Device and method for measuring thermal distortion of polarized beam splitter mirror

Abstract

The invention provides a device and a method for measuring the thermal distortion of a polarized beam splitter mirror. The device comprises a solid laser, a focusing lens, an energy optical fiber, an optical fiber shaping lens group, a beam splitter prism, a transmission plane mirror, a polarized beam splitter mirror, a zero-degree color filter, an attenuation light filter, a Fizeau interferometer and a computer, wherein the laser emitted from the solid laser is coupled to the energy optical fiber through the focusing lens, transmitted into a measuring room through the energy optical fiber, and is further radiated to the surface of the polarized beam splitter mirror in a theta angle through the optical fiber shaping lens group and the beam splitter prism; and the light emitted from the Fizeau interferometer is vertically radiated to the polarized beam splitter mirror through the light attenuation light filter and the zero-degree color filter. The device for measuring the thermal distortion of the polarized beam splitter mirror has the characteristics of simple structure, good stability and strong interference resistance, wavefront distortion of an optical film element under a laser radiation can be measured without contact, and moreover, the measurement can be carried out in continuous, single pulse or repeated pulse laser radiation.

Description

technical field [0001] The invention relates to a measuring device for thermal distortion of a polarized beam splitter, in particular to a measuring device and a measuring method for the thermal distortion of a polarized beam splitter after being irradiated by a high-frequency solid laser. Background technique [0002] When a strong laser beam acts on the surface of any optical thin film element of the optical system, due to the combined action of the optical element absorbing laser energy, the heat conduction of the film and the base material, and the heat convection of the air medium around the optical element, the surface of the optical element will be thermally deformed. , which in turn causes the wavefront to be distorted when the beam passes through the optical element, which affects the quality of the beam output of the strong laser system and the stability of the optical system. The polarizing beam splitter coated with polarizing beam splitting film is an important o...

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Problems solved by technology

[0003] In the study of thermal distortion of optical thin film components under laser irradiation, many scholars started from the heat conduction equation and thermoelastic equation, and used the finite difference and finite element methods to obtain the numerical results of the temperature field and deformation field distribution of optical components under laser irradiation ( Liu Mingqiang et al. analyzed the temperature field and deformation field of optical thin film samples, Acta Physica Sinica, 2008, Vol.57), but because there is no analytical solution for the two, the application in detection technology is limited

[0004] Currently used thin film non-destructive testing technologies such as photothermal deflection (PTD) and surface thermal lens technology (STL) mainly measure the signal change corresponding to surface deformation, and it is difficult to obtain the absolute size distribution of deformation morphology

In terms of other detection, people's attention is mainly focused on the detection of damage morphology of optical thin film components under low power (several milliwatts) small spot laser irradiation to study the mechanism of film damage (Liu Hongjie et al. Research on the influence of damage behavior, Acta Physica Sinica, 2010, Vol.29, No.2); previously, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences proposed an interferometric device for dynamic thermal distortion of solid-state lasers (application number: 200610029257, publication number: 1888839), but this device does not consider the influence of environmental factors on the interferometric accuracy during the operation of the laser, and there are still deficiencies

In short, the existing technology fails to measure the wavefront thermal distortion of the polarizing beam splitter according to the film properties and usage characteristics of the polarizing beam splitter in the experiment.

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