How to adjust the laser focus ?

Cutting objects in different height, need to readjust the laser focus.

Step 1

Put a gray paper at the height of the object.

Step 2

Wear protective glasses.

Step 3

Turn on the laser (strong).

Step 4

Trun the bottom of the laser left and right. Make the laser focus became smaller. The paper should be burned while the laser focus is smallest.

Step 5

Continue and move the paper. See the mark burned by the laser. Stop when the mark is small and continuity