How much surface size is needed for measuring distance by VL53L0X ?

SNish · ‎2021-05-12

We would like to know sensing distance target's size spec.

Our team had tested with some small pole as 1inch diameter and 2 inch height cylinder that put on table.

But from upper to bottom as in front of target VL53L0X cannot detect this cylinder distance.

We have tested some another medicine bottle also, it shows similar result.

My understanding of TOF is photon detect by SPAD with avalanche but it takes some level of volume reflection at surface in SPAD.

If there are some spec of this issue please let me know.

John E KVAM · ‎2021-05-28

The light goes out in a cone of 27 degrees. A little trig will tell you that the diameter of the illumination area is a touch under 1/2 the distance to the target.

So at 1 foot the circle of illumination is 6 inches in diameter.

Medicine bottles are going to be a problem. Plastic is really transparent to 940nm. And the color does not matter. The color in plastic is a dye - and most dyes and inks are transparent to 940 as well. (White is different - that's Titanium Dioxide. And metals are not transparent.)

The other issue that is bothering you is the shape. Light will hit that cylinder and if it's reasonably smooth, it will bounce off at a sharp angle. Only those photons that hit the perpendicular region will reflect back. But because of the plastic and the small region, you will not get enough to make a range.

Can you perhaps look down on the bottle. If it has a white plastic cap, that would be easier to see.

john

Our community relies on fruitful exchanges and good quality content. You can thank and reward helpful and positive contributions by marking them as 'Accept as Solution'. When marking a solution, make sure it answers your original question or issue that you raised.

ST Employees that act as moderators have the right to accept the solution, judging by their expertise. This helps other community members identify useful discussions and refrain from raising the same question. If you notice any false behavior or abuse of the action, do not hesitate to 'Report Inappropriate Content'

View solution in original post

John E KVAM · ‎2021-05-28

The light goes out in a cone of 27 degrees. A little trig will tell you that the diameter of the illumination area is a touch under 1/2 the distance to the target.

So at 1 foot the circle of illumination is 6 inches in diameter.

Medicine bottles are going to be a problem. Plastic is really transparent to 940nm. And the color does not matter. The color in plastic is a dye - and most dyes and inks are transparent to 940 as well. (White is different - that's Titanium Dioxide. And metals are not transparent.)

The other issue that is bothering you is the shape. Light will hit that cylinder and if it's reasonably smooth, it will bounce off at a sharp angle. Only those photons that hit the perpendicular region will reflect back. But because of the plastic and the small region, you will not get enough to make a range.

Can you perhaps look down on the bottle. If it has a white plastic cap, that would be easier to see.

john

Our community relies on fruitful exchanges and good quality content. You can thank and reward helpful and positive contributions by marking them as 'Accept as Solution'. When marking a solution, make sure it answers your original question or issue that you raised.

ST Employees that act as moderators have the right to accept the solution, judging by their expertise. This helps other community members identify useful discussions and refrain from raising the same question. If you notice any false behavior or abuse of the action, do not hesitate to 'Report Inappropriate Content'