Welcher Weg? A Trajectory Representation of a Quantum Young’s Diffraction Experiment

The double slit problem is idealized by simplifying each slit by a point source. A composite reduced action for the two correlated point sources is developed. Contours of the reduced action, trajectories and loci of transit times are developed in the region near the two point sources. The trajectory through any point in Euclidean 3-space also passes simultaneously through both point sources.     

Tunable subnanosecond laser pulse generation using an active mirror concept

We report (theory, experimental check) an improved approach for generation of a tunable, subnanosecond pulse (0.1–0.4 ns), based on a single pulsation (“spike”) separation from the transient oscillations in a dye laser with active mirror (AMIR). A pumping by 20–50 ns pulses from Q-switched Nd:YAG laser is considered. The separation is in original, two-spectral selective channels cavity, where the forced by AMIR quenched generation at one of the wavelength stops initially started spiking generation at the other wavelength after the first spike development. The AMIR quickly starts the quenching generation at a precisely controlled moment and with necessary intensity thus assuring the desired separation. An advantage is a high reproducibility of the separation for high (~250%) pump power fluctuations combined with tuning in large range (~20 nm). To obtain such an operation we form ~1 ns leading front pump pulse by electrooptical temporal cutting of the input pump pulse and use an optical delay line. This increases also a few times the power in the separated spike (to be ~100 kW). Our approach widens the combinations of lasers for effective applications of spike separation technique (dye lasers excited by Q-switched solid-state or Cu-vapor lasers).     

Magnetoconductivity of Hubbard bands induced in silicon MOSFETs

Sodium impurities are diffused electrically to the oxide-semiconductor interface of a silicon MOSFET to create an impurity band. At low temperature and at low electron density, the band is split into an upper and a lower sections under the influence of Coulomb interactions. We used magnetoconductivity measurements to provide evidence for the existence of Hubbard bands and determine the nature of the states in each band.     

Combined implementing the hole-drilling method and reflection hologram interferometry for residual stresses determination in cylindrical shells and tubes

Main features inherent in simplified approach to residual stresses determination in cylindrical shells and tubes, external diameter of which is not less than 60 mm, by combing the hole-drilling method and reflection hologram interferometry are discussed in detail. Initial experimental information in a form of hole diameter increments in principal stress directions is derived from high-quality reflection holograms recorded near cylindrical objects of intermediate curvature value. Converting measured parameters into required stress values is based on the transition model that corresponds to plane stress conditions of pure membrane type. The technique developed is capable of determining residual stress component values within 5% accuracy in an absence of stress gradients over the probe hole diameter when a type of residual stress field corresponds to the transition model adopted. The accuracy analysis involved is based on matrix formulation of conventionally direct problem and an assumption on a pure membrane character of residual stress field under study for thin-walled shell. Required error estimations in a case of inspecting thick-walled cylindrical tube are obtained by combining the above-mentioned approach and an analogy of reconstructed fringe patterns with actual and artificial interferograms, which follow from drilling blind hole of the same geometrical parameters in thick-walled plates. Experimental verification of the developed approach is founded upon a determination of actual stresses in thin-walled cylindrical shell and obtaining residual stress distributions at the proximity of welded joint in thick-walled cylindrical tube.     

Automatic fringe analysis of two-beam interference patterns for measurement of refractive index and birefringence profiles of fibres

Automatic fringe pattern analysis is a powerful and inexpensive digital image-processing technique. Two-beam polarizing interference Pluta microscope [Pluta M. Opt Acta 1971;18:661, Pluta M. J Microsc 1972;96:309] is automated by the computer-aid via CCD camera and digital frame grabber. Software program is prepared to deal with the duplicated (separated and overlapped) Microinterferograms produced by two-beam polarizing microscope. It also gives an accurate and fast automatic measurement of refractive index and birefringence profiles for fibres. In this paper, the refractive index and birefringence profiles of two different types of fibres, basalt and polypropylene (PP) fibres are presented. A new method to determine the birefringence profile of fibres from non-duplicated microinterferogram is suggested. The cold drawing process for PP fibres is studied.     

Phase calculation with a swept source in optical coherence tomography: Jitter influence

An analysis of phase modifications introduced by laser jitter in frequency-domain optical coherence tomography (OCT) is described. It is shown that a 1D spurious phase function is introduced as a consequence of this phenomenon. This phase function is added to any other introduced by the object under analysis causing a superposition of both. The result may impose some limitations for unambiguous determination of phase changes of objects. Experimental and theoretical results are presented.     

Interference law for coherent stochastic electromagnetic beams

Two-beam interference law for the superposition of stochastic, spatially coherent, electromagnetic beams is derived. Only a single phase is found to enter the interference law, in spite of the vector nature of the problem. The meaning of the phase is elucidated.     

Information hiding based on the optical interference principle

An information hiding method based on the optical interference principle is proposed. In this method, a secret image can be obtained by two light beams' interference. One of the beams is modulated by our assigned host image; and the other is modulated by a noise-like complex distribution, which is regard as the encrypted image. The transmission of the encrypted image can be implemented by hiding it in the host image to prevent the communication from being perceived by unauthorized person. In addition, this method can also realize simultaneous encryption and hiding for two images. A series of numerical simulation results are presented to verify the feasibility of our proposed method.     

Design of laser interferometric system for measurement of gear tooth flank

A laser interferometric system (LIS) based on oblique incidence and phase shifting technique has been designed for the measurement of gear tooth flank. For a spur involute gear with a module of 2.0, 60 teeth, and a 20-mm facewidth, some critical parameters of the LIS are calculated, the oblique incidence angle is 84.5°, the beam diameter is 20 mm, and the focal length of imaging lens is 100 mm, and the resolution of CCD camera is 1360 × 1024 pixels. To test the capability of the designed LIS, the numerical simulation is done for the LIS. The actual LIS is built on an optical platform and the experiment is carried out. Both interference fringe patterns from the numerical simulation and the actual experiment are good and coincident with each other, which show the designed LIS is feasible.