Virtual wavefront calibration method based on ray tracing for alignment error compensation in the interferometric bearing ball measurement system

Abstract

The accuracy of laser interferometry for measuring bearing balls is limited because it is challenging to realize null positioning of the ball being assessed. Even a slight alignment error causes the reflected wavefront to carry an uncertain aberration, which results in the surface error being obscured by the wavefront aberration. To effectively separate the surface error from the reflected wavefront, a virtual wavefront calibration method of ray tracing for alignment error compensation in the interferometric bearing ball measurement system is proposed. A virtual wavefront measurement model with variable alignment vector of the system is established based on the ray tracing principle and coordinate transform theory. According to the virtual wavefront, a calibration process is achieved in the virtual model with a known regularization and optimization method; as a result, no accurate adjustment mechanism is required to adjust the position of the bearing ball in the actual measurement system. Simulation and experiment results indicate that the proposed method is effective, and the repeatability of this measurement system is better than λ/40 peak–valley value. The final results may promote the application of this method in other fields of optical measurement.