A laser optoelectronic device capable of emitting a coherent beam of light (a unidirectional, monochromatic radiation with a wavelength between infrared and ultraviolet) through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The term “laser“ originated as an acronym for “light amplification by stimulated emission of radiation“. The first laser was built in 1960 by Theodore H. Maiman at Hughes Research Laboratories, based on theoretical work by Charles Hard Townes and Arthur Leonard Schawlow.
Laser working principle
All lasers consist primarily of three components:
- an external pump source (which supplies energy to the active medium) that conducts the external energy to the laser;
- an active laser medium (i.e., a material – gas, crystal, liquid – that emits light) placed inside the laser. Depending on the design, the laser medium may consist of a gas mixture (CO2 laser), a crystal body (YAG laser), or glass fibers (fiber laser). When transferred to the laser medium through the pump, energy is emitted as radiation;
- a resonator (i.e., a light trap): the active laser medium is placed between two mirrors, the “resonator.” One of these mirrors is unidirectional. The radiation of the active laser medium is amplified by the resonator. At the same time, only a certain amount of radiation can leave the resonator through the unidirectional mirror. This directed radiation is the laser radiation.
Laser radiation has three basic properties:
- monochromaticity: this means that the radiation consists of only one wavelength;
- high coherence and therefore phase coincidence;
- coherence makes the laser waves approximately parallel.
Because of these properties, laser light is used in many areas of modern material processing. The intensity is maintained for a long time due to the coherence and can be directed even more with the help of lenses. The laser beam strikes the surface of the material, is absorbed and thus heats the material. For this heat generation the material can be removed or evaporate completely. This allows a wide range of materials to be engraved, marked or cut.