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IR LED irradiance, radiant exposure and radiance

  1. Apr 20, 2015 #1

    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


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    2017 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.
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