Biomedical subjects

Fucai Zhang

Publications and source records attributed to Fucai Zhang.

3 recordsLinked to original sources

PubMed2006

Reconstruction algorithm for high-numerical-aperture holograms with diffraction-limited resolution.

A fast algorithm is proposed for the reconstruction of digital holograms that are recorded at high numerical aperture. The method directly evaluates the Rayleigh-Sommerfeld diffraction integral by use of a fast convolution algorithm. A shift parameter that accounts for the coordinate system's transverse displacement of the object plane and the hologram plane is introduced in a discrete representation of the diffraction kernel. Combination of the samplings reconstructed with different shift values yields diffraction-limited resolution over the full field of view. The algorithm is suitable for various applications such as holographic microscopy and metrology. Simulation and experimental results are presented.

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PubMed2004

Algorithm for reconstruction of digital holograms with adjustable magnification.

A new algorithm that allows for reconstruction of digital holograms with adjustable magnification is proposed. The algorithm involves two reconstruction steps implemented by a conventional single Fourier-transform algorithm. The advantages of the algorithm lie in its adaptability to various object sizes and recording distances as well as in its capability to maintain the pitch of a reconstructed image, independent of the reconstruction distance and wavelength for objects larger than a CCD. The feasibility of the algorithm is demonstrated by experiments. The algorithm is especially useful for reconstructing color holograms and for metrological applications.

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PubMed2003

Wide temperature-range Brillouin and Rayleigh optical-time-domain reflectometry in a dispersion-shifted fiber.

The temperature dependences of spontaneous Brillouin and Rayleigh scattering intensities in a dispersion-shifted fiber have been measured over a wide temperature range by optical-time-domain reflectometry. It was found that spontaneous Brillouin and Rayleigh intensities normalized by room-temperature values have linear dependences on temperature, with coefficients (0.26 +/- 0.02)%/degrees C and (0.015 +/- 0.002)%/degrees C in temperature ranges -27-819 and 29-827 degrees C, respectively. Experimental results have demonstrated that both kinds of scattering can be used for distributed high-temperature measurement.

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