What Is a Laser Light Source?
A laser light source is a light source that emits laser light.
A laser is a highly directional light with a single wavelength and a high degree of photon wavelength identity. It has superior energy concentration compared to ordinary light. There are various laser light sources, ranging from semiconductor lasers suitable for projector light sources to YAG lasers, CO2 lasers, excimer lasers, and argon lasers suitable for cutting and processing objects. Lasers are classified into solid-state, semiconductor, and gas, based on the shape of the material they operate on.
Uses of Laser Light Sources
Laser light sources are used for a wide variety of means. The applications vary depending on the type.
1. Semiconductor Laser
Due to its long life and easy handling characteristics, it can be used as a projection light source for projectors.
2. YAG Laser
The YAG laser, a common solid-state laser, is used for laser processing, such as cutting and drilling of metals and various other materials; due to its optical characteristics, the YAG laser is not suitable for processing transparent materials.
3. CO2 Laser
In contrast to YAG lasers, CO2 lasers are suitable for processing transparent materials but are not suitable for processing metals.
Principle of Laser Light Sources
Laser light sources use as its light source light that is excited by giving energy to the molecules of the laser medium. When a laser source is given intense energy, a certain number of atoms in the laser medium enter an excited state.
- Pumping
An increase in the number of atoms in an excited state. - Inverted distribution state
A state in which the number of atoms in the excited state exceeds the number of atoms in the other states due to pumping. - Optical amplification
When an atom is irradiated with light of the same wavelength as the excitation light in the inverted distribution state, the atom receiving the light emits light of the same wavelength in the same direction as the light, causing other atoms to be excited.
Laser light sources are constructed with a mirror on the side where the light source is installed to cause light amplification and a partially reflecting mirror on the side where the laser light is emitted. The light excited by optical amplification is reflected by the partial reflection mirror and continues to reflect through the laser light sources while repeating optical amplification many times, finally passing through the transmission part of the partial reflection mirror as a high-energy laser beam.
Characteristics of Laser Light Sources
In addition to directionality, monochromaticity, and energy density, laser light sources have the characteristic of being in phase (waveform of light), which causes interference when they hit an object. This characteristic is used in laser interferometers and other distance-measuring instruments. Ordinary light is a mixture of various types of light with different phases, which makes interference difficult to occur.
Other Information on Laser Light Sources
Wavelengths of Laser Light Sources
There are various laser light sources, each of which can be classified by wavelength. Excimer lasers have wavelengths ranging from 150 to 308 nm, argon lasers from 488 nm, ruby lasers from 694.3 nm, YAG lasers from 1,064 nm, and CO2 lasers from 10,600 nm. The difference in wavelength is the difference in absorption rate when irradiated onto an object. Different absorption rates result in different temperatures.
Wavelength conversion is possible by using nonlinear optical crystals for the fundamental waves of the above lasers. For example, the fundamental wavelength of a YAG laser is 1,064 nm, and when passed through a nonlinear optical crystal, light with wavelengths of 532 nm at the second harmonic, 355 nm at the third harmonic, and 266 nm at the fourth harmonic can be extracted. It is also possible to create parametric oscillators with tunable wavelengths.