How do laser pointers work?
Laser pointers generate light in a laser diode and then put the laser beam through one or more mirrors.
Laser light is produced when you bounce light back and forth between two mirrors, in certain special mediums.
Here is the inside of a typical inexpensive red laser pointer:
And here is the inside of an expensive, green laser pointer:
In general, you generate the laser light in the Laser Diode (powered by batteries) and then put the light through one or more lenses to make the beam wider.