Until now, polyvinyl alcohol (PVA) gel cylinders have been used in electrolyte diodes as a connecting element between the acidic and alkaline reservoirs. In this paper, a new connecting element is reported: a breath figure templated polyvinyl butyral (PVB) membrane prepared with dip-coating from a dichloromethane solution of the polymer in a humid atmosphere. The procedure gives a 1.5-2 μm thick membrane with a hexagonal pattern, the average characteristic length of which is 1 μm. After an acidic etching, it was found to be a good connecting element. The voltage-current characteristics and dynamic properties of PVA and PVB were measured and compared. The PVB membrane has a faster response to voltage changes than the PVA gel, but in both cases, there was a slow drift in the current that prevented it from reaching a steady state. Reproducible characteristics can be obtained, however, after the current reaches a well-defined quasi-steady state.
We propose a method for performing binary intensity and continuous phase modulation of beams with a spatial light modulator (SLM) and a low-pass spatial filtering 4-f system. With our method it is possible to avoid the use of phase masks in holographic data storage systems or to enhance the phase encoding of the SLM by making it capable of binary amplitude modulation. The data storage capabilities and the limitations of the method are studied.
This goal of our research was to show that E-glass fiber bundles used for reinforcing composites can be enabled to transmit light in a common resin without any special preparation (without removing the sizing). The power of the transmitted light was measured and the attenuation coefficient, which characterizes the fiber bundle, was determined. Although the attenuation coefficient depends on temperature and the wavelength of the light, it is independent of the power of incident light, the quality of coupling, and the length of the specimen. The refractive index of commercially available transparent resins was measured and it was proved that a resin with a refractive index lower than that of the fiber can be used to make a composite whose fibers are capable of transmitting light. The effects of temperature, compression of the fibers, and the shape of fiber ends on the power of transmitted light were examined. The measurement of emitted light can provide information about the health of the fibers. This can be the basis of a simple health monitoring system in the case of general-purpose composite structures.
In the increasing number of system approaches published in the field of optical encryption, the security level of the system is evaluated by qualitative and empirical methods. To quantify the security of the optical system, we propose to use the equivalent of the key length routinely used in algorithmic encryption. We provide a calculation method of the number of independent keys and deduce the binary key length for optical data encryption. We then investigate and optimize the key length of the combined phase- and amplitude-modulated key encryption in the holographic storage environment, which is one of the promising solutions for the security enhancement of single- and double-random phase-encoding encryption and storage systems. We show that a substantial growth of the key length can be achieved by optimized phase and amplitude modulation compared to phase-only encryption. We also provide experimental confirmation of the model results.
Retroreflective materials are extensively used as traffic signs and security patterns. These goods are often realized by spherical glass-beads attached to some reflective substrate. New applications, especially 3D projection, require the precise evaluation and design of the characteristics of light backscattered from retroreflective screens. Simulation of such materials is not straightforward due to the different optical processes taking place: direct retroreflection involving small-angle diffraction effects, and multiple scattering resulting in wide-angle diffuse light. We propose a new complex method to describe the backscattering properties of glass-bead retroreflectors that uniquely combines diffraction calculations with ray tracing based on the microscopic properties of the screen. We validated our simulation method by measurements performed on commercial retroreflective samples.
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