VL53L4CD Cover Panel Design Requirements

[Brian_Azzopardi]

Hello all,

We will probably need to go for custom cover panels for our sensors, however, we could not find a clear list of requirements to follow.

Material: The product's datasheet (DS13812 - Rev 6) states that "the VL53L4CD achieves the best ranging performance in various ambient lighting conditions and for a wide range of cover glass materials." We were considering PMMA or PEI + PC as Gilisymo's / Hornix's cover panels for the VL53L4CD use these materials. Are there other materials worth considering?

Thickness and air gap: We came across AN5231 - Rev 1 that provides cover window guidelines for the VL53L1X sensor (not the VL53L4CD).  In Section 5.2.6 ST states that "for sub 1000 mm ranging
– Total air gap and cover window thickness = 2 mm maximum
– Cover window thickness <1.5 mm and air gap <0.5 mm"
Is this also valid for the VL53L4CD, or are the recommended air gap and cover window thickness values different?

Please let me know if there is documentation that provides cover window guidelines for the VL53L4CD.

Thanks!

Brian

[John E KVAM · Accepted solution]

There is an article I wrote - actually on this page, but in the Knowledge base.

https://community.st.com/t5/mems-and-sensors/time-of-flight-cover-glass/ta-p/49259

That Hornix was co-designed by ST and Hornix. Built specifically for customers like you. 

Glass, acrylic (PMMA) and Polycarbonate are all good choices. 

Close, Clear, Clean, Thin (I could not think of a 'C' word meaning thin) are the traits you are looking for.

Putting an opaque barrier between the Tx and Rx guarantee no crosstalk even in the presence of fingerprints and condensation. (Crosstalk is the light that goes from the TX side to the RX side without hitting your target. ) The Hornix glass gives you choices. The expensive one has the barrier, but it does cost more.

That document is valid for all the ToF sensors.  

[Brian_Azzopardi]

Thank you @John E KVAM! Your article (https://community.st.com/t5/mems-and-sensors/time-of-flight-cover-glass/ta-p/49259), together with AN5231 gave us the information we needed.

Brian