Hi, I have a VL53L1 board, I looked into the datasheets and it got me confused. I have a few questions and it would be very much helpful if u could explain to me.

[MBabu.2]

1. I cannot understand the term "coverglass crosstalk and smudge beyond 80 cm". Is the glass already in the sensor or does it mean that I can use any glass?
2. Can I program the sensor without setting the preset mode or is it mandatory

Thank you so much

[John E KVAM]

Crosstalk is the signal returned by the number of photons that hit the coverglass and reflect back. Even the best coverglass is only 95% transmissive.

You can use any glass, but some are better than others. But you really should use the glass.

Watch the video:

VL53L1X Dirty Cover Glass: https://youtu.be/BHM2CZVXZGc

it explains the problem, and provides one solution.

You probably do not need to go to this extreme.

The sensor has defaults, so you don't need to pick a preset mode, but knowing what you are doing is always better.

• john

[MBabu.2]

Thank You so much, I do have another doubt. The datasheet shows that the VL53L1 give maximum of 8m distance in Full FoV. Will the sensor give the same maximum distance when reducing the FoV or does the distance decrease with the decrease in FoV?

Thanks

[John E KVAM]

As with all datasheets that 8m is the distance at which we guarantee you cannot exceed.

if you have any ambient light - you cannot range as far.

If you have a target smaller than the full field of view, you cannot range as far

If you have a black target instead of a reflective one you cannot range as far.

If you want faster measurements, you cannot range as far.

And of course narrowing the FoV turns off elements in the Single Photon Avalanche Diode (SPAD) array - and you can't range as far.

In fact that 8M was designed expressly to focus a projector - and projector screens are pretty reflective.

I tell people that the evaluation kit is essential for figuring out if the sensor will work in a given application.

The P-Nucleo-53L1A2 is some $50. And it's worth every penny.

If the Eval kit shows you the sensor cannot work in a given situation, you've saved a ton of work.

If the Eval kit give a good result, you can use it to compare with your design to insure you are on the right track.

Good luck,

• john

[MBabu.2]

Thank you so much!!!! I appreciate it...

[John E KVAM]

The glass is NOT in the sensor - you have to add that to protect your electronics from the envionment. Dust, dirt and moisture on the sensor is not good.

The crosstalk is the number of photons hitting the coverglass and reflecting back.

With the VL53L1CB software, all the refleted photons are isolated in the first bins of the histogram. So after 80cm it's not possible to get confused.

But the crosstalk does effect the near targets (up to 80cm) so we need to account for them.

If you are NOT using a coverglass, then you don't have a crosstalk issue.