Enhanced wavefront reconstruction by random phase modulation with a phase diffuser

• Published in: Optics and lasers in engineering Vol. 49; no. 2; pp. 252 - 257
• Main Authors: Almoro, Percival F., Pedrini, Giancarlo, Gundu, Phanindra N., Osten, Wolfgang, Hanson, Steen G.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-02-2011; Elsevier
• Subjects: Diffusers; Exact sciences and technology; Fundamental areas of phenomenology (including applications); General equipment and techniques; Holography; Imaging and optical processing; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Iterative algorithms; Optics; Phase modulation; Phase retrieval; Physics; Planes; Reconstruction; Reconstruction technique; Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing; Speckle; Speckle and moire patterns; Wave fronts; Wave optics; Wave propagation; Wave propagation, transmission and absorption; Wavefront sensing; Holography; Speckle; Phase retrieval; Reconstruction technique; Wavefront sensing; Positioning; Phase modulation; Random phase; Speckles; Algorithms; Wave front; Wavefront sensors; Electromagnetic wave propagation; Adaptive optics; Iterative methods; Phase reconstruction; Test object
• ISSN: 0143-8166; 1873-0302
• DOI: 10.1016/j.optlaseng.2010.09.012

A phase retrieval technique for enhanced wavefront reconstruction using random phase modulation and a phase diffuser is proposed. The speckle field generated is sampled at multiple axially displaced planes and the speckle patterns are used in an iterative algorithm based on the optical wave propagation in free space. The presentation of this technique is carried out using two setups. In the first setup, a diffuser plate is placed at the image plane of a metallic test object. The benefit of randomizing the phase of the object wave is the enhanced intensity recording due to high dynamic range of the diffusely scattered beam. The use of demagnification optics will also allow the investigations of relatively large objects. In the second setup, a transparent object is illuminated using a wavefront with random phase and constant amplitude by positioning the phase diffuser close to the object. The benefit of phase-only modulation is the increased resolution of the phase structures of the transparent test objects.