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opt301 characterization

Izrael John
Prodigy 30 points
Other Parts Discussed in Thread: OPT301

I am using the OPT301 for validating a color sensor design, but i have to characterize the photodiode first  with LEDs as source of light and if possible get the same response as the one given on the opt301 datasheet. But while trying to do that i keep on getting inconsistent results. e.g. the response from the yellow LED is way more than the Red LED (which doesn't tally with the datasheet). can you please help me with how to conduct the testing/characterization of the opt301 photodiode? and point out my error.. or any sort of suggestion on the matter is highly appreciated.

Thank you Regards,

  • 0
    Genius 5430 points

    Izrael;

    You need to know the exact peak wavelength of your LED and its spectral width. D you have a monochromator?

     

     

     

     

  • 0 in reply to Neil Albaugh
    Prodigy 30 points

    Thanx for yor reply,

    I dont have monochromator, i just tried using the datasheet of the LED to get the luminousity parameter and then calculating the radiant power. then i tried to keep the radiant power of the leds constant by adjusting their current supply(voltage with a series resistor). i m relying on my calculation using the formulas i found from the net.

  • 0 in reply to Izrael John
    Genius 5430 points

    Izrael;

    LED data sheet wavelength data is sometimes so unreliable that it is  no better than "red", orange", or "blue".  The exact center wavelength of a particular LED may be far from what the data sheet claims. To make matters worse, the spectral width of an LED can vary; some are fairly narrow but others are broad as a barn and may emit at more than a single wavelength.

    A monochromator could give you a known wavelength and width output for calibrating your photodiode. Short of that, the only source I can think of-- short of using lasers-- is to use a broad source (Deuterium lamp, etc.) and interference filters to create your calibration source.

  • 0 in reply to Neil Albaugh
    Prodigy 30 points

    Dear Neil,

    I dont have any experience on on using any monochromator, can u suggest a good one with fairly low price,

    and about monochromators, do i have to get different monochromator/filter for each wavelength? like if i am using red, blue, green... Leds  separately, do i need a filter for each of them?

     

    Thanx for your help

  • 0 in reply to Izrael John
    Genius 5430 points

    Izrael;

    A "monochromator" simply takes light from a broad wavelength source and gives you a narrow wavelength output; i.e., a tunable filter. They are built with diffraction gratings or prisms. A monochromator needs no extra filter. A filter can be used on a broad wavelength light source to give you a discrete, narrow output wavelength, similar to a monochromator. The disadvantage of the filter method is that it is not tunable so it requires as many filters as you need output wavelengths.

    You might be able to use some optical equipment in a nearby university; a physics lab should have what you need. Buying optical equipment may not be practical for only making a few measurements as it tends to be expensive,

    http://en.wikipedia.org/wiki/Monochromator