Nonimaging speckle interferometry for high-speed nanometer-scale position detection

Author(s): E. G. van Putten, A. Lagendijk, and A. P. Mosk


“We experimentally demonstrate a nonimaging approach to displacement measurement for complex scattering materials. By spatially controlling the wavefront of the light that incidents on the material, we concentrate the scattered light in a focus on a designated position. This wavefront acts as a unique optical fingerprint that enables precise position detection of the illuminated material by simply measuring the intensity in the focus. By combining two fingerprints we demonstrate position detection along one in-plane dimension with a displacement resolution of 2.1 nm. As our approach does not require an image of the scattered field, it is possible to employ fast nonimaging detectors to enable high-speed position detection of scattering materials.”

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Publication: Optics Letters, (subscription required)

Issue/Year/DOI: Optics Letters, Vol. 37, Issue 6, pp. 1070-1072 (2012)

Advanced Scanning Laser-Doppler Vibrometer with Computer Generated Holograms

Author(s): S. Zwick, M. Warber, T. Haist, F. Schaal, W. Osten, S. Boedecker, and C. Rembe


“In this paper we present a novel technique for steering the beam of a scanning laser-Doppler vibrometer (LDV) using a Spatial Light Modulator (SLM). Computer Generated Holograms (CGH) are employed to obtain the phase maps displayed by the SLM. Due to this approach, spurious diffraction orders are generated. We present concepts to suppress these diffraction orders so as to realize a scanning vibrometer. We discuss the properties and limitations of this solution. Different SLMs have been evalutated and a compact scanning vibrometer based on a Holoeye Pluto SLM has been realized. First measurement results are presented. In addition, we demonstrate simulations on the reduction of speckle related signal dropouts. Drop-Outs can be reduced by adapting the measurement-beam wavefront with the CGH to maximize the light power collected with the vibrometer aperture. We have explored an approach to optimize the signal strength by adapting the coefficients of the Zernike polynomials of an additional wavefront shift.”

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Issue/Year/DOI: AIP Conf. Proc., Volume 1253, pp. 279-290, May 28, 2010

Comparison and unification of speckle-based phase retrieval and holography with applications in phasefront alignment and recognition

Author(s): P. F. Almoro, G. Pedrini, F. Zhang, A. M. S. Maallo, A. Anand, P. N. Gundu, W. Wang, A. Asundi, W. Osten and S. G. Hanson


“Comparisons between various wavefront reconstruction methods such as wavefront curvature sensing and phase diversity have been reported in the literature. These comparative studies highlight the differences,
similarities, relative advantages, operating regimes and main applications of the various reconstruction methods. For coherent light metrological applications, especially on rough objects, Digital Holography (DH) is
considered one of the established interferometric methods because of its sub-wavelength accuracy. For investigations of smooth surfaces, Phase Retrieval (PR) or the non-interferometric approach offers a simple setup since no reference beam (RB) is required. In PR, recent trends favour the use of multiple intensity images, rather than a few images, due to its robustness against quantization error. Recently, a multiple speckle-pattern PR method was utilized in the interferometric analysis of object rotation and deformation and in the numerical correction of aberrations, indicating a point of convergence between the two, traditionally parallel, reconstruction methods. To the best of our knowledge, no comparative study has been done between PR and DH. Recognition of test objects has been carried out by correlation with a reference object wavefront obtained through DH. Since no RB is used, PR may offer a more robust recognition method. The objectives of this study are: 1) compare off-axis DH and PR in terms of setup and reconstruction algorithm; 2) present a new model for the PR method interpreting it as a special case of holography called “phase-shifting broadband DH”; 3) describe a novel method for phasefront alignment of uncorrelated laser beams using PR; and, 4) describe a novel method for object recognition using PR.”

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Publication: Fringe 09 – Proceedings of the 6th International Workshop on Advanced Optical Metrology, (via Google Books)

Issue/Year/DOI: Fringe 2009 – Proceedings, pp. 57 – 62 (2009)
DOI 10.1007/978-3-642-03051-2_8

Generation of fractal speckles by means of a spatial light modulator

Author(s): Hideki Funamizu and Jun Uozumi


“It was shown in previous studies that, when a diffuser is illuminated by coherent light with an average spatial intensity distribution obeying a negative power function, the scattered field in the Fraunhofer diffraction region exhibits random fractal properties. The method employed so far for producing such fields has a disadvantage in that generated speckle intensities are low due to small transmittance of fractal apertures used in the illumination optics. To overcome this disadvantage, a generation of fractal speckles by means of a spatial light modulator is proposed. The principle is explained and experimental results are also shown.”

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Publication: Optics Express (free download)

Issue/Year/DOI: Optics Express, Vol. 15, Issue 12, pp. 7415-7422 (2007)