Calibration VL53L0x with coverglass

[PRuiz.1]

Hi,

I'm working with vl053L0x sensor in a project to liquid measuremet. First I try to measure the empty cointainer 690 mm to tall but I'm not getting the correct measurement, I'm getting out of range 8191mm, or I'm getting a measurement with an offset of +- 40mm.

The measurements obtained depends of calibration. I have read the documentation but I have some questions about the calibration:

1) SPAD calibration, the function VL53L0X_PerformRefSpadManagement, It is necesary to remove the coverglas and execute this funciotn in a dark environment or normal environment?

*For the next points is necessary put the coverglass.

2) I have a black box to 10cm tall and the box bottom is black too, Would it be good to change the bottom of the box for a white background? Would offset on a white background or a black background be a big difference?

3) Crosstalk, this point is the most problematic, I try to calibrate the crosstalk with a white paper tube with 470mm to tall and a black background. I'm using the sensor in a dark environment, so to calibrate the crosstalk, Should it be necessary to use a black tube and a black background for a correct calibration?

For the other parameters that are calibrated, is it necessary to make any changes to the environment?

I have read in the documentation that if if you will go to use the sensor in a dark enviorement you need to configure the sensor like long range, but in this configuration I can't get a stable measurement.

I'm use the coverglass indicated by the documentation:

 

On the other hand, what are the limits to measure on a dark background?

Because the values ​​that appear in the documentation are on white or gray backgrounds.

 

There is something that needs to be changed to correctly calibrate the sensor, I can't get it to measure well inside the container in a dark environment, if I measure outside, I get the most accurate result than inside the container.

Regards,

Pablo

[John E KVAM]

8190+ are the numbers we put into the distance return when something goes wrong.

Read the RangeStatus register and figure out what is happening.

Black is the hardest thing to range on. White returns more photons and thus can range at a much further distance.

So painting the target white is a great idea if you can.

1) SPAD calibration, the function VL53L0X_PerformRefSpadManagement, It is necesary to remove the coverglas and execute this funciotn in a dark environment or normal environment? NO. Just run it.

*For the next points is necessary put the coverglass.

2) I have a black box to 10cm tall and the box bottom is black too, Would it be good to change the bottom of the box for a white background? Would offset on a white background or a black background be a big difference?

3) Crosstalk, this point is the most problematic, I try to calibrate the crosstalk with a white paper tube with 470mm to tall and a black background. I'm using the sensor in a dark environment, so to calibrate the crosstalk, Should it be necessary to use a black tube and a black background for a correct calibration?

Crosstalk is tricky. One needs to find that point where the sensor under-ranges by 10-20 percent.

This has to be done experimentally. A white target can end up quite far out. A dull target much farther in.

So start ranging and find that point.

Then run the crosstalk. That will be your number.

But if you use that hornix coverglass, you will likely not need the crosstalk unless you want to be very accurate.