ToF-Sensor to detect part distance

[Jun]

Hello, I'm trying to use a ToF-Sensor to track the distance of metal parts (sheets, cog wheels etc.) usually in the range of 0-60cm. The thing is that I am only interested in the distance of the surface that is directly below the sensor, the center of the FoV of the Sensor so to speak. I tried using the VL53L4CD Sensor, which is a Single Zone Sensor and while the readings where accurate for flat surfaces, they weren't for surfaces with sudden changes in height within the sensors FoV(obviously). Hence why I'm considering using a Multi-Zone Sensor to get the distance measurement I'm interested in.

So is it possible to only measure the distance of the surface which is in the center of the sensors FoV this way? Which sensor should I consider and what settings should I use to get the most accurate measurement?

[John E KVAM · Accepted solution]

What you want is a 'dot' laser. And we sell a flood-type laser.

I don't know of anyone with a dot-type laser in a small part. The trick is you need a lens to focus the light and as soon as you do that, you end up with a system that is NOT EYE-SAFE. Unfortuantely concentrating the light is dangerous. So you cannot do it if there is any chance a user might look into it. 

(It's why all the dot-type lasers are visible. You know to close your eyes, and punch the person who pointed it at you.)

Try the VL53L8CX. You get 8x8 zones out of our 45x45 degree pyrimid of light. I'm hopeful that the resulting 5x5 degree square is small enough to see just the part you want. You can even turn up the 'sharpening' parameter to eleminate the background. 

(The P-Nucleo-53L8A1 is $56 dollars - and you can prove it works before going further. A good inventment.)

One thing to note, when your target does not cover the entire field of view, the photon return times are averaged if the distances are close together. If the distance is greater than 60cm, you will get two targets. (A near and a far.)

But give the VL53L8CX a try and see if it works for you.