Dr. Karen K. Lin Profile

Dr. Karen K. Lin

Senior Scientist at A*STAR IMRE

SPIE Involvement:

Conference Program Committee | Editorial Board Member: Optical Engineering | Author

SPIE Journal Paper | 26 April 2021 Open Access

Terahertz spectroscopy analysis of human corneal sublayers

Lin Ke, Qing Yang Steve Wu, Nan Zhang, Zaifeng Yang, Ericia Pei Wen Teo, Jodhbir Mehta, Yu-Chi Liu

JBO, Vol. 26, Issue 04, 043011, (April 2021) https://doi.org/10.1117/12.10.1117/1.JBO.26.4.043011

KEYWORDS: Terahertz radiation, Cornea, Absorption, Terahertz spectroscopy, Reflection, Interfaces, Wave propagation, Spectroscopy, Sensors, Water

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Significance: Corneal diseases is a major cause of reversible blindness in the world. Monitoring the progression of human corneal edema or corneal scarring to prevent the disease entering into the end stage is crucial. Aim: We present a method for sensing human corneal composition at different depths, namely focused on the epithelium and stromal layer, using high-sensitivity terahertz (THz) broadband spectroscopy. Approach: From the proposed methodology, the THz temporal and absorption spectra of human corneas at different edema stages have been studied. THz wave signals were collected from the direct reflection and four other collection points along the THz wave propagation direction as reviewed from the simulation THz electrical field. Result: Our results show that the epithelium layer acts as a good barrier to maintain hydration level of the stroma, and the quality of the epithelium can be used to predict the level of corneal swelling in corneal edema. At the detection points near to the incident point, the THz frequency spectra demonstrated interference oscillation behavior. At the final edema observing time, results showed that the epithelium lose its barrier properties. The intactness of the epithelium can be used to predict the edema severity in the final stage. When the detection points are further away from the incident point, the THz spectra are believed to contain information from stromal layer. Stromal absorption spectra demonstrated correlation with optical coherence tomography thickness results. Conclusion: The hydration concentration from stromal layer was further quantitatively calculated. At the end of the experiment, all the corneal hydration levels reach to the same value which shows that the edema hydration has reached maximum saturation. The information of individual sublayers of the cornea is obtained by characterizing noninvasively with the use of THz spectroscopy. To our knowledge, this is the first report of using THz for noninvasive characterization of sublayers of the cornea.

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Proceedings Article | 19 April 2017 Paper

Nondestructive evaluation of defects in carbon fiber reinforced polymer (CFRP) composites

Andrew C. Ngo, Henry K. Goh, Karen Lin, W. H. Liew

Proceedings Volume 10169, 101691P (2017) https://doi.org/10.1117/12.2260331

KEYWORDS: Nondestructive evaluation, Composites, Ultrasonics, Thermography, Adhesives, Fiber reinforced polymers, Aerospace engineering, Lamps, Halogens

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Proceedings Article | 24 October 2000 Paper

Low threshold current density and high-quantum-efficiency 980-nm cw QW laser

Karen Ke, Soo-Jin Chua, Wei Fan

Proceedings Volume 4227, (2000) https://doi.org/10.1117/12.405386

KEYWORDS: Quantum wells, Laser damage threshold, Continuous wave operation, Waveguide lasers, Semiconductor lasers, External quantum efficiency, Quantum efficiency, Waveguides, Fiber amplifiers, Indium gallium arsenide

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Proceedings Article | 9 October 2000 Paper

Theoretical design of low-threshold current density of InAlGaAs material system

Karen Ke, Soo-Jin Chua, Wei Fan

Proceedings Volume 4225, (2000) https://doi.org/10.1117/12.402685

KEYWORDS: Quantum wells, Semiconductor lasers, Laser damage threshold, Aluminum, Semiconductors, Quantum optics, Gallium arsenide, Laser optics, Solids, Fluctuations and noise

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Conference Committee Involvement (4)

Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications XVIII

25 January 2025 | San Francisco, California, United States

Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications XVII

29 January 2024 | San Francisco, California, United States

Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications XVI

30 January 2023 | San Francisco, California, United States

Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications XV

25 January 2022 | San Francisco, California, United States

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