The Experts below are selected from a list of 26205 Experts worldwide ranked by ideXlab platform

Xu Liu - One of the best experts on this subject based on the ideXlab platform.

  • Axial Resolution enhancement in light sheet microscopy using mode modulation
    Advanced Optical Imaging Technologies II, 2019
    Co-Authors: Zhang Chengfeng, Cuifang Kuang, Yuchen Chen, Xu Liu
    Abstract:

    Light sheet fluorescence microscopy (LSFM) is widely used in biological imaging because of its low photobleaching and phototoxicity. The Axial Resolution of LSFM is determined and also limited by the thickness of the light sheet and the numerical aperture (NA) of the detection objective. We propose a novel method, light sheet modulation fluorescence microscopy (LSMFM) which is able to achieve a promising Axial Resolution enhancement of light sheet microscopy.

  • Enhancing the Axial Resolution of two-photon imaging.
    Applied optics, 2019
    Co-Authors: Shiyi Sun, Zhimin Zhang, Wensheng Wang, Yang Xin, Cuifang Kuang, Xu Liu
    Abstract:

    An Axial-Resolution-enhanced two-photon laser scanning microscopy system is presented in this paper. In the proposed method, we use a spatial light modulator (SLM) for the phase modulation of the excitation light. The Axially split point spread function (PSF) is generated by loading a 0−π pattern on the SLM. The final quality-enhanced images are acquired by subtracting the two consecutive images acquired by the original PSF and the split PSF. Because of the fluorescence differential processing, the Axial elongation of the particles images is suppressed, and the Axial Resolution is enhanced accordingly. With the Axial Resolution enhanced, the overlap between layer images is also reduced, which decreases the background noise of the images and enhances the contrast and image quality of the acquired fluorescence images. The capability of Axial Resolution and contrast enhancement is successfully demonstrated by both theoretical calculation and experimental results.

  • Axial Resolution enhancement for light sheet fluorescence microscopy via using the subtraction method
    Optical Engineering, 2018
    Co-Authors: Xiaona Wang, Cuifang Kuang, Xu Liu
    Abstract:

    Light sheet fluorescence microscopy is an imaging method in which the sample is illuminated from the side by a wide and relatively thin light sheet. This method minimizes the out-of-focus excitation, provides a good balance between spatial Resolution and temporal Resolution, and mitigates photobleaching and photodamage. Unfortunately, the Axial Resolution of light sheet fluorescence microscopy is much lower than lateral Resolution, which limits the achievement of isotropic imaging. We propose to combine the subtraction method with light sheet fluorescence microscopy to improve the Axial Resolution. The experimental results demonstrate that the proposed method can produce higher Axial Resolution than that of conventional light sheet fluorescence microscopy. In addition, a way to reduce negative values in subtraction method is also discussed.

  • Improvements of Axial Resolution in confocal microscopy with fan-shaped apertures
    Applied optics, 2015
    Co-Authors: Cuifang Kuang, Wei Gong, Li Xue, Yao Zheng, Yifan Wang, Xu Liu
    Abstract:

    Based on diffraction theory, this paper theoretically demonstrates improvements in Axial Resolution in confocal microscopy with fan-shaped apertures. It provides the optimal geometric parameters of the fan-shaped pupils to give the maximum Axial Resolution for a given pinhole size. To fully understand the overall performance, the signal-to-background ratio and the signal level with regard to the geometric parameters are discussed.

Ernst H. K. Stelzer - One of the best experts on this subject based on the ideXlab platform.

  • Measurement of the 4Pi‐confocal point spread function proves 75 nm Axial Resolution
    Applied Physics Letters, 1994
    Co-Authors: Stefan W. Hell, Steffen Lindek, Christoph Cremer, Ernst H. K. Stelzer
    Abstract:

    In a 4Pi‐confocal microscope the specimen is illuminated and observed coherently from above and below such that the numerical aperture is increased [S. W. Hell, European Patent Application 91121368.4 (filed 1990, published 1992), S. W. Hell and E. H. K. Stelzer, J. Opt. Soc. Am. A 9, 2159 (1992)]. The point spread functions of 4Pi‐confocal and confocal microscopes were measured. Our measurements prove a three‐ to seven‐fold increase of Axial Resolution, thus opening the prospect for a powerful three‐dimensional imaging technique with an Axial Resolution down to 75 nm.

  • measurement of the 4pi confocal point spread function proves 75 nm Axial Resolution
    Applied Physics Letters, 1994
    Co-Authors: Stefan W. Hell, Steffen Lindek, Christoph Cremer, Ernst H. K. Stelzer
    Abstract:

    In a 4Pi‐confocal microscope the specimen is illuminated and observed coherently from above and below such that the numerical aperture is increased [S. W. Hell, European Patent Application 91121368.4 (filed 1990, published 1992), S. W. Hell and E. H. K. Stelzer, J. Opt. Soc. Am. A 9, 2159 (1992)]. The point spread functions of 4Pi‐confocal and confocal microscopes were measured. Our measurements prove a three‐ to seven‐fold increase of Axial Resolution, thus opening the prospect for a powerful three‐dimensional imaging technique with an Axial Resolution down to 75 nm.

  • Enhancing the Axial Resolution in Far-field Light Microscopy: Two-photon 4Pi Confocal Fluorescence Microscopy
    Journal of Modern Optics, 1994
    Co-Authors: Stefan W. Hell, Steffen Lindek, Ernst H. K. Stelzer
    Abstract:

    Abstract We demonstrate theoretically and experimentally a fourfold increase in Axial point Resolution in far-field light microscopy. The Resolution enhancement is achieved by coherently illuminating the specimen with two opposing objective lenses (4Pi confocal microscopy) and applying two-photon excitation. The point spread function and the Axial Resolution of this set-up are calculated in optical units. The Axial Resolution is measured and compared with predictions, both for the confocal and for the 4Pi confocal set-up, in single as well as in two-photon excitation mode.

Jonathan Ophir - One of the best experts on this subject based on the ideXlab platform.

  • trade offs between the Axial Resolution and the signal to noise ratio in elastography
    Ultrasound in Medicine and Biology, 2003
    Co-Authors: Raffaella Righetti, Jonathan Ophir, Seshadri Srinivasan
    Abstract:

    Abstract Elastography involves tracking the ultrasonic A-mode signals before and after mechanical compression of tissue to form a computed image of the local strains undergone by various tissue components. The quality of the strain estimates in elastography is typically quantified using factors such as the elastographic SNR ( SNR e ), contrast-to-noise ratio ( CNR e ), and the spatial Resolution. These quality factors depend on the mechanical parameters (such as the applied strain and the boundary conditions), the acoustic parameters (such as the sonographic SNR, the center frequency, and the bandwidth), and the signal-processing parameters (such as the window length and the window separation). Theoretical developments in elastography have established functional relationships between the SNR e and CNR e and these parameters. Similarly, simulations have established empirical relationships between the Axial Resolution and the acoustic and signal-processing parameters. We find that a trade-off exists between the achievable SNR e ( CNR e ) and the Axial Resolution in elastography and that the trade-off occurs only with respect to the signal-processing parameters. Theoretical work on the spatial Resolution accompanied with simulations and experiments were used to confirm such an observation. The trade-off between the SNR e ( CNR e ) and the Resolution was found to be nonlinear, with large improvements in the SNR e being possible at the expense of small reductions in the Axial Resolution. All the quality factors improve with the acoustic parameters, which suggests the preferred use of transducers with high absolute bandwidths and center frequencies. (E-mail: Jonathan.Ophir@uth.tmc.edu)

  • Axial Resolution in elastography.
    Ultrasound in Medicine & Biology, 2002
    Co-Authors: Raffaella Righetti, Jonathan Ophir, Periklis Y. Ktonas
    Abstract:

    The limits and trade-offs of the Axial Resolution in elastography were investigated using a controlled simulation study. The Axial Resolution in elastography was estimated as the distance between the full widths at half-maximum of the strain profiles of two equally stiff lesions embedded in a softer homogeneous background. The results show that the upper bound of the Axial Resolution in elastography is controlled by the physical wave parameters of the ultrasound (US) system used to acquire the data (transducer center frequency and band- width). However, an inappropriate choice of the parameters used to process the US data (cross-correlation window length and shift between consecutive windows) may compromise the best Resolution attainable. The measured elastographic Axial Resolution was found to be on the order of the ultrasonic wavelength. (E-mail: Jonathan.Ophir@uth.tmc.edu) © 2002 World Federation for Ultrasound in Medicine & Biology.

  • Elastographic Axial Resolution criteria: an experimental study
    IEEE transactions on ultrasonics ferroelectrics and frequency control, 2000
    Co-Authors: S.k. Alam, Jonathan Ophir, Tomy Varghese
    Abstract:

    In elastography, window size has been typically used synonymously with Resolution. Strain is estimated by computing the gradient of the displacement estimates, which have a direct dependence on the window size. However, the Resolution is also dependent on the separation between these windows. The intricate relationship between the window size, window shift, and Resolution has not previously been explored. In this article, we perform a controlled simulation experiment to evaluate the relationship among elastographic Axial Resolution, window size, and window shift. We conclude that the Axial Resolution can be expressed as a bilinear function of window size and window shift, the latter having a much larger weight.

Stefan W. Hell - One of the best experts on this subject based on the ideXlab platform.

  • Measurement of the 4Pi‐confocal point spread function proves 75 nm Axial Resolution
    Applied Physics Letters, 1994
    Co-Authors: Stefan W. Hell, Steffen Lindek, Christoph Cremer, Ernst H. K. Stelzer
    Abstract:

    In a 4Pi‐confocal microscope the specimen is illuminated and observed coherently from above and below such that the numerical aperture is increased [S. W. Hell, European Patent Application 91121368.4 (filed 1990, published 1992), S. W. Hell and E. H. K. Stelzer, J. Opt. Soc. Am. A 9, 2159 (1992)]. The point spread functions of 4Pi‐confocal and confocal microscopes were measured. Our measurements prove a three‐ to seven‐fold increase of Axial Resolution, thus opening the prospect for a powerful three‐dimensional imaging technique with an Axial Resolution down to 75 nm.

  • measurement of the 4pi confocal point spread function proves 75 nm Axial Resolution
    Applied Physics Letters, 1994
    Co-Authors: Stefan W. Hell, Steffen Lindek, Christoph Cremer, Ernst H. K. Stelzer
    Abstract:

    In a 4Pi‐confocal microscope the specimen is illuminated and observed coherently from above and below such that the numerical aperture is increased [S. W. Hell, European Patent Application 91121368.4 (filed 1990, published 1992), S. W. Hell and E. H. K. Stelzer, J. Opt. Soc. Am. A 9, 2159 (1992)]. The point spread functions of 4Pi‐confocal and confocal microscopes were measured. Our measurements prove a three‐ to seven‐fold increase of Axial Resolution, thus opening the prospect for a powerful three‐dimensional imaging technique with an Axial Resolution down to 75 nm.

  • Enhancing the Axial Resolution in Far-field Light Microscopy: Two-photon 4Pi Confocal Fluorescence Microscopy
    Journal of Modern Optics, 1994
    Co-Authors: Stefan W. Hell, Steffen Lindek, Ernst H. K. Stelzer
    Abstract:

    Abstract We demonstrate theoretically and experimentally a fourfold increase in Axial point Resolution in far-field light microscopy. The Resolution enhancement is achieved by coherently illuminating the specimen with two opposing objective lenses (4Pi confocal microscopy) and applying two-photon excitation. The point spread function and the Axial Resolution of this set-up are calculated in optical units. The Axial Resolution is measured and compared with predictions, both for the confocal and for the 4Pi confocal set-up, in single as well as in two-photon excitation mode.

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

  • Characterization of spectral-domain OCT with autocorrelation interference response for Axial Resolution performance
    Optics Express, 2018
    Co-Authors: Sucbei Moon, Zhongping Chen
    Abstract:

    We present a class of novel system characterization methods for spectral-domain optical coherence tomography (SD-OCT) particularly on getting optimized Axial Resolution performance. Our schemes uniquely utilize the autocorrelation interference response, also known as the self-interference product, which is generated by the optical fields from the imaging sample in automatic interferences. In our methods, an autocorrelation-inducing calibration sample was prepared which was made by sandwiching glass plates. OCT images of the calibration sample were captured by an SD-OCT system under testing. And the image data were processed to find various system characteristics based on the unique properties of autocorrelation interferograms, free of dispersion- and polarization-involved modulations. First, we could analyze the sampling characteristic of the SD-OCT’s spectrometer for spectral calibration that enables accurate linear-k resampling of detected spectral fringes. Second, we could obtain the systematic polarization properties for quantifying their impact on the achieved Axial Resolutions. We found that our methods based on the autocorrelation response provide an easy way of self-characterization and self-validation that is useful in optimizing and maintaining Axial Resolution performances. It was found very attractive that a variety of system characteristics can be obtained in a single-shot measurement without any increased system complexity.

  • optimization for Axial Resolution depth range and sensitivity of spectral domain optical coherence tomography at 1 3 µm
    Journal of the Korean Physical Society, 2009
    Co-Authors: Hyun Woo Jeong, Woonggyu Jung, Zhongping Chen
    Abstract:

    We have developed high-speed and high-Resolution spectral domain optical coherence tomography at 1.3 µm using an InGaAs line-scan camera and a broadband light source with the bandwidth of 170 nm that produces a theoretical Axial Resolution of 4.4 µm in air. We compared Axial Resolutions from point spread functions (PSFs) and depth ranges while changing the full spectral bandwidth detected by the camera and describing the optimization process for the Axial Resolution, the depth range, and the sensitivity for SD-OCT system. We found that SD-OCT at 1.3 µm cannot satisfy the conditions both below the Axial Resolution of 5 µm and above the depth range of 2 mm because of the restricted pixel number of the line-scan camera. To scan a large depth range, the Axial Resolution has to be sacrificed. In addition, the sensitivity rolls off slowly as a function of the depth if a large depth range is scanned. On the other hand, if the Axial Resolution needs to be close to the theoretical one, the depth range becomes limited and the sensitivity decays quickly. Since we have to maintain a reasonable depth range of 2.0 mm, we chose the spectrum full bandwidth of 214 nm captured by the detector to balance the Axial Resolution of 8.2 µm. In this setting, the sensitivity of our OCT system was measured at 107.1 dB. Theoretical and experimental results are compared and presented in this paper.