The swing arm profilometer realizes the measurement of the different surface shape by adjusting the axis of the arm bearing and the axis of the workpiece bearing for different spatial positional relationships,so the high precision positional relationship between the axis of the arm bearing and the axis of the workpiece bearing is the premise to obtain accurate result. This paper presents a way using four-based laser trackers to calibrate the axes of the swing arm profilometer,that satisfies the requirement of the high precision and the dynamic calibration. The four-based laser trackers system only uses the precise distances to obtain the coordinates of points. The coordinates of points in the rotate arc of the axes can fit the axes，and the relationship between the axes can be know. The study of the self-calibration of the four-based laser trackers, the arrangement of four-based laser trackers, the design of the calibration method and the processing of measurement data are included in this paper. Finally, the study is validated by the preliminary experiment.
When using the swing arm profilometer (SAP) to measure the aspheric mirror and the off-axis aspheric mirror, the error of the effective arm length of the SAP has an obvious influence on the measurement result. In order to reduce the influence of the effective arm length and increase the measurement accuracy of the SAP, the laser tracker is adopted to measure the effective arm length. Because the space position relationship of the probe system for the SAP is needed to measured before using the laser tracker, the point source microscope (PSM) is used to measure the space positional relationship. The measurement principle of the PSM and other applications are introduced; the accuracy and repeatability of this technology are analysed; the advantages and disadvantages of this technology are summarized.
A spectral confocal sensor was used to measure the centering error for probe of swing arm profilometer (SAP). The feasibility of this technology was proved through simulation and experiment. The final measurement results was also analyzed to evaluate the advantages and disadvantages of this technology.
When the swing arm profilometer(SAP) measuring the mirror, the effective arm length of SAP which haves an obvious influence on the measurement results of the mirror surface shape needs to be measured accurately. It requires the measurement uncertainty of the effective arm length to reach 10μm in order to meet the measurement requirements, in this paper, we present a kind of technology based on laser tracker to measure the effective arm length of SAP. When the swing arm rotates around the shaft axis of swing arm rotary stage, the probe and two laser tracker balls form three sections of circular arc around the shaft axis of swing arm rotary stage in space. Laser tracker tracks and measures the circular arcs of two laser tracker balls, the center coordinates of the circular plane of circular arc can be calculated by data processing. The linear equation that passes through the two center coordinates is the equation of the shaft axis of rotary stage, the vertical distance from the probe to the shaft axis of rotary stage which can be calculated refer to the equation from the point to the line is the effective arm length. After Matlab simulation, this measurement method can meet the measurement accuracy.