I want to calibrate my RGB LEDS, cheap spectrometer options? - Page 1
Forum section: electronics / testgear

author: NaDobraNich
author_rank: Regular Contributor
timestamp: January 29, 2025, 10:09:29 pm
content: I was thinking something like this amazon link, it seems to have a fiber optic cable to a sensor. But wanted to ask first.I'm trying to balance the gain and output on my addressable RGB leds, get an intensity output (mcd, lux, whatever), and do a little color correction.https://www.amazon.com/Generic-Spectryx-Mobile-Educational-Spectrometer/dp/B0CRVR429L?dib=eyJ2IjoiMSJ9.zxj-lS2oK21v_Kc3Fx0KCbwi3HMD5cB2FSG3JiVSWrs4SEpcvL01x0kEcN7_xwRq.URr8Wz7axtrvl2m_IzTwW7OVyWtQ0z_Jo9J74yIx-bQ&dib_tag=se&m=A1V88RLMYYBHSB&marketplaceID=ATVPDKIKX0DER&qid=1738188546&s=merchant-items&sr=1-2I'm not sure if the tool I linked would work for this or not, it seems like these things are sold for mineral ID, and there are a lot of USB parts sold to detect printed colors but not LEDs.Anyone use something they like for this purpose? I'm trying to stay under $200.

author: BennoG
author_rank: Frequent Contributor
timestamp: January 30, 2025, 08:19:38 pm
content: I have this onehttps://nl.aliexpress.com/item/1005007241834839.htmlIt works surprisingly well.I also have this onehttps://thunderoptics.fr/product/sma-e-spectrometer/The last one is slower but you have the option to put a fiber cable on it, that makes some led measurements simpler.They both perform about the same, the spectrum of the AliExpress one is slightly wider than the thunderoptics.Benno

author: StrayElectrons
author_rank: Contributor
timestamp: January 30, 2025, 11:14:53 pm
content: Another suggestion when I used to work with TV as tv repair tech, is to do grey scale using test bars in black and white even on colour TVs. This way you correct everything, just not too bright and color comes out looking just right and not too blown, using this method.Cheers,

author: ledtester
author_rank: Super Contributor
timestamp: January 31, 2025, 05:18:33 am
content: Quote from: BennoG on January 30, 2025, 08:19:38 pmI just ran across these youtube videos which talk about the Little Garden unit:It's a dirt-cheap Spectrometer - But does it actually work?https://youtu.be/LxQmaJYMOAkThis one compare the Little Garden with another offering:A Small, Cheap Micro-Spectrometer - Review [Pt 1] -- starting at 8:20https://youtu.be/MOXryggwr_Q?t=8m20sAlso check out the other videos on the channel as well as searching youtube for "Little Garden Spectrometer"Update: On this video:Little Garden Spectrometer super detailed tutorial -- Lao Kanghttps://youtu.be/MwHuoXFh1A0I just spotted this comment form another forum member:

author: NaDobraNich
author_rank: Regular Contributor
timestamp: January 31, 2025, 09:21:39 pm
content: There are a couple of things I don't like about the Little Garden unit. All Chinese, but apparently works with standard softwares. And no fiber optic option, but I'll live with that. ThanksSoftware:https://www.effemm2.de/spectragryph/

author: Kean
author_rank: Unknown
timestamp: January 31, 2025, 11:40:01 pm
content: I started doing something similar back around 2010. At the time there wasn't any cheap options, other than some poorly documented diffraction grating + CCD designs requiring DIY calibration.So I started with one of your typical low cost handheld spectroscopes which I used with a digital microscope attached to the viewfinder - pretty dodgy. I soon ended up buying a Vernier SpectroVis Plus which is aimed at educational use. I think it was around US$600 not including a fiber optic adapter and the software which added maybe another $200. That worked pretty well for me.About 2017 I upgraded to some Ocean Optics Microspectrometer devices as I was working with flow-through cuvettes and automated fluorescence measurements with local scientists. Those were at least an order of magnitude more than your budget, but provided simple integration for the code I was writing on a Raspberry Pi.Now I am back to doing LED lighting projects, and occasional consulting to biologists and wholesale growers (typically of flowering garden plants, not the other stuff), I am interested in getting something handheld that shows both spectra and calibrated illuminance and PPFD measurements. Not really many cheap options for that. I do have a calibrated light sensor for solar irradiation (Pyranometer), although the calibration is out of date. I picked that up at a business liquidation sale.

author: bte
author_rank: Regular Contributor
timestamp: February 01, 2025, 09:38:26 pm
content: <tongue-in-cheek reply, triggered entirely by the keywords cheap and spectrometer>How about DIY?https://youtu.be/p3MzQ1OF3lk</tongue-in-cheek reply, triggered entirely by the keywords cheap and spectrometer>

author: ledtester
author_rank: Super Contributor
timestamp: February 02, 2025, 03:22:51 am
content: Quote from: bte on February 01, 2025, 09:38:26 pmThe Little Garden meter is indeed based on the design in the above video (the "Theremino" design). One big difference is that the Bayer filter has been removed (by hand) to improve the resolution of the camera module:It's a dirt-cheap Spectrometer, but pretty decent... -- Project 326https://youtu.be/9XIhMJAFPd4&t=4m27s

author: Tjuurko
author_rank: Regular Contributor
timestamp: February 02, 2025, 07:38:51 am
content: You can read about the features of the work of "Little Garden spectrometer":https://budgetlightforum.com/t/little-garden-spectrometer-impressions-opinions-discussion/225545"Response curve calibration, or a quick dive into CMOS sensors and their problems"

author: NaDobraNich
author_rank: Regular Contributor
timestamp: February 04, 2025, 04:40:53 pm
content: Quote from: Tjuurko on February 02, 2025, 07:38:51 amNot too great of a resource. "I can't get this working at all"

author: BillyGo
author_rank: Contributor
timestamp: February 04, 2025, 04:57:48 pm
content: I got confused by those some times. They advertised as spectrophotometer on AliExpress, but looks more like a colorimeter.Edit: It turns out that DVD tracks have much finer spacing than the diffraction gratings used in spectrophotometers for display calibration. What a pity—I ended up wasting my time on those old ColorMunki and Argyll setups, which offer only about 3.3 nm resolution even after dithering.