摘要:

Silver halide sensitized gelatin (SHSG) is an interesting technique for the production of holographic optical elements. It combines the high sensitivity of photographic emulsions with the well-known low scattering and high diffraction efficiency corresponding to dichromated gelatin. In this paper we describe SHSG holograms recorded on Slavich PFG-01 emulsions. We will show that real high diffraction efficiencies can be obtained (as high as 93% allowing for reflections) when using this material for recording phase transmission holograms. The influence of the bleach bath temperature and a hardening bath in the processing was studied and the procedure was optimized for these two parameters. Our investigations reveal that PFG-01 emulsion is not only a substitute for Agfa material, but also offers better results, at a moment in which Agfa has stopped its production of holographic material.

ISSN:0950-0340    

DOI:10.1080/09500349908231381

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Quantum-communication needs a source of entanglement which is accessible to non-local measurements. It is shown that an entangled pair of light beams may be generated from two bright amplitude squeezed beams. This is applicable to light pulses and to optical solitons in fibres. A possible experimental scheme for stroboscopic quantum teleportation is discussed.

ISSN:0950-0340    

DOI:10.1080/09500349908231382

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

We report an investigation of the laser beam quality, efficiency and photostability of rhodamine 590 solid state dye lasers with hosts based upon 2-hydroxyethylmethacrylate and methylmethacrylate P(HEMA:MMA) co-polymers and modified methylmethacrylate (MPMMA) polymers with ethanol and dimethylsulphoxide additives. Highest efficiencies were obtained with MPMMA, with slope efficiencies of up to 44% (corresponding to 61% optical-optical conversion) measured for ethanolic MPMMA. P(HEMA:MMA) hosts gave superior photostability, with the highest normalized photostability of 240 GJ mol−1obtained for a P(HEMA:MMA) 1:1 rod. A simple resonator has been used to compensate the effects of thermal lensing and pump mode-mismatch, resulting in optimized beam quality for MPMMA lasers.

ISSN:0950-0340    

DOI:10.1080/09500349908231383

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Experimental validation of structural intensity analytical and Finite Element calculations has traditionally relied on accelerometer and strain gauge point-wise measurements, although more recently laser vibrometry has been applied. Whole field measurements of structural intensity has been limited to out-of-plane component analysis using holographic interferometry, and is suitable only for plate and membrane studies. This paper describes a novel form of in-plane Electronic Speckle Interferometry. The interferometer has been developed specifically to assess the suitability of whole field speckle metrology for structural intensity analysis in three dimensional solids and objects, which require simultaneous in-plane velocity and strain measurements. A resonant beam is examined using the optical technique, with comparative data obtained from contact transducers.

ISSN:0950-0340    

DOI:10.1080/09500349908231384

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

In this paper, we study several models of two-channel atomic excitation involving quantized fields and search for field states that result in the trapping of the atomic population in a single bare state. This trapping is a result of quantum interference between the two channels. We study the following models: a two-level atom resonantly interacting with two quantized field modes, a two-level atom with competing one and three photon transitions, and a Raman coupled model containing both Stokes and anti-Stokes fields. We find a great variety of trapping states of the field, some of the states being highly non-classical. The effects of dissipation on the stability of the trapping states are discussed and a method for generating some of the states is presented.

ISSN:0950-0340    

DOI:10.1080/09500349908231385

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The possibility of realizing an optical memory with photo-refractive crystals using dynamic refreshment via phase conjugation is discussed. The experimental realization is based on photorefractive barium titanate crystals. Series of refresh cycles, dependent on several parameters, are simulated numerically. It is shown that an extension of the storage time can be reached.

ISSN:0950-0340    

DOI:10.1080/09500349908231386

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

We present an analytical perturbation analysis for studying the imaging characteristics of photon diffusion imaging in highly scattering media such as human tissues. Factors affecting the image formation in practical imaging system are taken into account, including the photon source, the optical properties of the sample, and the measurement system. A concise relationship between the internal structure and the detected signal is derived. Based on this, it is proved that photon diffusion imaging possess the property of linear shift invariance. The image formation mechanism in measurements such as functional imaging or tumour early diagnosis is illustrated from the viewpoint of the linear shift invariant system.

ISSN:0950-0340    

DOI:10.1080/09500349908231387

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Inhomogeneous media exhibit many properties that are very useful either in microwave circuits or in radiation components. In this paper a scattering analysis of cavity-backed microstrip patch antennas with inhomogeneous slabs is proposed. An equivalent variational formulation of the electromagnetic problem for this kind of antenna is derived, such that a very efficient Finite Element Method-Boundary Integral code can be straightforwardly applied. Numerical results are compared with those known in the literature showing an excellent agreement with them. The main scattering properties of the inhomogeneous substrates are also pointed out and compared with those of homogeneous substrates.

ISSN:0950-0340    

DOI:10.1080/09500349908231388

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

In an optical fibre of circular cross section, leaky skew rays transmit power in a different way from trapped and meridional rays. In this paper, a theoretical analysis of the evanescent wave absorption coefficient for leaky skew rays in multimode optical fibre evanescent wave absorption sensors is presented. Further, a comprehensive expression for the effective evanescent wave absorption coefficient is obtained. Some numerical results are given to illustrate this theoretical analysis. This work could be applied to optimize the design of fibre-optic evanescent wave absorption sensors.

ISSN:0950-0340    

DOI:10.1080/09500349908231389

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Higher-generation Schrödinger cat states of the quantized electromagnetic field can be produced in a high-Qcavity, starting from a coherent state, through the passage of prepared Rydberg atoms interacting dispersively across it. These states are natural generalizations of the even and odd coherent states, theNth-generations corresponding to specific superpositions of 2Nstates on a circle in phase space with well defined parity, and present very peculiar properties. Their photon statistics interchange between super- and sub-Poissonian behaviours and the nature of the photon bunching oscillates as the field intensity in the cavity is varied. For higher-generation even states, the minimum value of the Mandel factor almost reaches −1.0 and the state represents the Fock state |2N). Squeezing properties and the Wigner function of these higher-generation Schrödinger cat states are also considered.

ISSN:0950-0340    

DOI:10.1080/09500349908231390

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor