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David G. Lancaster - One of the best experts on this subject based on the ideXlab platform.

  • Fiber-Optic Skew Ray Sensors.
    Sensors (Basel Switzerland), 2020
    Co-Authors: George Y. Chen, Jinyu Wang, David G. Lancaster
    Abstract:

    The evanescent fields along multimode fibers are usually relatively weak. To enhance the sensitivity of the resulting sensors, Skew Rays have been exploited for their larger number of total internal reflections and their more comprehensive spread over the fiber surface. The uniform distribution of light–matter interactions across the fiber surface facilitates high sensitivity through an increased interaction area, while mitigating the risk of laser-induced coating-material damage and photobleaching. Power-dependent measurements are less susceptible to temperature effects than interferometric techniques, and place loose requirements on the laser source. This review highlights the key developments in this area, while discussing the benefits, challenges as well as future development.

  • light sheet Skew Ray enhanced localized surface plasmon resonance based chemical sensing
    ACS Sensors, 2020
    Co-Authors: Jinyu Wang, George Y. Chen, Tanya M. Monro, Tongyu Liu, David G. Lancaster
    Abstract:

    A stronger absorption of pump/probe light is desirable for maximizing the sensitivity to enable accurate measurements of trace chemical elements. We introduce a new sensing technique built on light...

  • optical hygrometer using light sheet Skew Ray probed multimode fiber with polyelectrolyte coating
    Sensors and Actuators B-chemical, 2019
    Co-Authors: George Y. Chen, Tanya M. Monro, C A Codemard, Xiaokong Liu, David G. Lancaster
    Abstract:

    Abstract The measurement of humidity provides valuable information to a range of industries. Existing hygrometers lack the combination of high sensitivity/low detection-limit, temperature insensitivity, fast response, high robustness and low cost. We present a new design of humidity sensors based on the combination of a polymer-coated multimode fiber interrogated by a light sheet (i.e. thin plane of light) designed to precision excite the optimum group of Skew Rays for enhanced sensitivity. The sensing mechanism is water absorption of light via evanescent-wave interaction mediated by a polymer-coated multimode fiber. For a 10.0 bilayer poly(diallyldimethylammonium) (PDDA)/poly(styrenesulfonate) (PSS)-coated sensing fiber, we demonstrated a sensitivity of up to 0.14 dB/%RH/cm, a detection limit of 0.007%RH, a temperature cross-sensitivity of less than ˜0.13%/°C, and response/recovery times of 115 ms and 200 ms. The tested dynamic range is between 10%RH and 94%RH. The dependence on the total optical power rather than the phase of light makes such sensors relatively insensitive to temperature while remaining sensitive to humidity. The PDDA/PSS functional coating inherently offers fast response. The use of multimode fibers and power meters make such fiber-optic sensors highly robust and relatively inexpensive, easing the translation to practical applications.

  • Light-Sheet Skew-Ray Enhanced Pump-Absorption for Sensing
    Journal of Lightwave Technology, 2019
    Co-Authors: George Y. Chen, Christophe A. Codemard, Alexandre François, Wen Qi Zhang, Tanya M. Monro, David G. Lancaster
    Abstract:

    We present a new sensing technique exploiting light-sheet excitation of Skew Rays in a multimode fiber, which can be applied to enhance the sensitivity of a range of sensing mechanisms such as pump absorption. The underlying principle is that a light sheet (i.e., thin plane of light) can selectively concentrate the optimum Ray group, giving rise to enhanced interaction between light and matter (e.g., fluorophores). We compared this excitation method with others in terms of attenuation of pump light through Rhodamine B. It was observed that the attenuation experienced by light-sheet Skew Rays can be up to one order of magnitude higher than that of collimated Skew Rays, and three orders of magnitude higher than that of normal-incidence Rays.

  • Force Sensors based on Skew-Ray-probed Optical Fibers
    Advanced Photonics 2018 (BGPP IPR NP NOMA Sensors Networks SPPCom SOF), 2018
    Co-Authors: George Y. Chen, Tanya M. Monro, Soroush Shahnia, David G. Lancaster
    Abstract:

    We demonstrate a bend-loss-based force sensor where pure Skew Rays can enhance its sensitivity by a factor of 3.8. We show a compression-loss-based force sensor that is stable against changes in the light launch-angle.

George Y. Chen - One of the best experts on this subject based on the ideXlab platform.

  • Fiber-Optic Skew Ray Sensors.
    Sensors (Basel Switzerland), 2020
    Co-Authors: George Y. Chen, Jinyu Wang, David G. Lancaster
    Abstract:

    The evanescent fields along multimode fibers are usually relatively weak. To enhance the sensitivity of the resulting sensors, Skew Rays have been exploited for their larger number of total internal reflections and their more comprehensive spread over the fiber surface. The uniform distribution of light–matter interactions across the fiber surface facilitates high sensitivity through an increased interaction area, while mitigating the risk of laser-induced coating-material damage and photobleaching. Power-dependent measurements are less susceptible to temperature effects than interferometric techniques, and place loose requirements on the laser source. This review highlights the key developments in this area, while discussing the benefits, challenges as well as future development.

  • light sheet Skew Ray enhanced localized surface plasmon resonance based chemical sensing
    ACS Sensors, 2020
    Co-Authors: Jinyu Wang, George Y. Chen, Tanya M. Monro, Tongyu Liu, David G. Lancaster
    Abstract:

    A stronger absorption of pump/probe light is desirable for maximizing the sensitivity to enable accurate measurements of trace chemical elements. We introduce a new sensing technique built on light...

  • optical hygrometer using light sheet Skew Ray probed multimode fiber with polyelectrolyte coating
    Sensors and Actuators B-chemical, 2019
    Co-Authors: George Y. Chen, Tanya M. Monro, C A Codemard, Xiaokong Liu, David G. Lancaster
    Abstract:

    Abstract The measurement of humidity provides valuable information to a range of industries. Existing hygrometers lack the combination of high sensitivity/low detection-limit, temperature insensitivity, fast response, high robustness and low cost. We present a new design of humidity sensors based on the combination of a polymer-coated multimode fiber interrogated by a light sheet (i.e. thin plane of light) designed to precision excite the optimum group of Skew Rays for enhanced sensitivity. The sensing mechanism is water absorption of light via evanescent-wave interaction mediated by a polymer-coated multimode fiber. For a 10.0 bilayer poly(diallyldimethylammonium) (PDDA)/poly(styrenesulfonate) (PSS)-coated sensing fiber, we demonstrated a sensitivity of up to 0.14 dB/%RH/cm, a detection limit of 0.007%RH, a temperature cross-sensitivity of less than ˜0.13%/°C, and response/recovery times of 115 ms and 200 ms. The tested dynamic range is between 10%RH and 94%RH. The dependence on the total optical power rather than the phase of light makes such sensors relatively insensitive to temperature while remaining sensitive to humidity. The PDDA/PSS functional coating inherently offers fast response. The use of multimode fibers and power meters make such fiber-optic sensors highly robust and relatively inexpensive, easing the translation to practical applications.

  • Light-Sheet Skew-Ray Enhanced Pump-Absorption for Sensing
    Journal of Lightwave Technology, 2019
    Co-Authors: George Y. Chen, Christophe A. Codemard, Alexandre François, Wen Qi Zhang, Tanya M. Monro, David G. Lancaster
    Abstract:

    We present a new sensing technique exploiting light-sheet excitation of Skew Rays in a multimode fiber, which can be applied to enhance the sensitivity of a range of sensing mechanisms such as pump absorption. The underlying principle is that a light sheet (i.e., thin plane of light) can selectively concentrate the optimum Ray group, giving rise to enhanced interaction between light and matter (e.g., fluorophores). We compared this excitation method with others in terms of attenuation of pump light through Rhodamine B. It was observed that the attenuation experienced by light-sheet Skew Rays can be up to one order of magnitude higher than that of collimated Skew Rays, and three orders of magnitude higher than that of normal-incidence Rays.

  • Force Sensors based on Skew-Ray-probed Optical Fibers
    Advanced Photonics 2018 (BGPP IPR NP NOMA Sensors Networks SPPCom SOF), 2018
    Co-Authors: George Y. Chen, Tanya M. Monro, Soroush Shahnia, David G. Lancaster
    Abstract:

    We demonstrate a bend-loss-based force sensor where pure Skew Rays can enhance its sensitivity by a factor of 3.8. We show a compression-loss-based force sensor that is stable against changes in the light launch-angle.

Psang Dain Lin - One of the best experts on this subject based on the ideXlab platform.

  • Third-order derivative matrix of a Skew Ray with respect to the source Ray vector at a flat boundary.
    Journal of the Optical Society of America. A Optics image science and vision, 2020
    Co-Authors: Psang Dain Lin
    Abstract:

    Our group recently showed that the Seidel primary Ray aberration coefficients of an axis-symmetrical system can be accurately determined using the third-order Taylor series expansion of a Skew Ray R¯m on an image plane. This finding inspires us to determine the third-order derivative matrix of R¯m with respect to the vector X¯0 of the source Ray, i.e., ∂R¯m3/∂X¯03, under reflection/refraction at a flat boundary. Finite difference methods using the second-order derivative matrix, ∂R¯m2/∂X¯02, require multiple Rays to compute ∂R¯m3/∂X¯03 and suffer from cumulative rounding and truncation errors. By contrast, the present method is based on differential geometry. Thus, it provides a greater inherent accuracy and requires the tracing of just one Ray. The proposed method facilitates the analytical investigation of the primary aberrations of an axis-symmetrical system and can be easily extended to determine the higher-order derivative matrices required to explore higher-order Ray aberration coefficients.

  • Roadmap for geometrical optics based on Taylor series expansion of Skew Ray
    Optics express, 2020
    Co-Authors: Psang Dain Lin
    Abstract:

    The Skew Ray R¯n on the image plane of an optical system possessing n boundary surfaces has the form of an n-layered deep composite function. It is hence difficult to evaluate the system performance using Ray tracing alone. The present study therefore uses the Taylor series expansion to expand R¯n with respect to the source Ray variable vector. It is shown that the paraxial Ray tracing equations, point spread function, caustic surfaces and modulation transfer function can all be explored using the first-order expansion. Furthermore, the primary and secondary Ray aberrations of an axis-symmetrical system can be determined from the third- and fifth-order expansions, respectively. It is thus proposed that the Taylor series expansion of the Skew Ray serves as a useful basis for exploring a wide variety of problems in geometrical optics.

  • Hessian Matrix of Optical Path Length
    Advanced Geometrical Optics, 2016
    Co-Authors: Psang Dain Lin
    Abstract:

    Chapter 14 presented a method for determining the Jacobian matrix of the optical path length (OPL) of a Skew Ray.

  • Skew-Ray Tracing of Geometrical Optics
    Advanced Geometrical Optics, 2016
    Co-Authors: Psang Dain Lin
    Abstract:

    In geometrical optics (or Ray optics), light propagation is described in terms of “Rays”, where each Ray is regarded as an idealized narrow bundle of light with zero width (Cornbleet, Proc IEEE 71:471–502 (1983), [1]). This is different from beam, which is a concept used in almost all fields of physics. Geometrical optics provides equations for predicting the paths followed by the Rays through an optical system. These equations are somewhat simplistic, and cannot therefore accurately describe such effects as diffraction and polarization.

  • Optical Modeling and Analysis of Laser Centering Tester
    2016
    Co-Authors: Te-tan Liao, Psang Dain Lin
    Abstract:

    Abstract. The decentration error of an optical lens has a significant effect on the quality of the image it produces. Accordingly, this study employs Skew Ray tracing based on a 4×4 homogeneous coordinate transformation matrix and Snell’s law to develop a detailed methodology for determining the decentration error of an optical lens using a laser centering tester. The current experimental and simulation results yield two important findings: (1) the decentration error and the radius of spot circle on the detector of the laser centering tester, when laser Ray passes through the measured lens, are related by a linear approximation when the decentration error is small; and (2) an approximate value of the decentration error can be obtained by taking the first-order differentiation of the mathematical expression for the decentration error. The methodology presented in this study provides a comprehensive and robust approach for evaluating the optical properties of a lens using a laser centering tester

Tanya M. Monro - One of the best experts on this subject based on the ideXlab platform.

  • light sheet Skew Ray enhanced localized surface plasmon resonance based chemical sensing
    ACS Sensors, 2020
    Co-Authors: Jinyu Wang, George Y. Chen, Tanya M. Monro, Tongyu Liu, David G. Lancaster
    Abstract:

    A stronger absorption of pump/probe light is desirable for maximizing the sensitivity to enable accurate measurements of trace chemical elements. We introduce a new sensing technique built on light...

  • optical hygrometer using light sheet Skew Ray probed multimode fiber with polyelectrolyte coating
    Sensors and Actuators B-chemical, 2019
    Co-Authors: George Y. Chen, Tanya M. Monro, C A Codemard, Xiaokong Liu, David G. Lancaster
    Abstract:

    Abstract The measurement of humidity provides valuable information to a range of industries. Existing hygrometers lack the combination of high sensitivity/low detection-limit, temperature insensitivity, fast response, high robustness and low cost. We present a new design of humidity sensors based on the combination of a polymer-coated multimode fiber interrogated by a light sheet (i.e. thin plane of light) designed to precision excite the optimum group of Skew Rays for enhanced sensitivity. The sensing mechanism is water absorption of light via evanescent-wave interaction mediated by a polymer-coated multimode fiber. For a 10.0 bilayer poly(diallyldimethylammonium) (PDDA)/poly(styrenesulfonate) (PSS)-coated sensing fiber, we demonstrated a sensitivity of up to 0.14 dB/%RH/cm, a detection limit of 0.007%RH, a temperature cross-sensitivity of less than ˜0.13%/°C, and response/recovery times of 115 ms and 200 ms. The tested dynamic range is between 10%RH and 94%RH. The dependence on the total optical power rather than the phase of light makes such sensors relatively insensitive to temperature while remaining sensitive to humidity. The PDDA/PSS functional coating inherently offers fast response. The use of multimode fibers and power meters make such fiber-optic sensors highly robust and relatively inexpensive, easing the translation to practical applications.

  • Light-Sheet Skew-Ray Enhanced Pump-Absorption for Sensing
    Journal of Lightwave Technology, 2019
    Co-Authors: George Y. Chen, Christophe A. Codemard, Alexandre François, Wen Qi Zhang, Tanya M. Monro, David G. Lancaster
    Abstract:

    We present a new sensing technique exploiting light-sheet excitation of Skew Rays in a multimode fiber, which can be applied to enhance the sensitivity of a range of sensing mechanisms such as pump absorption. The underlying principle is that a light sheet (i.e., thin plane of light) can selectively concentrate the optimum Ray group, giving rise to enhanced interaction between light and matter (e.g., fluorophores). We compared this excitation method with others in terms of attenuation of pump light through Rhodamine B. It was observed that the attenuation experienced by light-sheet Skew Rays can be up to one order of magnitude higher than that of collimated Skew Rays, and three orders of magnitude higher than that of normal-incidence Rays.

  • Force Sensors based on Skew-Ray-probed Optical Fibers
    Advanced Photonics 2018 (BGPP IPR NP NOMA Sensors Networks SPPCom SOF), 2018
    Co-Authors: George Y. Chen, Tanya M. Monro, Soroush Shahnia, David G. Lancaster
    Abstract:

    We demonstrate a bend-loss-based force sensor where pure Skew Rays can enhance its sensitivity by a factor of 3.8. We show a compression-loss-based force sensor that is stable against changes in the light launch-angle.

  • Force Sensors Using the Skew-Ray-Probed Plastic Optical Fibers
    IEEE Photonics Journal, 2018
    Co-Authors: George Y. Chen, Tanya M. Monro, Soroush Shahnia, David G. Lancaster
    Abstract:

    Simple optical force sensors have many uses but suffer from relatively low sensitivity or low fabrication-tolerance. We have demonstrated that pure Skew Rays can enhance the sensitivity of a bend-loss-based force sensor over the mixture of Rays created from a normal incidence by a factor of 3.8 to enable a sensitivity of 0.126 dB/N. The dynamic range was measured from 222.2 mN to >14.1 N. The response/recovery times were found to be 500 and 600 ms, respectively. We also showed a compression-loss-based force sensor exhibiting a small deviation of 6.7% in sensitivity of 0.015 dB/N against the changes in the launch angle of light. The dynamic range was tested from 875.0 mN to >24.2 N. The response/recovery times were observed as 350 and 300 ms, respectively. The sensitivity of these force sensors can be further enhanced with geometry and fiber-material changes, and the enhancement technique could be extended to other designs.

Te-tan Liao - One of the best experts on this subject based on the ideXlab platform.

  • Optical Modeling and Analysis of Laser Centering Tester
    2016
    Co-Authors: Te-tan Liao, Psang Dain Lin
    Abstract:

    Abstract. The decentration error of an optical lens has a significant effect on the quality of the image it produces. Accordingly, this study employs Skew Ray tracing based on a 4×4 homogeneous coordinate transformation matrix and Snell’s law to develop a detailed methodology for determining the decentration error of an optical lens using a laser centering tester. The current experimental and simulation results yield two important findings: (1) the decentration error and the radius of spot circle on the detector of the laser centering tester, when laser Ray passes through the measured lens, are related by a linear approximation when the decentration error is small; and (2) an approximate value of the decentration error can be obtained by taking the first-order differentiation of the mathematical expression for the decentration error. The methodology presented in this study provides a comprehensive and robust approach for evaluating the optical properties of a lens using a laser centering tester

  • Error analysis of Ray's light path for axis-symmetrical optical system by using Skew Ray tracing
    Applied Mechanics and Materials, 2013
    Co-Authors: Te-tan Liao, Chieh Kung, Chun Ta Chen, Psang Dain Lin
    Abstract:

    ωThis study applies a Skew Ray tracing approach based on a 4×4 homogeneous coordinate transformation matrix and Snell’s law to analyze the errors of a Ray’s light path as it passes through a series of optical elements for axis-symmetrical optical system. The proposed error analysis methodology considers two principal sources of light path error, namely: (1) the translational errors Δxi, Δyi and Δzi and the rotational errors Δωix, Δωiy and Δωiz, which determine the deviation of the light path at each boundary surface, and (2) the differential changes induced in the incident point position and unit directional vector of the refracted / reflected Ray as a result of differential changes in the position and unit directional vector of the light source. The validity of the proposed methodology is verified by analyzing the effects of optical errors in Petzval lens.

  • a Skew Ray tracing approach for the error analysis of optical elements with paraboloidal boundary surfaces
    Optik, 2009
    Co-Authors: Te-tan Liao
    Abstract:

    Abstract Using the error analysis methodology developed by the current author in previous studies for optical systems comprising elements with flat boundary surfaces, this study examines the errors induced in a light Ray's path as it is reflected or refracted at a paraboloidal boundary surface. In analyzing the light path, two principal sources of error are considered, namely (1) translational errors (Δ x i , Δ y i and Δ z i ) and rotational errors (Δ Γ i , Δ Ψ i and Δ Φ i ), which collectively determine the deviation of the light path at each boundary surface, and (2) the differential changes induced in the incident point position and unit directional vector of the refracted/reflected Ray as a result of differential changes in the position and unit directional vector of the light source. The validity of the proposed approach is verified using a generic parabaloidal boundary surface for illustration purposes. Overall, the results show that the proposed error analysis methodology provides a straightforward means of analyzing the performance of optical systems characterized by paraboloidal boundary surfaces such as headlight reflectors, optical telescope mirrors, flashlights and so forth.

  • CALCULATION OF MODULATION TRANSFER FUNCTION OF AN OPTICAL SYSTEM BY USING Skew Ray TRACING
    Transactions of the Canadian Society for Mechanical Engineering, 2009
    Co-Authors: Kuo-hwa Tseng, Te-tan Liao, Chieh Kung, Hao-peng Chang
    Abstract:

    The resolution and performance of an optical system can be characterized by a quantity known as the modulation transfer function (MTF), which is a measurement of an optical system’s ability to transfer contrast from the specimen to the intermediate image plane at a specific resolution. Accordingly, this study employs Skew Ray tracing based on a 4 × 4 homogeneous coordinate transformation matrix and Snell’s law to develop a detailed methodology for determining the spot diagram on the image plane when light Rays pass through the optical system. And the authors present calculations of the MTF of an optical system by using the spot diagram on the image plane. The numerical results of the proposed methodology are demonstrated using a symmetrical optical system.

  • Skew Ray tracing and error analysis of optical lens with cylindrical boundary surface
    Transactions of the Canadian Society for Mechanical Engineering, 2009
    Co-Authors: Te-tan Liao, Shih Hung Chen, Kuo Ying Chen, Chun Ta Chen
    Abstract:

    This study applies computational geometric algebra based on a 4 |4 homogeneous transformation matrix and Snell’s law of geometrical optics to analyze Skew Rays and the errors of a light Ray’s path as it passes through a cylindrical lens. The author addresses two important topics: (1) the determination of the direction of a reflected or refracted Ray by Snell’s law and (2) the expression of the combination of two principal sources of light path error using error analysis. In topic (2), one of the sources is the translational errors Ddix, Ddiy, and Ddiz and the rotational errors Dvix, Dviy, and Dviz that determine the deviation of the light path at each boundary surface, while the other source is the differential changes induced in the incident point position and the unit directional vector of the refracted/reflected Ray as a result of differential changes in the position and unit directional vector of the light source. The methodology presented in this study provides a comprehensive and robust approach for evaluating the error of a light Ray path as it passes through a cylindrical lens.