Looking for expert opinion - surgical headlamp project

smithers17 · 2022-08-03T23:37:29.000Z

Greetings everyone,

Working on an academic project with goal of creating functional surgical headlamp for use at a 22-26” working distance (forehead to operating field).

Primary goal is to have a uniform beam of approximately 3-4” diameter at 22-26” with minimal halo.
Currently using a COB LED with <15mm LES.
Encasement will be 3D printed to accommodate LED components/optics.
All components must be as small as possible.

Main issue so far is with the optics. We are experimenting with the components and are trying to find an optic that helps us achieve the above goals. Tried a few converging lenses +/- a diffuser so far but are still in the experimental stages. I believe a TIR with 5-7 degree beam angle would be ideal, but have had a hard time finding this online and may need to get it custom made.

I am learning as I go and thought you all may have some advice or input that would help. Open to any suggestions or guidance. I really appreciate your consideration.

Oli · 2022-08-04T01:09:01.000Z

It seems like every year somebody comes along with the same exact project. Did you dream this up or is some professor throwing this project idea out there? How many people are on the project?

turkeydance · 2022-08-04T23:44:49.000Z

is a sterile field one of the parameters?

chops728 · 2022-08-05T00:33:10.000Z

Build a Mule

Serlite · 2022-08-05T00:43:11.000Z

For an even, focused beam with zero spill, the simplest option is an aspheric lens. These look like a solid dome made of plastic or glass.
You can find them on FastTech or AliExpress, or you could rip one out of a cheap zooming flashlight.
Once you have one in hand, you just need to find the ideal distance to position it from the LED, and you’re set to print the enclosure.

smithers17 · 2022-08-05T02:17:33.000Z

Thank you! I will read more about this and try it out.

smithers17 · 2022-08-05T02:20:01.000Z

Not one of the parameters for the light. Headlights are never sterile, even in the OR. Can’t touch or readjust the light once it’s on unless you use a sterile towel.

Sirstinky · 2022-08-05T05:02:31.000Z

I also recommend an aspheric lens like a zoomie uses. You can get them in a variety of sizes and beam angles. I think you should buy some cheap zoomies from Aliexpress or eBay or Amazon and experiment with different sizes of lens. For your application with a COB, the convergence distance is going to be important to avoid artifacts and aberrations in the beam from the non-homogenous LES. You might be good using a standard, domeless monolithic LED with a round die.

smithers17 · 2022-08-08T04:15:40.000Z

I appreciate your feedback. I will take all of these recs into consideration. Thanks again

smithers17 · 2022-09-19T07:01:49.000Z

Here is the current prototype:

[Album] imgur.com

I am wondering if anyone has used a fresnel lens? I would like to tighten up the beam if possible. Currently using a TIR and aspheric lens.