Biomedical subjects

Zhu Luan

Publications and source records attributed to Zhu Luan.

7 recordsLinked to original sources

PubMed2006

Research on a scanner for tilting orthogonal double prisms.

The original scanner for tilting orthogonal double prisms is studied to test the tracking performance in intersatellite laser communications. With a reduction ratio of more than 100 times from the change rate of the angle of beam deviation to that of the tilting angle of each prism, the theoretical analysis performed, as well as the verification experiment, indicates that the scanner can meet the requirements of the scanning accuracy superior to 0.5 microrad with the scanning range greater than 500 microrad and can facilitate the mechanical structure design.

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PubMed2005

ABCD matrix for reflection and refraction of Gaussian beams at the surface of a parabola of revolution.

We report the formulation of an ABCD matrix for reflection and refraction of Gaussian light beams at the surface of a parabola of revolution that separate media of different refractive indices based on optical phase matching. The equations for the spot sizes and wave-front radii of the beams are also obtained by using theABCD matrix. With these matrices, we can more conveniently design and evaluate some special optical systems, including these kinds of elements.

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PubMed2005

Wave-front analysis method of circular aperture sampling for collimation testing.

A new type of wave-front analysis method for the collimation testing of laser beams is proposed. A concept of wave-front height is defined, and, on this basis, the wave-front analysis method of circular aperture sampling is introduced. The wave-front height of the tested noncollimated wave can be estimated from the distance between two identical fiducial diffraction planes of the sampled wave, and then the divergence is determined. The design is detailed, and the experiment is demonstrated. The principle and experiment results of the method are presented. Owing to the simplicity of the method and its low cost, it is a promising method for checking the collimation of a laser beam with a large divergence.

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PubMed2004

Jamin double-shearing interferometer for diffraction-limited wave-front test.

A Jamin double-shearing interferometer with three changeable schemes is proposed for the measurement of diffraction-limited laser wave front. A concept of detectable wave-front height is thus defined, and on this basis the limits of detectable wave-front height from the suggested schemes of interferometer are analyzed. The design is detailed, the simulation for wave aberrations is given, and the experiment is demonstrated. One of the major features of this interferometer is that it is capable of visually testing a diffraction-limited wave front immediately by the fringes with the matched accuracy and minimum detectable wave-front height on the order of 0.1lambda.

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PubMed2004

Optimal switching from recording to fixing for high diffraction from a LiNbO3:Ce:Cu photorefractive nonvolatile hologram.

An oscillatory characteristic of diffraction is observed as a result of strong beam coupling in a weakly oxidized LiNbO3:Ce:Cu crystal during the recording step in the production of nonvolatile photorefractive holograms. On this basis the optimal switching time from the recording step to the fixing step for high diffraction of a fixed hologram is studied. It is shown that switching after the first diffraction maximum leads theoretically to fixed diffraction of as much as 100% with a suitable switching time. Both an experimental demonstration and a theoretical simulation are presented.

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PubMed2003

Nearly-off-axis transmissivity of Solc birefringent filters.

The characteristics of light propagating near the axis of a birefringent filter are studied. A generalized formulation to describe the nearly-off-axis transmissivity of a Solc birefringent filter is derived. On this basis, the polarization conoscopic figures of Solc filters with different numbers of birefringent plates are simulated. Furthermore the variation of spectral transmission with angle of incidence is analyzed, and the field-of-view transmissivity and the spectral transmissivity averaged with respect to the spread of incident light are given. Primary experiments for verification are also demonstrated.

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PubMed2003

Uniform theory of the Talbot effect with partially coherent light illumination.

A uniform formulation for the self-imaging of gratings with any kind of partially coherent illumination is developed in terms of the cross mutual spectral density of the partial coherence theory. The formulation includes the time diffractive intensity distribution and the averaged diffractive intensity distribution at self-imaging distances and can be applied to both continuous and temporal illuminations with any kind of spectra. It is found that the averaged intensity distribution is related only to the intensity spectrum of illumination. The continuous polychromatic illumination and the ultrashort laser pulses with or without frequency chirp are then studied by a numerical stimulation. It is shown that the ultrashort laser pulse and the continuous polychromatic illuminations have similar averaged self-image distributions. Thus the Talbot effect may help in the study of the temporal and spectral characteristics of ultrashort laser pulses. An experiment with an LED is given, as well.

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