Research Of Spherical Coupling Fiber Probe Sensing Mechannism

With the development of modern fabrication and high-end manufacturingindustries, the demand for high aspect ratio of micro-structure characteristics ofproducts is increasingly urgent. But the dimension and profile measurementprecision of the microstructure with high aspect ratio is far from meeting themanufacturing requirement, and the detection of microstructures with high aspectratio has become the main obstacle restricting the development of high-endmanufacturing. At present, the method of measurement of three coordinatemeasuring machine with the probe sensor is considered to be one of the mosteffective way in the high-precision measurements of microstructures with highaspect ratio. For probe using for measurement of microstructures, each foreigntechnology has its own system, and all of them are still in the exploration anddevelopment stage. The researches of the probe sensor using for measurement ofmicrostructures mostly focus on solving the practical problems, but the research ofsensor mechanism is relatively less, and the demestic research of it is still in blancfield.For the measurement of microstructures, a spherical coupling fiber probesensor(SCP sensor) is proposed. In this paper, the author analyzes the properties ofSCP sensor theoretically, takes the performance verification, brings forwardeffective improvement measures in view of the existing performance defects andmade a new SCP sensor. Main research contents of the paper are given as follows:1. The mechanical sensing characteristics and frequency characteristics of theSCP sensor is explored. Appropriate cantilever beam model is establish. By modelanalysis, a sensing properties function and displacement magnification function ofSCP sensor are obtained. Meanwhile, the method of improving sensitivity of thesensor is analyzed, and the theoretical resolution of the SCP sensor is24nm. Theauthor creates a natural frequency of the sensor model, and analyzes the naturalfrequency of longitudinal and cross in both directions. While fabricating SCPsensors with different parameters, performance tests with these sensors verifies thatthe analysis of is valid and correct.2. Analysis of the internal light field distributions of SCP sensor. Through3D-FDTD simulation, it is obtained that the characteristics of coupling lighttransmission within the SCP sensor and main factors which affect light couplingefficiency. Based on the simulation, a simplified model of coupling lighttransmission is established and optimizated structural parameters of coupling light transmission efficiency is obtained. When the diameter ratio of the SCP sensor is inthe range of0.36~0.48, the coupling light transmission efficiency is optimal, whichprovides a theoretical foundation for getting a higher coupling light transmissionefficiency of SCP sensor.3. Through the experimental demenstration of the performance of SCP sensor,its spatial resolution is40nm, and the centroid stability of static output image inaxis-X and axis-Y are1.96pixel and0.57pixel respectively. The existingshortcomings of SCP sensor are analyzed, and a method of processing themicrostructure of fiber end-face is propose to improve the performance of SCPsensor. From both theoretical analysis and simulation experiment, an effectivemicro-structure on the fiber end-face is found.4. Fabricationg microstructure on the effluent fiber end-face, and itsverification tests on the shaping ability of beam is completed. A new SCP sensorwith the fiber end-face microstructure is made, and its performance test is chmpleted.The centroid stability of static output image in axis-X and axis-Y are0.40pixel and0.39pixel respectively,which improving390%and46%than before; the spatialresolution is30nm, and improving33%than before. The performance testing provesthe improvement of performance of the new SCP sensor.