1. Articles from Di Xu

    1-5 of 5
    1. Verification of cascade optical coherence tomography for freeform optics form metrology - Osa

      Verification of cascade optical coherence tomography for freeform optics form metrology - Osa

      Freeform optical components enable dramatic advances for optical systems in both performance and packaging. Surface form metrology of manufactured freeform optics remains a challenge and an active area of research. Towards addressing this challenge, we previously reported on a novel architecture, cascade optical coherence tomography (C-OCT), which was validated for its ability of high-precision sag measurement at a given point. Here, we demonstrate freeform surface measurements, enabled by the development of a custom optical-relay-based scanning mechanism and a unique high-speed rotation mechanism. Experimental results on a flat mirror demonstrate an RMS flatness of 14 nm (∼λ/44 at the He-Ne wavelength ...

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    2. Cascade optical coherence tomography (C-OCT)

      Cascade optical coherence tomography (C-OCT)

      Significant advances for optical systems in terms of both performance and packaging are enabled by freeform optical components. Yet, surface form metrology for freeform optics remains a challenge. We developed and investigated a point-cloud cascade optical coherence tomography (C-OCT) technique to address this metrology challenge. The mathematical framework for the working principle of C-OCT is presented. A novel detection scheme is developed to enable high-speed measurements. Experimental results validate the C-OCT technique with the prototype setup demonstrating single-point precision of ±26 nm (∼λ/24 at the He-Ne wavelength), paving the way towards full surface measurements on freeform optical components.

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    3. Absolute linear-in-k spectrometer designs enabled by freeform optics

      Absolute linear-in-k spectrometer designs enabled by freeform optics

      Linear-in-wavenumber, k , spectrometers have the merits of saving signal processing time and improving the sensitivity of spectral-domain optical coherence tomography (SD-OCT) by avoiding post- k -interpolation. We report on an approach leveraging freeform optics to linearize spectrometers in k to achieve an extremely low residual k -nonlinearity in design. A freeform lens reduced the k -nonlinearity from 2.47% for a benchmark spectrometer to 2.79 × 10 −5 % and 3.36 × 10 −9 % using the Fringe Zernike coefficients up to the 16 th term and 37 th term, respectively. A simulation model was developed to evaluate the performance of SD-OCT ...

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    4. Telecentric broadband objective lenses for optical coherence tomography (OCT) in the context of low uncertainty metrology of freeform optical components: from design to testing for wavefront and telecentricity

      Telecentric broadband objective lenses for optical coherence tomography (OCT) in the context of low uncertainty metrology of freeform optical components: from design to testing for wavefront and telecentricity

      Freeform optical components enable significant advances for optical systems. A major challenge for freeform optics is the current lack of metrology methods with measurement uncertainty on the order of tens of nanometers or less. Towards addressing this challenge, optical coherence tomography (OCT) is a viable technique. In the context of low uncertainty metrology, the design requirements pertaining to the sample arm of an OCT metrology system are explicitly addressed in this paper. Two telecentric, broadband, diffraction limited, custom objective lens designs are presented with their design strategies. One objective lens was fabricated and experimentally tested for wavefront performance and telecentricity ...

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    5. 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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    1-5 of 5
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  2. Topics in the News

    1. (5 articles) University of Rochester
    2. (5 articles) Jannick P. Rolland
    3. (1 articles) AlazarTech
    4. (1 articles) Yamagata University
    5. (1 articles) Bern University of Applied Sciences
    6. (1 articles) Medical University of Vienna
    7. (1 articles) University of Maryland
    8. (1 articles) Koen A. Vermeer
    9. (1 articles) Vishali Gupta
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    Freeform metrology using swept-source optical coherence tomography with custom pupil-relay precision scanning configuration Telecentric broadband objective lenses for optical coherence tomography (OCT) in the context of low uncertainty metrology of freeform optical components: from design to testing for wavefront and telecentricity Absolute linear-in-k spectrometer designs enabled by freeform optics Cascade optical coherence tomography (C-OCT) Verification of cascade optical coherence tomography for freeform optics form metrology - Osa Hybrid registration of retinal fluorescein angiography and optical coherence tomography images of patients with diabetic retinopathy Optical Coherence Tomography Angiography Quality Across Three Multicenter Clinical Studies of Diabetic Retinopathy The Role of Optical Coherence Tomography Angiography(OCTA) in Detecting Choroidal Neovascularization in DifferentStages of Best Macular Dystrophy: A Case Series Discrimination of diabetic retinopathy from optical coherence tomography angiography images using machine learning methods Quantitative analysis of vascular changes during photoimmunotherapy using speckle variance optical coherence tomography (SV-OCT) High-resolution, depth-resolved vascular leakage measurements using contrast-enhanced, correlation-gated optical coherence tomography in mice Longitudinal analysis of cotton wool spots in COVID-19 with high resolution spectral domain optical coherence tomography and optical coherence tomography angiography