1. Articles from Jianing Yao

    1-12 of 12
    1. Point-cloud noncontact metrology of freeform optical surfaces

      Point-cloud noncontact metrology of freeform optical surfaces

      Full Article Figures (16) Tables (2) Equations (14) References (52) Cited By (0) Back to Top Get PDF Abstract In this paper, we demonstrate the development of a point-cloud metrology method for the noncontact, high resolution, high precision testing of freeform surfaces. The method leverages swept source optical coherence tomography together with a common-path setup in the sample arm configured to mitigate the axial jitter caused by scanning and environmental perturbations. The lateral x-y scanning field was also rigorously evaluated for the sampling step, linearity, straightness, and orthogonality. Based on the finely engineered system hardware, a comprehensive system model was ...

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    2. Comparative study of shear wave-based elastography techniques in optical coherence tomography

      Comparative study of shear wave-based elastography techniques in optical coherence tomography

      We compare five optical coherence elastography techniques able to estimate the shear speed of waves generated by one and two sources of excitation. The first two techniques make use of one piezoelectric actuator in order to produce a continuous shear wave propagation or a tone-burst propagation (TBP) of 400 Hz over a gelatin tissue-mimicking phantom. The remaining techniques utilize a second actuator located on the opposite side of the region of interest in order to create three types of interference patterns: crawling waves, swept crawling waves, and standing waves, depending on the selection of the frequency difference between the two ...

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    3. Volumetric rendering and metrology of spherical gradient refractive index lens imaged by angular scan optical coherence tomography system

      Volumetric rendering and metrology of spherical gradient refractive index lens imaged by angular scan optical coherence tomography system

      In this paper, we develop the methodology, including the refraction correction, geometrical thickness correction, coordinate transformation, and layer segmentation algorithms, for 3D rendering and metrology of a layered spherical gradient refractive index (S-GRIN) lens based on the imaging data collected by an angular scan optical coherence tomography (OCT) system. The 3D mapping and rendering enables direct 3D visualization and internal defect inspection of the lens. The metrology provides assessment of the surface geometry, the lens thickness, the radii of curvature of the internal layer interfaces, and the misalignment of the internal S-GRIN distribution with respect to the lens surface. The ...

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    4. Experimental classification of surface waves in optical coherence elastography

      Experimental classification of surface waves in optical coherence elastography

      Various types of waves are produced when a harmonic force is applied to a semi-infinite half space elastic medium. In particular, surface waves are perturbations with transverse and longitudinal components of displacement that propagate in the boundary region at the surface of the elastic solid. Shear wave speed estimation is the standard for characterizing elastic properties of tissue in elastography; however, the penetration depth of Optical Coherence Tomography (OCT) is typically measured in millimeters constraining the measurement region of interest to be near the surface. Plane harmonic Rayleigh waves propagate in solid-vacuum interfaces while Scholte waves exist in solid-fluid interfaces ...

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    5. Crawling wave optical coherence elastography

      Crawling wave optical coherence elastography

      Elastography is a technique that measures and maps the local elastic property of biological tissues. Aiming for detection of micron-scale inclusions, various optical elastography, especially optical coherence elastography (OCE), techniques have been investigated over the past decade. The challenges of current optical elastography methods include the decrease in elastographic resolution as compared with its parent imaging resolution, the detection sensitivity and accuracy, and the cost of the overall system. Here we report for the first time, we believe, on an elastography technique—crawling wave optical coherence elastography (CRW-OCE)—which significantly lowers the requirements on the imaging speed and opens the ...

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    6. Simultaneous estimation of thickness and refractive index of layered gradient refractive index optics using a hybrid confocal-scan swept-source optical coherence tomography system

      Simultaneous estimation of thickness and refractive index of layered gradient refractive index optics using a hybrid confocal-scan swept-source optical coherence tomography system

      A hybrid confocal-scan swept-source optical coherence tomography metrology system was conceived for simultaneous measurements of the refractive index and thickness profiles of polymeric layered gradient refractive index (GRIN) optics. An uncertainty analysis predicts the metrology capability of the system and guides the selection of an optimum working numerical aperture. Experimental results on both a monolithic and a GRIN layered sheet are demonstrated to be in close agreement with theoretical predictions. Index measurement precision reached 0.0001 and 0.0008 for measuring 2.8 mm and ~300 µm thick layers, respectively. The thicknesses of these layers were simultaneously measured with a ...

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    7. Freeform metrology using swept-source optical coherence tomography with custom pupil-relay precision scanning configuration

      Freeform metrology using swept-source optical coherence tomography with custom pupil-relay precision scanning configuration

      The recent advances in the optics manufacturing industry to achieve the capability of fabricating rotationally nonsymmetric optical quality surfaces have considerably stimulated the optical designs with freeform components. This opens up new horizons for novel optical systems with larger fields of view and higher performance, or significantly more compact in volume at equal performance compared to conventional systems. A bottleneck to the broad industrial applications of freeform optics remains the lack of a high performance optical metrology tool capable of measuring significant surface departures and slopes of the parts. To address this issue, we have developed a fiber-based swept-source optical ...

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    8. Performance analysis of optical coherence tomography in the context of a thickness estimation task

      Performance analysis of optical coherence tomography in the context of a thickness estimation task

      Thickness estimation is a common task in optical coherence tomography (OCT). This study discusses and quantifies the intensity noise of three commonly used broadband sources, such as a supercontinuum source, a superluminescent diode (SLD), and a swept source. The performance of the three optical sources was evaluated for a thickness estimation task using both the fast Fourier transform (FFT) and maximum-likelihood (ML) estimators. We find that the source intensity noise has less impact on a thickness estimation task compared to the width of the axial point-spread function (PSF) and the trigger jittering noise of a swept source. Findings further show ...

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    9. Angular scan optical coherence tomography imaging and metrology of spherical gradient refractive index preforms

      Angular scan optical coherence tomography imaging and metrology of spherical gradient refractive index preforms

      The fabrication of high-performance spherical gradient refractive index (S-GRIN) optics requires nondestructive metrology techniques to inspect the samples. We have developed an angular-scan, swept-source-based, Fourier-domain optical coherence tomography system centered at 1318 nm with 5 mm imaging depth capable of 180̊ polar scan and 360̊ azimuthal scan to investigate polymeric S-GRIN preforms. We demonstrate a method that enables simultaneous mapping of the group optical thickness, physical thickness, the radially-averaged group refractive index, and the transmitted wavefront of the S-GRIN preforms. The angular scan OCT imaging and metrology enables direct visualization, molding uniformity characterization, and optical property evaluations of the preforms ...

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    10. Nondestructive metrology by optical coherence tomography empowering manufacturing iterations of layered polymeric optical materials

      Nondestructive metrology by optical coherence tomography empowering manufacturing iterations of layered polymeric optical materials

      In recent years, there has been an ever-growing interest in exploring different optical materials and components to develop compact and effective optical systems. The design and fabrication of high-performance optics require nondestructive metrology techniques to inspect the samples. We have investigated the capability of optical coherence tomography (OCT) to nondestructively characterize layered polymeric materials. Using a custom developed Gabor-domain optical coherence microscopy system centered at 800 nm with 120 nm full width at half maximum enabling unprecedented 2 μ m resolution both laterally and axially in an 8     mm 3 volume, we investigated the internal structure of 50 μ m thick films ...

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    11. Optical Coherence Tomography Enabling Non Destructive Metrology of Layered Polymeric GRIN Material

      Optical Coherence Tomography Enabling Non Destructive Metrology of Layered Polymeric GRIN Material

      Gradient Refractive INdex (GRIN) optical components have historically fallen short of theoretical expectations. A recent breakthrough is the manufacturing of nanolayered spherical GRIN (S-GRIN) polymer optical elements, where the construction method yields refractive index gradients that exceed 0.08. Here we report on the application of optical coherence tomography (OCT), including micron-class axial and lateral resolution advances, as effective, innovative methods for performing nondestructive diagnostic metrology on S-GRIN. We show that OCT can be used to visualize and quantify characteristics of the material throughout the manufacturing process. Specifically, internal film structure may be revealed and data are processed to extract ...

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    12. Nondestructive metrology of layered polymeric optical materials using optical coherence tomography

      Nondestructive metrology of layered polymeric optical materials using optical coherence tomography

      In recent years, there has been an ever-growing interest in exploring novel, highly efficient optical materials to develop compact and effective optical components. The design and fabrication of high-performance optics require nondestructive metrology techniques to inspect the samples. We have investigated the capability of optical coherence tomography (OCT) to nondestructively characterize layered polymeric materials. Using a swept-source OCT system with a wavelength range of 1.25 - 1.41 μm, we achieved micron-scale three-dimensional visualization of the interior structures and details of the layered polymers. The 3D OCT imaging also enabled accurate identification of the locations of defects within the samples ...

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    1-12 of 12
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    1. (12 articles) Jannick P. Rolland
    2. (11 articles) University of Rochester
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    Nondestructive metrology of layered polymeric optical materials using optical coherence tomography Optical Coherence Tomography Enabling Non Destructive Metrology of Layered Polymeric GRIN Material Nondestructive metrology by optical coherence tomography empowering manufacturing iterations of layered polymeric optical materials Angular scan optical coherence tomography imaging and metrology of spherical gradient refractive index preforms Performance analysis of optical coherence tomography in the context of a thickness estimation task Freeform metrology using swept-source optical coherence tomography with custom pupil-relay precision scanning configuration Simultaneous estimation of thickness and refractive index of layered gradient refractive index optics using a hybrid confocal-scan swept-source optical coherence tomography system Crawling wave optical coherence elastography Experimental classification of surface waves in optical coherence elastography Volumetric rendering and metrology of spherical gradient refractive index lens imaged by angular scan optical coherence tomography system Expert consensus published on use of imaging to guide heart attack treatment Impact of Swept Source optical coherence tomography in patients with photoreceptor dystrophies