I've always been fascinated by this topic as well. As a further experiment, you may be interested to know that these IR lights can pass straight through red wine that looks totally dark and opaque to the human eye. I took some photos to demonstrate this with a DSLR with the IR filter removed here [1], but you can test this yourself by using a smartphone to look at the IR light of a TV remote with a glass of red wine in between them.
[1] https://alexbock.github.io/blog/nir-water-red-wine-compariso...