I have a cheap 5MW green laser that. When I adjust the lens at the front by screwing it in or out the laser beam diameter becomes smaller or larger. When the beam is spread out I notice that the beam is not uniform, it contains round patches and there are radial patterns as well as show in this image:
Why does this happen? Is this an issue with the the lens or is it an issue with the quality of the laser?
Why does this happen? Is this an issue with the the lens or is it an issue with the quality of the laser?