Ruby laser: the principle of operation

The first lasers appeared several decades ago, and to this day this segment is promoted by the largest companies. Developers get all the new quality equipment, allowing users to more effectively use it in practice.

Solid-state ruby laser is not considered one of the most promising devices of this type, but for all its shortcomings, it nevertheless finds niches in operation.

General information

Ruby lasers are classified as solid-state devices. Compared with chemical and gas analogs, they have less 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 of hundreds of kilowatts. Among the features that distinguish the ruby laser, there is a high degree of monochromaticity, as well as coherence of radiation. In addition, some models give an increased concentration of light energy in space, which is enough for the realization of thermonuclear synthesis due to the heating of the plasma by the beam.

As the name suggests, the ruby crystal acts as the active medium of the laser, represented in the form of a cylinder. The ends of the rod are polished in a special way. To the ruby laser was able to provide the maximum possible radiation energy for it, the sides of the crystal are processed until the plane-parallel position is reached 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 are in some way 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 a source of energy that excites the atoms of the crystal. As a flash activator, a xenon flash lamp can be used. The light source is located along one axis of the resonator, which has a cylindrical shape. On the other axis there is a ruby element. As a rule, rods with a length of 2-25 cm are used.

Resonator almost all the light from the lamp sends to the crystal. It should be noted that in the conditions of high temperatures, which are required for optical pumping of the crystal, not all xenon lamps are capable of operating . For this reason, the ruby laser device, which includes xenon based light sources, is calculated for a continuous mode of operation, which is also called impulse. As for the rod, it is usually made of artificial sapphire, which can be appropriately modified for the operational requirements of the laser.

Principle of laser operation

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, which results in an avalanche increase in the number of emitted photons. At the same time, an inverse relationship is observed on the resonator, provided by mirror surfaces at the ends of the solid rod. This is how the narrow flow develops.

The pulse duration, as a rule, does not exceed 0.0001 s, which is shorter in comparison with the duration of the action 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 supported by mirrors interacting with the optical resonator.

Laser operating modes

Most often, a laser with a ruby rod is used in the mode of formation of the mentioned pulses in size in a millisecond. To achieve a longer time of activity, technologists increase the energy of optical pumping. This is done through the use of powerful impulse lamps. Since the pulse rise field due to the time of formation of the electric charge in the flash lamp is characterized by flatness, the work of the ruby laser begins with some delay at the moments when the number of active elements exceeds the threshold values.

Sometimes there are breakdowns of pulse generation. Such phenomena are observed at certain intervals after the power indices decrease, that is, when the power potential falls below the threshold value. Theoretically, a ruby laser can operate in a continuous mode, but such 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 inexpediency of using an element base with increased characteristics and, as a result, limiting the capabilities of the device.

Kinds

The benefit of the feedback effect is most pronounced in lasers with a nonresonant coupling. In such constructions, a scattering element is additionally used, which allows to radiate a continuous frequency spectrum. Ruby laser with a modulated Q-factor is also used - its structure includes two rods, cooled and uncooled. The temperature difference makes it possible to form two laser beams, which are separated along the wavelength by angstroms. These rays shine through the pulsed discharge, and the angle formed by their vectors differs by a small value.

Where is the ruby laser used?

Such lasers are characterized by a low coefficient of efficiency, but they differ in thermal stability. These qualities determine the directions of practical use of lasers. Today they are used in the creation of holography, as well as in industries where it is required to perform punching operations for high-precision holes. Use such devices in welding operations. For example, in the manufacture of electronic systems for the technical support of satellite communications. In medicine, a ruby laser also found its place. 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, which allow performing microsurgical operations.

Conclusion

The laser with a ruby active medium was in its time the first operating system of this type. But as the development of alternative devices with gas and chemical fillers, it became apparent that its performance has many disadvantages. And this is not to mention that the ruby laser is one of the most difficult in terms of manufacturing. As its working properties increase, so does the requirement for the elements that make up the structure. Accordingly, the cost of the device also grows. However, the development of models of lasers based on a ruby crystal has its bases, related, among other things, to the unique qualities of a solid-state active medium.