scholarly journals TRENDS IN THE DEVELOPMENT OF DEVICES FOR CONTROL OR GEOMETRIC PARAMETERS OF CONTACT LENSES

2021 ◽  
Vol 6 ◽  
pp. 136-143
Author(s):  
Maria I. Kilnevaya ◽  
Igor O. Mikhailov

The article shows the relevance of the control of the geometric parameters of contact lenses. The types of lenses, their advantage over glasses, as well as devices for monitoring the radii of curvature of the concave surface of the lens are considered. The shortcomings of the available devices and methods for monitoring contact lenses are revealed. The principle and features of operation of an optoelectronic device for non-contact control of geometric parameters of contact lenses are proposed.

Processes ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 24
Author(s):  
Michael Yurievich Alies ◽  
Yuriy Konstantinovich Shelkovnikov ◽  
Milan Sága ◽  
Milan Vaško ◽  
Ivan Kuric ◽  
...  

The article deals with the issues of improving the accuracy of measurements of the geometric parameters of objects by optoelectronic systems, based on a television multiscan. A mathematical model of a multiscan with scanistor activation is developed, expressions for its integral output current and video signal are obtained, and the mechanism of their formation is investigated. An expression for the video signal is obtained that reflects the dual nature of the discrete–continuous multiscan structure: the video signal can have a discrete (pulse) or analog (continuous) form, depending on the step voltage between the photodiode cells of the multiscan. A Vernier discrete–analog method for measuring the parameters of the light zone on a multiscan is proposed, in which in order to increase the accuracy of the measurements, the location of the video pulse is determined relative to the neighboring reference pulses of a rigid geometric raster due to the slope of the discrete structure of the multiscan. It is established that the Vernier method enables one to make precision measurements of the coordinates, dimensions, and movements of the light zones by an overlay on a video raster of reference pulses from cells—a uniform sequence of Vernier pulses with a recurrence interval, followed by determining the number of the Vernier pulse that coincides with the raster pulse. An optoelectronic device based on a discrete–continuous multiscan, implemented on the basis of the proposed Vernier method of measuring the coordinates of the light zones, which has a high sensitivity to movement, is characteristic of continuous structures, and has increased stability and linearity of the coordinate characteristics typical for discrete structures, is developed.


2014 ◽  
Vol 57 (7) ◽  
pp. 765-769 ◽  
Author(s):  
B. V. Skvortsov ◽  
A. N. Malysheva-Stroikova ◽  
I. Yu. Zhiganov

JAMA ◽  
1966 ◽  
Vol 195 (11) ◽  
pp. 901-903 ◽  
Author(s):  
J. M. Dixon
Keyword(s):  

Author(s):  
Joanna L. Batstone

Interest in II-VI semiconductors centres around optoelectronic device applications. The wide band gap II-VI semiconductors such as ZnS, ZnSe and ZnTe have been used in lasers and electroluminescent displays yielding room temperature blue luminescence. The narrow gap II-VI semiconductors such as CdTe and HgxCd1-x Te are currently used for infrared detectors, where the band gap can be varied continuously by changing the alloy composition x.Two major sources of precipitation can be identified in II-VI materials; (i) dopant introduction leading to local variations in concentration and subsequent precipitation and (ii) Te precipitation in ZnTe, CdTe and HgCdTe due to native point defects which arise from problems associated with stoichiometry control during crystal growth. Precipitation is observed in both bulk crystal growth and epitaxial growth and is frequently associated with segregation and precipitation at dislocations and grain boundaries. Precipitation has been observed using transmission electron microscopy (TEM) which is sensitive to local strain fields around inclusions.


Author(s):  
Jacob S. Hanker ◽  
Dale N. Holdren ◽  
Kenneth L. Cohen ◽  
Beverly L. Giammara

Keratitis and conjunctivitis (infections of the cornea or conjunctiva) are ocular infections caused by various bacteria, fungi, viruses or parasites; bacteria, however, are usually prominent. Systemic conditions such as alcoholism, diabetes, debilitating disease, AIDS and immunosuppressive therapy can lead to increased susceptibility but trauma and contact lens use are very important factors. Gram-negative bacteria are most frequently cultured in these situations and Pseudomonas aeruginosa is most usually isolated from culture-positive ulcers of patients using contact lenses. Smears for staining can be obtained with a special swab or spatula and Gram staining frequently guides choice of a therapeutic rinse prior to the report of the culture results upon which specific antibiotic therapy is based. In some cases staining of the direct smear may be diagnostic in situations where the culture will not grow. In these cases different types of stains occasionally assist in guiding therapy.


Author(s):  
Dean A. Handley ◽  
Lanping A. Sung ◽  
Shu Chien

RBC agglutination by lectins represents an interactive balance between the attractive (bridging) force due to lectin binding on cell surfaces and disaggregating forces, such as membrane stiffness and electrostatic charge repulsion (1). During agglutination, critical geometric parameters of cell contour and intercellular distance reflect the magnitude of these interactive forces and the size of the bridging macromolecule (2). Valid ultrastructural measurements of these geometric parameters from agglutinated RBC's require preservation with minimal cell distortion. As chemical fixation may adversely influence RBC geometric properties (3), we used chemical fixation and cryofixation (rapid freezing followed by freeze-substitution) as a comparative approach to examine these parameters from RBC agglutinated with Ulex I lectin.


1998 ◽  
Vol 21 (2) ◽  
pp. 55-59
Author(s):  
Maria Dolores Merindano ◽  
Marc Canals ◽  
Carlos Saona ◽  
José Potau ◽  
Jesús Costa

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