Sensor to read light spectrum? does it exist - Page 1
Forum section: electronics / beginners

author: maliqua
author_rank: Contributor
timestamp: January 20, 2015, 07:31:11 pm
content: Is there a device or sensor of some kind that I can expose to light and it tell me what wavelengths are present?or a series of binary sensors that would indicate if a particular wave length is present?

author: krivx
author_rank: Frequent Contributor
timestamp: January 20, 2015, 07:43:58 pm
content: It depends on your specific requirements... You might get a photodiode with a plastic coloured filter to work, or you might need something like thishttp://www.hamamatsu.com/us/en/4016.html

author: edpalmer42
author_rank: Super Contributor
timestamp: January 20, 2015, 07:49:44 pm
content: You can make a spectrometer with some trivial parts. Check here:http://www.spectralworkbench.org/Is that what you want?Ed

author: maliqua
author_rank: Contributor
timestamp: January 20, 2015, 08:05:06 pm
content: Ok the fancy hamamatsu devices look like the ideal choice but given the lack of pricing online that usually means many thousandsI'm not sure about the spectralworkbench because i don't fully understand it yet but there is much material to go over so i'll get back about that after more reading.what I'm trying to find is which of my bazillion LEDs are the right spectrum for plant growth so I can make my own aquarium lightsI noticed a lot of my LEDs that claim to be in the right spectrums (particularly the blues) which should make plants start taking in CO2 but my CO2 levels never drop, with HIDs and fluorescents they do and the lumens of appropriate spectrum *SHOULD* be the same as my hid's I'm comparing too. so the only explanation is I'm worse at math than i realized or the LEDs aren't to the spec the sticker on the bag claims they are.editspectralworkbench may do the trick for the level of precision i need its worth a try anyway since it also looks like an amusing projectso long story short i wanna reinvent the wheel and take the long road getting there (hobbies just need to fill time and be fun right : )

author: IconicPCB
author_rank: Super Contributor
timestamp: January 20, 2015, 10:17:08 pm
content: use a prism and calculate the divergence angle of incident light as a function of wavelength and refractive index of prism material... and then place a photo detector at the point where the right wave length is to be found

author: denelec
author_rank: Regular Contributor
timestamp: January 21, 2015, 01:00:40 am
content: Just buy a cheap spectroscope:http://www.amazon.com/High-Resolution-Quantitative-Spectroscope-400-700nm/dp/B00FGARIAO/ref=sr_1_2?ie=UTF8&qid=1421801410&sr=8-2&keywords=spectroscopeThis is the spectrum from an old compact fluorescent lightbulb:

author: dannyf
author_rank: Super Contributor
timestamp: January 21, 2015, 01:02:02 am
content: Just put a bunch of filters in front of their respective brightness (b&w) sensors.

author: Psi
author_rank: Super Contributor
timestamp: January 21, 2015, 05:26:03 am
content: http://www.tricorderproject.org/blog/sneak-peek-3d-printable-mini-spectrometer/

author: Gall
author_rank: Frequent Contributor
timestamp: January 21, 2015, 02:57:41 pm
content: The best one can do is to use a linear CCD device and a diffraction grating.

author: maliqua
author_rank: Contributor
timestamp: February 22, 2015, 06:16:00 pm
content: Well thanks to all who replied. To follow up I wanted to say thathttp://publiclab.org/wiki/foldable-specis perfect for what I wanted, worked great after I figured it out. Cost nothing to build just scraps of junk laying around. I highly recommend giving it a go if you have a few minutes to kill.

author: Scrts
author_rank: Frequent Contributor
timestamp: February 22, 2015, 07:10:30 pm
content: Or just take image sensor (from Omnivision or Aptina) and do a digital parametrizable filter? E.g. on FPGA.