scholarly journals Применение термообработки при формировании рельефно-фазовых голографических структур на бихромированном желатине

2020 ◽  
Vol 128 (10) ◽  
pp. 1507
Author(s):  
Н.М. Ганжерли ◽  
С.Н. Гуляев ◽  
И.А. Маурер
Keyword(s):  
High Temperature ◽  
Water Treatment ◽  
Spatial Frequency ◽  
Uv Radiation ◽  
Short Wave ◽  
Coherent Radiation ◽  
Steady Increase ◽  
Spatial Frequencies ◽  
Dichromated Gelatin ◽  
Relief Phase

A new method is proposed for the formation of a relief phase holographic structure on layers of dichromated gelatin (DCG). The method is based on the application of two types of alternative effects on gelatin: structuring using selective light tanning with coherent radiation from a He-Cd laser and destruction by irradiating the layers with short-wave UV radiation. To obtain highly effective holographic relief structures in the region of high spatial frequencies, up to 1500 mm–1, a time-shortened water treatment of samples, interrupted by an isopropanol bath, was previously proposed. In this paper, it is proposed to abandon the water treatment of DCG layers and replace it with heating the sample during irradiation with short-wave UV radiation. In the course of experiments, a steady increase in the diffraction efficiency was obtained regardless of the spatial frequency and thickness of the DCG layer, which is explained by the formation of a relief holographic structure due to evaporation and shrinkage of gelatin areas destroyed by UV radiation under the influence of high temperature.

Регистрация высокочастотных рельефно-фазовых голографических структур на фотоматериале ПФГ-04

2021 ◽  
Vol 47 (21) ◽  
pp. 13
Author(s):  
Н.М. Ганжерли ◽  
С.Н. Гуляев ◽  
И.А. Маурер ◽  
А.В. Архипов
Keyword(s):  
Spatial Frequency ◽  
Uv Radiation ◽  
Diffraction Efficiency ◽  
High Frequency ◽  
Short Wave ◽  
Destructive Effect ◽  
Holographic Gratings ◽  
New Variant ◽  
First Time ◽  
Relief Phase

A new variant of processing photographic plates for holography based on dichromed gelatin PFG-04 (produced by JSC "Slavich Company", Pereslavl-Zalessky) for the manufacture of high-frequency relief–phase holographic gratings with a spatial frequency up to 1500 mm-1 is proposed. The technology is based on the selective destructive effect of short-wave UV radiation on gelatin and subsequent etching of the layer with various reagents. For the first time, relief-phase high-frequency holographic gratings with a maximum diffraction efficiency of 67% were obtained on PFG-04 photographic plates.

scholarly journals Высокочастотные рельефно-фазовые голографические решетки на обработанном коротковолновым УФ-излучением бихромированном желатине

2019 ◽  
Vol 45 (12) ◽  
pp. 30
Author(s):  
Н.М. Ганжерли ◽  
С.Н. Гуляев ◽  
И.А. Маурер ◽  
Д.Р. Хазвалиева
Keyword(s):  
Spatial Frequency ◽  
Uv Radiation ◽  
High Spatial Frequency ◽  
Short Wave ◽  
Destructive Effect ◽  
Holographic Gratings ◽  
First Time ◽  
Relief Phase

For the first time, the possibility of creating relief-phase holographic gratings with a high spatial frequency of 1500 mm-1 on dichromate gelatin (DCG) layers using the destructive effect of short-wave UV radiation on gelatin is shown.

High-Frequency Relief-Phase Holographic Gratings on Dichromated Gelatin Processed by Short-Wave UV Radiation

2019 ◽  
Vol 45 (6) ◽  
pp. 613-615 ◽  
Author(s):  
N. M. Ganzherli ◽  
S. N. Gulyaev ◽  
I. A. Maurer ◽  
D. R. Khazvalieva
Keyword(s):  
Uv Radiation ◽  
High Frequency ◽  
Short Wave ◽  
Holographic Gratings ◽  
Dichromated Gelatin ◽  
Relief Phase

scholarly journals Numerical Simulation on Spatial-Frequency Domain Imaging for Estimating Optical Absorption and Scattering Properties of Two-Layered Horticultural Products

2021 ◽  
Vol 11 (2) ◽  
pp. 617
Author(s):  
Dong Hu ◽  
Yuping Huang ◽  
Qiang Zhang ◽  
Lijian Yao ◽  
Zidong Yang ◽  
...  
Keyword(s):  
Optical Properties ◽  
Optical Property ◽  
Optical Absorption ◽  
Spatial Frequency ◽  
Estimation Accuracy ◽  
Property Estimation ◽  
Spatial Frequencies ◽  
Stepwise Method ◽  
Horticultural Products ◽  
Layered Samples

Spatial-frequency domain imaging (SFDI) is a wide-field, noncontact, and label-free imaging modality that is currently being explored as a new means for estimating optical absorption and scattering properties of two-layered turbid materials. The accuracy of SFDI for optical property estimation, however, depends on light transfer model and inverse algorithm. This study was therefore aimed at providing theoretical analyses of the diffusion model and inverse algorithm through numerical simulation, so as to evaluate the potential for estimating optical absorption and reduced scattering coefficients of two-layered horticultural products. The effect of varying optical properties on reflectance prediction was first simulated, which indicated that there is good separation in diffuse reflectance over a large range of spatial frequencies for different reduced scattering values in the top layer, whereas there is less separation in diffuse reflectance for different values of absorption in the top layer, and even less separation for optical properties in the bottom layer. To implement the nonlinear least-square method for extracting the optical properties of two-layered samples from Monte Carlo-generated reflectance, five curve fitting strategies with different constrained parameters were conducted and compared. The results confirmed that estimation accuracy improved as fewer variables were to be estimated each time. A stepwise method was thus suggested for estimating optical properties of two-layered samples. Four factors influencing optical property estimation of the top layer, which is the basis for accurately implementing the stepwise method, were investigated by generating absolute error contour maps. Finally, the relationship between light penetration depth and spatial frequency was studied. The results showed that penetration depth decreased with the increased spatial frequency and also optical properties, suggesting that appropriate selection of spatial frequencies for a stepwise method to estimate optical properties from two-layered samples provides potential for estimation accuracy improvement. This work lays a foundation for improving optical property estimation of two-layered horticultural products using SFDI.

Harmonic basis functions for spatial coding in the cat striate cortex

1989 ◽  
Vol 3 (4) ◽  
pp. 351-363 ◽  
Author(s):  
V. D. Glezer ◽  
V. V. Yakovlev ◽  
V. E. Gauzelman
Keyword(s):  
Spatial Frequency ◽  
Striate Cortex ◽  
Weighting Function ◽  
Discrete Distribution ◽  
Basis Functions ◽  
Spatial Coding ◽  
Central Visual Field ◽  
Spatial Frequencies ◽  
The Absolute ◽  
Number Of Cycles

AbstractThe number of subregions in the activity profiles of simple cells varies in different cells from 2–8; that is, the number of cycles in the weighting function varies from 1–4. The distribution of receptive-field (RF) sizes at eccentricities of 0-6 deg are clustered at half-octave intervals and form a discrete distribution with maxima at 0.62, 0.9, 1.24, 1.8, 2.48, and 3.4 deg. The spatial frequencies to which the cells are tuned are also clustered at half-octave intervals, forming a discrete distribution peaking at 0.45, 0.69, 0.9, 1.35, 1.88, 2.7, 3.8, and 5.6 cycles/deg. If we divide the RF sizes by the size of the period of the subregions, then the average indices of complexity (really existing) or the number of cycles in the weighting function form (after normalization) the sequences: 1, 1.41, 2.0, 2.9, 4.15.The relation between the bandwidth of the spatial-frequency characteristic and the optimal spatial frequency is in accordance with predictions of the Fourier hypothesis. The absolute bandwidth does not change with the number of cycles/module. This means that inside the module the absolute bandwidth does not change with the number of the harmonic. The results allow us to suggest the following. A module of the striate cortex, which is a group of cells with RFs of equal size projected onto the same area of central visual field, accounts for the Fourier description of the image. The basis functions of the module are composed of four harmonics only, irrespective of size and position of the module.Besides linear cells (sinusoidal and cosinusoidal elements), the module contains nonlinear cells, performing a nonlinear summation of the responses of sinusoidal and cosinusoidal elements. Such cells are characterized by an index of complexity which is more than the number of cycles in the weighting function and by marked overlap of ON and OFF zones. The analysis of organization suggests that the cells can measure the amplitude and phase of the stimulus.

Spatial-frequency and orientation tuning in psychophysical end-stopping

1998 ◽  
Vol 15 (4) ◽  
pp. 585-595 ◽  
Author(s):  
CONG YU ◽  
DENNIS M. LEVI
Keyword(s):  
Spatial Frequency ◽  
Frequency Tuning ◽  
Spatial Filter ◽  
Orientation Tuning ◽  
Maximal Strength ◽  
Facilitation Effect ◽  
Spatial Filters ◽  
Spatial Frequency Tuning ◽  
Spatial Frequencies ◽  
Wide Range

A psychophysical analog to cortical receptive-field end-stopping has been demonstrated previously in spatial filters tuned to a wide range of spatial frequencies (Yu & Levi, 1997a). The current study investigated tuning characteristics in psychophysical spatial filter end-stopping. When a D6 (the sixth derivative of a Gaussian) target is masked by a center mask (placed in the putative spatial filter center), two end-zone masks (placed in the filter end-zones) reduce thresholds. This “end-stopping” effect (the reduction of masking induced by end-zone masks) was measured at various spatial frequencies and orientations of end-zone masks. End-stopping reached its maximal strength when the spatial frequency and/or orientation of the end-zone masks matched the spatial frequency and/or orientation of the target and center mask, showing spatial-frequency tuning and orientation tuning. The bandwidths of spatial-frequency and orientation tuning functions decreased with increasing target spatial frequency. At larger orientation differences, however, end-zone masks induced a secondary facilitation effect, which was maximal when the spatial frequency of end-zone masks equated the target spatial frequency. This facilitation effect might be related to certain types of contour and texture perception, such as perceptual pop-out.

scholarly journals Contrast thresholds reveal different visual masking functions in humans and praying mantises

2017 ◽  
Author(s):  
Ghaith Tarawneh ◽  
Vivek Nityananda ◽  
Ronny Rosner ◽  
Steven Errington ◽  
William Herbert ◽  
...  
Keyword(s):  
Spatial Frequency ◽  
Motion Detection ◽  
Visual Masking ◽  
High Spatial Frequency ◽  
Visual Noise ◽  
Frequency Noise ◽  
Detection Systems ◽  
Spatial Frequencies ◽  
Summary Statement ◽  
Contrast Thresholds

AbstractRecently, we showed a novel property of the Hassenstein-Reichardt detector: namely, that insect motion detection can be masked by “invisible” noise, i.e. visual noise presented at spatial frequencies to which the animals do not respond when presented as a signal. While this study compared the effect of noise on human and insect motion perception, it used different ways of quantifying masking in two species. This was because the human studies measured contrast thresholds, which were too time-consuming to acquire in the insect given the large number of stimulus parameters examined. Here, we run longer experiments in which we obtained contrast thresholds at just two signal and two noise frequencies. We examine the increase in threshold produced by noise at either the same frequency as the signal, or a different frequency. We do this in both humans and praying mantises (Sphodromantis lineola), enabling us to compare these species directly in the same paradigm. Our results confirm our earlier finding: whereas in humans, visual noise masks much more effectively when presented at the signal spatial frequency, in insects, noise is roughly equivalently effective whether presented at the same frequency or a lower frequency. In both species, visual noise presented at a higher spatial frequency is a less effective mask.Summary StatementWe here show that despite having similar motion detection systems, insects and humans differ in the effect of low and high spatial frequency noise on their contrast thresholds.

scholarly journals Elaborate pupils in skates may help camouflage the eye

2018 ◽  
Author(s):  
Sean Youn ◽  
Corey Okinaka ◽  
Lydia M Mäthger
Keyword(s):  
Light Intensity ◽  
Spatial Frequency ◽  
Experimental Evidence ◽  
Pupillary Response ◽  
Pupil Dilation ◽  
Primary Factor ◽  
Natural Substrate ◽  
Spatial Frequencies ◽  
Pupillary Responses ◽  
Changing Light

AbstractThe little skate Leucoraja erinacea has elaborately shaped pupils, whose characteristics and functions have not been studied extensively. It has been suggested that such pupil shapes may camouflage the eye; yet, no experimental evidence has been presented to support this claim. Skates are bottom-dwellers that often bury into the substrate with their eyes protruding. If these pupils serve any camouflage function, we expect there to be a pupillary response related to the spatial frequency (“graininess”) of the background against which the eye is viewed. Here, we tested whether skate pupils dilate or constrict in response to background spatial frequency. We placed skates on background substrates with different spatial frequencies and recorded pupillary responses at three light intensities. In experiment 1, the skates’ pupillary response to three artificial checkerboards of different spatial frequencies was recorded. Skates responded to changing light intensity with pupil dilation/constriction; yet, their pupils did not change in response to spatial frequency. In experiment 2, in which skates could bury into three natural substrates with different spatial frequencies, such that their eyes protruded above the substrate, the pupils showed a subtle but statistically significant response to changes in substrate spatial frequency. Given the same light intensity, the smaller the spatial frequency of the natural substrate, the more constricted the pupil. While light intensity is the primary factor determining pupil dilation, these experiments are the first to show that pupils also change in response to background spatial frequency, which suggests that the pupil may aid in camouflaging the eye.

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