The first lasers appeared several decades ago, and to this day this segment is promoted by the largest companies. Developers get more and more new equipment qualities, allowing users to more effectively apply it in practice.
A ruby solid-state laser is not considered one of the most promising devices of this type, but with all its shortcomings, it still finds niches in operation.
General information
Ruby lasers are classified as solid state devices. Compared with chemical and gas counterparts, they have a lower power. This is explained by the difference in the characteristics of the elements, due to which radiation is provided. For example, the same chemical lasers are capable of generating light fluxes with a power of hundreds of kilowatts. Among the features that distinguish a ruby laser, a high degree of monochromaticity, as well as radiation coherence, are noted. In addition, some models give an increased concentration of light energy in space, which is enough for the implementation of thermonuclear fusion due to the heating of the plasma beam.
As the name implies, the ruby crystal appears in the form of a cylinder as the active medium of the laser. In this case, the ends of the rod are polished in a special way. In order for the ruby laser to provide the maximum radiation energy possible for it, the sides of the crystal are processed until they reach a plane-parallel position relative to each other. At the same time, the ends should be perpendicular to the axis of the element. In some cases, the ends, which act in some way as mirrors, are additionally covered with a dielectric film or a layer of silver.
The device of ruby lasers
The device includes a camera with a resonator, as well as an energy source that excites atoms of the crystal. A xenon flash lamp can be used as a flash activator. The light source is located along one axis of the resonator having a cylindrical shape. On the other axis is a ruby element. As a rule, rods 2-25 cm long are used.
The resonator directs almost all the light from the lamp to the crystal. It should be noted that under conditions of elevated temperatures, which are required for optical pumping of the crystal, not all xenon lamps are able to work . For this reason, the ruby laser device, which includes xenon-based light sources, is designed for continuous operation, which is also called pulsed. As for the rod, it is usually made of artificial sapphire, which can accordingly be modified to meet the operational requirements for the laser.
Laser principle
When the device is activated by turning on the lamp, an inversion effect occurs with an increase in the level of chromium ions in the crystal, as a result of which an avalanche increase in the number of emitted photons begins. In this case, feedback is observed on the resonator provided by the mirror surfaces at the ends of the solid-state rod. This is how the development of a narrow flow occurs.
The pulse duration, as a rule, does not exceed 0.0001 s, which is shorter than the duration of the neon flash. The pulse energy of a ruby laser is 1 J. As in the case of gas devices, the principle of operation of a ruby laser is also based on the feedback effect. This means that the intensity of the light flux begins to be maintained due to mirrors interacting with the optical resonator.
Laser Modes
Most often, a ruby-rod laser is used in the mode of formation of the mentioned millisecond pulses. To achieve a longer activity time, technologists increase the optical pump energy. This is done through the use of powerful flash lamps. Since the field of rise of the pulse, due to the time of formation of the electric charge in the flash lamp, is characterized by a flatness, the ruby laser starts to work with a certain delay when the number of active elements exceeds threshold values.
Sometimes there are disruptions in the generation of pulses. Such phenomena are observed at certain intervals after a decrease in power indicators, that is, when the force potential drops below a threshold value. Theoretically, a ruby laser can operate in a continuous mode, but this operation requires the use of more powerful lamps in the design. Actually, in this case, the developers are faced with the same problems as when creating gas lasers - the inappropriateness of using an element base with enhanced characteristics and, as a result, limiting the capabilities of the device.
Kinds
The benefit of the feedback effect is most pronounced in nonresonant-coupled lasers. In such constructions, a scattering element is additionally used, which makes it possible to radiate a continuous frequency spectrum. A ruby Q-switched laser is also used - its structure includes two rods, one cooled and one uncooled. The temperature difference allows the formation of two laser beams that are separated by wavelength into angstroms. These rays shine through a pulsed discharge, and the angle formed by their vectors is small.
Where is the ruby laser used?
Such lasers are characterized by a low efficiency, but they differ in thermal stability. These qualities determine the practical use of lasers. Today they are used in the creation of holography, as well as in industries where it is required to perform operations of punching ultra-precise holes. Use such devices in welding operations. For example, in the manufacture of electronic systems for the technical support of satellite communications. A ruby laser also found its place in medicine. The application of technology in this industry is again explained by the possibility of high-precision processing. Such lasers are used as a replacement for sterile scalpels, allowing microsurgical operations.
Conclusion
A ruby-active laser was at one time the first working system of its kind. But with the development of alternative devices with gas and chemical fillers, it became apparent that its performance has many drawbacks. And this is not to mention that the ruby laser is one of the most complex in terms of manufacturing. As its working properties increase, so do the requirements for the elements making up the structure. Accordingly, the cost of the device is growing. However, the development of models of ruby-crystal lasers has its bases associated, among other things, with the unique qualities of a solid-state active medium.