Tolerancing the impact of mid-spatial frequency surface errors of lenses on distortion and image homogeneity

Ion Beam Figure (IBF) is believed to be one of the most effective technics that can fabricate lens with nano or even sub-nano accuracy. For different sizes of IBF removal functions, the correct effects in different spatial frequency range are different. Power Spectral Density (PSD) curve can describe surface errors in full spatial frequency range, so it is a very convenient way to evaluate the quality of lens’ surface. In this paper, firstly, the principles of IBF and PSD are introduced briefly; Secondly, IBF removal functions with sizes from 2 mm to 15 mm are generated. A lens with surface error more than PV value 400nm is simulated with different sizes of IBF removal functions by Lucy-Richardson algorithm. Finally, experiments are done by IBF plant. A lens is fabricated by different sizes of removal functions and the fabricate results are tested by interferometer precisely and calculated to PSD curves. By the comparison of these curves, the IBF fabricate effects with different removal sizes are analyzed, which show that the smaller the removal size, the better the removal effect in higher spatial frequency range, but in the meantime, it will take a much longer time. Also the reasons of the difference between theory simulation and actual fabrication result are taken into account, and several influence factors are analyzed.

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Spatial Frequency Domain Analysis of Heat Transfer in Microelectronic Chips With Applications to Temperature Aware Computing

ASME 2007 InterPACK Conference, Volume 2 ◽

10.1115/ipack2007-33793 ◽

2007 ◽

Cited By ~ 1

Author(s):

Keivan Etessam-Yazdani ◽

Hendrik F. Hamann ◽

Mehdi Asheghi

Keyword(s):

Transfer Function ◽

Spatial Frequency ◽

Frequency Domain ◽

Thermal Power ◽

Three Dimensional ◽

Heat Removal ◽

Frequency Domain Analysis ◽

Heat Diffusion ◽

The Impact ◽

Spatial Frequency Domain

In this paper we present a novel analytical approach for obtaining the thermal transfer function of multi-layer chips in the spatial frequency domain. The behavior of the transfer function is used to address a number of key issues such as 1) the appropriate power granularity required for microarchitecture thermal-power analysis, and 2) the impact of packaging and cooling solutions on heat removal from chip hotspots. The merit of the presented method is in 1) simplicity, such that even for rather complicated multi-layer structures the analysis takes only a fraction of a second, and 2) accuracy, because the approach is based on the exact solution of three-dimensional heat diffusion equations.

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The impact of high spatial frequency atmospheric distortions on weak-lensing measurements

Monthly Notices of the Royal Astronomical Society ◽

10.1111/j.1365-2966.2011.20312.x ◽

2012 ◽

pp. no-no ◽

Cited By ~ 10

Author(s):

Catherine Heymans ◽

Barnaby Rowe ◽

Henk Hoekstra ◽

Lance Miller ◽

Thomas Erben ◽

...

Keyword(s):

Spatial Frequency ◽

High Spatial Frequency ◽

Weak Lensing ◽

The Impact

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The Effect of Spatial Frequency on the Visual Category Representation in the Macaque Inferior Temporal Cortex

10.1101/2021.12.05.470960 ◽

2021 ◽

Author(s):

Esmaeil Farhang ◽

Ramin Toosi ◽

Behnam Karami ◽

Roxana Koushki ◽

Ehsan Rezayat ◽

...

Keyword(s):

Spatial Frequency ◽

Visual Processing ◽

Visual Information ◽

Temporal Cortex ◽

Inferior Temporal Cortex ◽

Category Representation ◽

Neural Basis ◽

Shape Information ◽

Category Information ◽

The Impact

ABSTRACTTo expand our knowledge about the object recognition, it is critical to understand the role of spatial frequency (SF) in an object representation that occurs in the inferior temporal (IT) cortex at the final stage of processing the visual information across the ventral visual pathway. Object categories are being recognized hierarchically in at least three levels of abstraction: superordinate (e.g., animal), mid-level (e.g., human face), and subordinate (e.g., face identity). Psychophysical studies have shown rapid access to mid-level category information and low SF (LSF) contents. Although the hierarchical representation of categories has been shown to exist inside the IT cortex, the impact of SF on the multi-level category processing is poorly understood. To gain a deeper understanding of the neural basis of the interaction between SF and category representations at multiple levels, we examined the neural responses within the IT cortex of macaque monkeys viewing several SF-filtered objects. Each stimulus could be either intact or bandpass filtered into either the LSF (coarse shape information) or high SF (HSF) (fine shape information) bands. We found that in both High- and Low-SF contents, the advantage of mid-level representation has not been violated. This evidence suggests that mid-level category boundary maps are strongly represented in the IT cortex and remain unaffected with respect to any changes in the frequency content of stimuli. Our observations indicate the necessity of the HSF content for the superordinate category representation inside the IT cortex. In addition, our findings reveal that the representation of global category information is more dependent on the HSF than the LSF content. Furthermore, the lack of subordinate representation in both LSF and HSF filtered stimuli compared to the intact stimuli provide strong evidence that all SF contents are necessary for fine category visual processing.

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Simple estimates for the effects of mid-spatial-frequency surface errors on image quality

Applied Optics ◽

10.1364/ao.39.002198 ◽

2000 ◽

Vol 39 (13) ◽

pp. 2198 ◽

Cited By ~ 58

Author(s):

Richard N. Youngworth ◽

Bryan D. Stone

Keyword(s):

Image Quality ◽

Spatial Frequency ◽

Surface Errors

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A novel multi-dimensional features fusion algorithm for the EEG signal recognition of brain's sensorimotor region activated tasks

International Journal of Intelligent Computing and Cybernetics ◽

10.1108/ijicc-02-2020-0019 ◽

2020 ◽

Vol 13 (2) ◽

pp. 239-260

Author(s):

Minghua Wei ◽

Feng Lin

Keyword(s):

Spatial Frequency ◽

Action Observation ◽

Classification Performance ◽

Eeg Signals ◽

Feature Maps ◽

Content Type ◽

Sensorimotor Region ◽

The Impact ◽

Frequency Features ◽

Fusion Features

PurposeAiming at the shortcomings of EEG signals generated by brain's sensorimotor region activated tasks, such as poor performance, low efficiency and weak robustness, this paper proposes an EEG signals classification method based on multi-dimensional fusion features.Design/methodology/approachFirst, the improved Morlet wavelet is used to extract the spectrum feature maps from EEG signals. Then, the spatial-frequency features are extracted from the PSD maps by using the three-dimensional convolutional neural networks (3DCNNs) model. Finally, the spatial-frequency features are incorporated to the bidirectional gated recurrent units (Bi-GRUs) models to extract the spatial-frequency-sequential multi-dimensional fusion features for recognition of brain's sensorimotor region activated task.FindingsIn the comparative experiments, the data sets of motor imagery (MI)/action observation (AO)/action execution (AE) tasks are selected to test the classification performance and robustness of the proposed algorithm. In addition, the impact of extracted features on the sensorimotor region and the impact on the classification processing are also analyzed by visualization during experiments.Originality/valueThe experimental results show that the proposed algorithm extracts the corresponding brain activation features for different action related tasks, so as to achieve more stable classification performance in dealing with AO/MI/AE tasks, and has the best robustness on EEG signals of different subjects.

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Effects of structured mid-spatial frequency surface errors on image performance

Applied Optics ◽

10.1364/ao.49.006522 ◽

2010 ◽

Vol 49 (33) ◽

pp. 6522 ◽

Cited By ~ 57

Author(s):

John M. Tamkin ◽

Tom D. Milster

Keyword(s):

Spatial Frequency ◽

Surface Errors ◽

Image Performance

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Effect of Thermal Insulation on Image Quality and Radiation Dose in Polytrauma Computed Tomography

Canadian Association of Radiologists Journal ◽

10.1177/0846537119894250 ◽

2020 ◽

Vol 71 (2) ◽

pp. 238-243

Author(s):

Paweł Podsiadło ◽

Robert Chrzan ◽

Grzegorz Liszka ◽

Tomasz Sanak ◽

Sylweriusz Kosiński ◽

...

Keyword(s):

Computed Tomography ◽

Image Quality ◽

Radiation Dose ◽

Thermal Insulation ◽

Noise Intensity ◽

Independent Risk Factor ◽

Ct Scans ◽

Self Heating ◽

The Impact ◽

Image Homogeneity

Purpose: Unintentional drop in body temperature in trauma victims is an independent risk factor for mortality. We aimed to assess the impact of thermal insulation on image quality and radiation dose in polytrauma computed tomography (CT). Methods: Thirteen different insulating covers were used to wrap CT phantoms. Images were assessed subjectively at a radiological workstation and analyzed digitally with dedicated software evaluating the noise intensity, spatial resolution, and image homogeneity. The radiation dose was measured using a dosimeter. Results: Most materials did not cause significant artifacts apart from 2 heating pads. Although the radiation dose was increased by the majority of insulating covers (up to 64.66%), certain covers decreased the absorbed radiation (up to −7.35%). Conclusions: The majority of insulating systems do not cause artifacts in CT scans. When using covers with self-heating warmers, removing the heating pad is suggested due to the risk of considerable artifacts appearing. Certain insulating covers may increase or decrease the radiation dose.

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The Role of the Laser-Induced Oxide Layer in the Formation of Laser-Induced Periodic Surface Structures

Nanomaterials ◽

10.3390/nano10010147 ◽

2020 ◽

Vol 10 (1) ◽

pp. 147 ◽

Cited By ~ 10

Author(s):

Camilo Florian ◽

Jean-Luc Déziel ◽

Sabrina V. Kirner ◽

Jan Siegel ◽

Jörn Bonse

Keyword(s):

Spatial Frequency ◽

Oxide Layer ◽

Structural Characteristics ◽

High Spatial Frequency ◽

Laser Pulses ◽

Surface Structures ◽

Layered System ◽

Periodic Surface ◽

New Type ◽

The Impact

Laser-induced periodic surface structures (LIPSS) are often present when processing solid targets with linearly polarized ultrashort laser pulses. The different irradiation parameters to produce them on metals, semiconductors and dielectrics have been studied extensively, identifying suitable regimes to tailor its properties for applications in the fields of optics, medicine, fluidics and tribology, to name a few. One important parameter widely present when exposing the samples to the high intensities provided by these laser pulses in air environment, that generally is not considered, is the formation of a superficial laser-induced oxide layer. In this paper, we fabricate LIPSS on a layer of the oxidation prone hard-coating material chromium nitride in order to investigate the impact of the laser-induced oxide layer on its formation. A variety of complementary surface analytic techniques were employed, revealing morphological, chemical and structural characteristics of well-known high-spatial frequency LIPSS (HSFL) together with a new type of low-spatial frequency LIPSS (LSFL) with an anomalous orientation parallel to the laser polarization. Based on this input, we performed finite-difference time-domain calculations considering a layered system resembling the geometry of the HSFL along with the presence of a laser-induced oxide layer. The simulations support a scenario that the new type of LSFL is formed at the interface between the laser-induced oxide layer and the non-altered material underneath. These findings suggest that LSFL structures parallel to the polarization can be easily induced in materials that are prone to oxidation.

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