aluminum or any other material is changing the optical geometry of the collimator. This would be equivalent to altering the shape of the mag reflector. Your beams would not go where they were supposed to go.

The incomplete internal reflection seen with these optics is, in my opinion, primarily a result of the non-point source nature of the emitter die and would be the cause of light loss out the sides of the cone.

Wilkey

Wilkey,

You are probably right! But, if it is not out of the question financially, I'm going to try it. The internal reflection should become total. How it will distribute within the beam, I haven't a clue. /ubbthreads/images/graemlins/grin.gif

Larry