Theoretical And Experimental Investigation Of Micro-force Sensor Based On Film Optics

Pressure sensor based on reflective intensity-modulated optical fiber has high sensitivity, simplestructure, low manufacturing cost, and good anti-disturbance capability. In addition, optical film hasgreat sensitivity for measuring micro-force. A micro-force sensor based on optical film was designedwhich combines film elasticity and optical properties. The sensor uses dual-concentric-type opticalfiber to receive optical signal. Besides the advantages of traditional optical fiber sensors, the sensoralso has good linearity, high accuracy, little requirements on instruments. Application prospects inengineering are expected.In the thesis, the sensitive performance on micro-force and modulating characteristics on lightintensity of the film was studied. The mathematic model is established. The simulating calculation isimplemented. In order to load the micro-force accurately, a test platform for measuring micro-forcewas designed and built. The micro-force can be tested after calibration by using standard particles.The holder driven by three-dimensional platform is used to ensure precise position and load of theparticle. Photoelectric conversion and signal processing circuit are designed to transfer the light signal.Industrial computer is used to manipulate the tested signals and to calculate the data. Furthermore,orthogonal experiment method was designed and applied to the experiments of loading andmeasurement of micro-force. The static characteristics of the sensor was also calibrated inexperiments.Through theoretical analysis and experimental research, the conclusions are given as follows.There are a good linearity, sensitivity and accuracy between the flux ratio of two receiving opticalfibers and the slope of reflecting surface of the film. The film with large radius, small thickness, andlow elastic modulus has a good sensitivity to micro-force. In addition, the sensitivity of the sensorcould be improved with the increase of the following factors: Numerical aperture of the launchingfiber, diameter of the launching fiber, diameter of outer receiving fiber, and the initial distancebetween the film and the optical fiber probe. With the decrease of the diameter of the inner receivingfiber, the sensor sensitivity will also be improved.