Laser intensity

[Gianluca]

So, I basically want to build a system that uses laser intensity to work, how do I accomplish this?

I'm referring to laser intensity to the amount of laser that can pass through a transparent object, the less transparent the object the less laser it allows through. If there is such thing as that.

https://i.imgur.com/tcbZ4Km.jpg Here's an example of what I mean.