This test allows us to understand how wide the depth of focus of our laser module is. The wider the depth of focus, the deeper we will be able to cut.
This file contains 5 horizontal lines which will be engraver at full power but at different speeds: F1200, F1000, F800, F600, F400.
The best material to use is black metal business card: they are very cheap and allow to have a good repeatability and comparison of results. You can find them at great prices on aliexpress.
To carry out this test it is necessary to prepare an inclined plane that allows you to see how much the laser loses focus when it moves away from the best focus point. I suggest preparing a 2cm high inclined plane.
Focus at the top of the inclined plane and let run the test. Looking at how far the laser trace can go without widening (and therefore losing power) it is possible to understand what is the limit of depth that we will be able to reach with our laser, and therefore the maximum thickness of material that we will presumably be able to cut.
If your laser does not engrave more than a quarter of card length, or engrave a very large trace, you will probably not be able to go beyond 5mm in thickness. If it reaches half of card length: 1cm. If it goes all the way without going out of focus, you will probably be able to cut plywood up to 2cm (but it will be difficult!).