Interesting optics thread

Thinking more about that lens. It’s interesting. :slight_smile:

  • cheap way of doing pre-collimation
  • the centre of the front lens must have different focal length the the rest - because light goes there through the channel, w/out 2 intermediate reflections
    • light that goes right next to the channel gets refracted
      • some (not much) will hit the channel side and TIR from it, then enter the second lens at off ang
      • some will enter the lens and join the light that passed the channel - but it was refracted and travels at different angle
      • you’re going to get a few artifacts with it
        • typically frosted aspheric lenses have frosting on the first surface. This has at the last so it can remove those artifacts
  • would like to see it tried

I wouldn’t expect too much innovation from a brand like Trustfire, but it looks to me that they introduced RXI-style lens to AAA sized lights.

I’m impressed!

ADDED: it actually may be the same lens as the one they use f.e. in MINI3:

Interesting light. I might get one to put in an E21A with 10mm virence board

There’s something going on with Trustfire MC1 as well.

Fresnelized TIR? Or maybe regular Fresnel?

I didn’t fully believe that and decided to check it out.
I took Lens Design Cloud | LightMachinery and drew a strong aspheric lens. Diameter 15, thickness 8, radius –4, conic constant –0.9, PMMA. I’m not sure what was the FL but definitely more than 3 mm. Placed it 0.1 mm in front of the LED. Result?
The beam was indeed very narrow unless I made the LES huge. 8 mm LES produced a 2m diameter beam at 1m. With 3mm FL it would be worse than that.

Though now that I think about it there’s an easy solution to having too narrow beam.
Add more emitters. :smiling_imp:
You’ll have higher output as well and probably higher efficiency as well than with a weaker lens and fewer emitters.

Actually I see 2 uses for these lenses.
Take a powerful mule like one of the Vinh’s superlights and replace the glass lens with a negative Fresnel (or positive Fresnel + glass).
You get similar high output, nice smooth beam but narrower with sharp cutoff. Higher brightness than pure mule over a smaller area. Myself I love this kind of beam.

The other use would be a zoomie, with this style LED setup.
In flood mode it would be superb, just like any zoomie.
In throw….it would be special, in a way that’s neither good nor bad.
Astrolux FT-02 is available with 2 emitters (third on the way but this is irrelevant).
Compared to the initial SST-40, XHP50.2 offers roughly:

  • twice lumens
  • half intensity
  • double power consumption

For some users XHP50.2 makes a significantly worse thrower but for others this kind of tradeoff works very well.
Here if we compare a regular aspheric to a super-strong fresnel we get:

  • 1.5-3 times the lumens
  • much lower intensity (I won’t try to guesstimate)
  • same power consumption

Clearly not for everyone but it doen’t look like intristically bad tradoff.
Would put more lumens down the range than any regular reflector light with the same LED, competing with recoil setups.

And super short focal length offers new packaging possibilities.
Typically zoomies are quite bulky for whatever battery they support. They can have very short length but if they do - the diameter is significantly larger than that of a comparable reflector light. To make a narrow zoomie, the entire zooming mechanism has to be placed in front of the battery. With regular focal lengths that makes the light very long. With this kind of lens that’s not the case…
Here’s a pic that shows the concept (I think it’s slightly too compact at some places but it’s meant to show the idea rather than a design)

As narrow as a tube light and length-wise it can compete with a reflector light as well.

So…a zoomie is usually a Jack of all trades and a master of none. This kind of setup could offer different tradeoffs than regular aspherics. In some ways much worse. In some much better.

I’ve got my Trustfire MINI3.
Yes, I think it uses RXI-style optics, though so far I’m failing to disassemble it so I only got view from the front.

The beam is unlike anything I’ve seen before. There’s a square hotspot like in almost focused aspheric lens, but also very wide secondary beam, almost like a mule.

I tried to make a comparison to Astrolux A01 219B at the same distance from a yellow wall:

Astrolux runs high powered 10440 while TF does its only mode while powered by AAA; any other combo would lead to the latter being way way brigher and spoil the comparison.
This picture does not really match what my eyes see but it’s as good as I could make with my phone.
The differences:

  • TF secondary beam looks like it’s prograssively dimming down and disappears. Really the dimming is not very visible but a sharp cutoff (way in the dark on this pic) - is. That is - it is visible when looking for it, normally it lights up everything down to the limits of eyesight. It is also blinding others.
  • TF looks green, my eyes don’t see that. Not rosy but if there’s green - I’m not disturbed by it.
  • TF has visible discolouration at the edge of the narrow beam which can’t be seen here

Ilenstech now also makes metalized plastic lenses which resemble RXI. Though I fail to see how this can work. :frowning:

Ah, interesting topic.

LEDGUHON has some nice optics molded into LED domes. Osram has done similar stuff before…but different.

I guess this one is meant to diffuse the beam so there’s no donut hole in the beam:

While here’s a very wide beam lens:

There’s also a SMD variant.

Note that they have an Aliexpress store, so if one wants to have fun with them, they are easy to obtain in small quantities.

I’m very interested in these coarse fresnel type optics. Not only do they offer really short aspect ratios, but I feel like this is the best way to achieve a mixed throwy beam without awful tint shift of reflectors and even some TIRs. By simply not collecting the light from the furthest 10 degrees or so, the green/yellow corona issue should almost vanish.

IMO, tint uniformity is at the top of the list of importance for overall color quality. 80cri and uniform vs 95cri with an egg yolk beam - 80cri wins.

I’ve seen a few cases of beaded or frosted or marble surface aspheric lenses.

I used to assume that they were somewhat analogues to beaded TIRs - less artifacts but still reasonable focus.
I ordered some from Yajiamei…and it turned out I was wrong.
They are purely for flooders. They don’t focus at all and as you try to move them farther from the LED they get no hotspot but some nasty artifacts instead.
So…they are pure flooders, but at least they are nice flooders.

A compound reflector that uses 2 different parabolas:

This reminds me of an idea (possibly dumb) I had recently… I’d be curious how a small waiven/spherical portion added to the bottom side of a parabolic aluminum reflector would perform. It’d be wide aperature/shallow sphere. The intent is to recycle the heaviest of tint shifted light and keep it from forming a urine colored corona… I know TIRs and collar+ashperic make more sense, but I think it’d be an interesting experiment.

Put one of them step reflectors in a Jaxman M2 with an XP-E2 Torch emitter…

Laser Beam…

Another light that folds the light path:

The Nitex optic is very interesting indeed. It doesn’t seem like a good color mixing design though. Of course I could be dead wrong.

I’m really interested in finding a TIR/Fresnel hybrid lens like in the Trustfire MC1. If TF is using them, they have to be available somewhere on Ali. I have no idea what search terms may track one down though.

Anybody know of a source?

Not sure if this may be a start: 11.17€ |Optischen Kunststoff Menschlichen Körper Induktion Infrarot Fresnel Objektiv Stirn Thermometer Linsen Arbeits Abstand 3 5cm Brennweite 19mm|Objektive| - AliExpress

Zoomable Color mixing Fresnel Type optics from Gaggione. Limited info right now. Datasheet dated Feb 2021, so these are new new

That’s very interesting, thanks for posting.
Am I the only one who sees the gaggione website for UFO very broken?

  • Adjusting cookie settings doesn’t work and I need to accept cookies to read the privacy policy. I need to blindly accept everything to even start using the site.
  • There’s a datasheet picture, clicking it does nothing
  • There are plus signs below each of 3 variants. Not clickable either
  • There’s “WATCH THE VIDEO OF UFO TUNABLE WHITE LENSES”. And a video below that has nothing to do with lenses, just some sights and music.

And I have 2 same with 2 browsers.

I see that samples are not available yet…I may get some once they appear on gaggione store. :slight_smile: