Device and method for measuring thermal focal length of laser medium

Abstract

The invention discloses a device and a method for measuring a thermal focal length of a laser medium, and belongs to the technical field of laser. The device comprises a rear end reflector, a to-be-measured laser medium, a cat eye module, an optical detector and a mounting frame for mounting the cat eye module and the optical detector; the distance between the focusing lens and a plano-convex lensin the cat eye group module can be adjusted; the optical detector is arranged on a focus of a convex surface of the plano-convex lens, critical points of a stable state and an unstable state of the laser are searched through the optical detector, and the thermal focal length of the to-be-measured laser medium is read on a stable area graph according to the distance between the focusing lens and the plano-convex lens. The device disclosed by the invention is suitable for laser media of an end pump and a side pump, the quick arrangement of the measurement device is realized by adopting an optical resonant cavity insensitive to the angle, the measurement of the thermal focal length of different laser media can be realized in a longer wavelength range, and the measurement can be easy to expand to the laser media of different wave bands.

Description

technical field [0001] The invention relates to the field of laser technology, in particular to a device and method capable of quickly measuring the focal length of a laser medium thermal lens with strong adaptability. [0002] technical background [0003] Solid-state lasers are widely used in military, processing, medical and scientific research fields due to their small size, convenient use, high output power, and good beam quality. In the working state of the solid-state laser, only a small part of the pump energy absorbed by the laser crystal as the gain medium is converted into laser output, and most of the remaining energy is absorbed by the laser crystal, forming a temperature gradient inside the crystal. The temperature gradient and thermal strain photoelasticity of the laser crystal lead to the uneven distribution of the refractive index inside the crystal, which produces a focusing effect similar to a focusing lens for the passing laser beam, which is called the th...

AI Technical Summary

Problems solved by technology

The disadvantage is that the resonant cavity needs to be built multiple times for different thermal focal lengths, and the flat cavity structure has high requirements on the parallelism of the cavity mirror, which makes it difficult to adjust and realize automatic control, which is time-consuming and laborious

The principle of this method is simple, but in actual operation, due to the small light spot and long depth of focus, it is difficult to determine the specific position of the focus, so the measurement result of this method is not accurate, or the measurement process is very complicated

In addition, because the probe light is different from the actual output laser wavelength, the measured thermal focal length and the actual wavelength will also cause a certain difference

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