Washing-out of the mean diffraction picture in the focal plane of a receiving lens, due to rain in a turbulent atmosphere

This work examines the expansion of a focused laser beam in the turbulent atmosphere. The formulation is based on Green's theorem and the valid assumption that the turbulent atmosphere is a forward-scatter medium for wavelengths of interest (0.6 μ < λ < 11 μ). The main results are: (1) the spot size at the free-space focal plane in the presence of turbulence is independent of the aperture radius, and is only weakly dependent on the wavelength, (2) the focal plane can be significantly shifted for small aperture radii, short wavelengths, and long free-space focal lengths, (3) the effect of the atmosphere is pronounced only close to the free-space focus and very far away, and (4) the turbulent atmosphere has a stronger effect on weakly focused beams rather than strongly focused beams, except very close to the free-space focus, where the effect is more pronounced for strongly focused beams.

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Distributions of the mean intensity of the laser beam during passage of the shock waves formed nose fairing ogival-shaped body, in turbulent atmosphere

24th International Symposium on Atmospheric and Ocean Optics: Atmospheric Physics ◽

10.1117/12.2503787 ◽

2018 ◽

Author(s):

Elizaveta Zaloznaya ◽

Artem A. Sukharev

Keyword(s):

Shock Waves ◽

Laser Beam ◽

Turbulent Atmosphere ◽

Mean Intensity ◽

Shaped Body ◽

The Mean

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Fourier Transform Infrared Imaging and Unsupervised Hierarchical Clustering Applied to Cervical Biopsies

Australian Journal of Chemistry ◽

10.1071/ch04137 ◽

2004 ◽

Vol 57 (12) ◽

pp. 1139 ◽

Cited By ~ 18

Author(s):

Keith R. Bambery ◽

Bayden R. Wood ◽

Michael A. Quinn ◽

Don McNaughton

Keyword(s):

Hierarchical Clustering ◽

Focal Plane ◽

Mercury Cadmium Telluride ◽

Clustering Algorithm ◽

Infrared Imaging ◽

Cervical Tissue ◽

Fourier Transform Infrared Imaging ◽

Hematoxylin And Eosin ◽

The Mean ◽

Hierarchical Clustering Algorithm

FTIR images of cervical tissue from patient biopsies were processed with an unsupervised hierarchical clustering algorithm and compared with hematoxylin- and eosin-stained adjacent sections. Anatomical and potential histopathological features were clearly resolved in the resultant cluster maps. The mean extracted spectra assigned to each cluster indicate that the major spectral differences between the different cells in tissue predictably occur in the amide I region (1700–1570 cm−1) and the phosphodiester/glycogen region (1200–1000 cm−1). FTIR imaging in which a focal plane array mercury–cadmium–telluride detector and unsupervised hierarchical clustering is used shows potential as a rapid, non-subjective diagnostic tool in cervical pathology.

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Neural networks application to determine the types and magnitude of aberrations from the pattern of the point spread function out of the focal plane

Journal of Physics Conference Series ◽

10.1088/1742-6596/2086/1/012148 ◽

2021 ◽

Vol 2086 (1) ◽

pp. 012148

Author(s):

P A Khorin ◽

A P Dzyuba ◽

P G Serafimovich ◽

S N Khonina

Keyword(s):

Neural Network ◽

Neural Networks ◽

Convolutional Neural Networks ◽

Point Spread Function ◽

Focal Plane ◽

Prediction Errors ◽

Point Spread ◽

The Neural Network ◽

Spread Function ◽

The Mean

Abstract Recognition of the types of aberrations corresponding to individual Zernike functions were carried out from the pattern of the intensity of the point spread function (PSF) outside the focal plane using convolutional neural networks. The PSF intensity patterns outside the focal plane are more informative in comparison with the focal plane even for small values/magnitudes of aberrations. The mean prediction errors of the neural network for each type of aberration were obtained for a set of 8 Zernike functions from a dataset of 2 thousand pictures of out-of-focal PSFs. As a result of training, for the considered types of aberrations, the obtained averaged absolute errors do not exceed 0.0053, which corresponds to an almost threefold decrease in the error in comparison with the same result for focal PSFs.

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