ToF sensor with highest sampling frequency

[Tom_pm]

In the search for a distance senor which can sample at highest rate. Given the constraint of a measurement range <1m and accuracy of relative distance changes in the low mm range. Ideally we could get a sampling rate of 1kHz.

The VL53L4 sensors would be priced quite reasonable, but I am afraid the sampling rate will not be sufficient to track the movement of our object.
Also, is my understanding correct that at he the same accuracy the VL53L4CX should result at twice the rate of returned distance measurements compared to the VL53L4CD. Due to the way how the A/B measurement results are combined. I.e. only one new A(or B) measurement taken and the other value used from before. The VL53L4xD directly returns the distance so I assume it can't be configured in a similar way or could it?

I have found a non ST part that could match our requirements, so I'm wondering if ST has any upcoming part with a higher sampling rate in the pipeline as well.

[John E KVAM · Accepted solution]

The holy grail of ToF is to get sub-mm accuracy. But it can't happen. The trick is that to measure the distance directly you would need to run in the pico-seconds. And small, simple chips don't do that. They infer a distance by counting the number of photons returned during each clock cycle. From this pattern, we come up with a really good guess as to where the target is. 

With faster clock cycles the guess would get better, but faster clocks means more power and more cost. So, it's a trade-off. And most people don't need that sort of accuracy.  

The next chips will 'see' farther - and wider, or they will get less expensive, but I see no plans to make one more accurate. 

Your other desire - 1Khz is also a tradeoff. As we are running a statistical process, more photons means a better result. And we probably could run at 1Khz, but only at the expense of accuracy.

All your requests could be done I suppose, but not in a single chip costing a few dollars. You would need a laboratory-level bunch of real scientific equipment.   

In order to detect radar aliasing we need to change the pulse repetition interval. if one runs continuously, alternating between the two settings is easy. Each A range is bracketed by a B range. 

But the VL53L4CD is expected to range in a non-continuous manner. So each single range consists of an A and a B range combined, giving a single result that is not dependent on any other range.  

- john