Study On Ultraprecise Measurement Method Of Micro-deep Cavity Based On Micro Focal-length Collimation

With the development of precise engineering and micro mechanism technology, modern technique products with precise profile of micro-deep cavity are needed urgently, such as high-quality engines. Therefore, it is important to find a solution to measure micro-deep cavities with ultraprecision. Stylus probe is one of the most available ways to measure micro-deep cavities with high accuracy. However, problems exist in reported methods as the low primary magnification of stylus sensor, the complicated measurement chains and the low measurement aspect ratio. These problems make it difficult to measure micro-deep cavities with ultraprecision, which further limits the improvement of manufacture technique of micro-deep cavities and the development of related fields.This dissertation of"Study on ultraprecise measurement of micro-deep cavity based on micro focal-length collimation (MFC)"is proposed to solve the problems mentioned above. Following the displacement sense theory in a collimation optical system, a fiber deflection probing method based on MFC is proposed. Related principle analysis, sensor design and sensing property tests are expatiated in this dissertation. The main innovative study works are as followings:1. A fiber deflection probing method based on MFC is proposed. Using fiber stem as a cylindrical collimation lens with micro focal-length, an optical system of collimating a point light source is built, in which ultrahigh primary magnification is achieved in small space. Hence, the fiber deflection can be easily detected with nano-resolution. This method solves the problem that the primary magnification of reported stylus sensors are lower than 50. Using a fiber stem of 22μm in radius, primary magnification of 10,000 and resolution of 1 nm can be achieved in an MFC optical system.2. An experimental equipment of micro-deep cavity sensor based on MFC is built completely. Combining the sensor equipment of micro-deep cavity to a length measuring machine, holes with nominal diameters ofФ0.3 mm,Ф0.5 mm andФ0.7 mm are measured with a repeatability of 0.03μm, and the extended measurement uncertainty is inferred to U=0.14μm (k=2).The fiber deflection probing method based on MFC has solved the problems in the measurement of micro-deep cavities. This method has enormously enhanced the primary magnification of fiber probe sensor, and can be used to measure micro holes ofФ0.1 mm in diameter and 5 mm in depth. It is very suitable to measure and calibrate micro cavities within size ofФ1 mm ~Ф0.1 mm and aspect ratio of 1 ~ 50 with ultraprecision.