摘要:

A method is proposed for subtracting two images using a polarization-shifted periodic carrier. The method has been successfully used to find the intensity gradient of a test object in the form of a transparency. Some experimental results are presented.

ISSN:0030-3909    

DOI:10.1080/713821219

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

This paper is the third in a series of papers on the diffraction and imaging properties of generalized curvilinear diffraction gratings. Here we study classes of plane uncrossed diffraction gratings which have the common property that their Fourier transform patterns consist of sharp-line caustics. These types of generalized gratings are referred to as ‘Euclidian diffraction gratings’, because the condition for the formation of line caustics is equivalent to the global vanishing of the gaussian curvature of the grating line pattern function. The analysis is applied to the laser material processing system discussed in our last paper [1].

ISSN:0030-3909    

DOI:10.1080/716099640a

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

This paper is the fourth in a series of papers [1, 2] on the diffraction and imaging properties of generalized curvilinear diffraction gratings. Here we discuss the Fraunhofer diffraction properties of plane crossed-line gratings which consist of a product of two uncrossed-line gratings. In particular, we establish a set of conditions which the grating functions must satsify for the diffraction pattern to consist of a purely singular line pattern. For these singular gratings, we show that the diffraction pattern consists of a product of the orders of each uncrossed-line grating plus additional orders due to couplings between the separate gratings.

ISSN:0030-3909    

DOI:10.1080/716099640b

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

This paper is the last in a series [1–4] of five papers on the diffraction and imaging properties of generalized curvilinear diffraction gratings. Here we show how the bifurcation properties of two-dimensional potential functions may be studiedviaa diffraction grating representation. In particular, we derive the grating functions appropriate to Thom's seven elementary catastrophes. We then present a detailed study of the cusp grating and discuss the behaviour of its point source image diffraction pattern (IDP) in the context of catastrophe theory. In this way, we show how catastrophe theory allows for a simple geometric interpretation of discontinuous type image diffraction patterns.

ISSN:0030-3909    

DOI:10.1080/716099640

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Mutual optical bistability is found for several modes in open cavities containing second- or third-order nonlinear materials. The quantum-statistical treatment yields the Fokker-Planck equation for any system of damped boson modes. Under certain conditions it is possible to state the extrema of the steady solution of the Fokker-Planck equation. They are compared with the steady states resulting from the classical deterministic treatment. In some cases both statements coincide.

ISSN:0030-3909    

DOI:10.1080/713821201

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

If the mutual intensity of partially coherent illumination is periodic in the lateral direction then it is also periodic in the longitudinal direction. This statement is proved for quasi-monochromatic light and for a cosine periodicity. Next an experimental set-up for the production of periodic mutual intensities is proposed. Finally, the theoretical result is generalized to other than cosine-shaped periodicities.

ISSN:0030-3909    

DOI:10.1080/713821220

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

We study anisotropic cylindrical dielectric waveguides under the following conditions: (1) their cross section Ω has arbitrary shape; (2) the dielectric permittivity tensor ε has discontinuities at the boundaries, as well as a graded spatial variation; (3) Ω is small, and ε minus the unit 3 × 3 matrix (I) is small and smooth, so that only one pair of propagation modes is allowed. A general and exact dispersion relation for the propagation modes is derived, using integral equation techniques and the long wavelength singularity of the free-space Green's function in two dimensions. We present approximate explicit solutions of the dispersion relation to first order in (ε−I), which exhibit a logarithmic dependence and birefringence, in general. Some numerical estimates are also given. Approximate dispersion relations up to and including second order in (ε −I) are also discussed. The scattering problem is treated briefly.

ISSN:0030-3909    

DOI:10.1080/713821213

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Fresnel diffraction fields of one-dimensional opaque objects under collimated gaussian beam illumination are described. The irradiance distribution function is derived and the resultant formulae are compared with the case of uniform beam illumination. Experimental observation of irradiance as a function of position is in good agreement with numerically calculated results.

ISSN:0030-3909    

DOI:10.1080/713821210

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The zero description of entire functions of exponential type is reviewed. Serial and parallel methods of zero location from sampled data are introduced, and the results of applying these methods to simulated data are given. One method is also suitable for locating the zeros of finite-degree polynomials, and is thus particularly useful for use with the zztransform of an input sequence. The relationship between the algorithms is discussed, and a recommendation of the most reliable method is given.

ISSN:0030-3909    

DOI:10.1080/713821202

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

A stacked system of phase Fourier holograms on which binary information is recorded has been built and its performance studied. The properties of the zero-order beam propagating through the stack have been investigated. The results show how the energy and intensity distributions of the read-out beam change as the beam propagates through the system, and the values of the imaging efficiency ηnof successive holograms and the signal-to-noise ratio (S/N) are measured in successive reconstructed images. The evolution of the zero-order beam is described mathematically.

ISSN:0030-3909    

DOI:10.1080/713821223

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor