OPTI 200 Lecture Notes - Lecture 7: Active Laser Medium, Stimulated Emission, Laser Cutting
30 Aug 2018
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Document Summary
Lasers originated from einstein stimulated emission of light can happen, its different than spontaneous. Normal light diverges and disperses, hits in all direction. Laser light is monochromatic, collimated (parallel, non diverging) , and coherent. Laser speckle random interference pattern result of beam being coherent striking a surface, cancel light creates little black dots. To make a laser gain medium, input source of energy, resonant cavity. Red laser pointers don"t use gas; collimated beam. Green laser have different wavelength than red. Green lasers beams expanded, collimated, filtered to the block. Ktp crystal is a frequency doubling crystal. Red v. green lasers both have batteries, red light comes out directly, green goes through 2 crystals. Lasers high power diodes are used for materials processing, stacks of linear arrays of diode lasers, near inferred wavelengths. Laser guide stars creates an artificial star with a yellow sodium line that fluoresce when it receives yellow light. Laser cutting/ laser welding, typically with co2 gas lasers.
