Compensation of the inherent wave front curvature in digital holographic coherent microscopy for quantitative phase-contrast imaging
TL;DR: An approach is proposed for removing the wavefront curvature introduced by the microscope imaging objective in digital holography, which otherwise hinders the phase contrast imaging at reconstruction planes and it is shown that a correction effect can be obtained at all reconstruction planes.
Abstract: An approach is proposed for removing the wave front curvature introduced by the microscope imaging objective in digital holography, which otherwise hinders the phase contrast imaging at reconstruction planes. The unwanted curvature is compensated by evaluating a correcting wave front at the hologram plane with no need for knowledge of the optical parameters, focal length of the imaging lens, or distances in the setup. Most importantly it is shown that a correction effect can be obtained at all reconstruction planes. Three different methods have been applied to evaluate the correction wave front and the methods are discussed in detail. The proposed approach is demonstrated by applying digital holography as a method of coherent microscopy for imaging amplitude and phase contrast of microstructures.
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21 Nov 2019
TL;DR: In digital holographic microscopy, phase aberrations, which are usually caused by the imperfections of components and nontelecentric configuration of the optical system, severely affect the visual quality of the image.
Abstract: In digital holographic microscopy, phase aberrations, which are usually caused by the imperfections of components and nontelecentric configuration of the optical system, severely affect the visualization and quantitative measurement for phase-contrast imaging. Here, we propose a purely numerical and automatic method to compensate for phase aberrations. Without any manual involvement of selecting a sample-free background, the compensation is cast as a surface fitting problem, in which the aberration surface is approximated by formulating an inverse problem. By adopting the l1-norm as the loss function and by minimizing an objective function, aberrations can be accurately fitted and thus removed numerically. Synthetic and experimental results are demonstrated to verify the efficacy of this method over the least squares method.
24 citations
TL;DR: In this paper, an automatic phase aberration compensation method for living cells investigation in digital holographic microscopy was proposed for osteoblastic living cells, where the phase aberrations were extracted and corrected automatically with a single hologram by using spectral energy analysis.
Abstract: Phase aberration compensation is crucial for quantitative phase-contrast imaging in digital holographic microscopy. In this paper, an automatic compensation method is proposed for living cells investigation in digital holographic microscopy. The phase aberrations are extracted and corrected automatically with a single hologram by using spectral energy analysis. Zernike polynomials are adopted to model the phase aberrations. The polynomial coefficients related to the amount of phase aberrations are calculated in a nonlinear optimization procedure, in which a spectral energy metric that places more weight on low-frequency components is maximized. The effectiveness of the proposed method is demonstrated with experimental result of mouse osteoblastic living cells.
24 citations
TL;DR: The main characteristics of the proposed method are the possibility of producing the 3D topography by a single shot over the complete field of view with sensitivity of λ/100, without phase perturbations introduced by the illuminating-imaging system, and with no further numerical processing beyond that required for recovering the phase map of the sample.
Abstract: In this work, an off-axis digital holographic microscope operating in reflection mode and a telecentric regimen to produce 3D topography of a microscopy sample is shown. The main characteristics of the proposed method, which make it different from the previous works in the field, are the possibility of producing the 3D topography by a single shot over the complete field of view with sensitivity of λ/100, without phase perturbations introduced by the illuminating-imaging system, and with no further numerical processing beyond that required for recovering the phase map of the sample. A complete analysis of the illuminating-imaging system of the digital holographic microscope is presented. The proposed digital holographic microscope is tested on imaging a USAF resolution test target and some micro-electromechanical systems (MEMs).
23 citations
TL;DR: A parallel two-step polarizing phase shifting interferometer based on a Double Cyclic Shear Interferometer (DCSI) is proposed in this paper for quantitative phase imaging and presents better stability against external configurations than other types of interferometers.
Abstract: A parallel two-step polarizing phase shifting interferometer based on a Double Cyclic Shear Interferometer (DCSI) is proposed in this paper for quantitative phase imaging. The system has the advantage of retrieving the derivative phase data map directly. Due to its configuration, it presents better stability against external configurations than other types of interferometers. The DCSI generates two π-shifted interferograms, which are recorded by the CCD camera in a single-shot. The separation between parallel interferograms can be varied in the two axes for convenience. To obtain the optical phase data map, a parallel phase shift between interferograms is obtained by rotating a half wave plate retarder. We analyzed the cases of four patterns with shifts of π/2 captured in two shots; the optical phase was processed by a four-step algorithm. Related experimental results obtained for microscopic transparent samples are presented.
23 citations
TL;DR: The concept of controlling parameters in image reconstruction of digital holograms in some real situations for inspecting silicon microelectronic-mechanical systems structures is demonstrated.
Abstract: Digital holograms recorded with a charge-coupled device array are numerically reconstructed in amplitude and phase through calculation of the Fresnel-Kirchhoff integral. The flexibility offered by the reconstruction process in digital holography allows exploitation of new possibilities of application in microscopy. Through the reconstruction process we will show that it is possible to control image parameters as focus distance, image size, and image resolution. Those explored potentialities open further the novel prospective of application of digital holography in single- and multiwavelengths operation either for display or metrological applications. We demonstrate the concept of controlling parameters in image reconstruction of digital holograms in some real situations for inspecting silicon microelectronic-mechanical systems structures.
23 citations
Cites methods from "Compensation of the inherent wave f..."
...This last reconstruction method is particularly indicated for microscopic metrological applications such as, for example, in microelectromechanical systems (MEMS) inspection and/or characterization [23]....
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References
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TL;DR: A new method is proposed in which the distribution of complex amplitude at a plane is measured by phase-shifting interferometry and then Fresnel transformed by a digital computer, which can reconstruct an arbitrary cross section of a three-dimensional object with higher image quality and a wider viewing angle than from conventional digital holography using an off-axis configuration.
Abstract: A new method for three-dimensional image formation is proposed in which the distribution of complex amplitude at a plane is measured by phase-shifting interferometry and then Fresnel transformed by a digital computer. The method can reconstruct an arbitrary cross section of a three-dimensional object with higher image quality and a wider viewing angle than from conventional digital holography using an off-axis configuration. Basic principles and experimental verification are described.
1,813 citations
TL;DR: The principle of recording holograms directly on a CCD target is described and a real image of the object is reconstructed from the digitally sampled hologram by means of numerical methods.
Abstract: The principle of recording holograms directly on a CCD target is described. A real image of the object is reconstructed from the digitally sampled hologram by means of numerical methods.
1,444 citations
TL;DR: A new application of digital holography for phase-contrast imaging and optical metrology and an application to surface profilometry shows excellent agreement with contact-stylus probe measurements.
Abstract: We present a new application of digital holography for phase-contrast imaging and optical metrology. This holographic imaging technique uses a CCD camera for recording of a digital Fresnel off-axis hologram and a numerical method for hologram reconstruction. The method simultaneously provides an amplitude-contrast image and a quantitative phase-contrast image. An application to surface profilometry is presented and shows excellent agreement with contact-stylus probe measurements.
1,202 citations
TL;DR: Off-axis holograms recorded with a magnified image of microscopic objects are numerically reconstructed in amplitude and phase by calculation of scalar diffraction in the Fresnel approximation to show that the transverse resolution is equal to the diffraction limit of the imaging system.
Abstract: We present a digital method for holographic microscopy involving a CCD camera as a recording device. Off-axis holograms recorded with a magnified image of microscopic objects are numerically reconstructed in amplitude and phase by calculation of scalar diffraction in the Fresnel approximation. For phase-contrast imaging the reconstruction method involves the computation of a digital replica of the reference wave. A digital method for the correction of the phase aberrations is presented. We present a detailed description of the reconstruction procedure and show that the transverse resolution is equal to the diffraction limit of the imaging system.
1,174 citations
TL;DR: The principles and major applications of digital recording and numerical reconstruction of holograms (digital holography) are described, which are applied to measure shape and surface deformation of opaque bodies and refractive index fields within transparent media.
Abstract: This article describes the principles and major applications of digital recording and numerical reconstruction of holograms (digital holography). Digital holography became feasible since charged coupled devices (CCDs) with suitable numbers and sizes of pixels and computers with sufficient speed became available. The Fresnel or Fourier holograms are recorded directly by the CCD and stored digitally. No film material involving wet-chemical or other processing is necessary. The reconstruction of the wavefield, which is done optically by illumination of a hologram, is performed by numerical methods. The numerical reconstruction process is based on the Fresnel–Kirchhoff integral, which describes the diffraction of the reconstructing wave at the micro-structure of the hologram. In the numerical reconstruction process not only the intensity, but also the phase distribution of the stored wavefield can be computed from the digital hologram. This offers new possibilities for a variety of applications. Digital holography is applied to measure shape and surface deformation of opaque bodies and refractive index fields within transparent media. Further applications are imaging and microscopy, where it is advantageous to refocus the area under investigation by numerical methods.
1,171 citations