Low-cost laser pointers include laser diodes that emit a red light. They act as optical pointers during the lecture. When used as intended, the green laser pointer is a safety device with a radiation output of up to 1 mW (laser class 2). There are more expensive Laser Pointer that emit green light on the market. But the color is different = the wavelength is different = the mechanism is different = the price is different. The simple red laser pointer has been around for a long time and can be bought very cheaply. If you don't have a laser pointer, you should start with red. Simply put, the laser is the light that gathers multiple layers of light of the same wavelength and emits it as a point. However, just like you can burn black paper with a magnifying glass, light is energy, so if you focus on a very narrow area, it will be very powerful.
The laser beam that heats the surface of the workpiece. The typical case hardening depth ranges from 0.1 to 1.5 mm, with some materials reaching 2.5 mm and above. In order to increase the depth of surface hardening, the surrounding volume needs to be increased. This quickly releases heat and cools the solidified area fast enough. Laser hardening requires a relatively small output density. At the same time, the workpiece must be processed on the same plane. Therefore, the laser beam can be used to irradiate the plane as much as possible.