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modulation transfer-function OF EFFERENT NEURONS IN THE GUINEA-PIG COCHLEA

HEARING RESEARCH 1988年第1期36卷 41-52页

作者： GUMMER, M YATES, GK JOHNSTONE, BM UNIV WESTERN AUSTRALIA DEPT PHYSIOL NEDLANDS WA 6009 AUSTRALIA

The dynamic properties of single olivocochlear efferent neurones in the guinea pig cochlea were examined using sinusoidally amplitude modulated (AM) pure tones. The neural discharge, when displayed as a cyclic histogram, clearly followed the rapid fluctuations in the continuous input sound. modulation transfer functions (MTFs) were constructed and in most cases showed a peak in the modulation response (MR) at a modulation frequency (MF) of 100 Hz. At this frequency a gain of as much as 12 dB was evident relative to the 30% modulated input signal. In 24% of neurones however, a large MR was present even at low MFs. This plurality of MTFs may be the result of recorded neurones emanating from a variety of cell bodies of origin Efferent group delays (mean of 8.2 .+-. 1.0 ms) were shorter and more tightly distributed than the minimum onset latency measurements (mean of 24.3 .+-. 12.5) made on the same neurones. It seems evident that a post-synaptic potential build is required from the onset of a stimulus to the first spike discharge. This may occur within a single afferent-interneurone(s)-efferent reflex arc. Among a variety of alternative explanations, the observation is consistent with the notion that the olivocochlear neurones receive facilitatory input from higher centres, which is suppressed under barbiturate anaesthesia. Continuous AM signals may allow post-synaptic build up and eliminate the dependence on this higher input and hence yield a short group delay.

关键词： Amplitude modulation Group delay Minimum onset latency modulation transfer function Neurone, single Olivocochlear efferent neurone

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modulation transfer function of implantable phakic intraocular contact lens (IPCL) for myopia and presbyopia

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GRAEFES ARCHIVE FOR CLINICAL AND EXPERIMENTAL OPHTHALMOLOGY 2024年第10期262卷 3201-3206页

作者： Yu, Chunjing Kamiya, Kazutaka Kawamorita, Takushi Kitasato Univ Dept Ophthalmol & Visual Sci Grad Sch Med Sci 1-15-1 KitasatoMinami Ku Sagamihara Kanagawa 2520373 Japan Kitasato Univ Sch Allied Hlth Sci Dept Orthopt & Visual Sci Sagamihara Japan

PurposeThis study aimed to assess the optical quality of myopic and presbyopic IPCLs with different additional powers, and to investigate the effects of pupil size on the optical quality of these IPCLs using an in-vitro modulation transfer function (MTF) measurement *** scatter functions (LSFs) were recorded using the OPAL Vector system and an eye phantom consisting of wet cells filled with a balanced salt solution. A myopic IPCL or a presbyopic IPCL was placed in the posterior chamber of this model. The MTF was calculated from the LSF using the fast Fourier transform techniques. The effective apertures were set at 2.0 to 5.0 mm in 1.0 mm *** in-focus MTF values of the myopic IPCL and presbyopic IPCL with additional powers of + 2.0 and + 4.0 diopters at 100 cycles/mm for an effective aperture of 3.0 mm were 43%, 27%, and 24%, respectively. The in-focus MTF value of both myopic and presbyopic IPCLs was the highest when the effective aperture was set at 3.0 mm, and it gradually worsened when the effective aperture became larger than 3.0 mm at 20, 60, and 100 cycles/*** myopic and presbyopic IPCLs provided excellent MTF values, but the additional power profile can deteriorate optical performance in presbyopic IPCL-implanted eyes, even with a low additional power. Pupil size can influence visual quality in IPCL-implanted eyes for both myopia and presbyopia. What is known:center dot Implantable phakic contact lens (IPCL) has been reported to be effective for the treatment of both myopia and presbyopia, with a noticeable advantage in reducing the patients' cost *** dot The optical properties of IPCL have not yet been thoroughly investigated, neither for myopic IPCLs nor for presbyopic *** is new:center dot The MTF of presbyopic IPCL was slightly lower than that of myopic IPCL even with a low additional *** dot The MTF values of both myopic and presbyopic IPCLs were the highest for a 3.0 mm-pupil size,

关键词： modulation transfer function Myopic IPCL Presbyopic IPCL Phakic IOL IPCL Pupil size

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modulation transfer-function CASCADE MODEL FOR A SAMPLED IR IMAGING-SYSTEM

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APPLIED OPTICS 1991年第13期30卷 1659-1664页

作者： de Luca, L Cardone, G The authors are with University of Naples Faculty of Engineering–DETEC I-80125 Naples Italy.

The performance of the infrared scanning radiometer (IRSR) is strongly stressed in convective heat transfer applications where high spatial frequencies in the signal that describes the thermal image are present. The need to characterize more deeply the system spatial resolution has led to the formulation of a cascade model for the evaluation of the actual modulation transfer function of a sampled IR imaging system. The model can yield both the aliasing band and the averaged modulation response for a general sampling subsystem. For a line scan imaging system, which is the case of a typical IRSR, a rule of thumb that states whether the combined sampling-imaging system is either imaging-dependent or sampling-dependent is proposed. The model is tested by comparing it with other noncascade models as well as by ad hoc measurements performed on a commercial digitized IRSR.

关键词： Discrete Fourier transforms Imaging systems Infrared systems modulation transfer function Spatial frequency Spatial resolution

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modulation transfer-function OF LAYERED INHOMOGENEOUS RANDOM-MEDIA USING THE SMALL-ANGLE APPROXIMATION

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APPLIED OPTICS 1986年第23期25卷 4382-4385页

作者： KUGA, Y ISHIMARU, A The authors are with University of Washington Department of Electrical Engineering Seattle Washington 98195.

Many random media such as clouds and fog are often inhomogeneously distributed and often have a layered structure. This paper presents the effects of such inhomogeneities on the image transmission in terms of the modulation transfer function (MTF). We derive an expression of the MTF for a layered inhomogeneous medium using the small-angle approximation which is valid for size parameters of >10 and optical distances of <5. We obtain numerical results and compare them with experimental data for different particle sizes and concentrations showing good agreement. We also explain the shower curtain effect using the expression for the MTF.

关键词： Image transmission Inhomogeneous optical media modulation transfer function Refractive index Turbid media Turbid media imaging

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modulation transfer function evaluation of cone beam computed tomography for dental use with the oversampling method

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DENTOMAXILLOFACIAL RADIOLOGY 2010年第1期39卷 28-32页

作者： Watanabe, H. Honda, E. Kurabayashi, T. Tokyo Med & Dent Univ Div Oral Hlth Sci Grad Sch Bunkyo Ku Tokyo 1138549 Japan Univ Tokushima Grad Sch Tokushima 770 Japan

Objectives: The aim was to investigate the possibility of evaluating the modulation transfer function (MTF) of cone beam CT (CBCT) for dental use using the oversampling method. Methods: The CBCT apparatus (3D Accuitomo) with an image intensifier was used with a 100 mu m tungsten wire placed inside the scanner at a slight angle to the plane perpendicular to the plane of interest and scanned. 200 contiguous reconstructed images were used to obtain the oversampling line-spread function (LSF). The MTF curve was obtained by computing the Fourier transformation from the oversampled LSF. Line pair tests were also performed using Catphan (R). Results: The oversampling method provided smooth and reproducible MTF Curves. The MTF Curves revealed that the spatial resolution in the Z-axis direction was significantly higher than that in the axial direction. This result was also confirmed by the line pair test. Conclusions: MTF analysis was performed successfully using the oversampling method. In addition, this Study clarified that the 3D Accuitomo had high spatial resolution, especially in the 7-axis direction. Dentomaxillofacial Radiology (2010) 39, 28-32. doi: 10.1259/dmfr/27069629

关键词： dental cone beam computed tomography modulation transfer function

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modulation transfer function of blazed diffractive optics produced by diamond turning

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OPTICAL REVIEW 1999年第4期6卷 288-292页

作者： Tamagawa, Y Ichioka, Y Osaka Univ Grad Sch Engn Dept Mat & Life Sci Suita Osaka 5650871 Japan

In blazed diffractive optics produced by the diamond turning process, the finite size of the tool determines the decrease in diffraction efficiency of the desired order. Diffracted light of other orders degrades the image quality. To analyze the influence of the tool, we evaluate diffraction efficiency and phase of periodic gratings based on the electromagnetic theory and calculate modulation transfer function using a linear system approach.

关键词： diffractive optical elements diamond turning modulation transfer function diffraction efficiency

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modulation transfer function OF AZ111 PHOTORESIST

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APPLIED OPTICS 1971年第9期10卷 2101-&页

作者： BRANDES, RG CURRAN, RK The authors are with Bell Telephone Laboratories Inc. Murray Hill New Jersey 07974.

For the utilization of photoresist materials it is desirable to describe quantitatively the photoresist image and thereby introduce control over photoresist processing. The photoresist AZ111 has been shown to be a linear image recording medium and a modulation transfer function (MTF) defined and measured. Measured and calculated image profiles in this resist are quite comparable.

关键词： Image processing Ion lasers Light wavelength modulation transfer function Scanning electron microscopy Spatial frequency

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modulation transfer-function AND NUMBER OF EQUIVALENT ELEMENTS FOR SPRITE DETECTORS

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APPLIED OPTICS 1988年第20期27卷 4331-4335页

作者： BOREMAN, GD PLOGSTEDT, AE MCDONNELL DOUGLAS ASTRONAUT CO TITUSVILLE FL 32780 USA

SPRITE (signal processing in the element) detectors are three-contact photoconductive structures made of HgCdTe, in which a time-delay-and-integration function is performed in the detector element itself without the need for external circuitry. Spatial frequency-dependent expressions are developed for the modulation transfer function and the number of equivalent elements N eq of the SPRITE. The development is based on a Green’s function method, which accounts for carrier generation, recombination, and diffusion processes. The usual low-frequency approach of defining a square resolution element on the SPRITE is avoided. The resulting expressions are functions of spatial frequency and are also dependent on physical variables such as the length of the SPRITE element, carrier lifetime, carrier mobility, and operating voltage. These expressions are then applied to the design of a SPRITE element, optimized for operation over a particular range of spatial frequencies.

关键词： Electric fields Infrared imaging modulation transfer function Signal processing Spatial frequency Spatial resolution

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modulation transfer function of intraocular collamer lens with a central artificial hole

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GRAEFES ARCHIVE FOR CLINICAL AND EXPERIMENTAL OPHTHALMOLOGY 2011年第7期249卷 1081-1085页

作者： Uozato, Hiroshi Shimizu, Kimiya Kawamorita, Takushi Ohmoto, Fumiko Kitasato Univ Sch Allied Hlth Sci Dept Orthopt & Visual Sci Minami Ku Sagamihara Kanagawa 2520373 Japan Kitasato Univ Grad Sch Med Sci Dept Ophthalmol & Visual Sci Sagamihara Kanagawa 2520373 Japan Kitasato Univ Sch Med Dept Ophthalmol Sagamihara Kanagawa 2520373 Japan

A modified implantable collamer lens (ICL) with a central hole (diameter 0.36 mm), "Hole-ICL", was created to improve aqueous humour circulation. The aim of this study is to investigate the effects of ICL power and the relationship between pupil size and modulation-transfer functions (MTFs) in a Hole-ICL in vitro. The ICL and intraocular lens (IOL) studied were the Collamer ICL (Model ICM, STAAR Surginal) and the monofocal IOL AF-1 (VA-60BBR, HOYA). The ICLs' powers were -20.0 diopters (D), -10.0 D, -5.0 D, +3.0 D, and +10.0 D. A modified ICL with a central hole (diameter 0.36 mm), "Hole-ICL", was created. The monofocal IOL, which was used as an artificial crystalline lens, was +30.0 D in power, and it was 13.0 mm in length with an optic diameter of 6.0 mm. The line-spread function (LSF) was recorded with the OPAL Vector System (Image Science Ltd.), and a model eye (Menicon Co.) was used that consisted of a wet cell. A conventional ICL or Hole-ICL was placed in the posterior chamber of the model eye. The MTF was calculated from the LSF using fast Fourier transform techniques. Furthermore, we investigated the relationship between pupil size and the MTF of the ICL for -5.0 D. The sizes of the effective aperture were 2.0, 3.0, 4.0, and 5.0 mm. The in-focus contrasts of the conventional ICL at 100 cyc/mm for a 3.0-mm effective aperture were 37%, 40%, 39%, 38%, and 39% for -20.0 D, -10.0 D, -5.0 D, +3.0 D, and +10.0 D respectively. The in-focus contrasts of the Hole-ICL at 100 cyc/mm for a 3.0-mm effective aperture were 37%, 40%, 39%, 38%, and 38% for -20.0 D, -10.0 D, -5.0 D, +3.0 D, and +10.0 D respectively. The results for a 2.0-mm effective diameter showed that the in-focus MTF in the Hole-ICL was lower than in the conventional ICL, although the difference was small. These results suggest that differences in MTF between the Hole-ICL and the conventional ICL for various ICL powers and effective pupil diameters were small and clinically negligible.

关键词： modulation transfer function Pupil size Phakic IOL ICL Hole ICL

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modulation transfer-function MEASUREMENT USING 3-BAR AND 4-BAR TARGETS

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APPLIED OPTICS 1995年第34期34卷 8050-8052页

作者： BOREMAN, GD YANG, S Center for Research and Education in Optics and Lasers Department of Electrical Engineering University of Central Florida Orlando Florida 32816

modulation-transfer-function (MTF) measurement often involves the use of three- and four-bar resolution targets. In the conversion of three- and four-bar image data to MTF, biased results can occur when we use series-expansion techniques appropriate for square-wave targets of infinite extent. For systems where the image data are digitally recorded, a convenient and accurate conversion of bar-target data to MTF can be performed using a Fourier-domain method.

关键词： Charge coupled devices Detector arrays Infrared systems modulation modulation transfer function Spatial frequency

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