VL53L1 calibration using water target surface

[LDMigotto]

Hello again!
I've been trying to measure water level using the VL53L1 sensor and reading forum posts on it, and I've gathered that RefSPAD calibration isn't really recommended anymore.

From my research on the topic, I know that water reflects only 2% of perpendicular incident light, with the rest getting transmitted and also that the transmitted rays will be fully absorbed at a minimum water level of 10cm.
I was wondering if doing the RefSPAD calibration utilizing the VL53L1 (with a cover glass) leveled parallel to a water suface from a body deep enough to absorb all transmitted laser could end up improving the sensor's results by giving more weight to SPADs more likely to detect those perfectly reflected photons.
Thanks in advance!

[Zhiyuan.Han · Accepted solution]

Hi 

I went through all the discussion on this topic. to be direct, RefSPAD seems not related with your issue. 

• The RefSPAD calibration is used to calibrate the reference SPAD array, to select the reference SPAD position and number. the reference SPADs are used to detect the light from VCSEL directly as time 0 reference.
• The issue you are met is return SPAD oscillation, the return SPADs are used to collect light signal come back from target. as John explained, the SPAD number and position selection are come for DSS algo deep inside the chip, this is depends on the target reflected light signal, by default our target is 20MCPS.
• No matter RefSPAD and return SPAD, we can't control the weight manually, as the weight is already add by HW configuration, the SPAD have different light attenuation, this means once the position is defined, the "weight" is already fixed. 

Br

Zhiyuan.Han