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

SNish
Associate

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.

1 ACCEPTED SOLUTION

Accepted Solutions
John E KVAM
ST Employee

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.)

0693W00000BZXkLQAX.pngThe 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

If this or any post solves your issue, please mark them as 'Accept as Solution' It really helps. And if you notice anything wrong do not hesitate to 'Report Inappropriate Content'. Someone will review it.

View solution in original post

1 REPLY 1
John E KVAM
ST Employee

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.)

0693W00000BZXkLQAX.pngThe 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

If this or any post solves your issue, please mark them as 'Accept as Solution' It really helps. And if you notice anything wrong do not hesitate to 'Report Inappropriate Content'. Someone will review it.