Device and method for detecting weak absorption of optical element

Abstract

The invention relates to a device and method for detecting the weak absorption of an optical element. The device comprises a pump laser, a nonlinear crystal, a dichroscope, a reflecting structure, a first focusing lens, a second focusing lens, a filtering element, a pinhole and a photoelectric detector. The nonlinear crystal is arranged at the laser emitting end of the pump laser, and an included angle exists between the dichroscope and the nonlinear crystal. The reflecting structure is used for reflecting a frequency doubling laser emitted by the dichroscope to the surface of the optical element. The second focusing lens is used for focusing the frequency doubling laser emitted by the reflecting structure to the surface of the optical element. The filtering element and the pinhole are sequentially arranged between the optical element and the photoelectric detector. The device and method for detecting the weak absorption of the optical element can overcome the defect that due to the different phases of pump lasers and detection lasers, direct-current components affect test results in a traditional mode, and the device and method for detecting the weak absorption of the optical element are particularly suitable for measuring short-pulse pump lasers and greatly improve the sensitivity and the precision of weak absorption tests of the optical element.

Description

technical field [0001] The invention relates to the technical field of measuring the absorption rate of optical elements, in particular to a device and method for detecting weak absorption of optical elements. Background technique [0002] The development of high-energy lasers requires very high-quality optical films, and the weak absorption of light by optical films is one of the main factors that limit the development of high-energy lasers, and affects the optical quality of optical films, and will cause thermal deposition of laser light in the film . Especially under the action of high-power lasers, even a very weak absorption of optical thin films is enough to cause catastrophic destruction of thin-film components. The study found that part of the absorption that causes damage comes from the intrinsic absorption of the film, and to a greater extent it comes from the local extra strong absorption caused by impurities and defects in the optical film. Therefore, it is nec...

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Problems solved by technology

In photothermal detection, commonly used analog weak signal detection instruments are phase-locked analyzers and Boxcar integrators, which increase the complexity of the system structure

Moreover, although it uses continuous output probe light, it cannot eliminate the DC component in the probe light, the sensitivity of the thermal lens on the surface of the system is low, and the measurement results are also low

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