THE HISTORY OF LASER DEVELOPMENT. GAS LASERS

Аннотация

This article explores the historical development of laser technology, with a particular focus on gas lasers. It traces the evolution from early theoretical foundations in quantum electronics to the realization of the first operational lasers. Special attention is given to gas lasers, such as helium-neon and carbon dioxide lasers, which played a crucial role in advancing laser applications due to their high monochromaticity and beam quality. The paper also highlights the contributions of pioneering scientists, key milestones, and the wide-ranging uses of gas lasers in industry, medicine, and scientific research. The significance of gas lasers in shaping modern photonics andoptical technologies isemphasized throughout the discussion. Keywords: Laser development, gas lasers, helium-neon laser, carbon dioxide laser, quantum electronics, monochromaticity, laser history, photonics, optical technology, scientific applications, industrial lasers. Laser Physics and Its Interconnection with Other Branches of Physics. The science of laser physics is closely interconnected with other branches of physics, as the history of laser development is the result of progress in optics, thermodynamics, and radiophysics. As we know, lasers are based onthree fundamental ideas: 1.Theconcept ofstimulated emission,proposed byEinstein, which is related to optics. 2. The concept of a non-thermodynamic equilibrium state, introduced by Fabrikant, which is connected to thermodynamics. 3.The concept of a system with positive feedback, which belongs to radiophysics. Studying laser physics in depth is very beneficial for our society because, nowadays, lasers are widely used in all areas of production — in both light and heavy industries, in geology, and essentially in every field. This can be clearly seen in the topic of laser technology. Radiation from light sources operating in the optical part of the spectrum is generally incoherent. For instance, the total radiation of such a source is composed of emission from its microscopic elements like atoms, molecules, ions, or free electrons, and these emissions are not mutually coherent. Examples of incoherent radiation include the glow of gas discharges, thermal radiation from artificial and natural sources, and luminescence stimulated byvarious methods. 185 Volume 4, issue 6, 2025 . The Active Element and Operation Principles of Lasers. The ions included in the active element are called “active centers”, and laser light is generated as a result of these centers (ions) emitting radiation parallel to the optical axis of the laser. In semiconductor lasers, the role of active centers is played by electron-hole pairs. The pumping system is used to excite the active centers. The method of excitation can vary depending on the type of active medium. In gas lasers, an electric current is passed through a gas (or gas mixture), forming a gas plasma, and the active centers are excited through collisions between particles. In solid-state lasers, where the active element is a solid material, the element is illuminated using a high-power light-emitting lamp (such as a flash lamp). In semiconductor lasers, current is passed through a p-n junction, resulting in injection of electron-hole pairs. Sometimes, chemical reactions or electron beams are used to excite the active element.The optical resonator can consist of two flat mirrors, one flat and one spherical mirror, or two spherical mirrors. Typically, one of the mirrors has a reflectivity of 100%, while the other is partially transmitting. In lasers with a high gain coefficient, the second mirror may simply be a transparent flat-parallel glass plate. There are many types of lasers, and they are used for various purposes. Most commonly, lasers are used in industry. Lasers can also emit different colors of light, depending on their construction and materials. Laser Technology and Its Applications.Laser technology processes can be conditionally divided into two main types. In the first type, the highly precise focusing of laser beams and the ability to accurately dose energy in both pulsed and continuous modes are utilized. In such technological processes, lasers with moderate average power are used, such as pulsed-periodic gas lasers and neodymium-doped yttrium aluminum garnet (Nd:YAG) crystal lasers. Using these lasers, technologies have been developed for: Drilling tiny holes (with diameters of 1–10 microns and depths of up to 10–100 microns) in rubies and diamonds for the watchmaking industry. Producing dies for drawing fine wires. The main field of application for low-power pulsed lasers is in microelectronics and the electrovacuum industry, where they are used for cutting and welding miniature components, and engraving marks on small parts. In the printing industry, lasers are used to automatically burn numbers, letters, and images onto various materials. As previously mentioned, the optical resonator of a laser ensures the collimation (directionality) of t