Can a TOF sensor detect a person through a plastic case?

[moon1003]

HI

We are thinking about a method for detecting people.

The prerequisite is that we need to detect people by penetrating a plastic case with a thickness of about 3mm (white).

The existing PIR cannot penetrate the case,

and radar sensors are expensive.

So we are considering TOF...

The key is to detect people by penetrating the plastic case.

I wonder if it is possible.

[John E KVAM]

I was about to reply that yes, the sensor can see through plastic. Up until you said "white". Turns out they make white plastic by adding titanium dioxide to the resin. And the sensor really cannot see through metals like TiO₂. If you wanted dark, or almost any other color they use a dye. And dyes do not affect the ToF sensor. 

Would you consider a dark area in your case?

with that, your problem is pretty trivial.

- john

[moon1003]

hello

I have some additional questions.

Does the white plastic necessarily contain TiO₂?

Are dark colored plastics generally free of any harmful ingredients?

Once I have reviewed the plastic components, I plan to do a detection test with a ToF sensor right away.

I would like to request a recommendation for a DEV.Kit that is recommended for the above use.

[John E KVAM · Accepted solution]

There is no rule that says one needs Titanium Dioxide. Lead would work as well to turn things white, but Lead is kind of a nasty chemical. 

One can use a dye to make things darker, but one cannot dye something lighter. And that's basically the issue. The dyes only affect the light spectrum you can see and have little effect on the 940nm light the sensor uses. 

I did find one source for an IR transmissive white material. 

If you are dead set on it, have a look at:

https://www.tokaioptical.com/en/product14/ 

I have NOT used their stuff, but I did have one customer who tried it. 

We do sell an evaluation kit. It's pretty inexpensive too. 

P-Nucleo-53L4A2 would be the part number for the VL53L4CX. 

And P-Nucleo-53L1A1 would be the part number for the VL53L1X. 

To go that 2Meters and through plastic, I'd recommend the VL53L4CX with it's 18 degree Field of View, or the VL53L1X. The L1X is a little more expensive, but it's easy to use.