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Li J, Jia P, Qian J, Wang J, An G, Xiong J. Fabrication of an all-silica microsphere-lens on optical fiber for free-space light coupling and sensing in extreme environments. Appl Opt 2022; 61:3743-3747. [PMID: 36256415 DOI: 10.1364/ao.453999] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Accepted: 04/05/2022] [Indexed: 06/16/2023]
Abstract
In this paper, an all-silica microsphere-lens was designed and fabricated on the fiber end face, which can effectively improve the coupling efficiency of free-space light. In the production process, a coreless silica fiber with specific length was spliced on the end face of the fiber and melted by a CO2 laser fusion splicer. Due to the effect of surface tension, the coreless silica fiber would form a microsphere-lens on the fiber end face and the diameter of the microsphere-lens could be adjusted by controlling the light-passing time of the CO2 laser fusion splicer. Through experiments, it can be found that the 3 dB bandwidth optical coupling distance of the microsphere-lens with a diameter of 270 µm is about 200 µm, and the focus depth is about 450 µm. In order to verify the feasibility of using the microsphere-lens in the fiber-optic Fabry-Perot sensors, a Fabry-Perot interferometer was constructed by using the microsphere-lens and the single-mode fiber end face. The experimental results showed that the interference spectrum of the Fabry-Perot interferometer has a good contrast ratio. Integrating the advantages of all-silica structure, simple manufacturing process, low cost, small size, and sturdy construction, the proposed microsphere-lens is expected to be a potential candidate for free-space light coupling and fiber-optic sensors in extreme environments.
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Abstract
Optical coherence tomography (OCT) is a cross-sectional imaging modality based on low coherence light interferometry. Within dermatology, it has found applications for in vivo diagnostic imaging purposes, as well as to guide Mohs micrographic surgery (MMS), due to its ability to visualize skin morphology up to several millimeters in depth. However, standard OCT probes have a large footprint and capture an extended area of the skin, making it difficult to precisely pinpoint clinically relevant location being imaged. Mohs surgeons stand to benefit from a handheld in vivo imaging device that can accurately trace surgical margins. In this study, we demonstrate the use of a single fiber OCT (sfOCT) instrument. Our imaging system features a miniature common path single fiber probe, and a novel speckle decorrelation technique that generates distortion free 2D images from manual scanning.By manually moving the single-fiber probe across the region of interest, the user can perform a lateral OCT scan while visualizing the location of the probe during data acquisition. Using the sfOCT, we have identified normal skin morphology, qualitatively correlated features of basal cell carcinoma and squamous cell carcinoma with histopathology, and quantified the disruption of the dermo-epidermal junction OCT pattern in skin tumors-each demonstrating the potential of utilizing sfOCT to differentiate tumor from normal skin. Using this imaging tool, a Mohs surgeon can enhance determination of surgical margins for the first stage of MMS, potentially decreasing the time and number of stages required for complete tumor removal.
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Affiliation(s)
- Nadiya Chuchvara
- Center for Dermatology, Rutgers Robert Wood Johnson Medical School, 1 Worlds Fair Drive, Somerset, NJ, 08873, USA
| | - Babar Rao
- Center for Dermatology, Rutgers Robert Wood Johnson Medical School, 1 Worlds Fair Drive, Somerset, NJ, 08873, USA
- Rao Dermatology, 95 First Avenue, Atlantic Highlands, NJ, 07716, USA
- Department of Dermatology, Weill Cornell Medicine, 1305 York Ave 9th Floor, New York, NY, 10021, USA
| | - Xuan Liu
- Department of Electrical and Computer Engineering, New Jersey Institute of Technology, University Heights, Newark, NJ, 07102, USA.
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Abid A, Mittal S, Boutopoulos C. Etching-enabled extreme miniaturization of graded-index fiber-based optical coherence tomography probes. J Biomed Opt 2019; 25:1-5. [PMID: 31707773 PMCID: PMC7010983 DOI: 10.1117/1.jbo.25.3.032006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Accepted: 10/18/2019] [Indexed: 06/10/2023]
Abstract
We introduced and validated a method to miniaturize graded-index (GRIN) fiber-based optical coherence tomography (OCT) probes down to 70 μm in diameter. The probes consist in an assembly of single-mode (SM), coreless (CL), and graded-index (GRIN) fibers. We opted for a probe design enabling controlled size reduction by hydrogen fluoride etching. The fabrication approach prevents nonuniform etching for both the GRIN and SM fiber components, while it requires no probe polishing postetching. We found that the miniaturized probes present insignificant loss of sensitivity (∼1 dB) compared to their thicker (125 μm) counterparts. We also showed that their focusing capabilities remain tunable and highly predictable. The fabrication process is simple and can be carried out by using inexpensive telecom equipment. Both the fabrication process and the developed probes can benefit the prototyping of minimally invasive endoscopic tools.
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Affiliation(s)
- Alexandre Abid
- University of Montreal, Institute of Biomedical Engineering, Montreal, Quebec, Canada
- Maisonneuve-Rosemont Hospital Research Centre, Montreal, Quebec, Canada
| | - Shiv Mittal
- Maisonneuve-Rosemont Hospital Research Centre, Montreal, Quebec, Canada
- University of British Columbia, Faculty of Applied Science, Vancouver, British Columbia, Canada
| | - Christos Boutopoulos
- University of Montreal, Institute of Biomedical Engineering, Montreal, Quebec, Canada
- Maisonneuve-Rosemont Hospital Research Centre, Montreal, Quebec, Canada
- University of Montreal, Department of Ophthalmology, Montreal, Quebec, Canada
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Park S, Rim S, Kim JW, Park J, Sohn IB, Lee BH. Analysis of Design and Fabrication Parameters for Lensed Optical Fibers as Pertinent Probes for Sensing and Imaging. Sensors (Basel) 2018; 18:s18124150. [PMID: 30486346 PMCID: PMC6308810 DOI: 10.3390/s18124150] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/13/2018] [Revised: 11/18/2018] [Accepted: 11/22/2018] [Indexed: 11/30/2022]
Abstract
A method for adjusting the working distance and spot size of a fiber probe while suppressing or enhancing the back-coupling to the lead-in fiber is presented. As the optical fiber probe, a lensed optical fiber (LOF) was made by splicing a short piece of coreless silica fiber (CSF) on a single-mode fiber and forming a lens at the end of the CSF. By controlling the length of the CSF and the radius of lens curvature, the optical properties of the LOF were adjusted. The evolution of the beam in the LOF was analyzed by using the Gaussian ABCD matrix method. To confirm the idea experimentally, 17 LOF samples were fabricated and analyzed theoretically and also experimentally. The results show that it is feasible in designing the LOF to be more suitable for specific or dedicated applications. Applications in physical sensing and biomedical imaging fields are expected.
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Affiliation(s)
- Soongho Park
- School of Electrical Engineering and Computer Science, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju 61005, Korea.
| | - Sunghwan Rim
- School of Electrical Engineering and Computer Science, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju 61005, Korea.
| | - Ju Wan Kim
- Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju 61005, Korea.
| | - Jinho Park
- Graduate School of Advanced Imaging Science, Multimedia and Film Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul 06974, Korea.
| | - Ik-Bu Sohn
- Advanced Photonics Research Institute, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju 61005, Korea.
| | - Byeong Ha Lee
- School of Electrical Engineering and Computer Science, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju 61005, Korea.
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Liu X, Zaki FR, Wu H, Wang C, Wang Y. Temporally and spatially adaptive Doppler analysis for robust handheld optical coherence elastography. Biomed Opt Express 2018; 9:3335-3353. [PMID: 29984101 PMCID: PMC6033568 DOI: 10.1364/boe.9.003335] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 06/20/2018] [Accepted: 06/20/2018] [Indexed: 05/21/2023]
Abstract
Optical coherence elastography (OCE), a functional extension of optical coherence tomography (OCT), can be used to characterize the mechanical properties of biological tissue. A handheld fiber-optic OCE instrument will allow the clinician to conveniently interrogate the localized mechanical properties of in vivo tissue, leading to better informed clinical decision making. During handheld OCE characterization, the handheld probe is used to compress the sample and the displacement of the sample is quantified by analyzing the OCT signals acquired. However, the motion within the sample inevitably varies in time due to varying hand motion. Moreover, the motion speed depends on spatial location due to the sample deformation. Hence, there is a need for a robust motion tracking method for manual OCE measurement. In this study, we investigate a temporally and spatially adaptive Doppler analysis method. The method described here strategically chooses the time interval (δt) between signals involved in Doppler analysis to track the motion speed v(z,t) that varies temporally and spatially in a deformed sample volume under manual compression. Enabled by temporally and spatially adaptive Doppler analysis, we report the first demonstration of real-time manual OCE characterization of in vivo tissue to the best of our knowledge.
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Zaki F, Wang Y, Su H, Yuan X, Liu X. Noise adaptive wavelet thresholding for speckle noise removal in optical coherence tomography. Biomed Opt Express 2017; 8:2720-2731. [PMID: 28663901 PMCID: PMC5480508 DOI: 10.1364/boe.8.002720] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 04/21/2017] [Accepted: 04/21/2017] [Indexed: 05/27/2023]
Abstract
Optical coherence tomography (OCT) is based on coherence detection of interferometric signals and hence inevitably suffers from speckle noise. To remove speckle noise in OCT images, wavelet domain thresholding has demonstrated significant advantages in suppressing noise magnitude while preserving image sharpness. However, speckle noise in OCT images has different characteristics in different spatial scales, which has not been considered in previous applications of wavelet domain thresholding. In this study, we demonstrate a noise adaptive wavelet thresholding (NAWT) algorithm that exploits the difference of noise characteristics in different wavelet sub-bands. The algorithm is simple, fast, effective and is closely related to the physical origin of speckle noise in OCT image. Our results demonstrate that NAWT outperforms conventional wavelet thresholding.
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Affiliation(s)
- Farzana Zaki
- Department of Electrical and Computer Engineering, New Jersey Institute of Technology, Newark, NJ 079102, USA
| | - Yahui Wang
- Department of Electrical and Computer Engineering, New Jersey Institute of Technology, Newark, NJ 079102, USA
| | - Hao Su
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Xin Yuan
- Bell Labs, Nokia, 600 Mountain Avenue, Murray Hill, NJ 07974, USA
| | - Xuan Liu
- Department of Electrical and Computer Engineering, New Jersey Institute of Technology, Newark, NJ 079102, USA
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