Adaptive optics interferometer using superspeckles for high resolution deformation measurement |
| |
Authors: | Phanindra Narayan Gundu Erwin Hack Pramod Rastogi |
| |
Institution: | a EMPA, Laboratory for Electronics/Metrology, Ueberlandstrasse 129, CH-8600 Dübendorf, Switzerland b Gemini Observatory Northern Operations Center, 670 N. A’ohoku Place, Hilo, HI 96720, USA c Applied Computing and Mechanics Laboratory (IMAC), Swiss Federal Institute of Technology Lausanne, CH-1015 Lausanne, Switzerland |
| |
Abstract: | Digital speckle pattern interferometry (DSPI) is a well-known technique for measuring deformations, but it is limited in range by speckle decorrelation. We developed an adaptive interferometer with increased measurement range by combining the DSPI set-up with a pupil filter that generates optical superresolution. As a result, a decrease in the transverse speckle size is observed accompanied with a substantial increase in the longitudinal speckle size. The increase in the speckle correlation length along the optical axis allows for obtaining an out-of-plane deformation measurement over a significantly extended depth. An experimental verification of this concept of superspeckles is presented with an intensity-only LCD spatial light modulator (SLM) acting as a pupil filter. Comparison of speckle correlation fringes with and without the superresolution filter confirms the proposed concept. The present work demonstrates a doubling of the measurement range when using the superresolution interferometer. A standard set-up in which the speckle length is comparably elongated by stopping down the lens has a similar loss of intensity, but its lateral resolution is only half as good. |
| |
Keywords: | |
本文献已被 ScienceDirect 等数据库收录! |
|