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OPT8241-CDK-EVM: minimum modulation contrast and full well depth

Oren Cohen80
Prodigy 10 points
Part Number: OPT8241-CDK-EVM
Other Parts Discussed in Thread: OPT8241, OPT3101

For academic studies in optical imaging, we wish to use the OPT8241 time-of-flight sensor for detecting low contrast modulation at 10-70MHz frequencies (i.e. under strong ambient light), with expected contrast (modulation depth) of approx. 1%


We wish to know whether that would be possible with the OPT8241-CDK-EVM, and specifically:

1) what is the minimum detectable modulation depth with this device?

2) What is the pixel full well depth of this device (which dictates (1))

3) What is the most sensitive time-of-flight sensor available to detect the weakest modulation

Any help would be greatly appreciated

  • 0
    TI__Expert 3800 points
    Hi!

    I am assuming that the modulation would be coherent with the demodulating signal of the sensor. Detecting such low contrast modulation would basically require a combination of high dynamic range and sensitivity. 1% is indeed a very low contrast.
    Currently, the best dynamic range system that TI can offer is based on OPT3101. It can certainly work at 1% modulation contrast. Please go through the datasheet of OPT3101 and let us know if it works for you. The modulation frequency is fixed, however you can go really low on the modulation contrast.

    You should be able to use OPT8241 also to detect signals at 1% modulation contrast. You can use the system estimator tool to simulate such conditions. OPT8241 will allow you to have a greater choice of modulation frequencies. However, I believe that you would be pushing the SNR of the system. You wold have to average information from multiple pixels or from multiple frames to achieve better SNR.

    1. From my estimates, the boundary of minimum "detectable" modulation depth would be at 10^-4. This carries a few assumptions with it. But this is the order of the minimum modulation depth.
    2. Unfortunately, we are not able to publish this information as it is a confidential spec of the pixel. Also, in addition to the full well depth, you can enhance the detection capability by averaging multiple frames, or averaging multiple pixels.
    3. OPT3101 would be able to detect the weakest modulation at a fixed frequency.

    Hope this helped.

    Regards,
    Subhash