The discovery of lasers and the invention of lasers
The invention of the laser dates back to the 50s of the 20th century. The theoretical principle of laser was discovered by Einstein as early as 1916, and in 1958, physicist Dickson Dyson first proposed the concept of laser and proposed to use a three-layer optical resonator to produce laser. In the same year, scientists Charles H. Townes and James P. Gordon invented a prototype laser at Columbia University, the microwave maser.
Then, in 1960, American physicist Theodore Maiman successfully manufactured the first laser at the Hewitt Research Laboratory in California, which is also considered to be the world's first laser. This laser uses synthetic sapphire crystals as the working medium and uses the structure of an optical resonator to emit a strong beam.
Maiman's invention attracted the attention and heated discussion of the global scientific community, and also ushered in a new era of laser technology. With the passage of time, laser technology has continued to grow and has become an indispensable part of modern science and technology, and has been widely used in medical, material processing, communication and other fields.
The principle of lasers
A laser is a highly concentrated, monochromatic, high-intensity beam. Its principle is to produce a highly focused beam by excitting atoms or molecules in the medium to produce stimulated radiation. The principle of laser can be explained in the following three steps:
The first step is to excite atoms or molecules in the medium. This is usually done by feeding energy into the medium. For example, atoms or molecules are placed in an excited state by the input of an electron beam, beam, or other photon beam.
The second step is spontaneous radiation. Once atoms or molecules are excited, they transition from high to low energy levels and release photons. These photons interact with surrounding molecules, resulting in more excitation and emission.
The third step is stimulated radiation. When a photon interacts with an atom or molecule in an excited state, it causes the atom or molecule to transition from a high energy level to a lower energy level, releasing another photon. This process is called stimulated radiation, and it produces photons with the same energy, direction, and phase as the original photon.
Since the process of stimulated radiation leads to the continuous amplification of photons, a laser is a beam of light with high intensity, monochromacy and directionality. Its high intensity is due to the repeated propagation of photons in the medium and the amplification of stimulated radiation, monochromaticity is due to the fact that the excitation medium emits photons at only one wavelength, and directionality is due to the fact that the wavefront of the laser is coherent rather than random.
The generation of lasers requires a laser medium, which can be solid, liquid or gas. The choice of laser medium depends on the required laser wavelength and application area. For example, carbon dioxide lasers use carbon dioxide gas as the laser medium, emitting light wavelengths of about 10 microns, suitable for material processing and medical fields; Semiconductor lasers use semiconductor materials as laser media, emitting light wavelengths between several hundred nanometers and several microns, suitable for communication and display fields.
Applications of lasers:
Medical applications: Laser can be used for eye surgery, skin cosmetology, dental treatment, etc., with the advantages of small trauma and fast recovery.
Communication applications: Lasers have been widely used in optical fiber communication, and the monochromatic light generated by lasers is used to transmit information, which has the advantages of high speed and stability.
Material processing applications: Laser can be used in metal cutting, plastic cutting, welding and other processes, becoming an efficient and precise processing method.
Measurement application: laser can be used for distance measurement, speed measurement, spectral measurement, etc., and is widely used in geographical surveying, building surveying, vehicle speed measurement and other fields.
Entertainment applications: Lasers can be used for stage performances, games, laser shows and other entertainment projects, becoming a fashionable and innovative way of entertainment. Now many movie theaters have used laser projection, which has a better color gamut effect than the traditional light bulb light source.
Scientific research application: Lasers have been widely used in physics, chemistry, biology and other fields, such as laser interferometer, laser confocal microscope, etc.
In short, the application of lasers involves many fields, and new applications are constantly emerging, which can be said to be an indispensable and important part of modern science and technology. Do you know what things in your life use lasers?