VL53L0X Calibration Target - What to use?

[Josh Yu]

Posted on March 24, 2018 at 14:24

The user manual mentions using one 88% reflectance target and 17% reflectance target for calibration. I don't know what material has those reflectance values. What exactly should I use for calibration and where can I get those?

[Legacy member]

Posted on March 24, 2018 at 22:07

Hello,

Have a look at this lecture presentation: 

https://www.cs.cmu.edu/afs/cs/academic/class/15462-f09/www/lec/lec8.pdf

 

Also, Wikipedia offers quite good explanation: 

https://en.wikipedia.org/wiki/Reflectance

 

However, I wasn't able to find some online trustworthy database of reflectance of various materials.

David

[Josh Yu]

Posted on March 25, 2018 at 05:25

Thanks David! The two links you posted explained what reflectance is pretty well. It sounds like the white target is probably something opaque and with a smooth surface finish. And the dark target is probably something with a rougher finish?

I found this chart on Google. I don't know how trustworthy this is but I thought it was interesting enough.

https://www.automation.com/images/uploaded/chart1.bmp

[Josh Yu]

Posted on March 26, 2018 at 05:46

I've found this sentence from the VL53L0X datasheet (under 'Performance' -> 'Measurement Conditions'):

Reflectance targets are standard ones (Grey 17% N4.74 and White 88% N9.5 Munsell charts).

So it seems like the targets are Munsell color cards. Now the problem becomes how to get those color cards... A quick search online only reveals small pocket sized color cards, which is probably not big enough...

[John E KVAM · Accepted solution]

Posted on May 08, 2018 at 01:26

It’s called Munsell Color Paper

X-rite Inc

4300 44th street S.E.

Grand Rapids, Mi 49512

Tel 877-888-1720

The stuff is expensive. Like $26 per sheet expensive.

We use 5%, 17%, 42% and 88% reflectances in our testing. One color per sheet.

MUNSEL NOTATION N2.75/

STM275MA4

5% REFLECTANCE

STMN475/MA4

17% REFLECTANCE

STMN95/MA4

88% REFLECTANCE

STMN675/MA4

42% REFLECTANCE

But standard Photo grade white paper is close enough to 88%, that it will work unless you are really particular.

Black spray paint is 5% reflective. Use a couple of coats. Doesn't matter if it's flat or gloss.

I don't have a good source of 17% gray.