VL53L1X Recommended conditions for offset calibration About 140mm

[KArai.2]

Hello,

I am developing a system using VL53L1X.
I have read UM2356 (VL53L1X API user manual).

I would like to know the background of the recommended conditions for the offset calibration procedure Chart distance: 140mm.
Is it a peculiar point that Chart distance: 140mm is characteristic of the sensor?
If anyone knows the effects of calibrating at other than 140mm, it would be helpful if you could let me know.

 

Best regards.

[John E KVAM]

I'm pretty sure that one uses 140mm to do the offset calibration. And that distance is kind of arbitrary. The distance was chosen so a reasonably reflective target (White paper) would not be overly affectived by the crosstalk.

Once you've done the offset, then you can move on to the crosstalk calibration. The best way to do this is to choose a reasonably dark target (Dark Gray paint should do it) and range until you find a point where the measured distance is 10-20% less than the actual distance. 

Then call the crosstalk function, giving it the actual distance. By knowing the real distance and the measured distance the code will work out how many photons were refected by the glass.

From here extract the calibration data, and store it in your host. At reboot, download the calibration data as part of your boot procedure. 

- john

[KArai.2]

Hello John-san,

Thank you for your answer.
It was helpful.

Best regards.