Complete topographic measurement of the monolithic multi-surface workpiece on a cylindrical cavity. (June 2023)

• Record Type: Journal Article
• Authors: Li, Zexiao; Liu, Lei; Li, Chen; Fang, Changshuai; Miao, Li; Zhu, Linlin; Zhang, Xiaodong
• Is Part Of: Optics & laser technology. Volume 161(2023)
• Publication Date: 2023-06
• Subjects: Complete topographic measurement -- Monolithic multi-surface workpiece -- System calibration; Optics -- Periodicals; Lasers -- Periodicals; Electronic journals; 621.366
• DOI: 10.1016/j.optlastec.2023.109222
• Languages: English
• ISSNs: 0030-3992

Abstract

Highlights: A complete topographic method of the cylindrical-distributed MMSW is proposed. The measuring system is established via a single point probe on the ultra-precision machine. The Model of system error is established to calibrate the measuring configuration. The measuring path of monolithic multi-surfaces workpieces is planned. A freeform four-mirror optical system is measured to evaluate each sub-surface's topography. Abstract: Monolithic multi-surfaces workpieces (MMSWs) are widely used in aerospace, advanced optics, and other fields. The complete topographic measurement of each sub-surface in MMSWs requires high measurement flexibility and strong space constraints since each sub-surface is located in an inner cylindrical cavity. This paper proposes a complete topographic measuring method for MMSWs based on a four-axis measuring system with a rotating single-point probe. Several basic geometric parameters of the measuring system are identified in the calibration. The mapping relation between the theoretical surface equations and measuring system coordinates is established by searching for reference points. The measurement scanning paths with different orientations are designed for each sub-surface. The iterative measurement and optimization are adopted to compensate for the measurement errors from the coupling of the probe and the four-axis measuring system. A standard sphere is measured, and the deviation of the fitting radius is below 0.5 μm. Besides, a freeform four-mirror optical system is selected as the experimental study case, where the complete topographic measurement of each sub-surface is completed on an ultra-precision machine tool. The form error and the standard deviation of each sub-surface can reach the micron level.