Acoustic method for judging damage to film and optical element

Abstract

The invention belongs to the measuring field of judgment of damage to a film and an optical element and particularly relates to an acoustic method for judging damage of the film and the optical element. The prior art for testing a laser damage threshold has the problems that the testing repeatability is difficult to be ensured and the testing accuracy is also difficult to be ensured. In order to overcome the problems of the prior art, the invention provides a technical scheme that a damage judging method based on acoustics comprises the following steps: detecting an acoustic time domain strength signal instantly caused by film damage, so as to perform Fourier transform on the acoustic time domain strength signal; after performing the Fourier transform, extracting a frequency domain feature of the acoustic time domain strength signal, namely showing a specific frequency which uniquely represents if the film is damaged; and comprehensively giving an accurate criterion indicating if the film is damaged according to the acquired acoustic time domain strength signal and the frequency domain feature of the acoustic time domain strength signal, namely indicating if the time domain has a strength peak and if the frequency domain has a feature frequency. The acoustic method provided by the invention has excellent repeatability and high accuracy.

Description

technical field [0001] The invention belongs to the measurement field of film and optical element damage discrimination, in particular to an acoustic method for film and optical element damage discrimination. Background technique [0002] The laser damage resistance of thin films and optical components is an important technical index in device applications. However, there are two main problems in the laser damage threshold test. One is that the repeatability of the test is difficult to guarantee; the other is that the accuracy of the test is difficult to guarantee, and The main reason for the above problems is that the method of judging film damage is unscientific and has defects. At present, the method used in the national standards and ISO to judge the damage of thin films and optical components is the manual observation method of phase contrast microscope. The proposed method for judging scattered light damage is based on the change of scattered light at the detection po...

AI Technical Summary

Problems solved by technology

[0002] The laser damage resistance of thin films and optical components is an important technical index in device applications. However, there are two main problems in the laser damage threshold test. One is that the repeatability of the test is difficult to guarantee; the other is that the accuracy of the test is difficult to guarantee, and The main reason for the above problems is that the method of judging film damage is unscientific and has defects.

At present, the method used in the national standards and ISO to judge the damage of thin films and optical components is the manual observation method of phase contrast microscope. The proposed method for judging scattered light damage is based on the change of scattered light at the detection point to judge whether the detection point is damaged, and can realize online measurement. However, due to different measurement objects (such as different film functions), the change of scattered light The magnitude difference is very large, so it is difficult to give a unified damage judgment standard; another reported plasma flash judgment method believes that the moment of film damage is accompanied by plasma flash, which can be measured online; however, different thin film materials As well as the different flash wavelength bands of optical component materials, it is also difficult to give a unified damage judgment standard

The photothermal deflection film damage discrimination method developed in recent years, this method is actually a set of laser photothermal spectroscopy detection technology, requires a corresponding sample moving platform, obtains the photothermal image of the film by scanning, and judges whether the film is damaged through identification. The device is complex and difficult to judge in time

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