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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10 Feb 2017
TL;DR: In this paper, a digital holographic microscopy (DHM) system with multiple magnifications and the aberration compensation method was used to obtain 3D profile images and estimated the precise quantitative sizes of not only a profile with an aperture of 6.41 mm and a curvature radius of 8.39 m, but also a scratch with a line-equivalent width of 0.28 nm and a pit with an equivalent diameter of 1.86μm and an equivalent depth of 42.95 nm.
Abstract: In the development and production process of laser gyros, reflective mirrors have always been a core component, as they are directly related to the performance of laser gyros. Besides, surface profile deviation and surface defects of mirrors may lead to irreversible serious damages to gyros. In order to achieve effective three-dimensional (3D) quantitative measurements of their surface profiles and defects, we adopt digital holographic microscopy (DHM). Using a DHM system with multiple magnifications and the aberration compensation method, we obtained 3D profile images and estimated the precise quantitative sizes of not only a profile with an aperture of 6.41 mm and a curvature radius of 8.39 m, but also a scratch with a line-equivalent width of 0.45μm and an equivalent depth of 137.28 nm and a pit with an equivalent diameter of 0.86μm and an equivalent depth of 42.95 nm. These results demonstrate that the method is feasible and effective to meet the requirements of engineering practice.
1 citations
Cites methods from "Compensation of the inherent wave f..."
...In this paper, we adopt the two-step phase subtraction method to correct the phase aberration [13]....
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01 Jan 2009
1 citations
Cites background or methods from "Compensation of the inherent wave f..."
...24 291 [22] Ferraro P, De Nicola S, Finizio A, Coppola G, Grilli S, Magro C and Pierattini G 2003 Compensation of the inherent wave front curvature in digital holographic coherent microscopy for quantitative phase-contrast imaging Appl....
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...Digital interference holography for optical tomographic imaging [19-24], as well as multiwavelength quantitative phase contrast digital holography for high resolution microscopy [25-28], was demonstrated....
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...12 643-647 [22] Yu L, Myung M K 2005 Wavelength scanning digital interference holography for variable tomographic scanning Opt....
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01 Jan 2012
TL;DR: Methods to numerically compensate the wave front curvature mismatch between reference and object beams, which is particularly important for measurements of cellular volume, are presented.
Abstract: Phase imaging of objects with optical height variation greater than the wavelength of light is ambiguous and causes phase wrapping. The unwrapping of those images is complicated by the presence of phase noise. Several unwrapping schemes are presented. The first technique is a digital holographic phase unwrapping method based on a comparison of phase images obtained by using various reconstruction distances. By utilizing information from multiple reconstruction planes, this method can effectively bypass the areas of phase noise. The second method is based on comparison of two phase images recorded at different wavelengths. These unwrapping methods are computationally fast and can process complex phase topologies. Also presented are methods to numerically compensate the wave front curvature mismatch between reference and object beams, which is particularly important for measurements of cellular volume. While being primarily developed to unwrap cellular images, these new methodologies are widely applicable to other phase imaging techniques.
1 citations
13 May 2013
TL;DR: In this article, a cylindrically symmetric structure of a capillary tube was used for the dynamic imaging of phase-type objects with different angles of illumination, and the Fourier diffraction was used to reconstruct the 3D map of refractive index.
Abstract: Digital holographic tomography, a computed tomography by use of digital holography, has a huge potential for
three-dimensional imaging of weakly-diffracting phase objects. But the need of multiple angles of illumination weakened
imaging capability of dynamic objects. For cylindrically symmetric object, we can use complex amplitude data of single
hologram under zero incidence angles to replace the other complex amplitude data under different incidence angles.
Therefore, it is possible to achieve the dynamic imaging of cylindrically symmetric objects. The digital holographic
tomography can provide a way for the dynamic imaging of phase-type objects having a cylindrically symmetric structure.
We report an experimental example of the capillary tube having a cylindrically symmetric structure. Tomography of the
capillary tube is performed by filtered back-projection algorithm and Fourier diffraction algorithm respectively to
reconstruct the 3-D map of refractive index. Experimental results show that, comparing with the filtered back-projection reconstruction, diffraction tomography based on the Rytov approximation better respects the dimensions of the capillary tube.
1 citations
TL;DR: In this article, a hybrid optical transport trap (HOTT) was proposed to transport polystyrene and red blood cells into and out of the optical tweezers trap in an orthogonal geometry.
Abstract: High throughput analysis of trapped samples requires effective loading and unloading into the trap in a microfluidic
environment. We demonstrate development of a hybrid optical transport trap (HOTT) which combines a tapered fiberoptic
2D trap for transport of microscopic objects into and out of the optical tweezers trap in an orthogonal geometry.
For small cone angle of the tip, the microscopic objects (polystyrene and red blood cells) were found to be trapped in
two-dimensions and pushed along the axial direction by domination of scattering force. This was found to be in
consistence with the estimated axial forces caused by the beam profiles emerging from the small-cone tapered fiber tip.
While for loading of the microscopic objects into the optical tweezers trap, the fiber tip was placed ~ 30μm away from
the tweezers trap, unloading was carried out in presence of the tip close (<15 μm) to the tweezers trap. Further, for a
fixed fiber trap and tweezers separation (~ 30 μm), both loading and unloading could be achieved by reducing the
tweezers trap power so that the scattering force exerted by the fiber trap exceeded the transverse gradient force of
tweezers trap. Since the tapered tip can be easily integrated onto a microfluidic channel, the proposed configuration can
find potential applications in lab-on-a-chip devices. We demonstrate analysis of transported microscopic objects using
digital holographic microscopy integrated with the HOTT.
1 citations
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