1
|
Zhao J, Liu L, Wang T, Zhang J, Wang X, Du X, Hao R, Liu J, Liu Y, Liu Y. Quantitative phase imaging of living red blood cells combining digital holographic microscopy and deep learning. JOURNAL OF BIOPHOTONICS 2023; 16:e202300090. [PMID: 37321984 DOI: 10.1002/jbio.202300090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 06/12/2023] [Accepted: 06/13/2023] [Indexed: 06/17/2023]
Abstract
Digital holographic microscopy as a non-contacting, non-invasive, and highly accurate measurement technology, is becoming a valuable method for quantitatively investigating cells and tissues. Reconstruction of phases from a digital hologram is a key step in quantitative phase imaging for biological and biomedical research. This study proposes a two-stage deep convolutional neural network named VY-Net, to realize the effective and robust phase reconstruction of living red blood cells. The VY-Net can obtain the phase information of an object directly from a single-shot off-axis digital hologram. We also propose two new indices to evaluate the reconstructed phases. In experiments, the mean of the structural similarity index of reconstructed phases can reach 0.9309, and the mean of the accuracy of reconstructions of reconstructed phases is as high as 91.54%. An unseen phase map of a living human white blood cell is successfully reconstructed by the trained VY-Net, demonstrating its strong generality.
Collapse
Affiliation(s)
- Jiaxi Zhao
- School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, China
| | - Lin Liu
- School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, China
| | - Tianhe Wang
- School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, China
| | - Jing Zhang
- School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, China
| | - Xiangzhou Wang
- School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, China
| | - Xiaohui Du
- School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, China
| | - Ruqian Hao
- School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, China
| | - Juanxiu Liu
- School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, China
| | - Yi Liu
- School of Physics, University of Electronic Science and Technology of China, Chengdu, China
| | - Yong Liu
- School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, China
| |
Collapse
|
2
|
Tanwar S, Wu L, Zahn N, Raj P, Ghaemi B, Chatterjee A, Bulte JWM, Barman I. Targeted Enzyme Activity Imaging with Quantitative Phase Microscopy. NANO LETTERS 2023; 23:4602-4608. [PMID: 37154678 PMCID: PMC10798004 DOI: 10.1021/acs.nanolett.3c01090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Quantitative phase imaging (QPI) is a powerful optical imaging modality for label-free, rapid, and three-dimensional (3D) monitoring of cells and tissues. However, molecular imaging of important intracellular biomolecules such as enzymes remains a largely unexplored area for QPI. Herein, we introduce a fundamentally new approach by designing QPI contrast agents that allow sensitive detection of intracellular biomolecules. We report a new class of bio-orthogonal QPI-nanoprobes for in situ high-contrast refractive index (RI) imaging of enzyme activity. The nanoprobes feature silica nanoparticles (SiO2 NPs) having higher RI than endogenous cellular components and surface-anchored cyanobenzothiazole-cysteine (CBT-Cys) conjugated enzyme-responsive peptide sequences. The nanoprobes specifically aggregated in cells with target enzyme activity, increasing intracellular RI and enabling precise visualization of intracellular enzyme activity. We envision that this general design of QPI-nanoprobes could open doors for spatial-temporal mapping of enzyme activity with direct implications for disease diagnosis and evaluating the therapeutic efficacy.
Collapse
Affiliation(s)
- Swati Tanwar
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Lintong Wu
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Noah Zahn
- Department of Chemical & Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Piyush Raj
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Behnaz Ghaemi
- The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University, School of Medicine, Baltimore, Maryland 21205, USA
- Cellular Imaging Section and Vascular Biology Program, Institute for Cell Engineering, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
| | - Arnab Chatterjee
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Jeff W M Bulte
- Department of Chemical & Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
- The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University, School of Medicine, Baltimore, Maryland 21205, USA
- Cellular Imaging Section and Vascular Biology Program, Institute for Cell Engineering, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
- F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Inc., Baltimore, Maryland 21205, USA
- Department of Oncology, Johns Hopkins University, Baltimore, Maryland 21287, USA
| | - Ishan Barman
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
- The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University, School of Medicine, Baltimore, Maryland 21205, USA
- Department of Oncology, Johns Hopkins University, Baltimore, Maryland 21287, USA
| |
Collapse
|
3
|
Pospíšil J, Vítovská D, Kofroňová O, Muchová K, Šanderová H, Hubálek M, Šiková M, Modrák M, Benada O, Barák I, Krásný L. Bacterial nanotubes as a manifestation of cell death. Nat Commun 2020; 11:4963. [PMID: 33009406 PMCID: PMC7532143 DOI: 10.1038/s41467-020-18800-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 09/03/2020] [Indexed: 12/18/2022] Open
Abstract
Bacterial nanotubes are membranous structures that have been reported to function as conduits between cells to exchange DNA, proteins, and nutrients. Here, we investigate the morphology and formation of bacterial nanotubes using Bacillus subtilis. We show that nanotube formation is associated with stress conditions, and is highly sensitive to the cells' genetic background, growth phase, and sample preparation methods. Remarkably, nanotubes appear to be extruded exclusively from dying cells, likely as a result of biophysical forces. Their emergence is extremely fast, occurring within seconds by cannibalizing the cell membrane. Subsequent experiments reveal that cell-to-cell transfer of non-conjugative plasmids depends strictly on the competence system of the cell, and not on nanotube formation. Our study thus supports the notion that bacterial nanotubes are a post mortem phenomenon involved in cell disintegration, and are unlikely to be involved in cytoplasmic content exchange between live cells.
Collapse
Affiliation(s)
- Jiří Pospíšil
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, 142 20, Prague 4, Czech Republic
| | - Dragana Vítovská
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, 142 20, Prague 4, Czech Republic
| | - Olga Kofroňová
- Laboratory of Molecular Structure Characterization, Institute of Microbiology of the Czech Academy of Sciences, 142 20, Prague 4, Czech Republic
| | - Katarína Muchová
- Department of Microbial Genetics, Institute of Molecular Biology, Slovak Academy of Sciences, 845 51, Bratislava, Slovakia
| | - Hana Šanderová
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, 142 20, Prague 4, Czech Republic
| | - Martin Hubálek
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, 160 00, Prague 6, Czech Republic
| | - Michaela Šiková
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, 142 20, Prague 4, Czech Republic
| | - Martin Modrák
- Laboratory of Bioinformatics/Core Facility, Institute of Microbiology of the Czech Academy of Sciences, 142 20, Prague 4, Czech Republic
| | - Oldřich Benada
- Laboratory of Molecular Structure Characterization, Institute of Microbiology of the Czech Academy of Sciences, 142 20, Prague 4, Czech Republic.
| | - Imrich Barák
- Department of Microbial Genetics, Institute of Molecular Biology, Slovak Academy of Sciences, 845 51, Bratislava, Slovakia.
| | - Libor Krásný
- Laboratory of Microbial Genetics and Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, 142 20, Prague 4, Czech Republic.
| |
Collapse
|
4
|
Lee W, Choi JH, Ryu S, Jung D, Song J, Lee JS, Joo C. Color-coded LED microscopy for quantitative phase imaging: Implementation and application to sperm motility analysis. Methods 2018; 136:66-74. [DOI: 10.1016/j.ymeth.2017.11.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 11/17/2017] [Accepted: 11/18/2017] [Indexed: 10/18/2022] Open
|
5
|
Majeed H, Sridharan S, Mir M, Ma L, Min E, Jung W, Popescu G. Quantitative phase imaging for medical diagnosis. JOURNAL OF BIOPHOTONICS 2017; 10:177-205. [PMID: 27539534 DOI: 10.1002/jbio.201600113] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Revised: 07/06/2016] [Accepted: 07/13/2016] [Indexed: 05/19/2023]
Abstract
Optical microscopy is an indispensable diagnostic tool in modern healthcare. As a prime example, pathologists rely exclusively on light microscopy to investigate tissue morphology in order to make a diagnosis. While advances in light microscopy and contrast markers allow pathologists to visualize cells and tissues in unprecedented detail, the interpretation of these images remains largely subjective, leading to inter- and intra-observer discrepancy. Furthermore, conventional microscopy images capture qualitative information which makes it difficult to automate the process, reducing the throughput achievable in the diagnostic workflow. Quantitative Phase Imaging (QPI) techniques have been advanced in recent years to address these two challenges. By quantifying physical parameters of cells and tissues, these systems remove subjectivity from the disease diagnosis process and allow for easier automation to increase throughput. In addition to providing quantitative information, QPI systems are also label-free and can be easily assimilated into the current diagnostic workflow in the clinic. In this paper we review the advances made in disease diagnosis by QPI techniques. We focus on the areas of hematological diagnosis and cancer pathology, which are the areas where most significant advances have been made to date. [Image adapted from Y. Park, M. Diez-Silva, G. Popescu, G. Lykotrafitis, W. Choi, M. S. Feld, and S. Suresh, Proc. Natl. Acad. Sci. 105, 13730-13735 (2008).].
Collapse
Affiliation(s)
- Hassaan Majeed
- Quantitative Light Imaging Lab, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana Champaign, 405 N. Mathews Ave., Urbana, IL, 61801, USA
| | - Shamira Sridharan
- Biomedical Engineering Department, University of California Davis, Genome and Biomedical Sciences Facility #2603B, 451 Health Science Dr., Davis, CA, 95616, USA
| | - Mustafa Mir
- Molecular and Cell Biology, University of California, Berkeley, 485 Li Ka Shing Center, 94720, Berkeley, CA, USA
| | - Lihong Ma
- Institute of Information Optics, Zhejiang Normal University, Jinhua, 321004, China
| | - Eunjung Min
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Ulsan, 44919, Republic of Korea
| | - Woonggyu Jung
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Ulsan, 44919, Republic of Korea
- Center for Soft and Living Matter, Institute for Basic Science (IBS), 50 UNIST-gil, Ulsan, 44919, Republic of Korea
| | - Gabriel Popescu
- Quantitative Light Imaging Lab, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana Champaign, 405 N. Mathews Ave., Urbana, IL, 61801, USA
| |
Collapse
|
6
|
Liu PY, Chin LK, Ser W, Chen HF, Hsieh CM, Lee CH, Sung KB, Ayi TC, Yap PH, Liedberg B, Wang K, Bourouina T, Leprince-Wang Y. Cell refractive index for cell biology and disease diagnosis: past, present and future. LAB ON A CHIP 2016; 16:634-44. [PMID: 26732872 DOI: 10.1039/c5lc01445j] [Citation(s) in RCA: 218] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Cell refractive index is a key biophysical parameter, which has been extensively studied. It is correlated with other cell biophysical properties including mechanical, electrical and optical properties, and not only represents the intracellular mass and concentration of a cell, but also provides important insight for various biological models. Measurement techniques developed earlier only measure the effective refractive index of a cell or a cell suspension, providing only limited information on cell refractive index and hence hindering its in-depth analysis and correlation. Recently, the emergence of microfluidic, photonic and imaging technologies has enabled the manipulation of a single cell and the 3D refractive index of a single cell down to sub-micron resolution, providing powerful tools to study cells based on refractive index. In this review, we provide an overview of cell refractive index models and measurement techniques including microfluidic chip-based techniques for the last 50 years, present the applications and significance of cell refractive index in cell biology, hematology, and pathology, and discuss future research trends in the field, including 3D imaging methods, integration with microfluidics and potential applications in new and breakthrough research areas.
Collapse
Affiliation(s)
- P Y Liu
- Université Paris-Est, UPEM, F-77454 Marne-la-Vallée, France.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
7
|
Yoon J, Kim K, Park H, Choi C, Jang S, Park Y. Label-free characterization of white blood cells by measuring 3D refractive index maps. BIOMEDICAL OPTICS EXPRESS 2015; 6:3865-75. [PMID: 26504637 PMCID: PMC4605046 DOI: 10.1364/boe.6.003865] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 08/07/2015] [Accepted: 09/01/2015] [Indexed: 05/02/2023]
Abstract
The characterization of white blood cells (WBCs) is crucial for blood analyses and disease diagnoses. However, current standard techniques rely on cell labeling, a process which imposes significant limitations. Here we present three-dimensional (3D) optical measurements and the label-free characterization of mouse WBCs using optical diffraction tomography. 3D refractive index (RI) tomograms of individual WBCs are constructed from multiple two-dimensional quantitative phase images of samples illuminated at various angles of incidence. Measurements of the 3D RI tomogram of WBCs enable the separation of heterogeneous populations of WBCs using quantitative morphological and biochemical information. Time-lapse tomographic measurements also provide the 3D trajectory of micrometer-sized beads ingested by WBCs. These results demonstrate that optical diffraction tomography can be a useful and versatile tool for the study of WBCs.
Collapse
Affiliation(s)
- Jonghee Yoon
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 305-701, South Korea
| | - Kyoohyun Kim
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 305-701, South Korea
| | - HyunJoo Park
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 305-701, South Korea
| | - Chulhee Choi
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-701, South Korea
| | - Seongsoo Jang
- Department of Laboratory Medicine, University of Ulsan, College of Medicine and Asan Medical Center, Seoul 138-736, South Korea
| | - YongKeun Park
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 305-701, South Korea
| |
Collapse
|
8
|
Jafarfard MR, Tayebi B, Lee S, Bae YS, Kim DY. Optimum phase shift for quantitative phase microscopy in volume measurement. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2014; 31:2429-2436. [PMID: 25401354 DOI: 10.1364/josaa.31.002429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Volume measurement of a phase object is one of the most distinctive capabilities of quantitative phase microscopy (QPM). However, the accuracy of a measured volume is limited by the different noises of a measurement system and the finite bandpass filter used in the phase extraction algorithm. In this paper, we analyze the inherent errors in volume measurement with QPM and propose the optimum condition that can minimize these errors. We find that phase information of a sample in the frequency domain nonlinearly oscillates as a function of the phase shift corresponding to the sample and its medium, and that the phase information of a sample inside the bandpass filter can be maximized by a proper phase shift. Through numerical simulations and actual experiments, we demonstrate that the error in phase volume measurement can be effectively reduced by the enhancement of the phase signal inside the bandpass region using an optimum amount of phase, which can be controlled by changing either the medium index or the wavelength of illumination.
Collapse
|
9
|
Marquet P, Depeursinge C, Magistretti PJ. Exploring neural cell dynamics with digital holographic microscopy. Annu Rev Biomed Eng 2013; 15:407-31. [PMID: 23662777 DOI: 10.1146/annurev-bioeng-071812-152356] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In this review, we summarize how the new concept of digital optics applied to the field of holographic microscopy has allowed the development of a reliable and flexible digital holographic quantitative phase microscopy (DH-QPM) technique at the nanoscale particularly suitable for cell imaging. Particular emphasis is placed on the original biological information provided by the quantitative phase signal. We present the most relevant DH-QPM applications in the field of cell biology, including automated cell counts, recognition, classification, three-dimensional tracking, discrimination between physiological and pathophysiological states, and the study of cell membrane fluctuations at the nanoscale. In the last part, original results show how DH-QPM can address two important issues in the field of neurobiology, namely, multiple-site optical recording of neuronal activity and noninvasive visualization of dendritic spine dynamics resulting from a full digital holographic microscopy tomographic approach.
Collapse
Affiliation(s)
- P Marquet
- Centre de Neurosciences Psychiatriques, Centre Hospitalier Universitaire Vaudois (CHUV), Département de Psychiatrie, Site de Cery, CH-1008 Prilly/Lausanne, Switzerland
| | | | | |
Collapse
|
10
|
Quantitative phase imaging techniques for the study of cell pathophysiology: from principles to applications. SENSORS 2013; 13:4170-91. [PMID: 23539026 PMCID: PMC3673078 DOI: 10.3390/s130404170] [Citation(s) in RCA: 222] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Revised: 03/11/2013] [Accepted: 03/18/2013] [Indexed: 11/17/2022]
Abstract
A cellular-level study of the pathophysiology is crucial for understanding the mechanisms behind human diseases. Recent advances in quantitative phase imaging (QPI) techniques show promises for the cellular-level understanding of the pathophysiology of diseases. To provide important insight on how the QPI techniques potentially improve the study of cell pathophysiology, here we present the principles of QPI and highlight some of the recent applications of QPI ranging from cell homeostasis to infectious diseases and cancer.
Collapse
|
11
|
Kim YR, Lee SE, Kang IC, Nam KI, Choy HE, Rhee JH. A bacterial RTX toxin causes programmed necrotic cell death through calcium-mediated mitochondrial dysfunction. J Infect Dis 2012; 207:1406-15. [PMID: 23225896 DOI: 10.1093/infdis/jis746] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Vibrio vulnificus, a halophilic estuarine bacterium causing fatal septicemia and necrotic wound infection, is highly cytotoxic to eukaryotic cells. We have reported that RtxA1 toxin kills host cells only after they come into contact with bacteria and plays an essential role in the pathogenesis of V. vulnificus. This study was performed to elucidate the mechanism by which the RtxA1 toxin mediates the death of HeLa cells. By using confocal microscopy and immunoblot analysis, we show that the 501-kDa RtxA1 toxin is processed into 2 fragments after its secretion into host cells. The largerN-terminal fragment (RtxA1-N; approximately 370 kDa) remained at the host cell membrane, whereas the smaller C-terminal fragment (RtxA1-C; approximately 130 kDa) was internalized into the host cell cytoplasm. RtxA1-N is believed to polymerize and form pores at the host cell membrane and to induce an increase in necrotic volume related to calcium. The RtxA1 toxin caused an increase in the intracellular Ca(2+) concentration and the subsequent activation of JNK. The cell death mechanism occurred via calcium-dependent mitochondrial pathways, which caused calcium sequestration in the mitochondria, accompanied by irreversible mitochondrial membrane dysfunction and adenosine triphosphate depletion, and was later accompanied by the disruption of the integrity of the plasma membrane.
Collapse
Affiliation(s)
- Young Ran Kim
- Clinical Vaccine R&D Center, Department of Microbiology, Chonnam National University Medical School, 5 Hak-Dong, Dong-Gu, Gwangju 501–746, Korea
| | | | | | | | | | | |
Collapse
|
12
|
Lue N, Kang JW, Hillman TR, Dasari RR, Yaqoob Z. Single-shot quantitative dispersion phase microscopy. APPLIED PHYSICS LETTERS 2012; 101:84101. [PMID: 22991482 PMCID: PMC3436913 DOI: 10.1063/1.4745785] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Accepted: 07/30/2012] [Indexed: 05/18/2023]
Abstract
We present an imaging modality capable of providing high-speed optical dispersion measurements of live cells. The technique permits wide-field measurement of the optical phase shifts introduced by a sample for multiple discrete wavelengths in a single image capture. Utilizing spatial modulation and the wavelength dependence of the interference-fringe spacing, average refractive index as a function of wavelength is obtained, yielding optical dispersion measurements of the sample under observation. Because of its simple and low-cost design, the technique can be readily integrated into a standard microscope to collect additional diagnostic information about biological cells.
Collapse
Affiliation(s)
- Niyom Lue
- George R. Harrison Spectroscopy Laboratory, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
| | | | | | | | | |
Collapse
|