spherical lens
Recently Published Documents


TOTAL DOCUMENTS

186
(FIVE YEARS 36)

H-INDEX

18
(FIVE YEARS 3)

2022 ◽  
Vol 12 (2) ◽  
pp. 638
Author(s):  
Ali H. Alqahtani ◽  
Yosef T. Aladadi ◽  
Mohammed T. Alresheedi

This paper proposes a dielectric slabs-based lens for millimeter-wave beamforming systems. The proposed lens is based on the graded steps of the effective refractive index of the semi-spherical lens. It consists of multiple dielectric slabs that match the selected gradient effective refractive index. These slabs have the same thicknesses and different radii. The slab thickness in this lens should not exceed a quarter of the operating wavelength to keep on a similar effective refractive index of the original semi-spherical lens. A horn antenna is used to examine the performance of the designed lens at 28 GHz frequency in terms of the maximum gain, sidelobe level, and 3 dB beamwidth. Sixteen switchable horn antennas are used to demonstrate lens capability for millimeter-wave beamforming. Every single antenna element is selected individually, thus the dielectric lens steers and enhances the corresponding radiation of the selected element in the desired direction.


2022 ◽  
Author(s):  
James R. Chism ◽  
Mark Gragston ◽  
Zachary B. Riley ◽  
Ricardo Perez ◽  
Michael Spottswood ◽  
...  

Author(s):  
Nidhi Sohrot ◽  
Indrayani Jhadhav ◽  
Sohan Lohiya

Background: Astigmatism is an abnormality within the curvature of the attention. It occurs when light rays strike a spherical lens obliquely, or the line of vision to its principal axis is not parallel. Refraction away from the axis occurs when light strikes a lens obliquely and distorts the image formed. Aim: This study aimed to look at the prevalence of against-the-rule, with the-rule, and oblique-axis astigmatism in children. The change in cylinder index of refraction power and alignment of astigmatism in babies and young children is studied. Methodology: To conduct the study and thoroughly search the literature separately, references and abstracts were reviewed. Books like Parson’s diseases of the Eye by Dr. Radhika Tandon and several articles, WHO website, etc., were referred. Results: The study relied upon many studies on refractions procured by the near-retinoscopy methodology that knowledgeable Refractionist accomplished. Conclusion: It can be concluded that young children have a high incidence of against (???) type of astigmatism and that after this age (which age?), most children are with the rule.


2021 ◽  
Vol 59 (7) ◽  
pp. 516-516
Author(s):  
Thomas B. Greenslade
Keyword(s):  

Author(s):  
H. Hastedt ◽  
T. Luhmann ◽  
H.-J. Przybilla ◽  
R. Rofallski

Abstract. For optical 3D measurements in close-range and UAV applications, the modelling of interior orientation is of superior importance in order to subsequently allow for high precision and accuracy in geometric 3D reconstruction. Nowadays, modern camera systems are often used for optical 3D measurements due to UAV payloads and economic purposes. They are constructed of aspheric and spherical lens combinations and include image pre-processing like low-pass filtering or internal distortion corrections that may lead to effects in image space not being considered with the standard interior orientation models. With a variety of structure-from-motion (SfM) data sets, four typical systematic patterns of residuals could be observed. These investigations focus on the evaluation of interior orientation modelling with respect to minimising systematics given in image space after bundle adjustment. The influences are evaluated with respect to interior and exterior orientation parameter changes and their correlations as well as the impact in object space. With the variety of data sets, camera/lens/platform configurations and pre-processing influences, these investigations indicate a number of different behaviours. Some specific advices in the usage of extended interior orientation models, like Fourier series, could be derived for a selection of the data sets. Significant reductions of image space systematics are achieved. Even though increasing standard deviations and correlations for the interior orientation parameters are a consequence, improvements in object space precision and image space reliability could be reached.


2021 ◽  
Vol 6 ◽  
pp. 58-66
Author(s):  
Danil A. Gurin

The article analyzes the choice of the initial side of a spherical glass lens processing. The analysis was carried out on the basis of a survey of employees of the optical shop and familiarization with the description of a typical technological process for manufacturing lenses at one of the instrument-making enterprises in Novosibirsk, as well as by a retro-review of technical publications on the manufacture of optical parts. Two schemes of decision-making about the initial side of spherical lens processing are revealed: selection (assignment) or calculation by formula. The results of the analysis are formulated and the tasks of further research are defined.


Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2421
Author(s):  
Yao Hu ◽  
Jiahang Lv ◽  
Qun Hao

The refractive index is one of the most important parameters of optical glasses and has a significant effect on optical properties. The measurement of optical glasses, especially for optical elements such as lenses, is urgently needed. However, several presented methods require the immersion of the sample in liquid and provide indirect measurements, while others require structural parameters as priori knowledge, which is complex and time-consuming. In this study, a Brewster-Law-based direct and simple measurement method for the refractive index of glasses with arbitrary shapes is proposed, and a laser beam is focused on the surface of the sample as a probe. The incident angle of the chief ray is close to the Brewster angle. The reflected light is collected by an array detector. The refractive index is calculated from the minimum intensity position obtained with image processing. Additionally, a symmetric measurement scheme is proposed to improve the accuracy. Using these methods, a prism and four spherical lens samples with different refractive indices or radii of curvature are tested and error analyses are carried out. Results indicate that the accuracy can reach 10−4.


2021 ◽  
Author(s):  
M Madhangi ◽  
Debanjan Dutta ◽  
Sautan Show ◽  
Vishwanath K Bhat ◽  
Mohammad I Rather ◽  
...  

Abstract Isolated Microspherophakia (MSP) is an autosomal recessive disorder characterized by a smaller than normal spherical lens. Till date, LTBP2 is the only gene shown to cause MSP. We used homozygosity mapping and whole-exome sequencing and identified a homozygous mutation, c.1148C > T (p.Pro383Leu), in the WDR8 (or WRAP73) gene in two Indian MSP families. In vitro experiments showed that the missense mutation renders the protein unstable. WDR8 is a centriolar protein that has important roles in centrosomal assembly, spindle pole formation and ciliogenesis. Co-immunoprecipitation experiments from HeLa cells indicated that the mutation interferes with the interaction of WDR8 with its binding partners. In zebrafish, both morpholino-mediated knockdown and CRISPR/Cas knockout of wdr8 resulted in decreased eye and lens size. The lack of wdr8 affected cell cycle progression in the retinal cells, causing a reduction in cell numbers in the retina and lens. The reduction in eye size and the cell cycle defects were rescued by exogenous expression of the human wild-type WDR8. However, the human mutant WDR8 (p.Pro383Leu) was unable to rescue the eye defects, indicating that the missense mutation abrogates WDR8 protein function. Thus, our zebrafish results suggested that WDR8 is the causative gene for MSP in these Indian families.


Sign in / Sign up

Export Citation Format

Share Document