Bilateral form characterization of curved transparent components using chromatic confocal sensor.

To accurately characterize the geometric form of key components in industrial products, many profile measuring instruments have been developed to date. However, there are some special components, such as the hemispherical resonators featuring thin curved transparent surfaces, which are difficult to be measured using general instruments. The chromatic confocal technology was introduced in this paper to conduct the bilateral form characterization of this type of surfaces. Based on the assumption of tilted plate approximation, a modified ray tracing model was presented to correct the errors produced by the curved surfaces. The experiment of measurement on tilted, fused silica plates was conducted to demonstrate the effectiveness of the proposed model. Results show that the developed model improves the measurement accuracy of plates with large tilt angle. A three-axis motion stage was built with self-developed chromatic confocal sensor to obtain the bilateral profiles of the resonator. By fitting the spheres with the scanning profiles, the form error between the measurement points and the fitted spheres can be calculated. Partial form errors along the circumferential and axial directions of the resonator are evaluated, and an intuitive assessment of its thickness variation along the circumferential direction was made. [ABSTRACT FROM AUTHOR]