In the last few years renewed attention has been paid to the study of light scattering from random media. This due to the recent discovery of a phenomenon that dynamic light scattering from a fluctuating random medium may produce shifts of spectral lines, even when the source and the scattering medium are at rest relative to the observer. It has also been demonstrated that a similar phenomenon may occyr in static light scattering from spatially random media without dynamic fluctuations.By the well-known analogy between the processes of scattering and radiation, these phenomena in scattering are found to be closely related to the correlation-induced spectral changes in the coherence theory which are often referred to as the Wolf effect. In this paper some recent developments are reviewed on research regarding the phenomena of changes in the attempts for elucidating the effects of multiple scattering on these phenomena.

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The maximum axial trapping efficiency Q_max has been measured in water, ethanol, butanol and octanol for polystyrene latex spheres having a diameter of 2-15 μm. The effects of the diameter of the particle as well as the refractive index and the viscosity of surrounding medium have been investigated.For particles of d≥7 μm, Q_max is almost independent of particle size, while it decreases as the diameters decrease to d≤5 μm. It is also noted that Q_maxis affected by the viscosity rather than the refractive index of the surrounding medium.

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We measured the two-dimensional birefringence compensation in laser-diode(LD) pumped Nd:glass(HAP4) laser rods with a high-sensitivity polarimeter.The compensation was performed by inserting a 90° quartz rotator between two identical LD pumped Nd:glass rods with conductive cooling.A considerable reduction of birefringence loss from 9.8% to less than 0.9% after compensation was observed.

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Poled silica and germanosilicate thin films are prepared with typical sol-gel processing.Second-order nonlinearity about one order of magnitude larger than that of quartz crystal is realized.Substrate effect and dopant effect on the nonlinearity are discussed.

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Through numerical experiments we show that the use of spatial solitons in second-order parametric interactions could make possible the observation of solitons in the vicinity of the vacuum ultraviolet.

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We propose a computed tomography (CT) for the incoherent optical system based on a generalized analytic reconstruction method from discrete samples(GARDS), by which an object image defined in a continuous space is reconstructed from discrete images acquired through the imaging system. We apply this method to reconstruct depth structures of micro-specimens using conventional fluorescence microscopes. Also, we discuss the optimal sampling distance in the depth direction through a generalized singular value decomposition of a continuous -to-discrete imaging system. We next apply the GARDS-based CT method to a double-axis microscope, in which two microscopes are set up perpendiculrly to cover a missing frequency band of each microscopic imaging system. We show simulation results which verify the effectiveness of our proposed method.

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Characteristics of guided acoustic wave Brillouin scattering in polarization maintaining fibers are investigated theoretically and experimentally. Spectra of polarized and depolarized scattering are measured for two different types of polarization maintaining fibers: the PANDA(polarization maintaining and absorption reducing) fibers and the elliptical-jacket fibers. Calculated results are in agreement with experimental ones in the low frequency region.

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A compact zone-plate interferometer is developed to measure the shape error of concave mirrors. A diffracted light of (0, 0) and that of (-1, -1) or (+1, +1) are used in the interferometer. The interferometer enables us to measure the shap error of mirrors with a large numerical aperture and a steep asphericity. the shape errors of a spherical mirror and a parabolic mirror are measured by the interferometer, and that of the former agrees well with that measured by Fizeau interferometer. Methods for adjustments of zone plates and the mirrors being tested are proposed to perform precise measurements of mirror shapes.

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We propose and confirm a novel technique of optical frequency domain reflectometry based on multidigitized coherence using a multimode laser. The proposed system can easily provide the potential for high resolution on the order of 10 μm without scanning frequencies as in frequency domain reflectometers of either continuous or stepwise sweep. The theoretical approach agrees well with the experimental results demonstrated using a commercially available multimode laser diode.

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A new incoherent Doppler lidar scheme is proposed using a high resolution Mach-Zehnder interferometer discriminator with sinusoidal transmission functions. A two-channel differential discrimination technique is developed which provides high sensitive velocity measurement. The aerosol and molecular backscatter signals can be separately measured and the backscatter ratio obtained. Principle of the measurement is described and the characteristics of this technique are analyzed and compared. Numerical calculation for a moderate size 1.064 μm lider shows that an accuracy better than 1 m/s for the velocity measurement and 18 0.000000or the backscatter ratio measurement can be obtained up to a height of 10 km by a 500 shot average.

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We conducted an experiment in which subjects observed a picture of natural scene while the picture was displaced according to a subject's saccades. The threshold displacement ratio (the length of picture displacement/the length of saccade) that allowed subjects to perceive the stable picture was measured. In experiment 1 the threshold ratio was measured for each of five pictures when the picture was displaced in the same direction as each saccade. In experiment 2 the direction of the picture displacement was set in the same, opposite or orthogonal to the movement of the eye to examine effects of the relative displacement direction. The results showed that the subjects perceived a picture as stable despite fairly large displacement during saccades; the threshold ratio was influenced by the picture and ranged from 18% to 26%. It was also found that the displacement in the same direction as the eye was more detectable than in the opposite direction.

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