Journal of Optical Technology
ISSN : 1070-9762
Published by: The Optical Society (10.1364)
Total articles ≅ 4,018
Latest articles in this journal
Journal of Optical Technology, Volume 88, pp 477-482; https://doi.org/10.1364/jot.88.000477
A mathematical model of operation of an indicating polymer coating with an embedded fiber-optic piezoelectroluminescent (PEL) sensor is developed for diagnosing multiple mechanical force actions by digital processing of an informative luminous flux at the output of the optical fiber of the sensor. Distributed force action is caused by a multipoint low-velocity impact of multiple rigid particles, e.g., hail impacts, and the indentation of particles across the outer surface of the coating. The results of the numerical modeling of the sequence of informative light pulses at the output of the optical fiber of the PEL sensor are presented. The effects of the amplitude of the control voltage at the sensor contacts and the possible intersections of the “perturbation zones” of the adjacent globular particles on the amplitude and shape of light pulses are identified via numerical analysis. The filtering of informative signals of the indicating PEL coating based on the control sensor voltage is studied to exclude the effect of insignificant (outside of the operational range) external mechanical actions on the detected informative light signal.
Journal of Optical Technology, Volume 88, pp 441-444; https://doi.org/10.1364/jot.88.000441
A model of a multispectral camera that can capture images at five wavelengths—532, 612, 780, 850, and 940 nm—is designed and fabricated. The obtained multispectral images are analyzed. Algorithms of artificial neural network operation in the processing of multispectral images are discussed. A convolutional neural network for identification and classification of multispectral images in real-time is developed.
Journal of Optical Technology, Volume 88, pp 454-459; https://doi.org/10.1364/jot.88.000454
We describe the effects of vacuum ultraviolet light (λ=173nm) on the microfungus species Cladosporium herbarum, Rhodotorula colostri, and Saccharomyces cerevisiae. The survival probability was found to depend on the fungus concentration in the sample, which indicates that a shadowing effect may be responsible. The survival probabilities of the microfungi during the exponential growth phase were independent of fungus species, and this may result from insufficient accumulation of protective pigment in the cell wall. Infrared spectroscopy and atomic force microscopy of irradiated samples show breakdown of sugars and proteins in the cell wall. Electrophoresis revealed double-strand breaks in the DNA of Rhodotorula colostri but not Cladosporium herbarum, which may be because the latter produces the protective pigment melanin. When antioxidants (GSH, I2, KI) were added to the culture medium, the microfungi showed improved survival probability, indicating that an indirect mechanism is contributing to the inactivation process. The contribution of this indirect mechanism reached 50% for energy densities of 5−20mJ/cm2.
Journal of Optical Technology, Volume 88, pp 469-476; https://doi.org/10.1364/jot.88.000469
This paper presents the results of a study of the refractive-index dispersion for the AgBr–TlI, AgBr–TiBr0.46I0.54, and AgCl–AgBr crystal systems in the spectral range from 0.4 to 56 µm, along with the results of the development and fabrication of single-mode microstructured IR fibers by extrusion from solid solutions of metal halides. The fibers had a central insert 16 µm in diameter of composition 2.6 mol% TlI in AgBr, located in a matrix of composition 2.3 mol% TlI in AgBr with external diameter 525 µm. Inserts with diameter 16 µm of composition 2.0 mol% TlI in AgB were placed in the matrix in hexagonal order. The distribution of the radiation emitted from the fibers in the far field at wavelength 10.6 µm was studied, along with the influence of local heating of a section of the fiber on the transport of the IR radiation. The mode-field diameter was experimentally estimated as 120±30µm. The fibers were suitable for transporting both laser and thermal radiation from heated objects to a thermal viewer.
Journal of Optical Technology, Volume 88, pp 435-440; https://doi.org/10.1364/jot.88.000435
Peculiarities of using optical coherence tomography for examining the condition of valuable paintings are considered. A full-field optoelectronic system for determination of the internal microstructure of inhomogeneous media with high resolution and operation speed using a Wiener adaptive filtering algorithm for dynamic signal processing in time-domain optical coherence tomography is presented. Examples of determination of specific features of the microstructure of antique easel tempera paintings, such as thickness of the varnish layer and characteristics of its craquelure, morphology of the subsequent overpaint of the author layer, and loss of the varnish-and-paint layer by shelling, for determining the condition of an art object are presented.
Journal of Optical Technology, Volume 88, pp 460-463; https://doi.org/10.1364/jot.88.000460
The spectral dependences of the refractive index of liquid crystal compositions sensitized with different concentrations of tungsten disulfide (WS2) nanotubes are considered in the present study in the visible spectral range. A correlation between the refractive index and the dynamic properties of liquid crystal cells is established. The characteristics of laser-induced breakdown under the influence of a pulsed laser with a wavelength of 1.54 µm are also considered. The concentration of the WS2 nanoparticles doping the liquid crystal mesophase, at which the phase transition to a quasi-smectic state occurs, was determined. This finding significantly enhances the application range of liquid crystal cells in optoelectronic systems.
Journal of Optical Technology, Volume 88, pp 484-484; https://doi.org/10.1364/jot.88.000484
This erratum corrects typographical errors that appeared in Fig. 2 of J. Opt. Technol.88, 364 (2021).JOTEE41070-976210.1364/JOT.88.000364
Journal of Optical Technology, Volume 88, pp 464-468; https://doi.org/10.1364/jot.88.000464
The basic properties of materials can be changed by structuring their volume with various nanoparticles as well as by surface modification. In this study, calcium fluoride (CaF2) is selected as a model matrix for investigating the characteristic surface properties, and its spectral and mechanical properties, as well as the surface wetting of a CaF2 surface modified with carbon nanotubes, are compared with the properties of pure crystals. Laser-oriented deposition and an additional electric field varied in the range of 100–600 V/cm are applied for surface structuring. The experimental results are confirmed by quantum-chemical modeling.
Journal of Optical Technology, Volume 88, pp 409-419; https://doi.org/10.1364/jot.88.000409
This review is devoted to an analysis of measurements of the absolute magnitudes of the laser-induced damage thresholds of transparent dielectrics. The factors considered here are neglected not only in experiments, but also in existing ISO 21254 standards for measuring the absolute magnitudes of damage thresholds. It is shown that the use of multifrequency lasers causes large errors in the measured powers (by a factor of 5–10) as a consequence of the generation of unrecorded ultrashort pulses of various widths and peak powers. The aberrations that arise when radiation is focused into the volume of the samples is another source of substantial errors of the absolute power density. This paper discusses how low-threshold defects, multiphoton absorption, and self-focusing affect the study of intrinsic laser-induced damage. It is shown that almost all published results were measured with the participation of self-focusing. It must be concluded that the overwhelming majority of papers involve large errors and need to be completely revised.
Journal of Optical Technology, Volume 88, pp 401-405; https://doi.org/10.1364/jot.88.000401
To measure the radiant flux of light-emitting diodes, sphere integration, goniophotometric, and pulsed methods have been considered. A convenient method to calculate the radiant flux using the indicatrix of radiant intensity and an integrating sphere design to measure the total radiant flux of light-emitting diodes with a wide angular distribution of radiation have been proposed. Moreover, the calibration of measurement equipment has been considered. The proposed methods and measurement tools help enable the measurement of the radiant flux of light-emitting diodes in the range of 1 mW to tens of watts. The measurement results are compared using different methods. A method to estimate the absolute measurement error is proposed.