Research On All Quartz Fiber-Optic Acceleration Sensor Based On Incident-Angle Sensitive Detection Mechanism

Developed with the optical fiber communication technology, the fiber-optic sensing technology began in 1977, with its unique advantages, fiber-optical sensor has achieved people's attention and has been widely developed and applied to daily life. As a kind of fiber-optical sensor, fiber-optical acceleration sensor is mainly used for measuring vibration acceleration, now has been widely applied in some fields of modern industrial production such as bridge health monitoring system and seismic monitoring system etc. Among them, with the characteristic of simple structure, reliable performance, flexible design and low price, intensity modulation fiber-optic acceleration sensor is most practical. However, low measurement precision and low temperature performance also limits its development. In order to improve the acceleration measurement precision and temperature performance, in this paper, an all quartz structure intensity modulation type fiber-optic acceleration sensor based on incident angle sensitive detection mechanism was designed and demonstrated. The main research work is as follows:The basic structure, the working principle and the theoretical model of fiber-optical fiber acceleration sensor designed in this article were introduced and analyzed. In order to improve the acceleration measurement precision of the fiber-optical acceleration sensor, three detection mechanism such as light transfer mechanism of the collimator, beam transformation mechanism of the cantilever and incident-angle detection mechanism of collimator were analyzed and theoretically calculated; In order to improve the temperature performance of the fiber-optical acceleration sensor, two structures such as the collimator structure and all quartz structure were theoretically analyzed.The incident-angle sensitive detection mechanism of the collimator of the fiber-optical acceleration sensor was measured practically. The characteristic relationship curve between the intensity attenuation of the incident light and the incident angle was drew and compared with the theoretical results. According to the characteristics of the relationship curve, the static working point tunable principle was used to further improve the measuring accuracy of the fiber-optical acceleration sensor.Based on the theoretical analysis, the fiber-optical acceleration sensor was fabricated and the acceleration characteristics test and temperature characteristic tests were carried on respectively. Test results are as follows:With the static working point of 0.04° and 0.34° and 0.43° and 0.51°, the acceleration detection sensitivity were 17.9 dB/g,83.4 dB/g,79.8 dB/g, 107 dB/g, and the corresponding minimum detection limit were 1 mg,0.25 mg,0.1 mg,0.08 mg respectively. With the increasement of the static working point, the acceleration detection sensitivity and minimum detection limit also increase, which agree well with previous theoretical analysis results. With the static working point of 0.43°, the detection sensitivity was 83.4dB/g and the detection limit was 0.1 mg, the good acceleration detection performance of the sensor designed in this article was demonstrated. At the same time, the temperature coefficient of the sensor is 0.008 dB/?,, the good temperature performance of the fiber-optical acceleration sensor designed in this article was demonstrated.