Comment by reaperman | Hacker News Reader

Comment by reaperman | Hacker News Reader

I saw "artificial sunlight" and thought "oh wow I'd love to see the spectrogram of the lighting solution this person came up with". I was disappointed to merely see "CRI 95+".

https://www.youtube.com/watch?v=lH_owRxupC0

This is great video on the shortcomings of "CRI" - it explains in detail CRI, CRI extended, TLCI, TM-30, and SSI.

Brightness and color temperature are only two small parts of lighting - more people should start investigating the utility of taking their own spectroscopy measurements to figure out what lighting works best for them personally. My friends have very, very diverse opinions on what spectral distributions they like/hate, but they lack the language and experience to identify or communicate their preferences except for "Ooh I like/hate this bulb".

I mostly use LED bulbs to keep heat generation down (I pay for the heat twice in Houston: once to generate it and again for the A/C to negate it). But I always mix in a bit of incandescents / halogens (2400-3000K) which provide full-spectrum blackbody radiation to see ALL the wonderful colors in my world.

Do you have any insight on how to take spectroscopy measurements at home on a <1k€ budget? And how to select an LED manufacturing supplier when CRI is often the only thing available on the datasheet?

Starting points for first question: Look into i1Pro (later models of the first generation), which can be had for $200-400. Combine with some free or $99 Windows/Mac/Android software [0] [1].

Second question: It is still too hard even to find CRI for most offerings. It's pretty much a "buy, test, return the ones you don't like" situation. If independent reviewers start publishing spectrograms and making YouTube/etc videos, perhaps the industry will move forward some day.

0: https://www.argyllcms.com/doc/instruments.html#i1p2

1: https://rmimaging.com/spectrashop_brochure.pdf

The luxeon 2835 website that’s linked in the article has a data sheet for the LED source. Scroll down and you’ll see the spectra for various subtypes of that source.

A little garden spectrometer is pretty good, and around $60: https://www.youtube.com/watch?v=LxQmaJYMOAk . And the LED supplier should give a spectrometer graph. If you can get a dual peak LED that will give a better spectrum distribution. The Amaran 200x S is one of the best.

Very cool! I definitely want a spectrometer at home now! edit: looks like it's more of a DIY project than a commercial thing. Maybe DIY spectrometer is my next project then!

Mid level, $750: https://www.aseq-instruments.com/LR1.html

Entry (?) untested, $350: https://thunderoptics.fr/product/sma-e-spectrometer/

I bought a little garden on aliexpress from the guy who makes it. It's very plug and play and it does about 350-1100nm, which is pretty impressive. I used it to verify how my own DIY sun reproduction setup works. https://www.aliexpress.us/item/3256807055520087.html

There is also this commercial one that is Bluetooth and more portable for around $150, similar spectrum range but lower spectrum resolution than the little garden one. https://www.youtube.com/watch?v=MOXryggwr_Q

https://www.amazon.com/Analytical-Wavelength-340-1000nm-Spec...

The hopocolor vis light ones are also fairly widespread and are more stand alone for about $280: https://www.aliexpress.us/item/3256807972511960.html

My current issue is finding a 250-400nm UV spectrometer or IR spectrometers beyond 1000nm that don't go into the $1000+ range. Standard mass market CMOS sensors don't go into those ranges, so they become far more specialized parts and thus way more pricy.

With some LEDs, and especially the warm whites, I get this feeling of „artificiality“, for lack of a better word. Like the surroundings are somehow fabricated. It’s an interesting idea to mix and match those with other light sources, I‘m going to try that.

I think most people at least know the difference between warm and cool light, which helps a lot, but otherwise I agree. As I’m reading this, I’m realizing I have no vocabulary for this topic. That’s… kinda strange to experience!

Huh, incandescents have been banned here (Australia) for years. Even compact fluorescents are out.

There appear to be enough loopholes and lack of enforcement that you can still piece a solution together: https://electricalproducts.com.au/incandescent-lamps.html?p=...

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