VL53L8A at 4m

[xukong]

Hello.
Today I will test the VL53L8A evaluation version in the outdoor (cloudy) test data, the code is automatically generated by the STM32Cube. I irradiated VL53L8A to the wall, at about 1.75m, with almost no data. At 4m, the serial port directly showed no data. Is there any problem with my use?
In the future, I may use 950nm narrowband filter in outdoor test, any suggestions?

The picture shows the measured values around 4m.

[John E KVAM]

There is no problem except perhaps of understanding. The sensor shoots out a tiny bit 940nm light and then looks for a retuning signal. The Sun shoots out tons of 940nm light, and it becomes noise in our system. 

1) The sensor is sensitive to ambient light. The effect is it cannot range as far. IN really bright light the max range might go down as low as 1 Meter. And if your integration time is low, the problem is exacerbated. If you move in closer, you will find it starts working at some point. And that point will change with the brighness of the sun, location of the sun, and reflectivity of the target.

2) The sensor filters out all but the 940nm light. Unfortunately the sun generates way more 940nm light than does the sensor. And that is your issue. You cannot filter the sun's 940nm light without also filtering the sensor's 940nm light.

3) Modify that code to show the range status when don't get a range (printing x is silly). Try 0xXX when the status is bad, so instead of seeing a useless X you know the status. 

People have proposed adding an external 940nm filter, but it adds crosstalk, and cost. If you get the cost down, it can help a bit - some light will 'blow through' our filter, and your filter can help that.

- john

 

 

[xukong]

hello.
I have been busy recently. I am very sorry to reply so late.
We found that increasing the 940nm filter was indeed useful, and in sunlight, the result was much better after increasing the filter. However, its final effect has not reached our expected results, and we may have to consider other plans in the future.

[John E KVAM]

Can you share with us all how you increased the 940nm filter?

I'm sure that could help a lot of others as well.

I'm sorry the sensor did not meet your goals, but I'm happy you could run the test without having to build you device and invest a lot of money and time. 

- john