1
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Seesan T, Mukherjee P, Abd El-Sadek I, Lim Y, Zhu L, Makita S, Yasuno Y. Optical-coherence-tomography-based deep-learning scatterer-density estimator using physically accurate noise model. BIOMEDICAL OPTICS EXPRESS 2024; 15:2832-2848. [PMID: 38855681 PMCID: PMC11161371 DOI: 10.1364/boe.519743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 03/19/2024] [Accepted: 03/26/2024] [Indexed: 06/11/2024]
Abstract
We demonstrate a deep-learning-based scatterer density estimator (SDE) that processes local speckle patterns of optical coherence tomography (OCT) images and estimates the scatterer density behind each speckle pattern. The SDE is trained using large quantities of numerically simulated OCT images and their associated scatterer densities. The numerical simulation uses a noise model that incorporates the spatial properties of three types of noise, i.e., shot noise, relative-intensity noise, and non-optical noise. The SDE's performance was evaluated numerically and experimentally using two types of scattering phantom and in vitro tumor spheroids. The results confirmed that the SDE estimates scatterer densities accurately. The estimation accuracy improved significantly when compared with our previous deep-learning-based SDE, which was trained using numerical speckle patterns generated from a noise model that did not account for the spatial properties of noise.
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Affiliation(s)
- Thitiya Seesan
- Computational Optics Group, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan
| | - Pradipta Mukherjee
- Computational Optics Group, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan
| | - Ibrahim Abd El-Sadek
- Computational Optics Group, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan
- Department of Physics, Faculty of Science, Damietta University, New Damietta City 34517, Damietta, Egypt
| | - Yiheng Lim
- Computational Optics Group, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan
| | - Lida Zhu
- Computational Optics Group, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan
| | - Shuichi Makita
- Computational Optics Group, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan
| | - Yoshiaki Yasuno
- Computational Optics Group, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan
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2
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Neuhaus K, Khan S, Thaware O, Ni S, Aga M, Jia Y, Redd T, Chen S, Huang D, Jian Y. Real-time line-field optical coherence tomography for cellular resolution imaging of biological tissue. BIOMEDICAL OPTICS EXPRESS 2024; 15:1059-1073. [PMID: 38404311 PMCID: PMC10890841 DOI: 10.1364/boe.511187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 01/17/2024] [Accepted: 01/18/2024] [Indexed: 02/27/2024]
Abstract
A real-time line-field optical coherence tomography (LF-OCT) system is demonstrated with image acquisition rates of up to 5000 B-frames or 2.5 million A-lines per second for 500 A-lines per B-frame. The system uses a high-speed low-cost camera to achieve continuous data transfer rates required for real-time imaging, allowing the evaluation of future applications in clinical or intraoperative environments. The light source is an 840 nm super-luminescent diode. Leveraging parallel computing with GPU and high speed CoaXPress data transfer interface, we were able to acquire, process, and display OCT data with low latency. The studied system uses anamorphic beam shaping in the detector arm, optimizing the field of view and sensitivity for imaging biological tissue at cellular resolution. The lateral and axial resolution measured in air were 1.7 µm and 6.3 µm, respectively. Experimental results demonstrate real-time inspection of the trabecular meshwork and Schlemm's canal on ex vivo corneoscleral wedges and real-time imaging of endothelial cells of human subjects in vivo.
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Affiliation(s)
- Kai Neuhaus
- Casey Eye Institute, Oregon Health & Science University , Portland, OR 97239, USA
| | - Shanjida Khan
- Casey Eye Institute, Oregon Health & Science University , Portland, OR 97239, USA
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, OR 97239, USA
| | - Omkar Thaware
- Casey Eye Institute, Oregon Health & Science University , Portland, OR 97239, USA
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, OR 97239, USA
| | - Shuibin Ni
- Casey Eye Institute, Oregon Health & Science University , Portland, OR 97239, USA
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, OR 97239, USA
| | - Mini Aga
- Casey Eye Institute, Oregon Health & Science University , Portland, OR 97239, USA
| | - Yali Jia
- Casey Eye Institute, Oregon Health & Science University , Portland, OR 97239, USA
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, OR 97239, USA
| | - Travis Redd
- Casey Eye Institute, Oregon Health & Science University , Portland, OR 97239, USA
| | - Siyu Chen
- Casey Eye Institute, Oregon Health & Science University , Portland, OR 97239, USA
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, OR 97239, USA
| | - David Huang
- Casey Eye Institute, Oregon Health & Science University , Portland, OR 97239, USA
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, OR 97239, USA
| | - Yifan Jian
- Casey Eye Institute, Oregon Health & Science University , Portland, OR 97239, USA
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, OR 97239, USA
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3
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Mazlin V. Optical tomography in a single camera frame using fringe-encoded deep-learning full-field OCT. BIOMEDICAL OPTICS EXPRESS 2024; 15:222-236. [PMID: 38223177 PMCID: PMC10783898 DOI: 10.1364/boe.506664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 11/29/2023] [Accepted: 12/03/2023] [Indexed: 01/16/2024]
Abstract
Optical coherence tomography is a valuable tool for in vivo examination thanks to its superior combination of axial resolution, field-of-view and working distance. OCT images are reconstructed from several phases that are obtained by modulation/multiplexing of light wavelength or optical path. This paper shows that only one phase (and one camera frame) is sufficient for en face tomography. The idea is to encode a high-frequency fringe patterns into the selected layer of the sample using low-coherence interferometry. These patterns can then be efficiently extracted with a high-pass filter enhanced via deep learning networks to create the tomographic full-field OCT view. This brings 10-fold improvement in imaging speed, considerably reducing the phase errors and incoherent light artifacts related to in vivo movements. Moreover, this work opens a path for low-cost tomography with slow consumer cameras. Optically, the device resembles the conventional time-domain full-field OCT without incurring additional costs or a field-of-view/resolution reduction. The approach is validated by imaging in vivo cornea in human subjects. Open-source and easy-to-follow codes for data generation/training/inference with U-Net/Pix2Pix networks are provided to be used in a variety of image-to-image translation tasks.
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Affiliation(s)
- Viacheslav Mazlin
- Institut Langevin, ESPCI Paris, PSL University, CNRS, 1 rue Jussieu, 75005 Paris, France
- Quinze-Vingts National Eye Hospital, 28 Rue de Charenton, 75012 Paris, France
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4
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Zhu L, Makita S, Tamaoki J, Lichtenegger A, Lim Y, Zhu Y, Kobayashi M, Yasuno Y. Multi-focus averaging for multiple scattering suppression in optical coherence tomography. BIOMEDICAL OPTICS EXPRESS 2023; 14:4828-4844. [PMID: 37791259 PMCID: PMC10545188 DOI: 10.1364/boe.493706] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 08/01/2023] [Accepted: 08/04/2023] [Indexed: 10/05/2023]
Abstract
Multiple scattering is one of the main factors that limits the penetration depth of optical coherence tomography (OCT) in scattering samples. We propose a method termed multi-focus averaging (MFA) to suppress the multiple-scattering signals and improve the image contrast of OCT in deep regions. The MFA method captures multiple OCT volumes with various focal positions and averages them in complex form after correcting the varying defocus through computational refocusing. Because the multiple-scattering takes different trajectories among the different focal position configurations, this averaging suppresses the multiple-scattering signal. Meanwhile, the single-scattering takes a consistent trajectory regardless of the focal position configuration and is not suppressed. Hence, the MFA method improves the ratio between the single-scattering signal and multiple-scattering signal, resulting in an enhancement in the image contrast. A scattering phantom and a postmortem zebrafish were measured to validate the proposed method. The results showed that the contrast of intensity images of both the phantom and zebrafish were improved using the MFA method, such that they were better than the contrast provided by the standard single focus averaging method. The MFA method provides a cost-effective solution for contrast enhancement through multiple-scattering reduction in tissue imaging using OCT systems.
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Affiliation(s)
- Lida Zhu
- Computational Optics Group, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Shuichi Makita
- Computational Optics Group, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Junya Tamaoki
- Department of Molecular and Developmental Biology, Institute of Medicine, University of Tsukuba, Japan
| | - Antonia Lichtenegger
- Computational Optics Group, University of Tsukuba, Tsukuba, Ibaraki, Japan
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Yiheng Lim
- Computational Optics Group, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Yiqiang Zhu
- Computational Optics Group, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Makoto Kobayashi
- Department of Molecular and Developmental Biology, Institute of Medicine, University of Tsukuba, Japan
| | - Yoshiaki Yasuno
- Computational Optics Group, University of Tsukuba, Tsukuba, Ibaraki, Japan
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5
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Samaei S, Nowacka K, Gerega A, Pastuszak Ż, Borycki D. Continuous-wave parallel interferometric near-infrared spectroscopy (CW πNIRS) with a fast two-dimensional camera. BIOMEDICAL OPTICS EXPRESS 2022; 13:5753-5774. [PMID: 36733725 PMCID: PMC9872890 DOI: 10.1364/boe.472643] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 09/16/2022] [Accepted: 10/01/2022] [Indexed: 06/02/2023]
Abstract
Interferometric near-infrared spectroscopy (iNIRS) is an optical method that noninvasively measures the optical and dynamic properties of the human brain in vivo. However, the original iNIRS technique uses single-mode fibers for light collection, which reduces the detected light throughput. The reduced light throughput is compensated by the relatively long measurement or integration times (∼1 sec), which preclude monitoring of rapid blood flow changes that could be linked to neural activation. Here, we propose parallel interferometric near-infrared spectroscopy (πNIRS) to overcome this limitation. In πNIRS we use multi-mode fibers for light collection and a high-speed, two-dimensional camera for light detection. Each camera pixel acts effectively as a single iNIRS channel. So, the processed signals from each pixel are spatially averaged to reduce the overall integration time. Moreover, interferometric detection provides us with the unique capability of accessing complex information (amplitude and phase) about the light remitted from the sample, which with more than 8000 parallel channels, enabled us to sense the cerebral blood flow with only a 10 msec integration time (∼100x faster than conventional iNIRS). In this report, we have described the theoretical foundations and possible ways to implement πNIRS. Then, we developed a prototype continuous wave (CW) πNIRS system and validated it in liquid phantoms. We used our CW πNIRS to monitor the pulsatile blood flow in a human forearm in vivo. Finally, we demonstrated that CW πNIRS could monitor activation of the prefrontal cortex by recording the change in blood flow in the forehead of the subject while he was reading an unknown text.
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Affiliation(s)
- Saeed Samaei
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
- Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Ks. Trojdena 4, 02-109, Warsaw, Poland
| | - Klaudia Nowacka
- International Centre for Translational Eye Research, Skierniewicka 10A, 01-230 Warsaw, Poland
| | - Anna Gerega
- Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Ks. Trojdena 4, 02-109, Warsaw, Poland
| | - Żanna Pastuszak
- Department of Neurosurgery, Mossakowski Medical Research Center Polish Academy of Sciences, Pawińskiego 5, 02-106 Warsaw, Poland
| | - Dawid Borycki
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
- International Centre for Translational Eye Research, Skierniewicka 10A, 01-230 Warsaw, Poland
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6
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Makita S, Azuma S, Mino T, Yamaguchi T, Miura M, Yasuno Y. Extending field-of-view of retinal imaging by optical coherence tomography using convolutional Lissajous and slow scan patterns. BIOMEDICAL OPTICS EXPRESS 2022; 13:5212-5230. [PMID: 36425618 PMCID: PMC9664899 DOI: 10.1364/boe.467563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 08/27/2022] [Accepted: 08/28/2022] [Indexed: 06/16/2023]
Abstract
Optical coherence tomography (OCT) is a high-speed non-invasive cross-sectional imaging technique. Although its imaging speed is high, three-dimensional high-spatial-sampling-density imaging of in vivo tissues with a wide field-of-view (FOV) is challenging. We employed convolved Lissajous and slow circular scanning patterns to extend the FOV of retinal OCT imaging with a 1-µm, 100-kHz-sweep-rate swept-source OCT prototype system. Displacements of sampling points due to eye movements are corrected by post-processing based on a Lissajous scan. Wide FOV three-dimensional retinal imaging with high sampling density and motion correction is achieved. Three-dimensional structures obtained using repeated imaging sessions of a healthy volunteer and two patients showed good agreement. The demonstrated technique will extend the FOV of simple point-scanning OCT, such as commercial ophthalmic OCT devices, without sacrificing sampling density.
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Affiliation(s)
- Shuichi Makita
- Computational Optics Group,
University of Tsukuba, 1–1–1 Tennodai, Tsukuba, Ibaraki 305–8573, Japan
| | - Shinnosuke Azuma
- Topcon Corporation, 75–1 Hasunumacho, Itabashi, Tokyo 174–8580, Japan
| | - Toshihiro Mino
- Topcon Corporation, 75–1 Hasunumacho, Itabashi, Tokyo 174–8580, Japan
| | - Tatsuo Yamaguchi
- Topcon Corporation, 75–1 Hasunumacho, Itabashi, Tokyo 174–8580, Japan
| | - Masahiro Miura
- Department of Ophthalmology, Tokyo Medical University Ibaraki Medical Center, 3–20–1 Chuo, Ami, Ibaraki 300–0395, Japan
| | - Yoshiaki Yasuno
- Computational Optics Group,
University of Tsukuba, 1–1–1 Tennodai, Tsukuba, Ibaraki 305–8573, Japan
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7
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Han L, Tan B, Hosseinaee Z, Chen LK, Hileeto D, Bizheva K. Line-scanning SD-OCT for in-vivo, non-contact, volumetric, cellular resolution imaging of the human cornea and limbus. BIOMEDICAL OPTICS EXPRESS 2022; 13:4007-4020. [PMID: 35991928 PMCID: PMC9352278 DOI: 10.1364/boe.465916] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 06/08/2022] [Indexed: 05/12/2023]
Abstract
In-vivo, non-contact, volumetric imaging of the cellular and sub-cellular structure of the human cornea and limbus with optical coherence tomography (OCT) is challenging due to involuntary eye motion that introduces both motion artifacts and blur in the OCT images. Here we present the design of a line-scanning (LS) spectral-domain (SD) optical coherence tomography system that combines 2 × 3 × 1.7 µm (x, y, z) resolution in biological tissue with an image acquisition rate of ∼2,500 fps, and demonstrate its ability to image in-vivo and without contact with the tissue surface, the cellular structure of the human anterior segment tissues. Volumetric LS-SD-OCT images acquired over a field-of-view (FOV) of 0.7 mm × 1.4 mm reveal fine morphological details in the healthy human cornea, such as epithelial and endothelial cells, sub-basal nerves, as well as the cellular structure of the limbal crypts, the palisades of Vogt (POVs) and the blood microvasculature of the human limbus. LS-SD-OCT is a promising technology that can assist ophthalmologists with the early diagnostics and optimal treatment planning of ocular diseases affecting the human anterior eye.
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Affiliation(s)
- Le Han
- Department of Physics and Astronomy,
University of Waterloo, Waterloo, Ontario
N2L 3G1, Canada
- Contributed equally
| | - Bingyao Tan
- Department of Physics and Astronomy,
University of Waterloo, Waterloo, Ontario
N2L 3G1, Canada
- School of Chemical and Biomedical
Engineering, Nanyang Technological
University, 637460, Singapore
- SERI-NTU Advanced Ocular
Engineering (STANCE), 639798, Singapore
- Singapore Eye Research Institute,
Singapore National Eye Center, 169856,
Singapore
- Contributed equally
| | - Zohreh Hosseinaee
- Department of Physics and Astronomy,
University of Waterloo, Waterloo, Ontario
N2L 3G1, Canada
- Department of Systems Design Engineering,
University of Waterloo, Waterloo, Ontario
N2L 3G1, Canada
| | - Lin Kun Chen
- Department of Physics and Astronomy,
University of Waterloo, Waterloo, Ontario
N2L 3G1, Canada
| | - Denise Hileeto
- School of Optometry and Vision Science,
University of Waterloo, Waterloo, Ontario
N2L 3G1, Canada
| | - Kostadinka Bizheva
- Department of Physics and Astronomy,
University of Waterloo, Waterloo, Ontario
N2L 3G1, Canada
- Department of Systems Design Engineering,
University of Waterloo, Waterloo, Ontario
N2L 3G1, Canada
- School of Optometry and Vision Science,
University of Waterloo, Waterloo, Ontario
N2L 3G1, Canada
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8
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Zhu L, Makita S, Oida D, Miyazawa A, Oikawa K, Mukherjee P, Lichtenegger A, Distel M, Yasuno Y. Computational refocusing of Jones matrix polarization-sensitive optical coherence tomography and investigation of defocus-induced polarization artifacts. BIOMEDICAL OPTICS EXPRESS 2022; 13:2975-2994. [PMID: 35774308 PMCID: PMC9203103 DOI: 10.1364/boe.454975] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 04/13/2022] [Accepted: 04/13/2022] [Indexed: 06/15/2023]
Abstract
Here we demonstrate a long-depth-of-focus imaging method using polarization sensitive optical coherence tomography (PS-OCT). This method involves a combination of Fresnel-diffraction-model-based phase sensitive computational refocusing and Jones-matrix based PS-OCT (JM-OCT). JM-OCT measures four complex OCT images corresponding to four polarization channels. These OCT images are computationally refocused as preserving the mutual phase consistency. This method is validated using a static phantom, postmortem zebrafish, and ex vivo porcine muscle samples. All the samples demonstrated successful computationally-refocused birefringence and degree-of-polarization-uniformity (DOPU) images. We found that defocusing induces polarization artifacts, i.e., incorrectly high birefringence values and low DOPU values, which are substantially mitigated by computational refocusing.
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Affiliation(s)
- Lida Zhu
- Computational Optics Group, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Shuichi Makita
- Computational Optics Group, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Daisuke Oida
- Computational Optics Group, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Arata Miyazawa
- Computational Optics Group, University of Tsukuba, Tsukuba, Ibaraki, Japan
- Sky technology Inc., Tsukuba, Ibaraki, Japan
| | - Kensuke Oikawa
- Computational Optics Group, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Pradipta Mukherjee
- Computational Optics Group, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Antonia Lichtenegger
- Computational Optics Group, University of Tsukuba, Tsukuba, Ibaraki, Japan
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Martin Distel
- Innovative Cancer Models, St. Anna Children’s Cancer Research Institute, Vienna, Austria
| | - Yoshiaki Yasuno
- Computational Optics Group, University of Tsukuba, Tsukuba, Ibaraki, Japan
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9
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Tomczewski S, Węgrzyn P, Borycki D, Auksorius E, Wojtkowski M, Curatolo A. Light-adapted flicker optoretinograms captured with a spatio-temporal optical coherence-tomography (STOC-T) system. BIOMEDICAL OPTICS EXPRESS 2022; 13:2186-2201. [PMID: 35519256 PMCID: PMC9045926 DOI: 10.1364/boe.444567] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 02/20/2022] [Accepted: 02/23/2022] [Indexed: 06/14/2023]
Abstract
For many years electroretinography (ERG) has been used for obtaining information about the retinal physiological function. More recently, a new technique called optoretinography (ORG) has been developed. In one form of this technique, the physiological response of retinal photoreceptors to visible light, resulting in a nanometric photoreceptor optical path length change, is measured by phase-sensitive optical coherence tomography (OCT). To date, a limited number of studies with phase-based ORG measured the retinal response to a flickering light stimulation. In this work, we use a spatio-temporal optical coherence tomography (STOC-T) system to capture optoretinograms with a flickering stimulus over a 1.7 × 0.85 mm2 area of a light-adapted retina located between the fovea and the optic nerve. We show that we can detect statistically-significant differences in the photoreceptor optical path length (OPL) modulation amplitudes in response to different flicker frequencies and with better signal to noise ratios (SNRs) than for a dark-adapted eye. We also demonstrate the ability to spatially map such response to a patterned stimulus with light stripes flickering at different frequencies, highlighting the prospect of characterizing the spatially-resolved temporal-frequency response of the retina with ORG.
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Affiliation(s)
- Sławomir Tomczewski
- International Centre for Translational Eye Research, Skierniewicka 10A, 01-230, Warszawa, Poland
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warszawa, Poland
- Equal contributors
| | - Piotr Węgrzyn
- International Centre for Translational Eye Research, Skierniewicka 10A, 01-230, Warszawa, Poland
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warszawa, Poland
- Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warszawa, Poland
- Equal contributors
| | - Dawid Borycki
- International Centre for Translational Eye Research, Skierniewicka 10A, 01-230, Warszawa, Poland
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warszawa, Poland
| | - Egidijus Auksorius
- International Centre for Translational Eye Research, Skierniewicka 10A, 01-230, Warszawa, Poland
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warszawa, Poland
- Center for Physical Sciences and Technology (FTMC), Saulėtekio al. 3, LT-10257 Vilnius, Lithuania
| | - Maciej Wojtkowski
- International Centre for Translational Eye Research, Skierniewicka 10A, 01-230, Warszawa, Poland
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warszawa, Poland
| | - Andrea Curatolo
- International Centre for Translational Eye Research, Skierniewicka 10A, 01-230, Warszawa, Poland
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warszawa, Poland
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10
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Puyo L, Spahr H, Pfäffle C, Hüttmann G, Hillmann D. Retinal blood flow imaging with combined full-field swept-source optical coherence tomography and laser Doppler holography. OPTICS LETTERS 2022; 47:1198-1201. [PMID: 35230326 DOI: 10.1364/ol.449739] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 01/14/2022] [Indexed: 06/14/2023]
Abstract
Full-field swept-source optical coherence tomography (FF-SS-OCT) and laser Doppler holography (LDH) are two holographic imaging techniques presenting unique capabilities for ophthalmology. We report on interlaced FF-SS-OCT and LDH imaging with a single instrument. Effectively, retinal blood flow and pulsation could be quasi-simultaneously monitored. This instrument holds potential for a wide scope of ophthalmic applications.
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11
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Auksorius E, Borycki D, Wegrzyn P, Žičkienė I, Adomavičius K, Sikorski BL, Wojtkowski M. Multimode fiber as a tool to reduce cross talk in Fourier-domain full-field optical coherence tomography. OPTICS LETTERS 2022; 47:838-841. [PMID: 35167538 DOI: 10.1364/ol.449498] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 12/28/2021] [Indexed: 06/14/2023]
Abstract
Fourier-domain full-field optical coherence tomography (FD-FF-OCT) is an emerging tool for high-speed eye imaging. However, cross-talk formation in images limits the imaging depth. To this end, we have recently shown that reducing spatial coherence with a fast deformable membrane can suppress the noise but over a limited axial range and with substantial data processing. Here, we demonstrate that a multimode fiber with carefully chosen parameters enables cross-talk-free imaging over a long axial range and without significant artifacts. We also show that it can be used to image the human retina and choroid in vivo with exceptional contrast.
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12
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Krafft L, Gofas-Salas E, Lai-Tim Y, Paques M, Mugnier L, Thouvenin O, Mecê P, Meimon S. Partial-field illumination ophthalmoscope: improving the contrast of a camera-based retinal imager. APPLIED OPTICS 2021; 60:9951-9956. [PMID: 34807185 DOI: 10.1364/ao.428048] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 10/06/2021] [Indexed: 05/18/2023]
Abstract
Effective and accurate in vivo diagnosis of retinal pathologies requires high performance imaging devices, combining a large field of view and the ability to discriminate the ballistic signal from the diffuse background in order to provide a highly contrasted image of the retinal structures. Here, we have implemented the partial-field illumination ophthalmoscope, a patterned illumination modality, integrated to a high pixel rate adaptive optics full-field microscope. This non-invasive technique enables us to mitigate the low signal-to-noise ratio, intrinsic of full-field ophthalmoscopes, by partially illuminating the retina with complementary patterns to reconstruct a wide-field image. This new, to the best of our knowledge, modality provides an image contrast spanning from the full-field to the confocal contrast, depending on the pattern size. As a result, it offers various trade-offs in terms of contrast and acquisition speed, guiding the users towards the most efficient system for a particular clinical application.
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13
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Javidi B, Carnicer A, Anand A, Barbastathis G, Chen W, Ferraro P, Goodman JW, Horisaki R, Khare K, Kujawinska M, Leitgeb RA, Marquet P, Nomura T, Ozcan A, Park Y, Pedrini G, Picart P, Rosen J, Saavedra G, Shaked NT, Stern A, Tajahuerce E, Tian L, Wetzstein G, Yamaguchi M. Roadmap on digital holography [Invited]. OPTICS EXPRESS 2021; 29:35078-35118. [PMID: 34808951 DOI: 10.1364/oe.435915] [Citation(s) in RCA: 68] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 09/04/2021] [Indexed: 05/22/2023]
Abstract
This Roadmap article on digital holography provides an overview of a vast array of research activities in the field of digital holography. The paper consists of a series of 25 sections from the prominent experts in digital holography presenting various aspects of the field on sensing, 3D imaging and displays, virtual and augmented reality, microscopy, cell identification, tomography, label-free live cell imaging, and other applications. Each section represents the vision of its author to describe the significant progress, potential impact, important developments, and challenging issues in the field of digital holography.
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14
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Leitgeb R, Placzek F, Rank E, Krainz L, Haindl R, Li Q, Liu M, Andreana M, Unterhuber A, Schmoll T, Drexler W. Enhanced medical diagnosis for dOCTors: a perspective of optical coherence tomography. JOURNAL OF BIOMEDICAL OPTICS 2021; 26:JBO-210150-PER. [PMID: 34672145 PMCID: PMC8528212 DOI: 10.1117/1.jbo.26.10.100601] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 09/23/2021] [Indexed: 05/17/2023]
Abstract
SIGNIFICANCE After three decades, more than 75,000 publications, tens of companies being involved in its commercialization, and a global market perspective of about USD 1.5 billion in 2023, optical coherence tomography (OCT) has become one of the fastest successfully translated imaging techniques with substantial clinical and economic impacts and acceptance. AIM Our perspective focuses on disruptive forward-looking innovations and key technologies to further boost OCT performance and therefore enable significantly enhanced medical diagnosis. APPROACH A comprehensive review of state-of-the-art accomplishments in OCT has been performed. RESULTS The most disruptive future OCT innovations include imaging resolution and speed (single-beam raster scanning versus parallelization) improvement, new implementations for dual modality or even multimodality systems, and using endogenous or exogenous contrast in these hybrid OCT systems targeting molecular and metabolic imaging. Aside from OCT angiography, no other functional or contrast enhancing OCT extension has accomplished comparable clinical and commercial impacts. Some more recently developed extensions, e.g., optical coherence elastography, dynamic contrast OCT, optoretinography, and artificial intelligence enhanced OCT are also considered with high potential for the future. In addition, OCT miniaturization for portable, compact, handheld, and/or cost-effective capsule-based OCT applications, home-OCT, and self-OCT systems based on micro-optic assemblies or photonic integrated circuits will revolutionize new applications and availability in the near future. Finally, clinical translation of OCT including medical device regulatory challenges will continue to be absolutely essential. CONCLUSIONS With its exquisite non-invasive, micrometer resolution depth sectioning capability, OCT has especially revolutionized ophthalmic diagnosis and hence is the fastest adopted imaging technology in the history of ophthalmology. Nonetheless, OCT has not been completely exploited and has substantial growth potential-in academics as well as in industry. This applies not only to the ophthalmic application field, but also especially to the original motivation of OCT to enable optical biopsy, i.e., the in situ imaging of tissue microstructure with a resolution approaching that of histology but without the need for tissue excision.
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Affiliation(s)
- Rainer Leitgeb
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
- Medical University of Vienna, Christian Doppler Laboratory OPTRAMED, Vienna, Austria
| | - Fabian Placzek
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
| | - Elisabet Rank
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
| | - Lisa Krainz
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
| | - Richard Haindl
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
| | - Qian Li
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
| | - Mengyang Liu
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
| | - Marco Andreana
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
| | - Angelika Unterhuber
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
| | - Tilman Schmoll
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
- Carl Zeiss Meditec, Inc., Dublin, California, United States
| | - Wolfgang Drexler
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
- Address all correspondence to Wolfgang Drexler,
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15
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Valente D, Vienola KV, Zawadzki RJ, Jonnal RS. Simultaneous directional full-field OCT using path-length and carrier multiplexing. OPTICS EXPRESS 2021; 29:32179-32195. [PMID: 34615295 PMCID: PMC8687100 DOI: 10.1364/oe.435761] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 09/02/2021] [Accepted: 09/07/2021] [Indexed: 06/13/2023]
Abstract
Full-field swept-source optical coherence tomography (FF-SS-OCT) is an emerging technology with potential applications in ophthalmic imaging, microscopy, metrology, and other domains. Here we demonstrate a novel method of multiplexing FF-SS-OCT signals using carrier modulation (CM). The principle of CM could be used to inspect various properties of the scattered light, e.g. its spectrum, polarization, Doppler shift, or distribution in the pupil. The last of these will be explored in this work, where CM was used to acquire images passing through two different optical pupils. The two pupils contained semicircular optical windows with perpendicular orientations, with each window permitting measurement of scattering anisotropy in one dimension by inducing an optical delay between the images formed by the two halves of the pupil. Together, the two forms of multiplexing permit measurement of differential scattering anisotropy in the x and y dimensions simultaneously. To demonstrate the feasibility of this technique our carrier multiplexed directional FF-OCT (CM-D-FF-OCT) system was used to acquire images of a microlens array, human hair, onion skin and in vivo human retina. The results of these studies are presented and briefly discussed in the context of future development and application of this technique.
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Affiliation(s)
- Denise Valente
- Vision Science and Advanced Retinal Imaging Laboratory (VSRI), Department of Ophthalmology and Vision Science, University of California Davis, Sacramento, CA 95817, USA
| | - Kari V. Vienola
- Vision Science and Advanced Retinal Imaging Laboratory (VSRI), Department of Ophthalmology and Vision Science, University of California Davis, Sacramento, CA 95817, USA
| | - Robert J. Zawadzki
- Vision Science and Advanced Retinal Imaging Laboratory (VSRI), Department of Ophthalmology and Vision Science, University of California Davis, Sacramento, CA 95817, USA
- EyePod Small Animal Ocular Imaging Laboratory, Department of Cell Biology and Human Anatomy, University of California Davis, Davis, CA 95616, USA
| | - Ravi S. Jonnal
- Vision Science and Advanced Retinal Imaging Laboratory (VSRI), Department of Ophthalmology and Vision Science, University of California Davis, Sacramento, CA 95817, USA
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16
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Auksorius E. Fourier-domain full-field optical coherence tomography with real-time axial imaging. OPTICS LETTERS 2021; 46:4478-4481. [PMID: 34525026 DOI: 10.1364/ol.435104] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 08/11/2021] [Indexed: 06/13/2023]
Abstract
Fourier-domain full-field optical coherence tomography (FD-FF-OCT) is a fast interferometric imaging technique capable of volumetric sample imaging. However, half of the backscattered light from a sample is lost as it passes through a 50/50 beam splitter, which is at the heart of almost every interferometer. Here, it is demonstrated that this light could be extracted by spatially splitting the illumination pupil plane and detecting it with a separate camera. When a line camera is used to detect the recovered signal, it enables real-time axial imaging of the human cornea in vivo, which serves as a useful visual feedback for aligning a patient for imaging.
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17
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Pandiyan VP, Jiang X, Kuchenbecker JA, Sabesan R. Reflective mirror-based line-scan adaptive optics OCT for imaging retinal structure and function. BIOMEDICAL OPTICS EXPRESS 2021; 12:5865-5880. [PMID: 34692221 PMCID: PMC8515964 DOI: 10.1364/boe.436337] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 08/16/2021] [Accepted: 08/20/2021] [Indexed: 05/06/2023]
Abstract
Line-scan OCT incorporated with adaptive optics (AO) offers high resolution, speed, and sensitivity for imaging retinal structure and function in vivo. Here, we introduce its implementation with reflective mirror-based afocal telescopes, optimized for imaging light-induced retinal activity (optoretinography) and weak retinal reflections at the cellular scale. A non-planar optical design was followed based on previous recommendations with key differences specific to a line-scan geometry. The three beam paths fundamental to an OCT system -illumination/sample, detection, and reference- were modeled in Zemax optical design software to yield theoretically diffraction-limited performance over a 2.2 deg. field-of-view and 1.5 D vergence range at the eye's pupil. The performance for imaging retinal structure was exemplified by cellular-scale visualization of retinal ganglion cells, macrophages, foveal cones, and rods in human observers. The performance for functional imaging was exemplified by resolving the light-evoked optical changes in foveal cone photoreceptors where the spatial resolution was sufficient for cone spectral classification at an eccentricity 0.3 deg. from the foveal center. This enabled the first in vivo demonstration of reduced S-cone (short-wavelength cone) density in the human foveola, thus far observed only in ex vivo histological preparations. Together, the feasibility for high resolution imaging of retinal structure and function demonstrated here holds significant potential for basic science and translational applications.
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Affiliation(s)
- Vimal Prabhu Pandiyan
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA
- Co-first authors with equal contribution
| | - Xiaoyun Jiang
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA
- Co-first authors with equal contribution
| | - James A Kuchenbecker
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA
| | - Ramkumar Sabesan
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA
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18
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Auksorius E, Borycki D, Wojtkowski M. Multimode fiber enables control of spatial coherence in Fourier-domain full-field optical coherence tomography for in vivo corneal imaging. OPTICS LETTERS 2021; 46:1413-1416. [PMID: 33720200 DOI: 10.1364/ol.417178] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 02/15/2021] [Indexed: 05/08/2023]
Abstract
Fourier-domain full-field optical coherence tomography (FD-FF-OCT) has recently emerged as a fast alternative to point-scanning confocal OCT in eye imaging. However, when imaging the cornea with FD-FF-OCT, a spatially coherent laser can focus down on the retina to a spot that exceeds the maximum permissible exposure level. Here we demonstrate that a long multimode fiber with a small core can be used to reduce the spatial coherence of the laser and, thus, enable ultrafast in vivo volumetric imaging of the human cornea without causing risk to the retina.
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19
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Wang Y, Liu X. Line field Fourier domain optical coherence tomography based on a spatial light modulator. APPLIED OPTICS 2021; 60:985-992. [PMID: 33690414 PMCID: PMC8341167 DOI: 10.1364/ao.404162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 01/08/2021] [Indexed: 06/12/2023]
Abstract
In this study, we developed a line-field Fourier domain optical coherence tomography (LF-FDOCT) system that performs lateral scanning using a two-dimension spatial light modulator and detects multiple channels of spectral domain OCT signal in parallel using a two-dimensional sensor. The LF-FDOCT system eliminates the need for mechanical scanning to acquire volumetric OCT data. It allows parallel acquisition of signal for B mode scan imaging through snapshot detection and offers unprecedented flexibility to select a fast scanning dimension. In this work, we describe the principle of LF-FDOCT imaging and present experimental results to demonstrate the effectiveness of this technology.
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20
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Valente D, Vienola KV, Zawadzki RJ, Jonnal RS. Kilohertz retinal FF-SS-OCT and flood imaging with hardware-based adaptive optics. BIOMEDICAL OPTICS EXPRESS 2020; 11:5995-6011. [PMID: 33150001 PMCID: PMC7587251 DOI: 10.1364/boe.403509] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 09/15/2020] [Accepted: 09/21/2020] [Indexed: 05/18/2023]
Abstract
A retinal imaging system was designed for full-field (FF) swept-source (SS) optical coherence tomography (OCT) with cellular resolution. The system incorporates a real-time adaptive optics (AO) subsystem and a very high-speed CMOS sensor, and is capable of acquiring volumetric images of the retina at rates up to 1 kHz. While digital aberration correction (DAC) is an attractive potential alternative to AO, it has not yet been shown to provide resolution allowing visualization of cones in the fovea, where early detection of functional deficits is most critical. Here we demonstrate that FF-SS-OCT with hardware AO permits resolution of foveal cones, imaged at eccentricities of 1° and 2°, with volume rates adequate to measure light-evoked changes in photoreceptors. With the reference arm blocked, the system can operate as a kilohertz AO flood illumination fundus camera with adjustable temporal coherence and is expected to allow measurement of light-evoked changes caused by common path interference in photoreceptor outer segments (OS). In this paper, we describe the system's optical design, characterize its performance, and demonstrate its ability to produce images of the human photoreceptor mosaic.
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Affiliation(s)
- Denise Valente
- Vision Science and Advanced Retinal Imaging Laboratory (VSRI), Department of Ophthalmology and Vision Science, University of California Davis, Sacramento, CA 95817, USA
| | - Kari V. Vienola
- Vision Science and Advanced Retinal Imaging Laboratory (VSRI), Department of Ophthalmology and Vision Science, University of California Davis, Sacramento, CA 95817, USA
| | - Robert J. Zawadzki
- Vision Science and Advanced Retinal Imaging Laboratory (VSRI), Department of Ophthalmology and Vision Science, University of California Davis, Sacramento, CA 95817, USA
- EyePod Small Animal Ocular Imaging Laboratory, Department of Cell Biology and Human Anatomy, University of California Davis, Davis, CA 95616, USA
| | - Ravi S. Jonnal
- Vision Science and Advanced Retinal Imaging Laboratory (VSRI), Department of Ophthalmology and Vision Science, University of California Davis, Sacramento, CA 95817, USA
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21
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Auksorius E, Borycki D, Stremplewski P, Liżewski K, Tomczewski S, Niedźwiedziuk P, Sikorski BL, Wojtkowski M. In vivo imaging of the human cornea with high-speed and high-resolution Fourier-domain full-field optical coherence tomography. BIOMEDICAL OPTICS EXPRESS 2020; 11:2849-2865. [PMID: 32499965 PMCID: PMC7249809 DOI: 10.1364/boe.393801] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 04/22/2020] [Accepted: 04/23/2020] [Indexed: 05/06/2023]
Abstract
Corneal evaluation in ophthalmology necessitates cellular-resolution and fast imaging techniques that allow for accurate diagnoses. Currently, the fastest volumetric imaging technique is Fourier-domain full-field optical coherence tomography (FD-FF-OCT), which uses a fast camera and a rapidly tunable laser source. Here, we demonstrate high-resolution, high-speed, non-contact corneal volumetric imaging in vivo with FD-FF-OCT that can acquire a single 3D volume with a voxel rate of 7.8 GHz. The spatial coherence of the laser source was suppressed to prevent it from focusing on a spot on the retina, and therefore, exceeding the maximum permissible exposure (MPE). The inherently volumetric nature of FD-FF-OCT data enabled flattening of curved corneal layers. The acquired FD-FF-OCT images revealed corneal cellular structures, such as epithelium, stroma and endothelium, as well as subbasal and mid-stromal nerves.
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Affiliation(s)
- Egidijus Auksorius
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
- Equal contribution
| | - Dawid Borycki
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
- Equal contribution
| | - Patrycjusz Stremplewski
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Kamil Liżewski
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Slawomir Tomczewski
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Paulina Niedźwiedziuk
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Bartosz L. Sikorski
- Department of Ophthalmology, Nicolaus Copernicus University, 9 M. Sklodowskiej-Curie St., Bydgoszcz 85-309, Poland
- Oculomedica Eye Research & Development Center, 9 Broniewskiego St, 85-391 Bydgoszcz, Poland
| | - Maciej Wojtkowski
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
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22
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Borycki D, Auksorius E, Węgrzyn P, Wojtkowski M. Computational aberration correction in spatiotemporal optical coherence (STOC) imaging. OPTICS LETTERS 2020; 45:1293-1296. [PMID: 32163948 DOI: 10.1364/ol.384796] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Spatiotemporal optical coherence (STOC) imaging is a new technique for suppressing coherent cross talk noise in Fourier-domain full-field optical coherence tomography (FD-FF-OCT). In STOC imaging, the time-varying inhomogeneous phase masks modulate the incident light to alter the interferometric signal. Resulting interference images are then processed as in standard FD-FF-OCT and averaged incoherently or coherently to produce cross-talk-free volumetric optical coherence tomography (OCT) images of the sample. Here, we show that coherent averaging is suitable when phase modulation is performed for both interferometer arms simultaneously. We explain the advantages of coherent over incoherent averaging. Specifically, we show that modulated signal, after coherent averaging, preserves lateral phase stability, enabling computational phase correction to compensate for geometrical aberrations. Ultimately, we employ it to correct for aberrations present in the image of the photoreceptor layer of the human retina that reveals otherwise invisible photoreceptor mosaics.
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23
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Auksorius E. Light-efficient beamsplitter for Fourier-domain full-field optical coherence tomography. OPTICS LETTERS 2020; 45:1240-1243. [PMID: 32108815 DOI: 10.1364/ol.383823] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Any full-field optical coherence tomography (FF-OCT) system wastes almost 75% of light, including 50% of the OCT signal, because it uses a 50/50 beamsplitter (BS) in the standard implementation. Here, a design of a light-efficient BS is presented that loses almost no light when implemented in Fourier-domain FF-OCT. It is based on pupil engineering and a small highly asymmetric BS. The presented signal-to-noise ratio (SNR) analysis demonstrates almost four times improvement over the conventional design. In addition, it is shown that the light-efficient BS can be used to suppress specular reflections from a sample and, thus, further improve the SNR.
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