Adding Deep Red Leds for improved CRI and R9

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mdeni
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Adding Deep Red Leds for improved CRI and R9

I had an idea about improving the spectrum of a light to get a better CRI and R9 values for a light. And i stumbled upon one old thread on another forum about the same idea. The point is to supplement the spectrum of a LED to improve the light quality.

If you get a 4 LED flashlight for example, do you think it would be wise to add RED and CYAN leds in addition to the basic high cri emitters. The cyan spectrum is lower usually, but the R9 red spectrum is especially lacking in almost all of them. So adding one ~700nm red emitter, and one cyan-blue 470nm emitter should be really beneficial.

Illustrated:

What are your opinions and calculations? I know deep red emitters are really lacking, and I haven’t really found some with high power also.

Lets hope the next generation leds will cover the whole spectrum.

LightRider
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Interesting thought. I know that I loved the color reproduction of an rgbw light I had. It had dr jones rgbw driver so I could adjust each channel independently. I set it for full neutral white, 25% red, 5% green, and 10% blue. The result was a beautiful rosy tint. Kind of the same idea.

I have one more dr jones rgbw drivers left. I’ve been working on a 4x xml rgbw and 1x xpg3 90+ cri led. Man… It’s taking some time though Smile

hank
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There’s a good reason fluorescent lights (including LEDs) cover that native intense blue emission with phosphors.
https://www.google.com/search?q=blue+light+hazard+400nm
Now there’s no “bright line” boundary — 399 is barely different from 401 — but the range below 400nm is considered UV-A.
Those are mighty energetic photons.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3586554/

Quote:
Exposure of human skin to solar ultraviolet radiation (UVR), a powerful carcinogen [1] comprising ~95% UVA and ~5% UVB at the Earth’s surface ….
… UVA causes primarily oxidative damage [8] and leads to immediate pigment darkening

The phosphors — multiple different chemicals that phosphoresce under the blue-to-UV illumination — are being mixed with varying success to produce high-CRI lights, and the combinations are much written about (and patented); google that subject for more.
mdeni
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Come again?

The led is already emitting at 420nm we like it or not. The supplementation is in the 470nm, and especially the 700nm spectrum. If you don’t like the cyan part, it is fine as I said before, the red part is the on where the most of the light is missing. And as humans we derive a lot of information from the red spectrum. Most importantly food and dyes, the colors appear live and vibrant and the food looks a lot more delicious.

A lot of the CFL lights even had Negative R9 values, and made the whole dinner table look disgusting.

Barkuti
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Interesting. Speaking of violets, I commented on them the other day in the CRI vs. alternatives with measurement examples thread. Maybe adding one of those (ubiquitous?) 405nm light sources would improve them to the required levels for outstanding full spectrum colour rendition. +1 with the deeeep reds too. 

 

Cheers Party

randy0331
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This is a very interesting idea. Looking at the TCS9 spectral reflectance, we know the sweet spot is somewhere past 600 nm. But I wonder at longer wavelengths like 700 nm, how much it will actually contribute to red color rendering since it is very near the threshold for the visible spectrum.

ARsee
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Hey Hank. When will my light get shipped?

I'm kidding.

But this was my first thought when I noticed your forum name. I bet you get a lot of questions regarding light orders!!

 

randy0331
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OP – also just came across this SPD simulation tool, which I think might come close to answering your question.

zerodish
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I used to work in a photo lab. The inspectors had an incandescent light surrounded by a circular fluorescent light. My job was to measure the colors of photos to see if the printing equipment was drifting. We only used 3 colors. So theoretically you can make a color corrected light by using 3 LED’s. The standard white light is blue heavy so you can improve it by adding yellow. It will all depend on who is looking at it and under what conditions. As a bonus yellow is more efficient than white. No matter which colors you chose they will never be perfect. A surface that reflects a very pure color between two LED’s will be a bit darker than natural light will give you.

snakebite
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the problem of adding colored leds to a multi led light is getting uniform distribution of color.
given the characteristics of common triple or quad optics and the differences between different dice used in different color leds getting acceptable uniformity is going to be difficult.