为了解决微深孔的精密测量问题,介绍了一种基于双光纤耦合原理的微深孔测量方法。该方法属于瞄准触发式测量方法,通过双光纤耦合器及显微物镜将光纤传感器触测头在微深孔内的微小位移量转变为CCD图像捕捉系统的横向位移量,利用图像空间定位算法得到CCD上的光斑中心位置。由CCD上光斑能量中心位置与传感器触测点在空间位置的一一对应关系即可得出传感器触测头在孔内部与孔壁的接触状况,从而实现对被测孔测量时的高精度瞄准。光纤传感器瞄准后将发出信号给测量长装置,如双频激光干涉仪,以实现对微深孔的精密测量。最后运用该方法对直径为0.2mm、深2.0mm深盲孔的直径进行了测量,其测量结果的重复不确定度优于0.4μm。同时运用该方法对直径为0.3mm、深1.0mm的微深孔的圆柱度进行了测量。
In order to resolve the problem of precision measurement of micro holes with aspect ratio, an aiming and triggering measurement method based on double optical fiber coupling was presented. In this method the small displacement of a fiber probe in a micro hole could be transformed into the transverse displacement of a CCD image through double optical fibers coupler and imaging lens. The location of the light spot center on CCD could be obtained by using image spatial locating algorithm, the contact situation of the fiber probe with the sidewall of a micro hole could be resolved by the location relationship between the spot energy center on CCD and the spatial location of the probing spot. The high precision aiming of a micro hole to be measured could be achieved using the correlation. After the sensor aimed, an "aimed signal" was sent to length measuring equipment, for example double frequency interferometer, to measure the micro hole with high aspect ratio. The diameter of a blind micro hole of 2.0 mm depth with diameter about 0.2 mm was measured with a repeatability uncertainty of less than 0.4μm, and the cylindricity of a hole of 1.0 mm depth with diameter 0.3 mm was also measured using this method.