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OPT3101: Ambient light calibration

mahiro.aikawa
Prodigy 80 points
Part Number: OPT3101

When calibrating the ambient light, if I keep the target amplitude (between 16000 and 24000) as written in the datasheet, can I get the same result even if the target material is different?


What is ambient data based on? Does it change with illumination?

Also, I am adjusting the angle of the halogen lamp to change the "ambient data" for ambient light calibration, but are there any bad points?

Do not change the position of the halogen lamp. Change ambient data by changing angle.

  • 0
    TI__Expert 6800 points

    Hi Mahiro,

    After a successful calibration, the ambient rejection of the device should work up to 130 lux of ambient light hitting the device. Changing target material may effect the amount of ambient light reflecting onto the device.

    Thank you,

    Brent Elliott

  • 0
    TI__Expert 6800 points

    Hi Mahiro,

    Please let me know if you have any follow-up questions on this.

    Thank you,

    Brent Elliott

  • 0 in reply to Brent Elliott
    Prodigy 80 points

    additional questions

    www.ti.com/.../opt3101.pdf

    URL above
    Datasheet table 171
    Distance accuracy 2% For an object with 18% reflectivity

    If the distance between opt3101 and object with 18% reflectivity is 1530mm, how much error will occur?
    1530 ±30.6 mm? 1530-30.6mm? 1530+30.6mm?

    Also, does the accuracy of the distance value increase as the object reflectance increases? Will it be smaller?

  • 0 in reply to mahiro.aikawa
    TI__Expert 6800 points

    Hi Mahiro,

    In this instance, 2% accuracy means +-2%, so 1530 ±30.6 mm.

    The accuracy will increase at the reflectance increases. If you want to try out some settings and get a feel for the device performance under a variety of conditions, you can use the system estimator tool here.

    Thank you,

    Brent Elliott

  • 0 in reply to Brent Elliott
    Prodigy 80 points

    It is an additional question.
    The data sheet says:
    The ambient coefficient scaling factor SCALE_AMB_PHASE_CORR_COEFF should be selected such that all the coefficient values fit within 8-bit signed number (–128 to 127)

    However, we ended up with a value of "coefficent" less than -128. Please tell me how to deal with this.

    I calculated the separation slope as shown in the image.
    After that the coefficent is -161.856
    Slope=-40.464
    coefficent=slope * 2^(2 + scale) = -40.464 * 2^(2 + 0) =-161.856

    Do I have to take physical measures such as changing the lens?

  • 0 in reply to mahiro.aikawa
    TI__Expert 6800 points

    Hi Mahiro,

    What are the coefficient values if you select different values for SCALE_AMB_PHASE_CORR_COEFF?

    Thank you,

    Brent Elliott