A novel instrument for ultra-precise measurement of diameter

A novel instrument that can attain ultra-precision for measuring diameter of both orifice and cylinder is presented in this paper. The instrument is based on a combination of blazed grating, air-lubricated hydrostatic slide guide and ruby probe. The measure method is touch absolute measurement. Air-lubricated hydrostatic slide guide is adopted here to guarantee straightness. The blazed grating and ruby probe are applied to assure high resolution of Edge-checkout and length measurement. Meanwhile, the measurement force control system is controlled by electromagnetism so that the touch force between workpiece and ruby probe can be decreased. Therefore, the transform of the testing workpiece, which caused by touch force is decreased. The way of testing temperature control and vibration control is also used to ensure system high accuracy and measurement repeatability.