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Arias-Sosa YC, Moreno-Vega G, Lopes RM, Valin-Rivera JL, Valin-Fernández M, Gonçalves E, Ricardo-Pérez JO. Improvement of digital Gabor holographic microscopy using a lens in plankton studies. Heliyon 2024; 10:e29441. [PMID: 38694032 PMCID: PMC11058717 DOI: 10.1016/j.heliyon.2024.e29441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 04/08/2024] [Accepted: 04/08/2024] [Indexed: 05/03/2024] Open
Abstract
This work utilizes a Gabor Holographic Optical Scheme integrated with a microscope objective and a thin convex plane lens. This bi-telecentric lens system corrects spherical aberration from the objective, maintains consistent magnification across various reconstruction distances, and ensures a plane incidence on CMOS. Depending on the focal lengths of the objective and lens, the final image can be enlarged or reduced compared to the classic Gabor system, resulting in high-quality reconstructed phase images without spherical aberration. This setup was employed to capture phase distribution and intensity images of planktonic objects, such as copepods, achieving superior image quality.
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Affiliation(s)
- Yaumel C. Arias-Sosa
- Physics Department, Faculty of Natural and Exact Sciences, Universidad de Oriente, Santiago de Cuba, Cuba
| | - Gelaysi Moreno-Vega
- Physics Department, Higher Institute for Mining-Metallurgical, Moa, Holguín, Cuba
- Oceanographic Institute, University of São Pablo, São Pablo, Brazil
| | - Rubens M. Lopes
- Oceanographic Institute, University of São Pablo, São Pablo, Brazil
| | - José-Luis Valin-Rivera
- Pontifícia Universidad Católica de Valparaíso, Escuela de Ingeniería Mecánica, Valparaíso, Chile
| | - Meylí Valin-Fernández
- Department of Mechanical Engineering (DIM), Faculty of Engineering (FI), University of Concepción, Chile
| | - Edison Gonçalves
- Departamento de Mecatrônica e Sistemas Mecânicos, Escola Politécnica da Universidade de São Paulo (USP), São Paulo, SP, Brazil
| | - Jorge O. Ricardo-Pérez
- Physics Department, Faculty of Natural and Exact Sciences, Universidad de Oriente, Santiago de Cuba, Cuba
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Zhang X, Han Y, Liu H, Xiao X, Hu Y, Fu Q, Feng L, Hu X, Wang C, Wang J, Wang A. MEMS-based two-photon microscopy with Lissajous scanning and image reconstruction under a feed-forward control strategy. OPTICS EXPRESS 2024; 32:1421-1437. [PMID: 38297694 DOI: 10.1364/oe.510979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Accepted: 12/13/2023] [Indexed: 02/02/2024]
Abstract
Two-photon microscopy (TPM) based on two-dimensional micro-electro-mechanical (MEMS) system mirrors shows promising applications in biomedicine and the life sciences. To improve the imaging quality and real-time performance of TPM, this paper proposes Lissajous scanning control and image reconstruction under a feed-forward control strategy, a dual-parameter alternating drive control algorithm and segmented phase synchronization mechanism, and pipe-lined fusion-mean filtering and median filtering to suppress image noise. A 10 fps frame rate (512 × 512 pixels), a 140 µm × 140 µm field of view, and a 0.62 µm lateral resolution were achieved. The imaging capability of MEMS-based Lissajous scanning TPM was verified by ex vivo and in vivo biological tissue imaging.
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Hall ML, McCall P, Towers CE, Towers DP. Improved three-dimensional localization of multiple small objects in close proximity in digital holography. APPLIED OPTICS 2021; 60:A285-A295. [PMID: 33690380 DOI: 10.1364/ao.404432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 10/17/2020] [Indexed: 06/12/2023]
Abstract
Using intensity gradient- or sparsity-based focus metrics, the ability to accurately localize the three-dimensional (3D) position of a small object in a digital holographic reconstruction of a large field of view is hindered in the presence of multiple nearby objects. A more accurate alternative method for 3D localization, based on evaluation of the complex reconstructed volume, is proposed. Simulations and experimental data demonstrate a reduction in depth positional error for single objects and a notably improved axial resolution of multiple objects in close proximity.
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Huang G, Tian W, Qi M, Gong X, Zhang G. Improving axial resolution for holographic tracking of colloids and bacteria over a wide depth of field by optimizing different factors. OPTICS EXPRESS 2018; 26:9920-9930. [PMID: 29715938 DOI: 10.1364/oe.26.009920] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 03/27/2018] [Indexed: 06/08/2023]
Abstract
Improving the axial resolution for multiparticle three-dimensional (3D) holographic tracking is crucial but challenging. Here we study the impacts of incident light power, uniformity of the illumination as well as image pixel size on the axial tracking resolution for digital holographic microscopy (DHM). We demonstrate that the resolution highly depends on the image pixel size and the uniformity of the illumination. A 3D localization algorithm based on local-intensity-maxima searching and a Gaussian fit to the integrated intensity of the reconstructed lateral images along the axial direction proves a robust strategy to enhance the axial resolution for colloids and bacteria within a wide depth of field over several tens of micrometers.
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Dohet-Eraly J, Yourassowsky C, Dubois F. Fast numerical autofocus of multispectral complex fields in digital holographic microscopy with a criterion based on the phase in the Fourier domain. OPTICS LETTERS 2016; 41:4071-4074. [PMID: 27607975 DOI: 10.1364/ol.41.004071] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The knowledge of the complex amplitude of optical fields, that is, both quantitative phase and intensity, enables numeric reconstruction along the optical axis. Nonetheless, a criterion is required for autofocusing. This Letter presents a robust and rapid refocusing criterion suitable for color interferometric digital holographic microscopy, and, more generally, for applications where complex amplitude is known for at least two different wavelengths. This criterion uses the phase in the Fourier domain, which is compared among wavelengths. It is applicable whatever the nature of the observed object: opaque, refractive, or both mixed. The method is validated with simulated and experimental holograms.
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Memmolo P, Paturzo M, Javidi B, Netti PA, Ferraro P. Refocusing criterion via sparsity measurements in digital holography. OPTICS LETTERS 2014; 39:4719-4722. [PMID: 25121857 DOI: 10.1364/ol.39.004719] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Several automatic approaches have been proposed in the past to compute the refocus distance in digital holography (DH). However most of them are based on a maximization or minimization of a suitable amplitude image contrast measure, regarded as a function of the reconstruction distance parameter. Here we show that, by using the sparsity measure coefficient regarded as a refocusing criterion in the holographic reconstruction, it is possible to recover the focus plane and, at the same time, establish the degree of sparsity of digital holograms, when samples of the diffraction Fresnel propagation integral are used as a sparse signal representation. We employ a sparsity measurement coefficient known as Gini's index thus showing for the first time, to the best of our knowledge, its application in DH, as an effective refocusing criterion. Demonstration is provided for different holographic configurations (i.e., lens and lensless apparatus) and for completely different objects (i.e., a thin pure phase microscopic object as an in vitro cell, and macroscopic puppets) preparation.
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Dubois F, El Mallahi A, Dohet-Eraly J, Yourassowsky C. Refocus criterion for both phase and amplitude objects in digital holographic microscopy. OPTICS LETTERS 2014; 39:4286-4289. [PMID: 25078158 DOI: 10.1364/ol.39.004286] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
For digital holographic microscopy applications, we modify the focus criterion based on the integration of the amplitude modulus to make possible its use regardless of the phase or amplitude nature of the objects under test. When applied on holographic data, the original criterion gives, at the focus plane, a minimum or a maximum, for amplitude or phase objects. The criterion we propose here operates on high-pass filtered complex amplitudes. It is shown that the proposed criterion gives a minimum for both types of objects when the focus plane is reached. Experimental results on real samples and simulations are provided, illustrating the efficiency and the potential of the method.
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Minetti C, Podgorski T, Coupier G, Dubois F. Fully automated digital holographic processing for monitoring the dynamics of a vesicle suspension under shear flow. BIOMEDICAL OPTICS EXPRESS 2014; 5:1554-68. [PMID: 24877015 PMCID: PMC4026899 DOI: 10.1364/boe.5.001554] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Revised: 04/10/2014] [Accepted: 04/11/2014] [Indexed: 05/16/2023]
Abstract
We investigate the dynamics of a vesicle suspension under shear flow between plates using DHM with a spatially reduced coherent source. Holograms are grabbed at a frequency of 24 frames/sec. The distribution of the vesicle suspension is obtained after numerical processing of the digital holograms sequence resulting in a 4D distribution. Obtaining this distribution is not straightforward and requires special processing to automate the analysis. We present an original method that fully automates the analysis and provides distributions that are further analyzed to extract physical properties of the fluid. Details of the numerical implementation, as well as sample experimental results are presented.
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Affiliation(s)
- Christophe Minetti
- Service de Chimie-Physique EP, Université libre de Bruxelles, 50 Avenue F. Roosevelt, CP16/62, B-1050 Brussels, Belgium
| | - Thomas Podgorski
- Laboratoire Interdisciplinaire de Physique, CNRS-UMR 5588, Université Grenoble I, B.P. 87, 38402 Saint Martin d’Hères Cedex, France
| | - Gwennou Coupier
- Laboratoire Interdisciplinaire de Physique, CNRS-UMR 5588, Université Grenoble I, B.P. 87, 38402 Saint Martin d’Hères Cedex, France
| | - Frank Dubois
- Service de Chimie-Physique EP, Université libre de Bruxelles, 50 Avenue F. Roosevelt, CP16/62, B-1050 Brussels, Belgium
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Dohet-Eraly J, Yourassowsky C, Dubois F. Refocusing based on amplitude analysis in color digital holographic microscopy. OPTICS LETTERS 2014; 39:1109-1112. [PMID: 24690683 DOI: 10.1364/ol.39.001109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A refocusing criterion adapted to red-green-blue (RGB) digital holographic microscopy is established. It is applicable for both amplitude and phase objects. This color criterion is based on a monochromatic criterion, using the integrated modulus amplitude. Simulated RGB holograms show the value of having color information, even for colorless samples; in addition, the position of the focus plane along the optical axis is determined more accurately. Simulations take into account both the numerical apertures of lenses and noise during the holographic process. We also implement an algorithm exponentially reducing the computation time required for detecting the focus plane. The method is validated on experimental holograms.
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Di Caprio G, El Mallahi A, Ferraro P, Dale R, Coppola G, Dale B, Coppola G, Dubois F. 4D tracking of clinical seminal samples for quantitative characterization of motility parameters. BIOMEDICAL OPTICS EXPRESS 2014; 5:690-700. [PMID: 24688806 PMCID: PMC3959837 DOI: 10.1364/boe.5.000690] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 12/06/2013] [Accepted: 12/30/2013] [Indexed: 05/02/2023]
Abstract
In this paper we investigate the use of a digital holographic microscope, with partial spatial coherent illumination, for the automated detection and tracking of spermatozoa. This in vitro technique for the analysis of quantitative parameters is useful for assessment of semen quality. In fact, thanks to the capabilities of digital holography, the developed algorithm allows us to resolve in-focus amplitude and phase maps of the cells under study, independently of focal plane of the sample image. We have characterized cell motility on clinical samples of seminal fluid. In particular, anomalous sperm cells were characterized and the quantitative motility parameters were compared to those of normal sperm.
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Affiliation(s)
- Giuseppe Di Caprio
- Institute for Microelectronics and Microsystems, Unit of Naples - National Research Council, Naples 80121, Italy
- Currently at the Rowland Institute at Harvard, Harvard University, Cambridge, MA, 02142, USA
| | - Ahmed El Mallahi
- Microgravity Research Centre, Université Libre de Bruxelles, Brussels, 1050, Belgium
| | - Pietro Ferraro
- National Institute of Optics, Unit of Naples - National Research Council, Pozzuoli 80078, Italy
| | - Roberta Dale
- Center for Assisted Fertilization - CFA, Naples 80123, Italy
| | | | - Brian Dale
- Center for Assisted Fertilization - CFA, Naples 80123, Italy
| | - Giuseppe Coppola
- Institute for Microelectronics and Microsystems, Unit of Naples - National Research Council, Naples 80121, Italy
| | - Frank Dubois
- Microgravity Research Centre, Université Libre de Bruxelles, Brussels, 1050, Belgium
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El Mallahi A, Dubois F. Separation of overlapped particles in digital holographic microscopy. OPTICS EXPRESS 2013; 21:6466-6479. [PMID: 23482216 DOI: 10.1364/oe.21.006466] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
In this paper, we present a procedure to separate aggregates of overlapped particles in digital holograms, based on a focus plane analysis applied to each particle. The method can be applied either on phase or on amplitude objects, according that each object has a border in one focus plane. Numerical simulations are performed to quantify the robustness of the process by increasing the overlapping areas between the particles. The separation algorithm is successfully demonstrated experimentally on different types of aggregates.
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Affiliation(s)
- Ahmed El Mallahi
- Université Libre de Bruxelles, Microgravity Research Center, 50 Av F Roosevelt, CP 165/62, B-1050 Brussel,
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El Mallahi A, Minetti C, Dubois F. Automated three-dimensional detection and classification of living organisms using digital holographic microscopy with partial spatial coherent source: application to the monitoring of drinking water resources. APPLIED OPTICS 2013; 52:A68-80. [PMID: 23292424 DOI: 10.1364/ao.52.000a68] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
In this paper, we investigate the use of a digital holographic microscope working with partially coherent spatial illumination for an automated detection and classification of living organisms. A robust automatic method based on the computation of propagating matrices is proposed to detect the 3D position of organisms. We apply this procedure to the evaluation of drinking water resources by developing a classification process to identify parasitic protozoan Giardia lamblia cysts among two other similar organisms. By selecting textural features from the quantitative optical phase instead of morphological ones, a robust classifier is built to propose a new method for the unambiguous detection of Giardia lamblia cyst that present a critical contamination risk.
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Affiliation(s)
- Ahmed El Mallahi
- Microgravity Research Center, Université Libre de Bruxelles, 50 Avenue F. Roosevelt, CP 165/62, Brussels B-1050, Belgium.
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Sato A, Pham QD, Hasegawa S, Hayasaki Y. Three-dimensional subpixel estimation in holographic position measurement of an optically trapped nanoparticle. APPLIED OPTICS 2013; 52:A216-A222. [PMID: 23292397 DOI: 10.1364/ao.52.00a216] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Accepted: 10/07/2012] [Indexed: 06/01/2023]
Abstract
We propose three-dimensional (3D) subpixel estimation in the position measurement of a nanoparticle held in optical tweezers in water by using an in-line, low-coherence digital holographic microscope. The 3D subpixel estimation was performed with the addition of axial subpixel estimation to the lateral subpixel estimation introduced in our previous work [Appl. Opt.50, H183 (2011)]. The axial subpixel estimation allowed the step length in the diffraction calculation of a hologram to be increased to ~20 nm while keeping the axial resolution of ~3 nm. This drastically decreased the computation time of the diffraction calculation to less than 10% of the two-dimensional subpixel estimation.
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Affiliation(s)
- Akira Sato
- Center for Optical Research and Education (CORE), Utsunomiya University, 7-1-2 Yoto, Utsunomiya 321-8585, Japan
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Memmolo P, Iannone M, Ventre M, Netti PA, Finizio A, Paturzo M, Ferraro P. On the holographic 3D tracking of in vitro cells characterized by a highly-morphological change. OPTICS EXPRESS 2012; 20:28485-93. [PMID: 23263084 DOI: 10.1364/oe.20.028485] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Digital Holography (DH) in microscopic configuration is a powerful tool for the imaging of micro-objects contained into a three dimensional (3D) volume, by a single-shot image acquisition. Many studies report on the ability of DH to track particle, microorganism and cells in 3D. However, very few investigations are performed with objects that change severely their morphology during the observation period. Here we study DH as a tool for 3D tracking an osteosarcoma cell line for which extensive changes in cell morphology are associated to cell motion. Due to the great unpredictable morphological change, retrieving cell's position in 3D can become a complicated issue. We investigate and discuss in this paper how the tridimensional position can be affected by the continuous change of the cells. Moreover we propose and test some strategies to afford the problems and compare it with others approaches. Finally, results on the 3D tracking and comments are reported and illustrated.
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Affiliation(s)
- Pasquale Memmolo
- Center for Advanced Biomaterials for Health Care@CRIB, Istituto Italiano di tecnologia, Largo Barsanti e Matteucci 53, 80125 Napoli, Italy.
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Memmolo P, Finizio A, Paturzo M, Miccio L, Ferraro P. Twin-beams digital holography for 3D tracking and quantitative phase-contrast microscopy in microfluidics. OPTICS EXPRESS 2011; 19:25833-25842. [PMID: 22273976 DOI: 10.1364/oe.19.025833] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We report on a compact twin-beam interferometer that can be adopted as a flexible diagnostic tool in microfluidic platforms with twofold functionality. The novel configuration allows 3D tracking of micro-particles and, at same time, can simultaneously furnish Quantitative Phase-contrast maps of tracked micro-objects by interference microscopy, without changing the configuration. Experimental demonstration is given on for in vitro cells in a microfluidic environment.
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Affiliation(s)
- Pasquale Memmolo
- CNR - Istituto Nazionale di Ottica, via Campi Flegrei 34, Pozzuoli, Italy
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Jia W, Chen Z, Wen FJ, Zhou C, Chow YT, Chung PS. Coaxial holographic encoding based on pure phase modulation. APPLIED OPTICS 2011; 50:H10-H15. [PMID: 22192995 DOI: 10.1364/ao.50.000h10] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We describe a simple technique for coaxial holographic image recording and reconstruction, employing a spatial light modulator (SLM) modified in pure phase mode. In the image encoding system, both the reference beam in the outside part and the signal beam in the inside part are displayed by an SLM based on the twisted nematic LCD. For a binary image, the part with amplitude of "1" is modulated with random phase, while the part with amplitude of "0" is modulated with constant phase. After blocking the dc component of the spatial frequencies, a Fourier transform (FT) hologram is recorded with a uniform intensity distribution. The amplitude image is reconstructed by illuminating the reference beam onto the hologram, which is much simpler than existing phase modulated FT holography techniques. The technique of coaxial holographic image encoding and recovering with pure phase modulation is demonstrated theoretically and experimentally in this paper. As the holograms are recorded without the high-intensity dc component, the storage density with volume medium may be increased with the increase of dynamic range. Such a simple modulation method will have potential applications in areas such as holographic encryption and high-density disk storage systems.
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Affiliation(s)
- Wei Jia
- Department of Electronic Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon Tong, Kowloon, Hong Kong, China
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Sandoz P, Jacquot M. Lensless vision system for in-plane positioning of a patterned plate with subpixel resolution. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2011; 28:2494-2500. [PMID: 22193262 DOI: 10.1364/josaa.28.002494] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Whereas vision is an efficient way for noncontact sensing of many physical quantities, it assumes a cumbersome imaging system that may be very problematic in confined environments. In such contexts, the design of a compact vision probe can be based on digital holography that is a lensless imaging principle. In this interferometric method, object scenes are reconstructed numerically through wave propagation computations applied to a diffracted optical field recorded as an interferogram. We applied this approach to the visual positioning of a micropatterned glass plate. The pseudoperiodic pattern deposited on the surface is suited for absolute in-plane position determination as well as for fine object-feature interpolation leading to subpixel resolution. Results obtained demonstrate a lateral resolution of 0.1 μm, corresponding to 1/20th of a pixel, from a 150 μm period of the pseudoperiodic pattern and with a demonstrated excursion range of 1.6 cm. In the future, such position encoding could be applied to the backside of standardized sample holders for the easy localization of regions of interest when specimens are transferred from an instrument to another one, for instance in nanotechnology processes.
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Affiliation(s)
- Patrick Sandoz
- Département de Mécanique Appliquée, Institut FEMTO-ST, UMR CNRS, Université de Franche-Comté, Besançon, France
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Merola F, Miccio L, Paturzo M, Finizio A, Grilli S, Ferraro P. Driving and analysis of micro-objects by digital holographic microscope in microfluidics. OPTICS LETTERS 2011; 36:3079-3081. [PMID: 21847166 DOI: 10.1364/ol.36.003079] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We propose an optical configuration in which floating particles in a microfluidic chamber can be characterized by an interference microscopy configuration to obtain quantitative phase-contrast maps. The configuration is simply made by two laser beams from the same laser source. One beam provides the optical forces for driving the particle along appropriate paths, but at same time works as the object illumination beam in the holographic microscope. The second beam plays the role of the reference beam, allowing recording of an interference fringe pattern (i.e., the digital hologram) in an out-of-focus image plane. The system and method are illustrated and experimental results are offered for polymeric particles as well as for in vitro cells with the aim to demonstrate the approach.
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Affiliation(s)
- F Merola
- Istituto Nazionale di Ottica (CNR-INO), Via Campi Flegrei 34, 80078 - Pozzuoli, Naples, Italy.
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