| Zugriffsnummer | 13985 |
| Dokumenttyp | Konferenzartikel |
| Sprache | Englisch |
| Titel | Measurement of steep aspheres: a step forward to nanometer accuracy |
| Autor(in); Institution |
Weingärtner, Ingolf; 4.21, Bildoptik und Spektrometrie, PTB-Braunschweig
Schulz, Michael; 4.21, Bildoptik und Spektrometrie, PTB-Braunschweig
Thomsen-Schmidt, Peter; 5.12, Mikro- und Nanotopographie, PTB-Braunschweig
Elster, Clemens; 8.31, Softwarequalitätssicherung und Messdatenverarbeitung, PTB-Berlin
|
| Quelle/Jahr | Optical metrology roadmap for the semiconductor, optical, and data storage industries II:(2001), 195 - 204 |
| Schriftenreihe | Proceedings of SPIE: 4449 |
| ISSN | 0277-786X |
| ISBN | 0-8194-4163-5 |
| DOI | |
| Verlag | Bellingham, Wash.: SPIE |
| Konferenzangaben | Optical metrology roadmap for the semiconductor, optical, and data storage industries II, San Diego, Calif., 02-03, August, 2001, USA |
| Freie Schlagworte | aspheres ; complex surfaces ; ultra-precision ; topography ; curvature |
| Zusammenfassung | It is a promising method for measuring steep aspheres and complex surfaces with nanometer and sub-nanometer accuracy to measure the curvature and to calculate the topography from it, since unlike slope and distance, the curvature is an intrinsic property of a surface and less insensitive to error influences. For the development of a measuring instrument based on the physical property of curvature, various topics have been investigated. Calculation of topography from curvature: The curvature contains information about the figure of a surface. A method and an algorithm were developed to derive the topography (and slope) from the curvature with high accuracy. This method is insensitive to noise and can be applied to various macroscopic shapes of a surface under test. Displacement of the curvature sensor along a surface: The shape of modern aspheres and complex surfaces the curvature sensor has to follow is complicated. The sensor is placed perpendicular to the individual surface elements and also at a well-defined, constant distance. Large-area curvature sensor and its calibration: A special curvature sensor was developed which allows transparent and noise-insensitive curvature measurements to be realized. This curvature sensor is traced back to the base unit of length and can be calibrated with high accuracy. Calculation of curvature from large-area information: Principles and algorithms were developed by which the curvature can be determined on the basis of information over a small portion of the surface with high lateral resolution. Here the principles of surface type- and error type-matched fitting are applied. This allows both high vertical and lateral resolution to be achieved at the same time. The method described does not rely on external form references, and the errors of the scanning stages and the whole-body movement of the artifact have only little influence on the accuracy. In comparison to other measuring techniques, it is an advantageous feature of the curvature measuring technique that distance and angle between sensor and surface element can be controlled and kept constant during scanning as it is the curvature and not the distance or the slope which is the measurand. This leads to the result that, apart from the calibration of the curvature sensor, the whole system no longer suffers from first- and second-order errors. The uncertainty budget shows that nanometer accuracy is achievable. |
Zitierung
Weingärtner, I., Schulz, M., Thomsen-Schmidt, P., & Elster, C. (2001). Measurement of steep aspheres: a step forward to nanometer accuracy. Optical metrology roadmap for the semiconductor, optical, and data storage industries II, San Diego, Calif., 02-03, August, 2001, USA. https://doi.org/10.1117/12.450095