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Journal ArticleDOI

Implementation of a speckle-correlation-based optical lever with extended dynamic range.

01 Aug 2019-Applied Optics (Optical Society of America)-Vol. 58, Iss: 22, pp 5982-5988
TL;DR: Two types of computer-automated SC-OptLevs, an open-source-based computing system with a low-cost image sensor and a commercial computing system, are presented with assistive computational modules.
Abstract: A speckle-correlation-based optical lever (SC-OptLev) is constructed for the measurement of small changes in the orientation angle of a surface. The dynamic range of SC-OptLev is found to be twice that of a conventional OptLev for the same experimental configurations. Different filtering mechanisms are implemented, and the correlation results are compared. Two types of computer-automated SC-OptLevs, an open-source-based computing system with a low-cost image sensor and a commercial computing system, are presented with assistive computational modules.
Citations
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TL;DR: In this paper, the authors used a randomly multiplexed bifocal binary diffractive Fresnel zone lenses fabricated using electron beam lithography for super-resolution 3D imaging.
Abstract: Fresnel incoherent correlation holography (FINCH) is a self-interference based super-resolution three-dimensional imaging technique. FINCH in inline configuration requires an active phase modulator to record at least three phase-shifted camera shots to reconstruct objects without twin image and bias terms. In this study, FINCH is realized using a randomly multiplexed bifocal binary diffractive Fresnel zone lenses fabricated using electron beam lithography. The object space is calibrated by axially scanning a point object along the optical axis and recording the corresponding point spread holograms (PSHs). An object is mounted within the calibrated object space, and the object hologram was recorded under identical experimental conditions used for recording the PSHs. The image of the object at different depths was reconstructed by a cross-correlation between the object hologram and the PSHs. Application potential including bio-medical optics is discussed.

20 citations

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TL;DR: A new hybrid diffractive optical element (HDOE) was designed by randomly multiplexing an axicon and a Fresnel zone lens and generates two mutually coherent waves, namely a conical wave and a spherical wave, for every on-axis point object in the object space.
Abstract: A new hybrid diffractive optical element (HDOE) was designed by randomly multiplexing an axicon and a Fresnel zone lens. The HDOE generates two mutually coherent waves, namely a conical wave and a spherical wave, for every on-axis point object in the object space. The resulting self-interference intensity distribution is recorded as the point spread function. A library of point spread functions are recorded in terms of the different locations and wavelengths of the on-axis point objects in the object space. A complicated object illuminated by a spatially incoherent multi-wavelength source generated an intensity pattern that was the sum of the shifted and scaled point spread intensity distributions corresponding to every spatially incoherent point and wavelength in the complicated object. The four-dimensional image of the object was reconstructed using computer processing of the object intensity distribution and the point spread function library.

15 citations


Cites background from "Implementation of a speckle-correla..."

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TL;DR: In this paper , the authors survey several recently proposed techniques to control the parameters of coded aperture imaging (CAI) by engineering the aperture of the system and present the prime architectures of these indirect methods of imaging.
Abstract: Coded aperture imaging (CAI) is a technique to image three-dimensional scenes 12 with special controlled abilities. In this review, we survey several recently proposed 13 techniques to control the parameters of CAI by engineering the aperture of the system. The 14 prime architectures of these indirect methods of imaging are reviewed. For each design, we 15 mention the relevant application of the CAI recorders and summarize this overview with a 16 general perspective on this research topic. 17

10 citations

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TL;DR: This tutorial discusses one of the basic optical configurations of a lensless QPI technique based on the phase-retrieval algorithm andmented codes in Octave for image acquisition and automation using a web camera in an open source operating system are provided.
Abstract: Quantitative phase imaging (QPI) techniques are widely used for the label-free examining of transparent biological samples. QPI techniques can be broadly classified into interference-based and interferenceless methods. The interferometric methods which record the complex amplitude are usually bulky with many optical components and use coherent illumination. The interferenceless approaches which need only the intensity distribution and works using phase retrieval algorithms have gained attention as they require lesser resources, cost, space and can work with incoherent illumination. With rapid developments in computational optical techniques and deep learning, QPI has reached new levels of applications. In this tutorial, we discuss one of the basic optical configurations of a lensless QPI technique based on the phase-retrieval algorithm. Simulative studies on QPI of thin, thick, and greyscale phase objects with assistive pseudo-codes and computational codes in Octave is provided. Binary phase samples with positive and negative resist profiles were fabricated using lithography, and a single plane and two plane phase objects were constructed. Light diffracted from a point object is modulated by phase samples and the corresponding intensity patterns are recorded. The phase retrieval approach is applied for 2D and 3D phase reconstructions. Commented codes in Octave for image acquisition and automation using a web camera in an open source operating system are provided.

10 citations


Cites methods from "Implementation of a speckle-correla..."

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TL;DR: Nonlinear reconstruction (NLR) as discussed by the authors was developed in 2017 to reconstruct the object image in the case of optical-scattering modulators, which can reconstruct an object image modulated by an axicons, bifocal lenses and even exotic spiral diffractive elements, which generate deterministic optical fields.
Abstract: Indirect-imaging methods involve at least two steps, namely optical recording and computational reconstruction. The optical-recording process uses an optical modulator that transforms the light from the object into a typical intensity distribution. This distribution is numerically processed to reconstruct the object’s image corresponding to different spatial and spectral dimensions. There have been numerous optical-modulation functions and reconstruction methods developed in the past few years for different applications. In most cases, a compatible pair of the optical-modulation function and reconstruction method gives optimal performance. A new reconstruction method, termed nonlinear reconstruction (NLR), was developed in 2017 to reconstruct the object image in the case of optical-scattering modulators. Over the years, it has been revealed that the NLR can reconstruct an object’s image modulated by an axicons, bifocal lenses and even exotic spiral diffractive elements, which generate deterministic optical fields. Apparently, NLR seems to be a universal reconstruction method for indirect imaging. In this review, the performance of NLR isinvestigated for many deterministic and stochastic optical fields. Simulation and experimental results for different cases are presented and discussed.

9 citations

References
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TL;DR: This work examines the relationship between phase and amplitude in the case of alphanumeric characters, with and without noise, using a computer simulation and compares the phase-only and amplitude-only filters to the classical matched filter using the criteria of discrimination, correlation peak, and optical efficiency.
Abstract: From image processing work, we know that the phase information is significantly more important than amplitude information in preserving the features of a visual scene. Is the same true in the case of a matched filter? From previous work [ J. L. Horner , Appl. Opt.21, 4511( 1982)], we know that a pure phase correlation filter can have an optical efficiency of 100% in an optical correlation system. We examine this relationship between phase and amplitude in the case of alphanumeric characters, with and without noise, using a computer simulation. We compare the phase-only and amplitude-only filters to the classical matched filter using the criteria of discrimination, correlation peak, and optical efficiency. Three-dimensional plots of the autocorrelation and cross-correlation functions are presented and discussed.

914 citations

Journal ArticleDOI

[...]

TL;DR: In this paper, the first atomic-resolution image of a surface obtained with an optical implementation of the atomic force microscope (AFM) was presented, where the native oxide on silicon was imaged with atomic resolution, and ≊5nm resolution images of aluminum, mechanically ground iron, and corroded stainless steel were obtained.
Abstract: We present the first atomic‐resolution image of a surface obtained with an optical implementation of the atomic‐force microscope (AFM). The native oxide on silicon was imaged with atomic resolution, and ≊5‐nm resolution images of aluminum, mechanically ground iron, and corroded stainless steel were obtained. The relative merits of an optical implementation of the AFM as opposed to a tunneling implementation are discussed.

636 citations

Journal ArticleDOI

[...]

TL;DR: Its performance in the presence of noise is found to be superior to that of other blind deconvolution algorithms and the algorithm is developed further to incorporate functional forms of the point-spread function with unknown parameters.
Abstract: A blind deconvolution algorithm based on the Richardson–Lucy deconvolution algorithm is presented. Its performance in the presence of noise is found to be superior to that of other blind deconvolution algorithms. Results are presented and compared with results obtained from implementation of a Weiner filter blind deconvolution algorithm. The algorithm is developed further to incorporate functional forms of the point-spread function with unknown parameters. In the presence of noise the point-spread function can be evaluated with 1.0% error, and the object can be reconstructed with a quality near that of the deconvolution process with a known point-spread function.

425 citations

Journal ArticleDOI

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TL;DR: In this paper, a noncontact and automatic method of measuring surface strain was developed, which makes use of the speckle displacement that is detected by cross correlating the signals from a photodiode array.
Abstract: A new non-contact and automatic method of measuring surface strain has been developed. It makes use of the speckle displacement that is detected by cross correlating the signals from a photodiode array. According to a theory the difference between the speckle displacements for a pair of symmetrically incident laser beams is proportional to the surface strain parallel to the plane of incidence and independent of the translational and rotational components. This relation is verified by experiments using a metal specimen subject to uniaxial strain that is measured by a resistance gauge. The gauge length of the present method is given by the laser spot size and the sensitivity is of the order of the array pitch divided by sensor distance. They are 1 mm and 20 microstrain, respectively, in the experiments.

322 citations

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TL;DR: The improved algorithm was found to determine displacement components with an uncertainty of less than 1% of a pixel and with negligible systematic errors in ideal experimental conditions.
Abstract: Electronic speckle photography offers a simple and fast technique for measuring in-plane displacement fields in solid and fluid mechanics. An improved algorithm is presented and analyzed by use of both computer-simulated speckle patterns and real experiments. The idea of the improved algorithm is to maximize the correlation between correlated subimages from different images by shifting one of them by nonintegral pixel values. The improved algorithm was found to determine displacement components with an uncertainty of less than 1% of a pixel and with negligible systematic errors in ideal experimental conditions.

203 citations