ISSN:0950-0340    

DOI:10.1080/09500349214552041

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

It is shown that the irradiance data from frequency-translated time-average holography and a recurrence relationship of Bessel function of the first kind can be very effectively used for the vibration analysis. The vibration amplitude can directly be determined from the irradiance values at any image point without the traditional fringe counting procedure. The theory of the process is presented.

ISSN:0950-0340    

DOI:10.1080/09500349214552051

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Photonic band structure has been computed using ellipsoidal grains in f.c.c. lattice. Bandgaps have been found and the conditions for the appearance of such gaps are discussed. The effective long-wavelength dielectric constants for the ordinary and the extraordinary rays are calculated and compared with the predictions of effective medium and Maxwell-Garnett theories.

ISSN:0950-0340    

DOI:10.1080/09500349214552061

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The spectral properties and the coherence properties of Gaussian Schell-model beams, propagating in dispersive and absorbing media, are discussed. Unlike in free space, the ratio of the transverse spectral correlation length to the beam width is found to increase on propagation. Consequently upon propagation the beam becomes spatially more coherent at each frequency. Numerical results for the spectrum and for the degrees of spectral and of temporal coherence of the field are presented for some selected values of the beam parameters and for several values of the propagation distance. Propagation in a gain medium is also briefly discussed.

ISSN:0950-0340    

DOI:10.1080/09500349214552071

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

We present a model for an end pumped microchip solid state laser with plane-parallel cavity mirrors. Our model has a transversely varying gain and gives the laser threshold, output intensity, frequency and the transverse mode profiles in terms of the cavity detuning, cavity losses and other relevant parameters. We have also adapted the model to derive the pump threshold for simultaneous operation of two transverse models. We find that these lasers almost always operate on the fundamental mode and only for broad pump beams and high pump powers can higher order modes be excited.

ISSN:0950-0340    

DOI:10.1080/09500349214552081

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

We have investigated the importance and influence of the initial phase in zone plates when they are used as integrated intensity optical sensors. They present its maximum sensitivity when the physical parameter, to be sensed, is at or near to the desired value. An interferometric method is proposed for generating controlled initial phases in zone plates.

ISSN:0950-0340    

DOI:10.1080/09500349214552091

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The delivering of two-frequency beams by optical fibres and interferometers and the interference of polarized waves is studied by using Jones' formalism and the complex-wave representation. Polarization encoding is shown to make the relation between the phase of the interference pattern and the difference in the optical path of interfering beams nonlinear, owing to the geometric contribution to the phase made by misalignments and unequal ellipticity of the normal modes of beam and interferometer. The polarization transport is analysed with the aid of the Poincaré representation, and a complete picture of the phenomena underlying nonlinearity and geometric noise is given. In the case of small aberrations approximate formulae and experimental observations are reported as well.

ISSN:0950-0340    

DOI:10.1080/09500349214552101

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

In this paper we discuss a method of wavefront phase detection by differentiation of the interferometric fringes. We show that only one phase step is required to determine the wavefront phase. In the process of differentiation, Moiré fringes are formed. Conditions on the angle of tilt introduced between the interfering beams to overcome the formation of Moiré fringes are also presented. The method is shown to be suitable for techniques such as null optical testing or interferometric methods where comparison is made between a master and a test. We present in this paper the theory of the method and experimental results obtained for bothspecularandspeckleinterferometric fringes.

ISSN:0950-0340    

DOI:10.1080/09500349214552111

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

We present here a differential method to calculate the fields diffracted by corrugated gratings characterized by a dielectric constant. We consider the general case in which the wave-vector of the incident plane wave is not contained in the main section of the grating. To simplify the boundary conditions the regions above and below the grating surface are transformed into half planes by means of conformal and non-conformal mappings. Numerical examples validating the effectiveness of the developed algorithm are provided for the case of cycloidal and triangular profile gratings.

ISSN:0950-0340    

DOI:10.1080/09500349214552121

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A general purpose collimator capable of collimation of radiation from an arbitrary thermal source of diffuse light is incompatible with the second law of thermodynamics. It is known, however, that diffusion of coherent light from a particular ground glass can be reversed holographically. A new collimator is presented which produces a partially collimated beam of increased radiance when placed close to a white (diffusely reflective) source.

ISSN:0950-0340    

DOI:10.1080/09500349214552131

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor