VL53 series measurements varies across liquids (oils/sauces)

[mlui-v]

Hi,

I'm trying out the VL53 series to try to measure the height of liquids in a container. In my use case, we are measuring sauce in sauce cups - ranch dressing, hot sauce, etc. One issue we have noticed is that with oil or oily sauces such as olive oil. The sensor is not responding with the correct depth measurement. The sauce can be 4-6 inches from the sensor.

Looking at the documentation, there could be some cross talk issue, however we don't what sauce will be used. (The user can provide different sauces) - Do you have recommendations on how to get better results with this sensor?

[John_Kvam]

I spent a lot of time on this exact subject and here is what I know.

Photons penetrate the liquid, are slowed down by it and reflect back.

The solution is to use a container with a flat (matte finish) black paint. I've found that a clear glass or plastic container sitting on a black surface works as well.

But eliminating the reflections off the bottom is imperative. 

Note that if the liquid is at least 15cm deep the light does not penetrate, so the problem goes away.

Another issue are the side walls. If the container is narrow, then the light hits the side walls and reflects. 

Using the VL53L4 is better in this regard than is the L0 or L1. The L4 has a narrower Field of view.

The 'spot' of illumination is 1/2 the distance on the L0 or L1, but only 1/3 the distance with the L4.

There is a crosstalk-free coverglass made my Hornix (www.hornix.com.tw) It will solve your crosstalk issue and protect the sensor even if it gets a little dirty. It's made of plastic and should be food-safe I think. Should ask them.