I have a 2AAA mini maglite that I stuck a TIR and 5mm Yuji into. I ran into a few issues.
fitment of the TIR vs. the closing of the bezel to the head, as it clearly wasn’t “meant” to fit into the 2aaa mag based on height. I believe this can be remedied with a reaming of the head, at the cost of inner anodizing, or I could trim away at the TIR to form a recessed bezel/lip…but I’d rather not screw with it for risk of deforming the only TIR I have of that form factor…
The Yuji dome is way too tall to fit under the TIR, which means only about a quarter turn’s worth of threading is currently engaged, which is not ideal for either water resistance nor head retention. This also means the light turns off when tightening anything past that. The beam, however, is quite nice in a rudimentary, unsophisticated way…
SO, before I mutilate one of a very limited supply of Yujis, I wanted to ask if anyone has tried filing down the dome on a Yuji for any reason, and if it would drastically alter the beam that comes out of the TIR?
Ideally, I would just remove a substantial cylindrical portion of the yuji and rebond the dome to whatever’s left, but my hands are too shakey for that…
I will also probably trim the lip off the base of the Yuji, and slighly ream out the seat of the plastic holder to gain a mm or so of recess…every little bit helps…
Absolutely. TIRs in general are designed for emitters with a Lambertian profile, with no secondary optic. A 5mm straw hat LED already comes with a secondary optic: the resin body itself. At the moment, without any modifications to the 5mm LED, you might as well not use the TIR, and the beam won’t change too much.
If you really want a TIR type beam, you gotta trim the straw hat until the actual LES is at the focal point of the TIR. Never tried TIRs with maglites but have modified 5mm LEDs for use in reflector-based 2AA mags.
I’ve tried this method a couple of times . If all else fails you can smooth up the beam with by sanding the the resin to a matte finish or applying some dc-fix milky to the lens.
I’ve used sanding/buffing blocks every time. Completely controllable and much safer than cutting–you can’t predict which way the resin will fracture, and there is no distortion to the bond wires.
As far as the “optics” involved, I was curious about that, as the “dome” itself seems to turn the thin rectangular emission surface into a proper circle, the image of which is further focused by the TIR (with some optical losses…I’ll follow up with a side by side on an underexposed dark surface later today.
I’m just going to put a high gloss paper between the TIR and the head housing, it should be thin enough not to mess with the assembly after I ream it out…
In the 5mm LEDs I’ve worked with, the LES appears to be circular with two slight interruptions by the bond wires. The actual blue die appears to sit at the bottom (i.e., vertex) of a tiny inverted cone cavity, which then gets filled by phosphor. Decent schematic here: https://www.ledsupply.com/images/5mm-LED-diagram.jpg
With an unmodified LED, I doubt that the TIR is doing much focusing. You could try to look into the TIR–I bet that the central circle of the TIR (i.e., the convex lens component) looks much, much brighter than the annulus surrounding it, which is the true TIR that collects sideways emission, which an unmodified 5mm LED has very little.
Under ideal conditions, these 5mm LEDs should produce a beam tighter than that of an Osram W1, due to the much smaller LES.
Here’s a side by side, shutter value at 1/180, WB of 3700k.
LED is about 1 foot away from the wall in both shots, with the TIR (collimator?) A couple inches further away to capture the characteristics of the beam.
Thanks for the beamshots! Looks like the original Yuji beam is floodier than I expected, and the TIR collimates it by a pretty good amount. Removing some dome material should definitely make the beam even tighter.
I’m going to give it a little more time before doing something irreversible, lol… but yeah, it totally does increase the throw substantially! I just took a closer look at the LED…the emitter itself IS circular and rather large…I don’t have a macro lens, unfortunately.
Given in part that the dome seems to already magnify the ignited portion, I’m worried that cutting the dome off will cause the TIR to pick up the filaments and other undesireable elements as well.
Nice photos! The LES does seem much larger than I’m used to seeing in 5mm LEDs.
Instead of cutting the dome off, one might consider sanding it off in small increments and buffing/polishing to preserve the dome’s curvature, which should essentially preserve the beam profile while solving the problem of mismatching physical dimensions. Can always practice on a cheap LED first!
The hotspot is a bit more condensed, and the red anodizing of the body seems to be affecting the tint…unless the encapsulation material is designed to remove the reddish/purple hues? No idea, but I’m going to take it down a wee bit further, just not tonight, lol.
**added a whitewall , 3700k WB, 1/180 shutter. Couldn’t lock the ev to -1.0, so it dropped down to -1.7.
The red ano might mess with the tint, and so might the matte LED surface and the reduced dome curvature. I might try to make the surface more dome-like (by sanding off just a tiny bit on the side) and polish it to a shine with a nail polishing block.
Back in the day, 5mm LEDs were available in “diffused” and “water clear”. The latter would act as a magnifying glass over the chip, especially the narrow-angle ones.
I don’t think I cared what “magnification”/angle, just that it was clear epoxy. I needed to squeeze in a LED into a tight spot, so sawed off the dome to just above the bond wire, and sanded it down to barely a hair’s breadth above the wire, then used polishing paper to get it as smooth as possible.
It was still hazy, but was so close to the chip that you could look at it from all angles and see pretty much just the chip.
Then I got brave and sanded down the sides so that it was a super-thin rectangle. It did fit, barely, and was as close to a point-source as you could get.
Anyhoo, a generic 5mm LED with the dome sanded off (no need to go thin) could give an approximation what the beam would look like in the TIR lens.
Leaving too much of the body above the chip could give it “tunnel vision” and keep stray light from hitting the bowl part of the lens.
The middle part of the lens is basically an aspheric lens, “magnifying” the chip itself, and the bowl part acts as a reflector. That’s why both parts do a great job mixing horrific emitters like G3s with shiite angular tint-shift, by throwing both parts forward to mix together, vs a reflector which has hotspot + spill.
Wall and dark table top shots from 2 feet away, running on alkaleaks to make the minimum Vf. I imagine it would last something like 60-70 hours till empty, maybe even a bit more like 80-90. I might just pop a couple lithium primaries in here and call it a decade in the glove box. I’m missing a lumen or two due to a few black plumber Orings used to seat the TIR, but overall it still throws a bunch of light forward.
