Best ToF sensor for liquid measurement

[LDMigotto]

Hi!

I've since given up on utilizing VL53L1X for liquid level measurement. @John E KVAM had previously reccomended me to use instead the VL53L4CD sensor for this sort of application (small recipients with water), and I plan to ship it next week. But I've also read about VL53L5CX which has the advantage of reading liquid level even when angled at about 15° due to its wider FoV.

Is there any other ToF sensor that should perform well for this kind of scenario that I'm not aware of? Even if being overall worse but having an specific advantage like VL53L5CX.

Thanks in advance!

Edit: I've noticed now that the VL53L4CD is out of stock on both stores I could ship from, but VL53L4CX is available. From this forum post, I gathered that I can run the ...CD software on the ...CX, but do they have any other difference besides processing power?

[John E KVAM]

ST has done a lot of work in this area. Go to: STSW-IMG039 - Liquid Level Monitoring Code Example using Time-of-Flight sensors - STMicroelectronics and have a look.

There is documentation and code for both the L4 and the L5 sensors. 

The trick is that you want the photons that hit the surface of the liquid and bounce back. And only the perpendicular ones do this. With the L5, you get an array of zones - each about 5 degrees square. And one of those zones will have a signal MUCH greater than the others. And that zone has the right answer. 

All the other zones contain photon arrival times that demonstrate how the photons are slowed by the water and bounce all over the place.

The L5 is a really good sensor for this application. But it is quite a bit more expensive than the single zone VL53L4CD (our least expensive). But that one 5 degree zone does have better data than the L4's 18 degree single zone. 

- john