Optical mirror surface shape on-site measurement based on reverse Hartmann test

Abstract

High-precision optical systems are increasingly being used in military, civil and aerospace fields. Computer numerical control small grinding head grinding technology, performing as an efficient ultra-precision machining method, has been widely used in the field of mirror processing and manufacturing. High-precision detection of the surface shape is a key step to ensure the quality of the precision processing of optical mirrors. This can be quickly and effectively achieved by on-site measurement, therefore improving processing efficiency. A method called reverse Hartmann test was proposed for ultra-precision grinding machine tools. This method not only ensures high detection accuracy, but also has the advantages of simple structure, high detection efficiency, and strong robust ability, which can be used to perform the on-site measurement inside the grinding machine tools. According to the application conditions, the actual reverse Hartmann surface shape on-site detection system was built inside the small grinding head machine tools, and the on-site measurement of the 250mm flat mirror was completed within 3 minutes. The surface shape measurement repeatability was better than λ/37, which proved the efficiency and feasibility of reverse Hartmann test shape on-site detection system.