I was looking into monitoring air quality and found that any affordable sensors aren't too accurate unless the air quality is really bad.
Is there a way i can use arduino and a small laser to measure the air quality?
I was looking into monitoring air quality and found that any affordable sensors aren't too accurate unless the air quality is really bad.
Is there a way i can use arduino and a small laser to measure the air quality?
You might want to specify the dynamic range you are looking for...
From my own position, all low cost (<$10,000USD) particle monitors are crap. MetOne has a lot of "low cost" monitors. The second problem is where you are using this sensor... a living room, workspace or clean room? If it is not a clean room, it will saturate and take hours to work properly.
A little scope can go a long way.
@spcomputing: I'm surprised they can be that expensive. Apart from clean-rooms, where else are these kinds of (10K USD-priced) air quality monitors used?
LASAIR II (low end 0.1um) "Used":
http://www.ebay.com/itm/Airborne-Particle-Counter-LASAIR-II-110-0-1-m-Particle-Measuring-Systems-/261060009276
Since zeig used the phrase "Air Quality" it must be for PM20 and PM2.5 measurements of living areas. The "dust sensor" is just a good as any low-end system since the discrimination of sizes on the 2-3 channel systems is highly suspect.
Well my price range is pretty low... around $30USD.
I just want it to "count" the particles in the air every set amount of time, this is for my house.
As far as design goes i was thinking of a small laser with a magnifier and an optical sensor of some kind all in an enclosure that has a can pull the air through it.
Is this too much to ask for $30?
PS: i dont want to just go buy an air quality device
Well, for that price range, the best "dust sensor" that I have seen data on is the Grove - Dust sensor.
http://www.seeedstudio.com/wiki/Grove_-_Dust_sensor
It runs the closest to those cheapy (~$290) laser particle counters when compared side by side:
No resolution other than a relative "dustiness" read out on analog. The only reason this one rises above the rest are the two pots. I like knobs 
You can at least calibrate it to something.
Hope that helps.
I've thought of salvaging a beam splitter from a CD/DVD drive, to provide a reference beam and a free-path beam. Differences in readings of the detectors would imply the presence of particles.
Not sure how sensitive it would be.
I've thought of salvaging a beam splitter from a CD/DVD drive, to provide a reference beam and a free-path beam. Differences in readings of the detectors would imply the presence of particles.
Not sure how sensitive it would be.
Current techniques use two types of "channels". On is called a Light Channel and the other is a Dark Channel.
What you describe with the CD/DVD would be an example of a Light Channel setup, which is the lower sensitivity of the two. The typical setup of a Light Channel would have a laser beam shoot into an attenuation block that would have a screen the size of the laser spot to block all laser light from the Photo Multiplying Tube (PMT) behind the screen. When the particle enters the laser-beam, it will deflect photons around the attenuation screen and hit the PMT to register. The photon(s) hits the charged plate of electrons and they scintillate to the anode of the vacuum tube and you now you have a sensitive signal
You use the reference beam for setting up the Automatic Gain Controller circuit. You can control the software thresholds this way and call the machine voltage calibrated.
Well, that is the theory, until you introduce very low quality PMTs and/or lasers which reduce the price and you get a "dust detector".