TIR as pre-collimator?

I have been trying to learn more about TIR optics, and I have read the posts I've been able to find here on CFP. One thing I've found as important is that you need a TIR designed for the emitter you have. This then leaves you at the mercy of hoping distributors have TIRs with the beam size you want for the emitter you plan to use. However, even a TIR wider than the one I want (a true spot/thrower) could point all of the emitter's light at an averaged diameter:focal length aspheric. Assuming an efficiency of 85% from the TIR, you would still be picking up more light which would have missed the lens than you are losing through efficiency. The worry I have is that light leaving a TIR is no longer leaving from a small point, like from an led, but rather from the entire front of the optic. The TIR i have found claims t have a beam of 15 degrees. I am hoping (doubtfully) that I can act as if the led is still the focal point, and that the led+TIR setup will simulate an led with a 15 degree beam. I believe this would work with a large lens that is far away (like a decently sized plastic fresnel lens), but my real hope would be to fit this into a flashlight head approximately 35mm tall with a 40mm diameter, which seems to me about as big as a "pocket carry" can be. At least, it fits into jacket pockets well enough.

You are going to be rather underwhelmed at the results. It can work if you are not going for all-out throw and add a diffuser to smooth out the horrendous artifacts that will result. But then if you have a properly designed TIR there really is no way to improve the beam. It also cannot work the same as the precollimator I used in the DEFT. You are right to foresee a problem in that the TIR would mean it is no longer a point source and will not then work with an aspheric.

Thanks for clearing it up for me. I keep hearing about the errible artifacts which will occur from trying to increase the amount of light that hits the lens, like with reflectors. Does anyone know where I could find a beamshot of this?

ballard_st said:

Thanks for clearing it up for me. I keep hearing about the errible artifacts which will occur from trying to increase the amount of light that hits the lens, like with reflectors. Does anyone know where I could find a beamshot of this?

Click to expand...

You no trust me huh? I don't know of anyone ever posting a TIR lens combo but have seen some reflector and lens combo beamshots posted. Couldn't tell you where they are though. Things very easily get buried around here.

haha of course i do. I'm just curious what it looks like, especially since it may still work for me. I don;t care too much about the beam's aesthetics.

http://i.imgur.com/k9CE8.jpg <- just the TIR
http://i.imgur.com/GFuAt.jpg <- TIR with aspheric (KD 52mm I believe, not 100% sure) over top at the only thing resembling a focus.
When I was sticking a piece of paper in there I determined that the reflector portion of the TIR is the spill and the lens portion of the TIR forms the hot spot in the center.
If I had to guess, I'd say the central lens on the TIR optic is too small to project an entire image of the die, hence the circle.
http://i.imgur.com/NaWZf.jpg <- Just aspheric,

http://www.candlepowerforums.com/vb/showthread.php?296379-1.25D-Mag-SST-90-TIR-light-mostly-done is the host for all of this with info on the TIR.

Those are awesome. Thank you very much.