scholarly journals Ultrahigh spatial-frequency, high-contrast periodic structures produced by interference lithography

1996 ◽  
Author(s):  
H. T. Nguyen ◽  
J. A. Britten ◽  
R. D. Boyd ◽  
B. D. Shore ◽  
M. D. Perry
Keyword(s):  
Spatial Frequency ◽  
Periodic Structures ◽  
Interference Lithography ◽  
High Contrast

2D periodic structures patterned on 3D surfaces by interference lithography for SERS

2018 ◽  
Vol 461 ◽  
pp. 171-174 ◽  
Author(s):  
Ivana Lettrichova ◽  
Agata Laurencikova ◽  
Dusan Pudis ◽  
Jozef Novak ◽  
Matej Goraus ◽  
...  
Keyword(s):  
Periodic Structures ◽  
Interference Lithography ◽  
3D Surfaces

Fabrication of high aspect ratio nanoscale periodic structures by the soft X-ray interference lithography

2017 ◽  
Vol 170 ◽  
pp. 49-53 ◽  
Author(s):  
Jun Zhao ◽  
Yanqing Wu ◽  
Chaofan Xue ◽  
Shumin Yang ◽  
Liansheng Wang ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Periodic Structures ◽  
Interference Lithography ◽  
X Ray

Measuring Optical Properties of Advanced Nano/Micro-Periodic Structures Fabricated by Multi-Exposure Interference Lithography

2020 ◽  
Author(s):  
Shuzo Masui ◽  
Masaki Michihata ◽  
Kiyoshi Takamasu ◽  
Satoru Takahashi
Keyword(s):  
Periodic Structures ◽  
Low Cost ◽  
Industrial Applications ◽  
Interference Lithography ◽  
High Dispersion ◽  
Optical Elements ◽  
Precise Control ◽  
Periodic Grating ◽  
Interference Fringes ◽  
Multiple Interference

Abstract Functional optical elements based on nano/micro-periodic structures have attracted much attention. Since the fabrication of these dual-periodic structures requires precise control of periodicity, the semiconductor process such as an electron beam lithography has been mainly employed. However, these techniques have problems with expensive and low throughput for industrial applications. Therefore, there remains a need for low cost and high throughput fabrication methods of dual-periodic structures. Then we developed a multi-exposure interference lithography (MEIL) system using rotational Lloyd’s mirror interferometer to overcome these problems. The advantages of interference lithography are a large processing area and low cost. Our developed rotational Lloyd’s mirror setup enables us to a highly precise superposition of multiple interference fringes by multi-exposure. Furthermore, we developed a measurement setup for reflective diffractive elements using a two axial rotating stage and measured the diffraction properties of the fabricated dual-periodic diffraction gratings. In this paper, as a demonstration, we succeeded in the fabrication of high-dispersion diffraction grating with an enhanced diffraction efficiency of the −3rd order light. The fabricated shapes have a periodicity of 1997 nm and 665 nm. Furthermore, it was confirmed that the intensity of the −3rd order light was enhanced by about 10 times compared to the single periodic grating.

Orientation Specificity and Spatial Selectivity in Human Vision

Perception ◽  
1973 ◽  
Vol 2 (1) ◽  
pp. 53-60 ◽  
Author(s):  
J A Movshon ◽  
C Blakemore
Keyword(s):  
Spatial Frequency ◽  
Human Visual System ◽  
Human Vision ◽  
Orientation Tuning ◽  
High Contrast ◽  
Vertical Grating ◽  
Spatial Frequencies ◽  
High Contrast Grating ◽  
Orientation Specificity ◽  
Adaptation Method

An adaptation method is used to determine the orientation specificity of channels sensitive to different spatial frequencies in the human visual system. Comparison between different frequencies is made possible by a data transformation in which orientational effects are expressed in terms of equivalent contrast (the contrast of a vertical grating producing the same adaptational effect as a high-contrast grating of a given orientation). It is shown that, despite great variances in the range of orientations affected by adaptation at different spatial frequencies (±10° to ±50°), the half-width at half-amplitude of the orientation channels does not vary systematically as a function of spatial frequency over the range tested (2·5 to 20 cycles deg−1). Two subjects were used and they showed significantly different orientation tuning across the range of spatial frequencies. The results are discussed with reference to previous determinations of orientation specificity, and to related psychophysical and neurophysiological phenomena.

Monkeys Show an Oblique Effect

Perception ◽  
1979 ◽  
Vol 8 (3) ◽  
pp. 247-253 ◽  
Author(s):  
Joseph A Bauer ◽  
Donald A Owens ◽  
Joseph Thomas ◽  
Richard Held
Keyword(s):  
Animal Model ◽  
Spatial Frequency ◽  
Oblique Effect ◽  
High Contrast ◽  
Square Wave ◽  
Spatial Frequencies

Monkeys aligned a cursor bar with high-contrast square-wave gratings presented in a variety of orientations. Alignment time increased with increasing spatial frequency from 6 to 24 cycles deg−1 regardless of the orientation of the grating. At higher spatial frequencies, alignment tasks took longer for obliquely oriented gratings than for horizontal and vertical ones. Reducing grating contrast by blurring the image of the 24 cycle deg−1 grating also produced longer alignment times for the obliques. These data indicate that monkeys have an oblique effect similar to that found in humans, implying that the monkey is a useful animal model for investigating the development of meridional anisotropies.

The Effect of Spatial Frequency and Contrast on Visual Persistence

Perception ◽  
1979 ◽  
Vol 8 (5) ◽  
pp. 529-539 ◽  
Author(s):  
Alison Bowling ◽  
William Lovegrove ◽  
Barry Mapperson
Keyword(s):  
Spatial Frequency ◽  
Visual Persistence ◽  
Published Data ◽  
High Contrast ◽  
Low Contrast ◽  
Spatial Frequencies ◽  
Sinusoidal Gratings

The visual persistence of sinusoidal gratings of varying spatial frequency and contrast was measured. It was found that the persistence of low-contrast gratings was longer than that of high-contrast stimuli for all spatial frequencies investigated. At higher contrast levels of 1 and 4 cycles deg−1 gratings, a tendency for persistence to be independent of contrast was observed. For 12 cycles deg−1 gratings, however, persistence continued to decrease with increasing contrast. These results are compared with recently published data on other temporal responses, and are discussed in terms of the different properties of sustained and transient channels.

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