VL53L1X calibration process

[HHaje.1]

Hi

Do we need to calibrate every sensor in the production line, or we just need to make the calibration once to the standard product?

Sensor: VL53L1X.

Thanks

[John E KVAM]

the solution to your crosstalk issue is to use a coverglass that is immune to crosstalk.

Go to hornix.com.tw and click on 'product'. Scroll to the bottom and you will find:

That coverglass will not have any crosstalk - because of the opaque barrier between the two sides of the chip. A bit more expensive this way, but worth it. No crosstalk, even if it gets dirty.

Buy this - or just use it as a reference.

But if you use a narrow FoV, you must set the FoV before your calibrate. (I know, it's a pain.)

The reason you under-range when you narrow the FoV is you get about the same number of photons from the glass, but fewer from the target. This throws off your answer.

[HHaje.1]

Thanks for your input,

I really need to ensure a point: I don't really perform any kind of calibration set after changing FoV, Should I perform it? (offset calibration, calibration of xTalk with uncalibrated offset returned xTalk of zero (0), as it over-ranges)

I'd like to mention that without performing the calibration, I get 'over-range' not vise-versa (160cm 8*8, 198cm 4*4), seems strange really, but this is the observation.

I appreciate your suggestion, it'll be in our option list for sure, but genuinely we are heading towards providing working prototypes to clients as quick as possible (We'd be testing on a test tank before that for sure).

Back to the issue: The sensor at daytime just reads the liquid level sufficiently, but starting at sunset and until the next day, the sensor sees the dear ghosts continuously xD.

Removing the coverglass will kill the chip (It goes decapped and defect) (because of water vapour, to our observations).

To recap, we currently have these options:

• FoV adjustment.
• xTalk calibration*.
• Distance mode (Set to Long)**.
• Zero-offset coverglass (extra hardware and delay).

* I'll try a cardboard instead of the black paper, perhaps to get the right condition.

** Short distance mode is limited to about 1.3m, by my tests xTalk calibration couldn't eliminate under-ranging, so I've set it back to Long (Medium is abscent at SDK).

Any ideas?

[John E KVAM]

Notes: Coverglasses are always recommended. Unless you are in a lab setting. Reducing the FoV is a good idea, but it does limit the ranging distance.

Water is a difficult problem. If you can 'see' a reflective bottom, then you will overrange. Only solution is to carefully create a look up table. You hvae to compensate for the photons that are slowed by the water and reflect off the bottom.

If you under-range, it's a crosstalk problem. If you over-range, you are 'seeing' the bottom.

If you change the FoV, you really should load the crosstalk calculation you did with that FoV.

Each different FoV should have it's own Xtalk calibration.

Or you could use the crosstalk free coverglass.

[HHaje.1]

Hi John, sorry again for incomplete statement.

The over-ranging with narrow FoV is observed at lab setting shared earlier. so there's no real thing it can see further 150 cm, I've made sure that the sensor faces the center of the black paper.

I'll try a cardboard instead and I will share updates soon.