Colored LEDs with the most narrow bandwidth: Anybody have suggestions for a che

ElectricAye

Hey brainiacs,

I'm thinking about building a crude, cheap transmission spectrophotometer that measures from about 250 nm to maybe 700 nm in steps of roughly 50 nm (250nm, 300nm, 350nm, etc. but not necessarily right on those specific bands: for example, 359 would be okay, etc.). So I'm on the hunt for cheap LEDs with the most narrow bandwidths. I don't want the bandwidths to overlap (much) and I'm not interested in buying interference filters, etc. I've been poking around Digikey but their wonderful search engine makes it difficult to pinpoint a spec like this, so I thought I would just ask to see if anyone here has some superbly cheap suggestions.

So far all I've found is what's in the attachment below, but the green version is probably too spread out and I'd like a lot more bands to cover the aforementioned spectrum.

thanks, y'all



▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Watching the world pass me by, one photon at a time.

rjo_

I suspect that you already know this, but just in case:

My sole experience is that I looked at this a few years ago... and my application far was less demanding than yours. But even though I was trying to do far less, I came to the conclusion that I would pretty much have to use dichroic filters... which I also didn't want to do and never pursued and might not be the right answer anyway.

What I do know is that if you can find almost what you want, then you can always use a single slit or even a small series of slits to spread the spectrum and throw away what you don't want. But then you might need an inexpensive light amplifier.

There are some experts in photonics that pop in and out of the Prop forum, who might be able to tell you exactly where to look; I don't know if they come here or not. If you don't have any luck here, try over there.

Rich

Tracy Allen

A good starting point might be www.forrestmims.org/publications.html, where you will find a long list of projects characterizing LEDs and using them in photospectrometry. Not with the resolution you are after, maybe, but with a good idea of the limitations and possibilities.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Tracy Allen
www.emesystems.com

ElectricAye

Ok, guys, I think I found what I need. I'll attach the pdfs after I get them downloaded in case anyone ever lands on this topic.

thanks, y'all