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Han Y, Zheng Y, Li N, Luo Y, Xue C, Bai J, Chen J. Acoustic Sensing Performance Investigation Based on Grooves Etched in the Ring Resonators. MICROMACHINES 2023; 14:512. [PMID: 36984918 PMCID: PMC10056882 DOI: 10.3390/mi14030512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 02/14/2023] [Accepted: 02/19/2023] [Indexed: 06/18/2023]
Abstract
Acoustic detection based on optical technology has moved in the direction of high sensitivity and resolution. In this study, an optical waveguide acoustic sensor based on a ring resonator with the evanescent field is proposed. Grooves are introduced into the ring resonators as a direct sensitive structure to excite the evanescent field. A series of resonators with diverse grooves are fabricated for a comparative analysis of acoustic performance. The acoustic parameters of bandwidth, sensitivity, and signal-to-noise ratio (SNR) vary with different grooves indicated by the Q-factor. The results show that the ring resonators with variable-sized grooves exhibit excellent capability of acoustics detection. A maximum frequency of 160 kHz and a high sensitivity of 60.075 mV/Pa is achieved, with the minimum detectable sound pressure being 131.34 µPa/Hz1/2. Furthermore, the resonators with high Q-factors represent a remarkable sound resolution reaching 0.2 Hz. This work is of great significance for optimizing acoustic sensors and broadening the application range.
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2
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Ma Z, Ding N, Li Z, Zhu K, Li A, Lin Z, Wang Y, Zhao Y, Yu Y, Luan J, Zhu X, Liu J. Spectral interference contrast based non-contact photoacoustic microscopy realized by SDOCT. OPTICS LETTERS 2022; 47:2895-2898. [PMID: 35648958 DOI: 10.1364/ol.458383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 05/15/2022] [Indexed: 06/15/2023]
Abstract
We introduce a method to extract the photoacoustic (PA) signal from a contrast reduction of the interference spectrum acquired by spectral domain optical coherence tomography (SDOCT). This all-optical detection is achieved in a noncontact manner directly on the water surface covered on the sample by using its specular reflection. During SDOCT exposure, the phase of the interference spectrum keeps shaking according to the water surface vibration induced by PA excitation. This results in an interference contrast reduction which is quantified by a fast Fourier transform (FFT) for PA imaging. A tungsten filament, asparagus fern leaf, and mouse auricle are imaged to demonstrate the method.
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3
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Cho SW, Park SM, Park B, Kim DY, Lee TG, Kim BM, Kim C, Kim J, Lee SW, Kim CS. High-speed photoacoustic microscopy: A review dedicated on light sources. PHOTOACOUSTICS 2021; 24:100291. [PMID: 34485074 PMCID: PMC8403586 DOI: 10.1016/j.pacs.2021.100291] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 07/18/2021] [Accepted: 08/03/2021] [Indexed: 05/05/2023]
Abstract
In recent years, many methods have been investigated to improve imaging speed in photoacoustic microscopy (PAM). These methods mainly focused upon three critical factors contributing to fast PAM: laser pulse repetition rate, scanning speed, and computing power of the microprocessors. A high laser repetition rate is fundamentally the most crucial factor to increase the PAM speed. In this paper, we review methods adopted for fast PAM systems in detail, specifically with respect to light sources. To the best of our knowledge, ours is the first review article analyzing the fundamental requirements for developing high-speed PAM and their limitations from the perspective of light sources.
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Affiliation(s)
- Soon-Woo Cho
- Department of Cogno-Mechatronics Engineering, Pusan National University, Busan, 46241, Republic of Korea
| | - Sang Min Park
- Department of Cogno-Mechatronics Engineering, Pusan National University, Busan, 46241, Republic of Korea
| | - Byullee Park
- Department of Electrical Engineering, Convergence IT Engineering, and Mechanical Engineering, Medical Device Innovation Center, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
| | - Do Yeon Kim
- Safety Measurement Institute, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
- Department of Bio-Convergence Engineering, Korea University, Seoul, 02841, Republic of Korea
| | - Tae Geol Lee
- Safety Measurement Institute, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
| | - Beop-Min Kim
- Department of Bio-Convergence Engineering, Korea University, Seoul, 02841, Republic of Korea
- Interdisciplinary Program in Precision Public Health, Korea University, Seoul, 02481, Republic of Korea
| | - Chulhong Kim
- Department of Electrical Engineering, Convergence IT Engineering, and Mechanical Engineering, Medical Device Innovation Center, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
| | - Jeesu Kim
- Department of Cogno-Mechatronics Engineering, Pusan National University, Busan, 46241, Republic of Korea
| | - Sang-Won Lee
- Safety Measurement Institute, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
- Department of Medical Physics, University of Science and Technology, Daejeon, 34113, Republic of Korea
| | - Chang-Seok Kim
- Department of Cogno-Mechatronics Engineering, Pusan National University, Busan, 46241, Republic of Korea
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4
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Zhu X, Huang Z, Li Z, Li W, Liu X, Chen Z, Tian J, Li C. Resolution-matched reflection mode photoacoustic microscopy and optical coherence tomography dual modality system. PHOTOACOUSTICS 2020; 19:100188. [PMID: 32577377 PMCID: PMC7300161 DOI: 10.1016/j.pacs.2020.100188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 04/22/2020] [Accepted: 04/29/2020] [Indexed: 06/11/2023]
Abstract
Photoacoustic microscopy (PAM) and optical coherence tomography (OCT) are sensitive to optical absorption and scattering characteristics, respectively. As such, the integration of these two modalities in order to combine important complementary information has garnered much attention. Due to the relatively low axial resolution of PAM, PAM and OCT dual modality systems generally have a large resolution gap, especially for reflection mode systems. In this study, based on a wide-band transparent pure-optical ultrasonic detector, we developed a dual modality system (PAM-OCT system) in which PAM has a similar spatial resolution (i.e. several micrometers in both the lateral and axial directions) to OCT. In addition, due to the optical transparency advantage, the integrated system works in reflection mode, which is ideal for in vivo biomedical imaging. We successfully imaged the skin of a mouse hindlimb, which cannot be done by a transmission mode dual modality system. Our work demonstrates this dual modality system has potential in biomedical studies with complementary imaging contrasts.
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5
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Shabairou N, Lengenfelder B, Hohmann M, Klämpfl F, Schmidt M, Zalevsky Z. All-optical, an ultra-thin endoscopic photoacoustic sensor using multi-mode fiber. Sci Rep 2020; 10:9142. [PMID: 32499607 PMCID: PMC7272416 DOI: 10.1038/s41598-020-66076-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 05/14/2020] [Indexed: 01/05/2023] Open
Abstract
Photoacoustic endoscopy (PAE) is a method of in-vivo imaging that uses tissue absorption properties. In PAE, the main tools used to detect the acoustic signal are mechanical ultrasound transducers, which require direct contact and which are difficult to miniaturize. All-optic photoacoustic sensors can challenge this issue as they can provide contact-free sensing. Here, we demonstrate sensing of photo-acoustic signals through a multimode fiber (MMF) which can provide an ultra-thin endoscopic photoacoustic sensor. Furthermore, we show the advantage of using the optical-flow method for speckle sensing and extract the photoacoustic signal despite the mode-mixing along the MMF. Moreover, it is demonstrated for the first time that the speckle reconstruction method can be used without the need for imaging of the speckles as this enables the use of multimode fibers for the speckle method.
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Affiliation(s)
- Nadav Shabairou
- Faculty of Engineering, Bar-Ilan University, Ramat-Gan, 52900, Israel.
| | - Benjamin Lengenfelder
- Institute of Photonic Technologies (LPT), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Konrad-Zuse-Straße 3/5, 91052, Erlangen, Germany.,Erlangen Graduate School in Advanced Optical Technologies (SAOT), Paul-Gordan-Straße 6, 91052, Erlangen, Germany
| | - Martin Hohmann
- Institute of Photonic Technologies (LPT), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Konrad-Zuse-Straße 3/5, 91052, Erlangen, Germany.,Erlangen Graduate School in Advanced Optical Technologies (SAOT), Paul-Gordan-Straße 6, 91052, Erlangen, Germany
| | - Florian Klämpfl
- Institute of Photonic Technologies (LPT), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Konrad-Zuse-Straße 3/5, 91052, Erlangen, Germany.,Erlangen Graduate School in Advanced Optical Technologies (SAOT), Paul-Gordan-Straße 6, 91052, Erlangen, Germany
| | - Michael Schmidt
- Institute of Photonic Technologies (LPT), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Konrad-Zuse-Straße 3/5, 91052, Erlangen, Germany.,Erlangen Graduate School in Advanced Optical Technologies (SAOT), Paul-Gordan-Straße 6, 91052, Erlangen, Germany
| | - Zeev Zalevsky
- Faculty of Engineering, Bar-Ilan University, Ramat-Gan, 52900, Israel.,Erlangen Graduate School in Advanced Optical Technologies (SAOT), Paul-Gordan-Straße 6, 91052, Erlangen, Germany
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6
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Lengenfelder B, Mehari F, Hohmann M, Löhr C, Waldner MJ, Schmidt M, Zalevsky Z, Klämpfl F. Contact-free endoscopic photoacoustic sensing using speckle analysis. JOURNAL OF BIOPHOTONICS 2019; 12:e201900130. [PMID: 31468729 PMCID: PMC7065617 DOI: 10.1002/jbio.201900130] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 07/04/2019] [Accepted: 08/20/2019] [Indexed: 05/17/2023]
Abstract
Photoacoustic endoscopy (PAE) is an emerging imaging modality, which offers a high imaging penetration and a high optical contrast in soft tissue. Most of the developed endoscopic photoacoustic sensing systems use miniaturized contact ultrasound transducers or complex optical approaches. In this work, a new fiber-based detection technique using speckle analysis for contact-free signal detection is presented. Phantom and ex vivo experiments are performed in transmission and reflection mode for proof of concept. In summary, the potential of the technique for endoscopic photoacoustic signal detection is demonstrated. The new technique might help in future to broaden the applications of PAE in imaging or guiding minimally invasive laser procedures.
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Affiliation(s)
- Benjamin Lengenfelder
- Department of Mechanical Engineering, Friedrich‐Alexander‐Universität Erlangen‐Nürnberg (FAU)Institute of Photonic Technologies (LPT)ErlangenGermany
- Erlangen Graduate School in Advanced Optical Technologies (SAOT)ErlangenGermany
| | - Fanuel Mehari
- Department of Mechanical Engineering, Friedrich‐Alexander‐Universität Erlangen‐Nürnberg (FAU)Institute of Photonic Technologies (LPT)ErlangenGermany
- Erlangen Graduate School in Advanced Optical Technologies (SAOT)ErlangenGermany
| | - Martin Hohmann
- Department of Mechanical Engineering, Friedrich‐Alexander‐Universität Erlangen‐Nürnberg (FAU)Institute of Photonic Technologies (LPT)ErlangenGermany
- Erlangen Graduate School in Advanced Optical Technologies (SAOT)ErlangenGermany
| | - Cita Löhr
- Department of Mechanical Engineering, Friedrich‐Alexander‐Universität Erlangen‐Nürnberg (FAU)Institute of Photonic Technologies (LPT)ErlangenGermany
| | - Maximilian J. Waldner
- Erlangen Graduate School in Advanced Optical Technologies (SAOT)ErlangenGermany
- Department of Medicine 1Friedrich‐Alexander‐Universität Erlangen‐Nürnberg (FAU)ErlangenGermany
| | - Michael Schmidt
- Department of Mechanical Engineering, Friedrich‐Alexander‐Universität Erlangen‐Nürnberg (FAU)Institute of Photonic Technologies (LPT)ErlangenGermany
- Erlangen Graduate School in Advanced Optical Technologies (SAOT)ErlangenGermany
| | - Zeev Zalevsky
- Erlangen Graduate School in Advanced Optical Technologies (SAOT)ErlangenGermany
- Faculty of EngineeringBar‐Ilan UniversityRamat‐GanIsrael
| | - Florian Klämpfl
- Department of Mechanical Engineering, Friedrich‐Alexander‐Universität Erlangen‐Nürnberg (FAU)Institute of Photonic Technologies (LPT)ErlangenGermany
- Erlangen Graduate School in Advanced Optical Technologies (SAOT)ErlangenGermany
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7
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Wissmeyer G, Pleitez MA, Rosenthal A, Ntziachristos V. Looking at sound: optoacoustics with all-optical ultrasound detection. LIGHT, SCIENCE & APPLICATIONS 2018; 7:53. [PMID: 30839640 PMCID: PMC6107019 DOI: 10.1038/s41377-018-0036-7] [Citation(s) in RCA: 113] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 05/08/2018] [Accepted: 05/11/2018] [Indexed: 05/03/2023]
Abstract
Originally developed for diagnostic ultrasound imaging, piezoelectric transducers are the most widespread technology employed in optoacoustic (photoacoustic) signal detection. However, the detection requirements of optoacoustic sensing and imaging differ from those of conventional ultrasonography and lead to specifications not sufficiently addressed by piezoelectric detectors. Consequently, interest has shifted to utilizing entirely optical methods for measuring optoacoustic waves. All-optical sound detectors yield a higher signal-to-noise ratio per unit area than piezoelectric detectors and feature wide detection bandwidths that may be more appropriate for optoacoustic applications, enabling several biomedical or industrial applications. Additionally, optical sensing of sound is less sensitive to electromagnetic noise, making it appropriate for a greater spectrum of environments. In this review, we categorize different methods of optical ultrasound detection and discuss key technology trends geared towards the development of all-optical optoacoustic systems. We also review application areas that are enabled by all-optical sound detectors, including interventional imaging, non-contact measurements, magnetoacoustics, and non-destructive testing.
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Affiliation(s)
- Georg Wissmeyer
- Institute of Biological and Medical Imaging, Helmholtz Zentrum München, Neuherberg, Germany
- Chair of Biological Imaging, Technische Universität München, Munich, Germany
| | - Miguel A. Pleitez
- Institute of Biological and Medical Imaging, Helmholtz Zentrum München, Neuherberg, Germany
- Chair of Biological Imaging, Technische Universität München, Munich, Germany
| | - Amir Rosenthal
- Andrew and Erna Viterbi Faculty of Electrical Engineering, Technion - Israel Institute of Technology, Haifa, Israel
| | - Vasilis Ntziachristos
- Institute of Biological and Medical Imaging, Helmholtz Zentrum München, Neuherberg, Germany
- Chair of Biological Imaging, Technische Universität München, Munich, Germany
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8
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Kolb JP, Pfeiffer T, Eibl M, Hakert H, Huber R. High-resolution retinal swept source optical coherence tomography with an ultra-wideband Fourier-domain mode-locked laser at MHz A-scan rates. BIOMEDICAL OPTICS EXPRESS 2018; 9:120-130. [PMID: 29359091 PMCID: PMC5772568 DOI: 10.1364/boe.9.000120] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 11/14/2017] [Accepted: 11/15/2017] [Indexed: 05/13/2023]
Abstract
We present a new 1060 nm Fourier domain mode locked laser (FDML laser) with a record 143 nm sweep bandwidth at 2∙ 417 kHz = 834 kHz and 120 nm at 1.67 MHz, respectively. We show that not only the bandwidth alone, but also the shape of the spectrum is critical for the resulting axial resolution, because of the specific wavelength-dependent absorption of the vitreous. The theoretical limit of our setup lies at 5.9 µm axial resolution. In vivo MHz-OCT imaging of human retina is performed and the image quality is compared to the previous results acquired with 70 nm sweep range, as well as to existing spectral domain OCT data with 2.1 µm axial resolution from literature. We identify benefits of the higher resolution, for example the improved visualization of small blood vessels in the retina besides several others.
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9
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Wang T, Pfeiffer T, Wu M, Wieser W, Amenta G, Draxinger W, van der Steen AFW, Huber R, Soest GV. Thermo-elastic optical coherence tomography. OPTICS LETTERS 2017; 42:3466-3469. [PMID: 28957064 DOI: 10.1364/ol.42.003466] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 08/08/2017] [Indexed: 05/23/2023]
Abstract
The absorption of nanosecond laser pulses induces rapid thermo-elastic deformation in tissue. A sub-micrometer scale displacement occurs within a few microseconds after the pulse arrival. In this Letter, we investigate the laser-induced thermo-elastic deformation using a 1.5 MHz phase-sensitive optical coherence tomography (OCT) system. A displacement image can be reconstructed, which enables a new modality of phase-sensitive OCT, called thermo-elastic OCT. An analysis of the results shows that the optical absorption is a dominating factor for the displacement. Thermo-elastic OCT is capable of visualizing inclusions that do not appear on the structural OCT image, providing additional tissue type information.
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10
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Bell KL, Hajireza P, Shi W, Zemp RJ. Temporal evolution of low-coherence reflectrometry signals in photoacoustic remote sensing microscopy. APPLIED OPTICS 2017; 56:5172-5181. [PMID: 29047569 DOI: 10.1364/ao.56.005172] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 05/22/2017] [Indexed: 05/22/2023]
Abstract
Recently, a new noncontact reflection-mode imaging modality called photoacoustic remote sensing (PARS) microscopy was introduced providing optical absorption contrast. Unlike previous modalities, which rely on interferometric detection of a probe beam to measure surface oscillations, the PARS technique detects photoacoustic initial pressures induced by a pulsed laser at their origin by monitoring intensity modulations of a reflected probe beam. In this paper, a model describing the temporal evolution from a finite excitation pulse is developed with consideration given to the coherence length of the interrogation beam. Analytical models are compared with approximations, finite-difference time-domain (FDTD) simulations, and experiments with good agreement.
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11
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Optical Coherence Microscopy. Methods Mol Biol 2017. [PMID: 28324609 DOI: 10.1007/978-1-4939-6810-7_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
The present chapter aims at demonstrating the capabilities of optical coherence microscopy (OCM) for applications in biomedical imaging. We furthermore review the functional imaging capabilities of OCM focusing on lable-free optical angiography. We conclude with a section on digital wavefront control and a short outlook on future developments, in particular for contrast enhancement techniques.
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12
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Tian C, Feng T, Wang C, Liu S, Cheng Q, Oliver DE, Wang X, Xu G. Non-Contact Photoacoustic Imaging Using a Commercial Heterodyne Interferometer. IEEE SENSORS JOURNAL 2016; 16:8381-8388. [PMID: 28210188 PMCID: PMC5305171 DOI: 10.1109/jsen.2016.2611569] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Most current photoacoustic imaging (PAI) systems employ piezoelectric transducers to receive photoacoustic signals, which requires coupling medium to facilitate photoacoustic wave propagation and are not favored in many applications. Here, we report an all-optical non-contact PAI system based on a commercial heterodyne interferometer working at 1550 nm. The interferometer remotely detects ultrasound-induced surface vibration and does not involve any physical contact with the sample. The theoretically predicated and experimentally measured noise equivalent detection limits of the optical sensor are about 4.5 and 810 Pa over 1.2 MHz bandwidth. Using a raster-scan PAI system equipped with the non-contact design, stereotactic boundaries of an artificial tumor in a pig brain were accurately delineated. The non-contact design also enables the tomographic PAI of biological tissue samples in a non-invasive manner. The preliminary results and analyses reveal that the heterodyne interferometer-based non-contact PAI system holds good potential in biomedical imaging.
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Affiliation(s)
- Chao Tian
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109 USA
| | - Ting Feng
- Department of Electronic Science and Engineering, Nanjing University, Nanjing 21000, China, and also with the Department of Radiology, University of Michigan, Ann Arbor, MI 48109 USA
| | - Cheng Wang
- School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
| | - Shengchun Liu
- College of Physical Science and Technology, Heilongjiang University, Harbin 150080, China
| | - Qian Cheng
- Institute of Acoustics, Tongji University, Shanghai 200092, China
| | | | - Xueding Wang
- Department of Biomedical Engineering and the Department of Radiology, University of Michigan, Ann Arbor, MI 48109 USA, and also with the Institute of Acoustics, Tongji University, Shanghai 200092, China
| | - Guan Xu
- Department of Radiology, University of Michigan, Ann Arbor, MI 48109 USA
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13
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Eom J, Shin JG, Park S, Rim S, Lee BH. An All-Fiber-Optic Combined System of Noncontact Photoacoustic Tomography and Optical Coherence Tomography. SENSORS 2016; 16:s16050734. [PMID: 27213392 PMCID: PMC4883425 DOI: 10.3390/s16050734] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2016] [Revised: 05/11/2016] [Accepted: 05/17/2016] [Indexed: 12/26/2022]
Abstract
We propose an all-fiber-based dual-modal imaging system that combines noncontact photoacoustic tomography (PAT) and optical coherence tomography (OCT). The PAT remotely measures photoacoustic (PA) signals with a 1550-nm laser on the surface of a sample by utilizing a fiber interferometer as an ultrasound detector. The fiber-based OCT, employing a swept-source laser centered at 1310 nm, shares the sample arm of the PAT system. The fiber-optic probe for the combined system was homemade with a lensed single-mode fiber (SMF) and a large-core multimode fiber (MMF). The compact and robust common probe is capable of obtaining both the PA and the OCT signals at the same position without any physical contact. Additionally, the MMF of the probe delivers the short pulses of a Nd:YAG laser to efficiently excite the PA signals. We experimentally demonstrate the feasibility of the proposed dual-modal system with a phantom made of a fishing line and a black polyethylene terephthalate fiber in a tissue mimicking solution. The all-fiber-optic system, capable of providing complementary information about absorption and scattering, has a promising potential in minimally invasive and endoscopic imaging.
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Affiliation(s)
- Jonghyun Eom
- Department of Medical System Engineering, Institute of Integrated Technology, Gwangju Institute of Science and Technology, 123 Cheomdan-gwagiro, Buk-gu, Gwangju 61005, Korea.
| | - Jun Geun Shin
- School of Information and Communications, Gwangju Institute of Science and Technology, 123 Cheomdan-gwagiro, Buk-gu, Gwangju 61005, Korea.
| | - Soongho Park
- School of Information and Communications, Gwangju Institute of Science and Technology, 123 Cheomdan-gwagiro, Buk-gu, Gwangju 61005, Korea.
| | - Sunghwan Rim
- School of Information and Communications, Gwangju Institute of Science and Technology, 123 Cheomdan-gwagiro, Buk-gu, Gwangju 61005, Korea.
| | - Byeong Ha Lee
- School of Information and Communications, Gwangju Institute of Science and Technology, 123 Cheomdan-gwagiro, Buk-gu, Gwangju 61005, Korea.
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14
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Aschinger GC, Schmetterer L, Doblhoff-Dier V, Leitgeb RA, Garhöfer G, Gröschl M, Werkmeister RM. Blood flow velocity vector field reconstruction from dual-beam bidirectional Doppler OCT measurements in retinal veins. BIOMEDICAL OPTICS EXPRESS 2015; 6:1599-615. [PMID: 26137367 PMCID: PMC4467707 DOI: 10.1364/boe.6.001599] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Revised: 03/06/2015] [Accepted: 03/06/2015] [Indexed: 05/21/2023]
Abstract
In this paper, we demonstrate the possibility to reconstruct the actual blood flow velocity vector field in retinal microvessels from dual-beam bidirectional Doppler optical coherence tomography measurements. First, for a better understanding of measured phase patterns, several flow situations were simulated on the basis of the known dual beam measurement geometry. We were able to extract the vector field parameters that determine the measured phase pattern, allowing for the development of an algorithm to reconstruct the velocity vector field from measured phase data. In a next step, measurements were performed at a straight vessel section and at a venous convergence; the obtained phase data were evaluated by means of the new approach. For the straight vessel section, the reconstructed flow velocity vector field yielded a parabolic flow. For the venous convergence, however, the reconstructed vector field deviated from a parabolic profile, but was in very good accordance with the simulated vector field for the given vessel geometry. The proposed algorithm allows predictions of the velocity vector field. Moreover, the algorithm is also sensitive to directional changes of the flow velocity as small as <1°, thereby offering insight in the flow characteristics of the non-Newtonian fluid blood in microvessels.
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Affiliation(s)
- Gerold C. Aschinger
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20/4L, A-1090 Vienna,
Austria
- Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Vienna,
Austria
| | - Leopold Schmetterer
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20/4L, A-1090 Vienna,
Austria
- Department of Clinical Pharmacology, Medical University of Vienna, Waehringer Guertel 18-20/6L, A-1090 Vienna,
Austria
| | - Veronika Doblhoff-Dier
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20/4L, A-1090 Vienna,
Austria
- Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Vienna,
Austria
| | - Rainer A. Leitgeb
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20/4L, A-1090 Vienna,
Austria
| | - Gerhard Garhöfer
- Department of Clinical Pharmacology, Medical University of Vienna, Waehringer Guertel 18-20/6L, A-1090 Vienna,
Austria
| | - Martin Gröschl
- Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Vienna,
Austria
| | - René M. Werkmeister
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20/4L, A-1090 Vienna,
Austria
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15
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Brezinski ME. Practical Challenges of Current Video Rate OCT Elastography: Accounting for Dynamic and Static Tissue Properties. JOURNAL OF LASERS, OPTICS & PHOTONICS 2014; 1:112. [PMID: 29286052 PMCID: PMC5743221 DOI: 10.4172/2469-410x.1000112] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Optical coherence tomography (OCT) elastography (OCTE) has the potential to be an important diagnostic tool for pathologies including coronary artery disease, osteoarthritis, malignancies, and even dental caries. Many groups have performed OCTE, including our own, using a wide range of approaches. However, we will demonstrate current OCTE approaches are not scalable to real-time, in vivo imaging. As will be discussed, among the most important reasons is current designs focus on the system and not the target. Specifically, tissue dynamic responses are not accounted, with examples being the tissue strain response time, preload variability, and conditioning variability. Tissue dynamic responses, and to a lesser degree static tissue properties, prevent accurate video rate modulus assessments for current embodiments. Accounting for them is the focus of this paper. A top-down approach will be presented to overcome these challenges to real time in vivo tissue characterization. Discussed first is an example clinical scenario where OTCE would be of substantial relevance, the prevention of acute myocardial infarction or heart attacks. Then the principles behind OCTE are examined. Next, constrains on in vivo application of current OCTE are evaluated, focusing on dynamic tissue responses. An example is the tissue strain response, where it takes about 20 msec after a stress is applied to reach plateau. This response delay is not an issue at slow acquisition rates, as most current OCTE approaches are preformed, but it is for video rate OCTE. Since at video rate each frame is only 30 msec, for essentially all current approaches this means the strain for a given stress is changing constantly during the B-scan. Therefore the modulus can't be accurately assessed. This serious issue is an even greater problem for pulsed techniques as it means the strain/modulus for a given stress (at a location) is unpredictably changing over a B-scan. The paper concludes by introducing a novel video rate approach to overcome these challenges.
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Affiliation(s)
- Mark E Brezinski
- Center for Optics and Modern Physics, Brigham and Women’s Hospital, 75 Francis Street, Boston, M.A. 02115, USA
- Harvard Medical School, 25 Shattuck Street, Boston, M.A. 02115, USA
- Department of Electrical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, M.A. 02139, USA
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