Here is a view of the hardware ready to do testing. An important recommendation is that the tests should be done in a light controlled environment similar the one I did. These tests cannot be done outdoors due to the strong solar radiation.

This is a screenshot of a healthy leaf.

This other image is a screenshot of an unhealthy leaf.

Below I show you the video where I did tests with three different types of plant leaves.

In the download section you can get the CSV file during the test.