Modulation Transfer Function Model Research Articles

Corrigendum to “Using whole cottonseed to replace dried distillers grains plus solubles and prairie hay in finishing beef cattle rations balanced for physically effective neutral detergent fiber” (Appl. Anim. Sci. 38:417–432)

The modulation transfer function (MTF) of graded band-gap AlGaAs/GaAs reflection-mode photocathodes was determined using two-dimensional Poisson and continuity equations through numerical method. Based on the MTF model, we calculated the theoretical MTF of graded and uniform band-gap reflection-mode photocathodes. We then analyzed the effects of Al composition, wavelength of incident photon, and thicknesses of AlGaAs and GaAs layer on the resolution. Calculation results show that graded band-gap structures can increase the resolution of reflection-mode photocathodes. When the spatial frequency is 800 lp/mm and wavelength is 600 nm, the resolution of graded band-gap photocathodes generally increases by 15.4–29.6%. The resolution improvement of graded band-gap photocathodes is attributed to the fact that the built-in electric field in graded band-gap photocathodes reduces the lateral diffusion distance of photoelectrons.

An Inversion Method for Coupled Typical Error Sources based on Remote Sensing Image

According to the error sources and their error amounts obtained by the remote sensing imaging coupled typical error sources inversion method, we can improve the imaging quality of optical systems and make high-quality remote sensing images more useful in military and civilian fields. Based on the distorted remote sensing images, this paper proposes a remote sensing imaging coupled typical error sources inversion method, which can accurately invert the typical error sources of remote sensing imaging and their error amounts. Firstly, a set of coupled typical error decoupled equations are constructed according to the modulation transfer function model of typical error sources and the decoupled principle of the coupled error sources. The initial values of coupled typical error sources are subsequently determined based on the Deep Residual Shrinkage Network (DRSN). Finally, the Levenberg Marquardt-Particle Swarm Optimization (LM-PSO) hybrid optimization algorithm is used to solve the system of coupled typical error decoupled equations to invert the typical error sources and their error amounts of the remote sensing imaging system. The experimental results show that the relative error between the inverse value and the real value of the coupled typical error sources of the distorted remote sensing images by the method in this paper does not exceed 20% at most, and most of them are below 10%, which has excellent inversion performance.

Effects of Charge Carrier Trapping on Image Resolution of Multilayer Photoconductive Detectors: Application to Amorphous Selenium X-ray Detectors

The effects of charge carrier trapping on image resolution in multilayer photoconductive imaging detectors was analyzed by developing an analytical model for calculating the modulation transfer function (MTF) of the imaging detectors. The MTF model was developed by considering the charge carrier trapping/recombination in the blocking layer and the distributed trapping in the bulk photoconductor layer of multilayer photoconductive imaging detectors. The relative importance of the bulk and blocking layer trapping, as well as the K-fluorescence reabsorption on the resolution, was also analyzed. The model was applied to amorphous selenium- (a-Se) based multilayer detectors for both chest radiographic and mammographic applications. The theoretical model agreed well with experimental results. The charge carrier trapping/recombination in the blocking layer and K-fluorescence reabsorption mainly controlled the resolution of the a-Se mammographic detectors. In addition to these two effects, the bulk trapping also had a significant effect on the resolution of chest radiographic detectors. The blocking layer thickness had more of a profound effect on the resolution than the amount of trap centers in the blocking layer. The resolution deteriorated drastically with increased blocking layer thickness.

Design of Photoelectric Detection System Used for Atmospheric Microdroplets and Modulation Transfer Function Model of Gaussian Beam

Atmospheric corrosion is an electrochemical corrosion process of metal materials in the atmospheric environment. Microdroplet phenomenon is an experimental phenomenon in the early stage of atmospheric corrosion, which is closely related to atmospheric corrosion. Photoelectric detection of microdroplet phenomenon has become a technical means to study atmospheric corrosion. A set of microdroplet photoelectric detection systems with small size, high integration, and low detection limit is designed and constructed. First, the microdroplet optical chip is designed and fabricated. The microdroplet chip with a single function is replaced by the microdroplet chip with optical microlenses, and the miRNA is detected on the photoelectric platform of the optical chip. The optical fiber is adopted to replace the traditional objective lens to excite the optical path, reduce the volume of the spatial optical path, and realize the miniaturization of the photoelectric detection system. Based on this system, the nonlinear relationship between atmospheric turbulence effect and atmospheric optical parameters is analyzed with Gaussian beams propagating in the atmosphere. In the experiment, the detection range of the photoelectric detection system is 5 nM~100 nM, and the linear correlation is 0.9958. The signals of Cy3 and Cy5 are detected by two groups of photomultiplier tube (PMT) to realize the detection of miRNA. Microlenses enhance the intensity of the photoelectric signal and reduce the detection limit. Microdroplets are used to encapsulate miRNA, reduce the amount of detection material, and solve the degradation of detection material by RNase. The modulation transfer function model of Gaussian beam is established with the assistance of the photoelectric detection system, which is suitable for the case that cannot be ignored in Kolmogorov turbulence under the action of internal/external scale.

Analysis of the influence of vibrations on the imaging quality of an integrated TDICCD aerial camera.

Taking the area CCD optical system as a whole, the analysis methods of the influence of vibrations on its imaging quality have been relatively mature. However, external vibrations will cause different vibrations of optical components inside the opto-mechanical structure. The existing methods are not suitable for analyzing optical components with different vibrations and TDICCD imaging. This paper studies the influence of vibrations on the imaging quality of the integrated TDICCD aerial camera. The relationship between the vibration responses of structures and the imaging quality is established by mathematical models. First, a vibration beam trajectory model of the integrated TDICCD aerial camera is established for the first time using geometric optics and ray tracing. The deviations of the optical axis caused by vibrations in the object plane can be obtained. Then, this paper establishes a TDICCD vibration modulation transfer function model based on statistical moments. The vibration MTF of pixels of each column in the complex two-dimensional moving image captured by the TDICCD can be obtained through this model. Furthermore, a simulation imaging model of the integrated TDICCD aerial camera is established. The influence of vibrations on the imaging quality can be directly obtained through images. Finally, the accuracy of the models established in this paper is verified by multiple tests. The results show that the imaging quality of the integrated TDICCD aerial camera decreases rapidly with the increase of the acceleration excitation.

Theoretical Model of Dynamic MTF of Low-Light-Level ICCD

During the integration time of the low-light intensified charge-coupled device(ICCD),the spatial vibration causes a decrease in the imaging quality of the low-light ICCD camera.In the case of imaging using low-light ICCD cameras in a vibrating environment,the dynamic modulation transfer function(MTF)is used to evaluate the effect of spatial vibration on imaging quality.Combined with the unique structure of the low-light ICCD camera,the dynamic MTF theoretical model of the low-light ICCD camera is proposed,which can be used to analyze the influence of different factors such as amplitude of vibration,period of vibration and integration time on the imaging quality in low-frequency and high-frequency sinusoidal vibrations.

Modulation transfer function of an imaging system with a hexagonal pixel array detector

The modulation transfer function (MTF) is the tool most commonly used for quantifying the performance of an electro-optical imaging system. Hexagonal sampling strategy for detector arrays can provide an improvement over rectangular sampling, thus the hexagonal pixel array detector is designed with hexagonal pixel and hexagonal sampling. In this paper, firstly, two dimensional MTF model of a hexagonal pixel array detector is deduced according to its definition. Then, the MTF of an imaging system with such a detector is established. Additionally, the MTFs of detectors with other shaped pixel geometry, but with the same photosensitive areas are compared. The results show that the values of hexagonal MTF are obviously larger than those of rectangular and triangular pixel array detectors at the same frequencies. In addition, with the increase of the atmospheric coherence length, the MTF values of the system become larger, and the system imaging capability will be improved.

Theoretical investigations of infrared optical wave modulation transfer function models in anisotropic marine turbulence.

The previously derived marine turbulence modulation transfer function (MTF) adopts the classical assumption of isotropic and Kolmogorov turbulence. However, more theoretical research shows that marine turbulence demonstrates anisotropic non-Kolmogorov properties. In this study, new long-exposure plane and spherical wave MTF models under anisotropic non-Kolmogorov marine turbulence will be investigated. Comparative analyses are performed for the new models and the existing ones that have been developed under the isotropic marine turbulence and the anisotropic terrestrial turbulence cases. It turns out that the anisotropic marine turbulence influences the electro-optical imaging system less than the isotropic marine turbulence does. Also, under the same turbulence strength condition, due to the humidity fluctuations of marine atmosphere, the anisotropic marine turbulence will reduce more severely the quality of electro-optical imaging systems than the anisotropic terrestrial turbulence. Investigations conducted in this paper are beneficial to understand better the electro-optical imaging mechanism in marine atmospheric turbulence media.

Image Degradation for Quality Assessment of Pan-Sharpening Methods

Wald’s protocol is the most widely accepted protocol to assess pan-sharpening algorithms. In particular, the synthesis property—which is usually validated on a reduced scale—is thought to be a necessary and sufficient condition of a success image fusion. Usually, the synthesis property is evaluated at a reduced resolution scale to take the original multispectral (MS) image as reference; thus, the image degradation method that is employed to produce reduced resolution images is crucial. In the past decade, the standard method has been to decimate the low-pass-filtered image where the filter is designed to match the modulation transfer function (MTF) of the sensor. The paper pointed out the deficiency of the method, and proposed a new image degradation method, referred to as method of spatial degradation for fusion validation (MSD4FV), which takes MTF compensation into account based on a simplified MTF model. The simulation results supported the implicit assumption of Wald’s protocol that image fusion performance is invariant among scales if the images have been properly degraded.

Модель функции передачи модуляции фоточувствительных СБИС при воздействии ОЗЧ

Модель функции передачи модуляции фоточувствительных СБИС при воздействии ОЗЧ

Simultaneous multi-piston measurement method in segmented telescopes.

We propose a method to simultaneously detect the multi-piston between segments. The relation between the piston of any two segments and amplitude of the modulation transfer function (MTF) sidelobes (MTFnph) is derived. The piston can be retrieved by this relation after measuring the MTFnph. This method's capture range is the operating light's coherence length, the accuracy is 0.026λ (λ = 633 nm) RMS. The MTF model of a mask with sparse multi-subaperture configuration is established. The arrangement rules, to avoid the sidelobes overlapping, are obtained. The mask with a sparse 18 sub-aperture configuration is designed, which makes the MTF sidelobes distribution non-redundant.

Dependence of Modulation Transfer Function on Electric Field Intensity of Photo conductor and Mobility-lifetime Product of Carriers in Polycrystalline Mercuric Iodide Based Flat Panel X-Ray Detectors: A Quantitative Approach and Error Analysis

Objective: In this Paper, a simplified mathematical model for Modulation Transfer Function (MTF) of Polycrystalline Mercuric Iodide based flat panel x-ray detector is applied on three different published prototypes of Polycrystalline Mercuric Iodide. Our aim was to fit the curves generated by simulation of MTF model with the curves acquired from experimental data. Method: Varied Electric field was employed to obtain the best fitting. Findings: The mobility-lifetime product for the best curve fitting was examined for each prototype. Percentage of fitting error has been estimated for each prototype. Finally, average absolute error has been calculated for all the incorporated prototypes. Application: This study can be further extended to develop a generic empirical model for the Modulation Transfer Function of polycrystalline mercuric iodide based flat panel x-ray detectors.

Atmosphere turbulence MTF models in moderate-to-strong anisotropic turbulence

In this study, based on the extended Rytov approximation theory and the modified anisotropic non-Kolmogorov turbulence refractive-index fluctuations spectrum, new analytic expressions of the atmospheric turbulence modulation transfer function (MTF) are derived for optical plane and spherical waves propagating through moderate-to-strong anisotropic non-Kolmogorov turbulence. The anisotropic factor which parameterizes the asymmetric turbulence cells or eddies in the horizontal and vertical directions is introduced. When the anisotropic factor equals one, the models derived in this work can reduce correctly to the previously published results in moderate-to-strong isotropic turbulence. In addition, a wide range of turbulence strengths (weak, moderate-to-strong, and strong turbulence) is considered in this work, and it has good consistency with the previous models which were developed in weak anisotropic non-Kolmogorov turbulence in the weak turbulence regime.

空间碎片天基光学探测系统离焦问题分析

the reasons of the generation of defocus were discussed and the defocus change was analysed from the relative distance, atmospheric pressure and temperature change. the modulation transfer function model was proposed to study the image quality influenced by defocus. then different defocus value leading image blurry was simulated. the simulation results indicate that the positive and negative defocus value induced by the relative distance, atmospheric pressure and temperature change can be counteracted. this paper provides an effective data to spatial camera design, compensating measure establishment and performance evaluation. © 2016, science press. all right reserved.

Comparison of Numerical Eye Models and its Representation within a Mechanical Eye Model

Abstract: Today the increased computer power admits very detailed numerical modelling of the human eye. Simultaneous new technologies as well as the defined production of aspherical lenses permits the realization of nearly realistic ex vivo mechanical simulation of the natural human eye. Amongst others such ex vivo mechanical eye models are used to verify the optical quality of new intraocular lenses. Measurements of modulation transfer function (MTF) performed by an ex vivo mechanical eye model and numerical analysis of saggital and tangential MTF are presented.

Satellite modulation transfer function estimation from natural scenes

We propose an in-orbit modulation transfer function (MTF) statistical estimation algorithm based on natural scene, called SeMTF. The algorithm can estimate the in-orbit MTF of a sensor from an image without specialized targets. First, the power spectrum of a satellite image is analyzed, then a two-dimensional (2-D) fractal Brownian motion model is adopted to represent the natural scene. The in-orbit MTF is modeled by a parametric exponential function. Subsequently, the statistical model of satellite imaging is established. Second, the model is solved by the improved profile-likelihood function method. In order to handle the nuisance parameter in the profile-likelihood function, we divided the estimation problem into two minimization problems for the parameters of the MTF model and nuisance parameters, respectively. By alternating the two iterative minimizations, the result will converge to the optimal MTF parameters. Then the SeMTF algorithm is proposed. Finally, the algorithm is tested using real satellite images. Experimental results indicate that the estimation of MTF is highly accurate.

Resolution characteristics of graded band-gap reflection-mode AlGaAs/GaAs photocathodes

The modulation transfer function (MTF) of graded band-gap AlGaAs/GaAs reflection-mode photocathodes was determined using two-dimensional Poisson and continuity equations through numerical method. Based on the MTF model, we calculated the theoretical MTF of graded and uniform band-gap reflection-mode photocathodes. We then analyzed the effects of Al composition, wavelength of incident photon, and thicknesses of AlGaAs and GaAs layer on the resolution. Calculation results show that graded band-gap structures can increase the resolution of reflection-mode photocathodes. When the spatial frequency is 800lp/mm and wavelength is 600 nm, the resolution of graded band-gap photocathodes generally increases by 15.4–29.6%. The resolution improvement of graded band-gap photocathodes is attributed to the fact that the built-in electric field in graded band-gap photocathodes reduces the lateral diffusion distance of photoelectrons.

Influence of anisotropic turbulence on the long-range imaging system by the MTF model

Theoretical and experimental investigations have shown that the atmospheric turbulence exhibits both anisotropic and non-Kolmogorov properties. In this paper, new analytic expressions for the anisotropic non-Kolmogorov turbulence modulation transfer function (MTF) based on Rytov approximation theory have been derived for optical plane and spherical waves propagating through weak anisotropic non-Kolmogorov atmospheric turbulence. Compared with the previously published results where the turbulence inner and outer scales were set separately to zero and infinite for calculation convenience, the concept of anisotropy at different turbulence cell scales and finite turbulence inner and outer scales are introduced to study the MTF models. Also, deviations from the classic 11/3 spectral power law behavior for Kolmogorov turbulence are allowed by assuming spectral power law value variations between 3 and 4. To reduce the complexity and calculation time of the analytic results, the asymptotic-fit expressions are also derived and they fit well with the closed-form ones. Calculations are performed to analyze the anisotropic non-Kolmogorov turbulence’s influence on the long-range imaging system.

Scanning Modulation Transfer Function Model of TDI CMOS Image Sensor

An analytical model of Modulation Transfer Function (MTF) for Time-Delay-Integration CMOS Image Sensor (TDI-CIS) in the scanning direction is proposed. Impacts of pixel valid sensitive ratio, scann...

Influence of moderate-to-strong non-Kolmogorov turbulence on the imaging system by atmospheric turbulence MTF

The atmospheric turbulence modulation transfer function (MTF) which describes the degrading effect of atmospheric turbulence on imaging system is investigated theoretically for plane and spherical waves propagating through moderate-to-strong non-Kolmogorov turbulence. In the investigation, the effective non-Kolmogorov spectral model is adopted, and it modifies the conventional non-Kolmogorov spectral model with a modified frequency filter function. The new expressions cover a more wide range of non-Kolmogorov turbulence strength, and reduce correctly to previously published analytic expressions for both weak non-Kolmogorov turbulence and moderate-to-strong (or strong) Kolmogorov turbulence cases. Numerical calculations show that the MTF model derived in this work deviates from those obtained with the Rytov theory as turbulence strength increases up to moderate-to-strong (or strong) non-Kolmogorov turbulence regime.