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High Sensitivity Fiber-optic Fabry Pérot Interferometer Sensor For Photoacoustic Imaging

Posted on:2022-07-19Degree:MasterType:Thesis
Country:ChinaCandidate:J LiuFull Text:PDF
GTID:2518306509467224Subject:Optical Engineering
Abstract/Summary:PDF Full Text Request
In medical practice and clinical medicine,whether it is clinical diagnosis or pathological research,we need to obtain the morphological and functional information of organs,tissues and even cellular and subcellular structures of organisms through various imaging techniques.As an emerging imaging technology,photoacoustic imaging combines the high selection characteristics of pure optical imaging and the high penetration characteristics of pure ultrasound imaging,and has the characteristics of high contrast,high resolution and deep imaging depth.The imaging depth and resolution of photoacoustic imaging are closely related to the photoacoustic sensor.Traditional ultrasonic detectors are made using piezoelectric materials.which are limited by their sensitivity to electromagnetic interference and reduction in sensitivity due to small element sizes.Fiber-optical Fabry-Pérot interferometer(FPI)sensor is widely used in biomedical sensing,environmental monitoring,structural health monitoring and other fields due to their advantages of anti-electromagnetic interference,chemical corrosion resistance,broadband characteristics,compact structure,simple fabrication and low cost.This paper is devoted to the design and development of FPI sensor with high sensitivity,focusing on the diaphragm type fiber-optic FPI sensor for photoacoustic imaging.Therefore,we established a theoretical model of the fiber-optical FPI photoacoustic sensor based on the pressure-sensitive film by analyzing the signal and noise characteristics of the fiber-optical FPI photoacoustic sensor.Based on the sensing mechanism of FPI sensor,the influencing factors of sensitivity are discussed for the measurement of different physical quantities,and the methods to improve the sensitivity are sought.The main research contents are as follows:1.Based on the literature research,the structure of the diaphragm fiber-optical FPI sensor system is introduced in detail,and the F-P interference principle and the sensitivity of FPI sensor are analyzed emphatically.From the perspective of elastic mechanics,the theory of membrane sound pressure sensing principle is introduced in detail.The influence of pressure-sensitive film parameters on its performance was analyzed,and propose the best plan for the design of the diaphragm optical-fiber FPI sensor.2.A theoretical model of the fiber-optic Fabry-Pérot interferometer sensor based on a pressure-sensitive film is developed by carefully analyzing the operation mechanism of the sensor.The total measurement noise is obtained by taking into account the dark current noise and thermal noise of the photodetector,the relative intensity noise and phase noise of the probe laser.By employing the model,the dependences of the signal-to-noise ratio(SNR)of the FPI sensor on the coating reflectivities,the Fabry-Pérot cavity length,the thickness and effective radius of the pressure-sensitive film are discussed in detail.It provides a theoretical basis for the development and performance optimization of fiber-optic FPI photoacoustic sensor...
Keywords/Search Tags:fiber-optic Fabry-Pérot interferometer sensor, sensitivity, signal-to-noise ratio, coating reflectivity, pressure-sensitive film
PDF Full Text Request
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