Using an external VCSEL

Hello! Could you elaborate on the possibility of using an external VCSEL:

-Should I buy the same VCSEL array with all similar parameters. Which one do you recommend to buy?

-How to use it? I have a simple solution in mind: to trigger the external VCSEL optically by the signal from the original ToF VCSEL. What problems would you see in this case?

-Are any programming changes need to be done or just doing the recalibration procedure will be enough?

Appreciate, if you could advise me on this. The reason I want to use an external VCSEL is that I could organize the collimation optics in a more flexible way.

Regards,

Anton.

  • 0
    •  Analog Employees 
    on Mar 5, 2021 11:37 AM 1 month ago

    If you want to use a different VCSEL or a different VCSEL configuration the recommendation is to make a new laser board.

    Driving an external VCSEL optically will generate additional delays for the laser pulses and most likely this will prevent the system from working.

    Changing the VCSEL configuration will require updating the ADDI9036 firmware and recalibrating the system.

    Can you share more details on what you are trying to accomplish? Maybe there are other ways to address what you're looking to do.

  • Dear Andrei,

    Generally, I would like to integrate my scanning device with your ToF device. The problem is that for my scanning device, I need to produce a collimated narrow (near 100 um diameter) laser beam. In this way, I would like to scan the whole field of view provided by the collection lens which will give me the possibility to increase the operational distance.  The main problem of 96-TOF1 is that there is an output diffuser with not a small size. Consequently, producing a collimated narrow beam starting from the diffuser is a challenging task (requires a lot of non-compact optics ). Trying to come up with easier solutions, I thought about removing the diffuser (which was not recommended by you) or use the external VCSEL. Appreciate, if you could propose another way to address the problem.

    Best regards,

    Anton.

  • 0
    •  Analog Employees 
    on Mar 9, 2021 8:24 AM 1 month ago in reply to AntonB

    Hi Anton,

    Removing the diffuser might damage the VCSEL, so this is not really a solution.

    If you just need to synchronize your scanning device with the frames from the ToF sensor, then you could use GPO6 of ADDI9036. This GPO outputs a square signal with a frequency equal to the frame rate and synchronized with the ADDI9036 frames.

    But if you want to use the light from the external scanning device as input to the depth sensor then a new laser board will have to be designed to include your laser.

    Regards,

    Andrei

  • Hi Andrei,

    What if I buy an identical VCSEL array with the same parameters, but will trigger it optically from the original VCSEL. From a naive point of view, it should be only a systematic constant error in distance estimation which is equal to the delay required to trigger optically the second VCSEL. As long as it is not too large, can it be just removed with recalibration? By "not too large" I mean no larger than the pulse width (which I believe the limit in the distance measurement).

    Best,

    Anton.

  • 0
    •  Analog Employees 
    on Mar 12, 2021 11:17 AM 29 days ago in reply to AntonB

    Hi Anton,

    If the delay is less than the pulse width then it should be possible to remove it through calibration or by adjusting the timing for the ADDI9036.

    Regards,

    Andrei

  • Dear Andrei,

    How do you think is this possible to make this delay less than the pulse width? Optical propagation is very fast, so it is not a problem, I care more about the triggering delay of the external VCSEL. 

    Also, am I right, that the original VCSEL is from Finnisar?

    Best regards,

    Anton.

  • 0
    •  Analog Employees 
    on Mar 17, 2021 8:42 PM 24 days ago in reply to AntonB

    Hi Anton,

    Yes, the VCSEL is from Finisar.

    The ADP5202 should be able to provide fast enough triggering.

    Regards,

    Andrei