Random-Phase-Shift-Interferometer

• Applicant: Professor Dr.-Ing. Rainer Tutsch
• Subject Area: Measurement Systems ; Production Systems, Operations Management, Quality Management and Factory Planning
• Term: from 2007 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 36903051

This application is the request for the extension of the project: TU-135/15-1, with the title "Random-Phase-Shift-Interferometer". The work of the former project has been finished and the results can be reviewed in the preliminary report. With the follow-up application, the Random-Phase-Shift-Interferometer for plane surfaces should be enhanced for the measurement of spherical surfaces. It is possible to use the former developed random-phase-shift algorithm also for the measurement of spherical surfaces. For that purpose it is necessary to develope a new method for the determination of the local random relative phase-shift between spherical reference and spherical test wavefront under the influence of vibration. An adequate approach for an evaluation algorithm which is based on the determination of the shift of the centre point of the spherical mirror already exists and is explained more in detail in the section for preliminary work. The already started simulations for the measurement setup to verify the new phase-determination method and to find an appropriate sensor configuration have to be continued. The simulations should also help to find failures during the selection process for the optical components for the setup. To measure spherical surfaces, the setup has to be modified. On the one hand a spherical test surface in combination with a transmission sphere to create the spherical reference wavefront has to be integrated. On the other hand the high temporal resolution detector for the determination of the random phase-shifts has to be modified and tested. At first comparative measurements on spherical surfaces with known shift in all three directions in space will be done with the new setup for the measurement of spherical surfaces, and the deviations between given and measured sphere movement will be analyzed. Finally measurements with different measurement objects of known surface topography on a table without vibration isolation will be made. These measurements will be done under the influence of random vibration, as it appears e.g. in a production environment. The objective of the measurements will be the determination of the relative measurement uncertainty. According to our present knowledge, no other institution currently works on a comparable approach to measure spherical surfaces under the influence of vibration.

• DFG Programme: Research Grants