VL53L1X recommended calibration setup

[SMasc.1]

Hi, i'm wondering what is the optimal distance and target reflectance for calibration process function VL53L1_PerformOffsetCalibration()?

Also about Xtalk calibration process function VL53L1_PerformSingleTargetXTalkCalibration() shall be feeded with a distance, may this distance parameter be the same as the distance for calibration process? shall it be related to the transparent protective cap thickness?

[John E KVAM · Accepted solution]

We use 140mm for offset - and a 17% dull gray target.

You can get measured paper from a company called X-Rite.

X-rite Pantone

4300 44th Street

Grand Rapids, MI 49512

(616)818-6769

Munsell PT/ Notation                 Avg % Refl 400-700nm  Size       Pirce USD

STMN2/MA4      N2/M                 3%                                      A4         $26.75 / sheet

STMN275/MA4 N2.75/M             5%                                      A4         $26.75 / sheet

STMN95/MA4   N9.5/M              88%                                   A4         $26.75 / sheet

STMN475/MA4 N4.75/M             17%                                   A4         $26.75 / sheet

STMN675/MA4 N6.75/M             42%                                   A4         $26.75 / sheet

But it's REALLY expensive.

I'd be tempted to use a matte finish dark gray spray paint. Several coats and if it works buy several cans from the same lot, so you can make more if you need them. Having exactly 17% is not that important, but consistency is.

What to choose for Crosstalk depend on how good your coverglass is. You must find that point where your system under-ranges by 10 or 20%. One does this by simple experiment. It will be shorter if you use a dull target - use a larger version of the offset target material. Once you have found that point, do the calibration. (The diameter of the target must be at least half the distance to the target to cover the entire FoV.) The software interprets the crosstalk from knowing the true distance, the measured distance and the signal strength.

Once both calibrations are done, extract them using the function call. Store them in your memory and re-insert them at the next reboot.

We have found that if your manufacturing is really consistent meaning your coverglass does not vary and the air gap does not change that the crosstalk will be very similar across your production. If this is true, you might not have to crosstalk calibrate every unit. Simply use the highest value out a good number of tests.