Research On Laser Speckle Vibration Detection Technology Based On Vision

The ability of extraction of remote speech signal has been one of the focuses of the national security department and the social security industry.Among the current interception methods,compared with the traditional telephone interception method and the listener-based interception method,the laser detection method has the advantages of non-contact,concealment and anti-jamming,so it has received widespread attention as a result.In fact,laser detection is actually a special application of laser vibration measurement technology.Laser vibration measurement technology includes three methods:interferometric,light reflection conditioning and laser speckle vibration measurement method.In the application of remote listening,laser speckle measurement technology overcomes the shortcomings of the other two technologies and has the following advantages:It is easy to separate the signals of different sound sources without using special source separation post processing algorithms;The detection system is simple,flexible and easy to maintain;Also it does not require a window to be positioned near the voice source.Based on the unique advantages of speckle vibrometry in the field of listening,laser speckle vibration measurement is used as the detection scheme in this paper and its application in audio detection is mainly studied.In this subject,an experimental system for vibration measurement at medium distance is set up,and an efficient and accurate algorithm is implemented to transform the speckle information obtained by machine vision technology into the vibration information of the target,which can meet the requirements of online detection.Finally,the audio signal is obtained by processing the speech noise reduction.The main work of this paper is as follows:?1?In this paper,the application background of laser speckle vibration measurement technology is systematically investigated,and the related principles and system structure of electronic speckle vibration measurement method and digital speckle vibration measurement method are deeply studied,providing theoretical guidance for the determination of vibration measurement scheme.?2?A special speckle vibration measurement algorithm based on multi-seed point fusion is implemented.The time complexity of speckle vibrometer is increased fromO(n^3/2)to O?1?,which improves the efficiency and real-time of speckle vibrometer greatly.?3?The overall design,algorithm implementation,hardware selection and system construction of the vision-based laser speckle vibrometer system are completed.In this paper,the system has the ability to detect the vibration of single-frequency vibrating object in the range of 0²000Hz within 2 meters when the error is less than 0.07%.And it can meanwhile detect the vibration of absorbing and audio frequency.The defocus degree of the lens is also more robust.?4?Extensive testing and analysis of the system was carried out,including:?a?the vibration measurement test of loudspeaker at medium and low frequency?b?the vibration measurement test of different materials?c?the vibration measurement test in real scene,including the measurement test of absorbing vibration and audio frequency vibration Through the work of this paper,a machine-vision-based laser speckle vibration measurement system is established,which provides a reference for the development of the application of the speckle vibrometer technology in the field of audio detection.