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OPT8241-CDK-EVM: OPT8241-CDK-EVM

Jason Seawall
Prodigy 20 points

Part Number: OPT8241-CDK-EVM

We are building a product based on the OPT-8241-EVM with 8 laser diodes instead of 4.  To do the calculations for laser eye safety, we need to know the minimum and maximum laser pulse length, but I can't find that information in any of the TI literature. 

  • 0
    TI__Expert 3800 points

    Hi Jason,

    Pleas refer to Figure 3 in OPT9221 datasheet for the modulation and demodulation timing of the chipset. These signals are used to generate the laser pulses.
    We can give advice on how to design the illumination driver circuits. However, for the purposes of laser safety, it is best to measure the laser pulses directly with an optical detector.

    Regards,
    Subhash

  • 0 in reply to Subhash Chandra Sadhu
    Prodigy 20 points

    Why we plan to do actual lab testing on the finished product, I would still like to do some estimates ahead of time-based on the maximum pulse length in the OPT-8241-EVM kit system, which we are basing our design on.  The datasheet OPT9221 explains how the modulation works, but I don't see anything that would tell me what the max laser pulse length for the OPT-8241-EVM might be.  Any information here would help.

    Thanks
    Jay

  • 0 in reply to Jason Seawall
    TI__Expert 3800 points
    The max laser pulse length depends on the register settings. Maximum value of pix_cnt_max is 2^22 which amounts to an exposure time of 47.38ms. This is the exposure time of just 1 quad. You might want to bunch them together if you are using lumped dead time. Please look at the behavior of registers in the timing coordinator integration duty cycle, pix_cnt_max, illum_en_early, etc. This would be under the timing coordinator section in OPT9221 datasheet.
    These registers control the amount of time the camera can expose for. Typically, the maximum possible continuous exposure would be very long. Do you have a target setting in your mind? Laser eye safety calculations need the laser emission power/energy at a lot of different time scales. It may get complicated to qualify the camera for every time scale. Do you think it may be a better idea to qualify the camera for a fixed setting? Usually final products work at a narrow range of settings.

    Regards,
    Subhash