How does the laser pointer output multiple colors?

Laser pointers are widely used in teaching demonstrations, astronomical instructions, conference instructions, etc. The widely used laser pointers are red laser pointers, blue laser pointers and green laser pointers. Red and blue laser pointers use red LD as the light-emitting element, and its principle is to directly convert current into laser output. The green laser pointer adopts green LD or applies all-solid-state laser technology, and uses SOSnmLD as the pump source to pump the laser crystal to produce green light output. Regardless of whether it is a red, blue or green laser pointer, it can only output one color of laser, and the color is relatively monotonous; therefore, the function is single and cannot meet the current market requirements. Red and blue laser pointers are easier to make than green laser pointers. Red and blue semiconductor diodes are readily available on the market, and the technology is mature. Because there is no ready-made green light semiconductor diode for green light, the structure of the green light laser pointer is more complicated, and the light stability is relatively poor. The generation of white lasers usually requires a mixture of red, blue, and green lasers.