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OPT9221: The way for long distance

kyeongmin choi
Intellectual 590 points
Part Number: OPT9221
Other Parts Discussed in Thread: OPT8241

hello

We are using tof sensor and controllor (opt9221/opt8241) to develope tof camera.

We want to get result for long distance using dealiasing mode.

 So i have below questions. could you plz reply~

1. When we use two frequency in dealiasing mode , laser is operated as two frequency at the same time?

   or respectively ?( ex. opreate dealiased frequency  after base frequency)

2. In page 33 opt9221 data sheet ( relate to original distance caculation), we should know dealiased phase , if we try to caculate original distance.

   But i dont understant what d=20m mean is  in equation 28?  How do we know that? 

  I think we can't know distance, just caculate original distance.

3. We want get good distance  for long distance like 15m. So i think we need much more power of laser .

   Laser current of EVM is almost 600mA . Is it possbile to increase current as using same laser(22045498) whose peak current  is 1.4A ? if we just change led driver.

   i guess, current of laser has limitation within very short pulse width. cuz both rising and falling time .   if increasing  current is possible , is it good working long distanec( like 15m) in dealiasing mode?

thanks

  • 0
    TI__Mastermind 49916 points
    Hello Kyeongmin,

    We have received your inquiry regarding the device OPT9221. The device applications team will get back to you with a response soon.
  • 0 in reply to Praveen Aroul
    TI__Expert 3800 points

    Hi Kyeongmin,

    My responses to your questions are in bullets:

    1. The laser operates in 2 frequencies 1 after the other. It does not emit both modulation frequencies at the same time.

    2. Equation 28 is only to demonstrate behavior of final dealiased phase output. So if the actual distance were 20m, it would give phase value of 3276. in actual sensor operation, you will not know distance. You will know phase given by OPT9221. You can use Equation 28 to calculate real distance.

    3. It is best to get information from Lumentum on peak current capacity of 22045498. We have operated it at up to 2.5A peak current. I think you are measuring the average current as 600mA. You can also consider VCSELs from various vendors in the market for long range applications.

    15m is a relatively long range and will require high laser powers. Can you give us more details on ambient light conditions, FoV, and frame rate requirement?

    Regards,
    Subhash