Development of a micro hole measuring system using an optical fiber probe (1st report) - Optical analysis and accuracy evaluation

This paper presents a micro hole measuring system using an optical fiber probe. The system is composed of a fiber probe, two floodlighting fibers and two double-light reception fibers in the X and Y directions. The fiber probe has an optical fiber of 30μm diameter with a ball of 50μm diameter on the end. When the fiber probe contacts a hole surface, it is deflected and this deflection is measured by an optical method. In this research, the design parameters of optical system are optimized by using ray tracing, and a prototype of the measuring system is manufactured on trial to verify the simulation results. Then, its measuring accuracies are examined by using the basic experimental apparatus. As a result, it is clarified that the resolution of the fiber probe is better than 15nm.