1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

IR LED irradiance, radiant exposure and radiance

  1. Apr 20, 2015 #1
    Hi!

    I'm trying to design a device to detect eye blinking while a person is sleeping.

    I have tried to use TCRT5000 sensor (http://www.vishay.com/docs/83760/tcrt5000.pdf) in the prototype and it works like charm !! However, since the TCRT5000 sensor has an IR emmitter I have some safety concerns regarding the IR exposure of the eyelids (mainly, since the eyes are closed) and the eye itself when he/she blinks.

    Consequenty, I would need the following information that we couldn't find in the factsheet:

    irradiance (W/m^2), radiant exposure (J/m^2) and radiance (W/(m^2 sr)) using the link about the sensor I provided

    I would really appreciated if someone could explain me how to compute it (which formulas i need) using the data I have in the pdf (which data i need)

    Moreover, it has to be considered that the person will be exposed to it 8h/day for their lifetime. If you know a way to low the intensity/power of the IR emitter it would be also apreciated.

    Best regards,
     
  2. jcsd
  3. Apr 25, 2015 #2

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    You want to keep a sensor 5mm above the eye of a sleeping person? Even if the person is moving? For the whole lifetime? May I ask how and why?

    All power values will depend on the way you operate your LED. For a detailed model you would need the angular dependence of the emitted light of the LED and other details, together with a good model for the eyes. I don't think all this is necessary: you are probably way below the amount of light an eye receives during daylight, so heating is not an issue and at 950 nm wavelength the eye cannot see it.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: IR LED irradiance, radiant exposure and radiance
Loading...