Search

The relationship between the dispersion capability and the temperature of argon arc plasma at 1 atm is deduced in view of the plasma's refractive index equation. The results indicate that argon arc plasma has a normal dispersion and its dispersion capability is nonlinear to the plasma's temperature in a wide range of temperature and wavelength region. According to the results of numerical calculation, the preferred optical methods are believed to be suitable for the diagnosis of argon arc plasma in different temperature regions.

A polydisperse sphere model with the complex refractive index is employed to describe the propagation of light in biological tissue. The scattering coefficient, absorption coefficient and scattering phase function are calculated. At the same time, the inverse problem on retrieving the particles size distribution, imaginary part of the refractive index and number density of scatterers is investigated. The result shows that the retrieval scheme together with the Chahine algorithm is effective in dealing with such an inverse problem. It is also clarified that a group of parameters including the scattering coefficient, absorption coefficient and phase function are associated with another group including the refractive index, particle size distribution and number density of scatterers, which is a problem described in two different ways and the anisotropy factor is not an independent variable, but is determined by the phase function.

An orthogonal projection sampling method is proposed in this paper for the reconstruction of incomplete data field by using the prior knowledge algorithm based on the modified algebra reconstruction technology (ART) in the optical computerized tomography (OCT). Experiments based to this method are studied. The satisfying reconstruction results are obtained with less sampling projection numbers and limited sampling angular range. The results indicate that orthogonal projection sampling can improve the precision in the reconstruction of incomplete data, and the precision reaches 10%. © 2006 Wiley Periodicals,Inc. Microwave Opt Technol Lett 48:2333–2336, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21947

Moire deviation tomography is proposed in this article to measure the infrared radiation temperature field generated by the burning pyrotechnic compositions. High-speed photography is used as the sampling method in this measurement. The results indicate that, due to its unique merits of noncontact, strong antiinterference, and large range, moire deviation tomography provides a new way for the measurement of high-temperature, high-brightness, and transient field. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2761–2763, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22879

A sphere queue model is introduced to calculate Mueller matrices of turbid media. Combined with the single scattering approximation, the backscattering Mueller matrices of turbid media can be computed rapidly by Mie theory. The numerical results agree with the azimuthal dependences of backscattering Mueller matrices' patterns from turbid media, which indicates that the major contribution to the Mueller matrices' patterns comes from the single scattering of the sphere queue, and the multiple scattering considered as a high-order correction does not change the patterns. The numerical analysis reveals that the contrast of Mueller matrices' patterns will decrease with increase of the concentration of media and the distance from the incident point.

Complex refractive indices are introduced to solve various boundary questions at the interfaces when modelling light migration within heterogeneous tissues. Combined with the complex refractive index, Fresnel's formulae are used to describe the reflection and transmission at the interfaces between two heterogeneous tissues layers. Using the Monte Carlo method, the influence of the complex refractive index on diffuse reflection of semi-infinite biological tissues is discussed. The results show that neglecting the imaginary part of the refractive index of tissues will bring a major deviation in the diffuse reflection of semi-infinite biological tissues when its emitting point is apart from the incident point.

A mathematical expression of reflectance point-spread function, which is defined as the spatial distribution of light diffuse-reflected from bio-tissues irradiated by an infinitely narrow photon beam, is derived from the diffusion approximation (DA) theory. With the introduction of reflectance point-spread function to describe the reflectance characteristics of bio-tissues, the convolution method is used to calculate the spatial resolved reflectance from dense and thick tissues irradiated by different photon beams. This is called the DA based convolution method and is used to calculate the responses of the semi-infinite bio-tissues irradiated by a Gaussian beam and a flat beam with different beam radius. The calculation results show that the DA based convolution method has much higher computing efficiency compared to the Monte Carlo method.

In this paper, optical computerized tomography (OCT) is first used for research on the heat elimination of a real aeroengine blade. The 3D temperature distribution and temperature topography of the blade are reconstructed. The results of the reconstruction match the measured results. This provides the experimental foundation for the design of an aeroengine blade. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 117–119, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10989

In this paper, three-dimensional optical computerized tomography in the case of severely incomplete projection data is discussed theoretically and experimentally. An orthogonal projection method has been proposed for optical tomography in the case of severely incomplete data. Some comparative numerical simulations and experimental results of traditional sampling method and the new method are given. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 57–59, 2001.

An extended model of the original Gladstone-Dale (G-D) equation is proposed for optical computerized tomography (OCT) diagnosis of flame flow fields. For the purpose of verifying the newly established model, propane combustion is used as a practical example for experiment, and moire deflection tomography is introduced with the probe wavelength 808 nm. The results indicate that the temperature based on the extended model is more accurate than that based on the original G-D equation. In a word, the extended model can be suitable for all kinds of flame flow fields whatever the components, temperature, and ionization are.

The argon arc plasma whose central temperature, 1.90x10(4) K, is used as a practical example for an experiment to research the applicability of moiré deflection tomography in arc plasma flow-field diagnosis. The experimental result indicates that moiré deflection of the measured argon arc plasma is very small, even smaller than that of a common flame with the maximal temperature of nearly 1.80x10(3) K. The refractive-index gradient in moiré deflection tomography mainly contributes to the temperature gradient in essence when the probe wavelength and pressure are certain in plasma diagnosis. The applicable temperature ranges of moiré deflection tomography in the argon arc plasma diagnosis are given with the probe wavelength 532 nm at 1 atm in certain measuring error requirements. In a word, the applicable temperature range of moiré deflection tomography for arc plasma diagnosis is intimately related to the probe wavelength and the practical measuring requirements.

The interrogation of a holo-specklegram from point to point results in two side lobes as well as the formation of central Young's fringes. It is proved theoretically and experimentally that these fringes in the side lobes are, in essence, the Young's interference fringes of the first-order diffractions of the pair of identical speckles in the holo-specklegram. A practical quantitative formula is presented to calculate the in-plane displacement.

In this paper, A CCD-based experimental setup with light oblique incidence is developed to obtain the backscattered Mueller matrices of turbid media. Based on the experimental measurements, the polarity of Mueller matrix's element and the influences of concentration on the backscattered Mueller matrices of Intralipid suspensions are discussed comprehensively. Moreover, the backscattered Mueller matrices of layered muscle tissue and liver tissue are also presented.

In this paper, a new scheme is proposed to describe the optical properties of biological tissues from three scales: molecules, cells, and tissues. The electric susceptibility, refractive index and radiative transfer parameters (including scattering coefficient, absorption coefficient, anisotropic factor, etc.) are the corresponding optical parameters on those three scales. And the dipole theory, electromagnetic scattering theory and radiative transfer theory are corresponding theoretical tools for analyzing the optical phenomena in biological tissues, respectively. Moreover, the relationships between those optical parameters are also discussed comprehensively.

In this paper, a new rotary interferometer is designed to obtain the multidirection interferometry projections instead of the multichannel interferometer used in the past. The projection data are subtracted to reconstruct the temperature field with the modified algebra reconstruction technique (MART). © 1998 John Wiley & Sons, Inc. Microwave Opt Technol Lett 19: 64–66, 1998.