I have performed crosstalk calibration of VL53L7CX ToF sensor using a 0.2 mm thick polycarbonate cover glass. I had used a sheet of white paper (assuming 80% reflections) placed at 600m as reference surface & 4 samples were used for calibration.
The calibrated sensor's accuracy was tested using a similar setup but with reference surface at 400 mm. The distance values observed in the 64 zones ranged from 396 to 426 mm. The standard deviation of the distance values were in the range of 2.2 to 4.5 mm. The heatmap of the zones also looked uniform.
But when I mounted the sensor in an enclosed space (around 1m X 1m X 1.5m) upside down pointed towards my objects of interest, I'm observing some random ghost detection in some of the zones. There are no objects in these zones at distances given by the ghost detections. But there could be objects/surfaces in nearby zones. Also, these ghost detections were not present when I did the same experiment in the same enclosed space & target objects without the cover glass (before performing crosstalk calibration).
What could be the reason for these ghost detections? What can be done to avoid them?
Thanks in advance.
