Optical transfer function

Within this work [7] a method and model to determine the optical transfer function (OTF) for the detector chain without detailed knowledge of the internal detector and camera characteristics was developed. The expected value of the signal S0.2 is calculated with... 

Abstract This is a tutorial about the main optical properties of the Earth atmosphere as it affects incoming radiation from astrophysical sources. Turbulence is a random process, of which statitical moments are described relying on the Kolmogorov model. The phase structure function and the Fried parameter ro are introduced. Analytical expressions of the degradation of the optical transfer function due to the turbulence, and the resulting Strehl ratio and anisoplanatism are derived. 

The Optical Transfer Function (OTF) is related to the phase stmcture function as follows (Roddier,1981)... 

Hashimoto, M., and Araki, T. 2001. Three dimensional coherent and optical transfer functions of coherent anti-stokes Raman scattering microscopy. J. Opt. Soc. Am. A 18 771-76. 

Heygster, G., Block, H., Gadomski, A., and Boseck, S. (1990). Modeling of the optical transfer function (OTF) of the scanning acoustic microscope (SAM) and its relation to the other scanning microscopes. Optik 85,89-98. [28, 200]... 

The factor 1.22 in Eq. 2.1 was empirically derived by Rayleigh. It may be derived from the radius of the circle, known as the Airy disk, from the optical transfer function. In 1873, the German physicist Ernst Karl Abbe (1840-1905) showed that the numerical... 

Another way to achieve the reading data with RCM is to use the multilayered recording medium in which photosensitive thin films and nonphotosensitive transparent films are alternately stacked. Since the photosensitive films are thinner than the depth of focus of the recording beam, the spatial-frequency distribution of the recorded-bit data is extended in the axial direction. The extended distribution overlaps the coherent optical transfer function of the RCM. 

Figure 16.19 shows the spatial-frequency distributions of bit data recorded with focused laser beam and coherent optical transfer function (CTF) of reflection type confocal microscopeFigure 16.19a shows a spatial-frequency distribution of bit datum recorded in very thick medium. This distribution coincides with the spatial-frequency distribution of the focused light to record the bit datum, because the bit is recorded with the focused beam. It is assumed that the NA of the objective lens is given by n sin a and k =l ulk, where A denotes the wavelength. 

An alternative readout system is a scanning differential phase-contrast microscope with a split detector as shown in Figure 16.5. The optical configuration is compact and easy to align. The memory medium, in which the data bits have been recorded, is located at the focus of an objective lens. The band limit of the optical transfer function (OTF) is the same as that of a conventional microscope with incoherent illumination. The resolution, especially the axial resolution of the phase-contrast microscope, is similar to that obtained by Zemike s phase-contrast microscope. The contrast of the image is much improved compared to that of Zernike s phase-contrast microscope, however, because the nondiffracted components are completely eliminated by the subtraction of signals between two detectors. The readout system is therefore sensitive to small phase changes. 

Measured Performance. Under the conditions of space invariance and incoherence, an image can be expressed as the convolution of the object irradiance and the point-spread function, Eq. (26.15). The corresponding statement in the spatial frequency domain, Eq.(26.28), is obtained by taking the Fourier transform of Eq. (26.15). This states that the frequency spectrum of the image irradiance equals the product of the frequency spectrum of the object irradiance distribution and the transform of the point-spread function. In this manner, optical elements functioning as linear operators transform a sinusoidal input into an undistorted sinusoidal output [Eq. (26.33)]. Hence the function that performs this service is the transform of the point-spread function 3 A(x, y), known as the optical transfer function 0 u, v] (OTF). This is a spatial frequency-dependent complex function with a modulus component called the modulation tranter function M u. v] (MTF) and a phase component called the phase tranfer function 4>[ , v] (PTF). The MTF is the ratio of image-to-object modulation, while the PTF is a measure of the relative positional shift from object to image. 

The optical transfer function (OTF) presents the fineness with which we can transmit spatial information in the spatial frequency domain. The OTF H s) is defined with s the spatial frequency. 

Optical transfer function Function measuring the complex amplitude of the image transmitted by an optical system illuminated by a unit-amplitude sinusoidal pattern, versus the spatial frequency. 

FIGURE 12 Optical transfer functions related to incoherent illumination of square (left) and round (right) pupils. T is proportional to the convolution of the pupil function [see top diagram and Eq. (45).]... 

C. Gabrielli, M. Keddam, H. Perrot, and R. Torresi [1994] Lithium Insertion in WO3 Studied by Simultaneous Measurements of Impedance, Electrogravimetric and Electro-Optical Transfer Functions. J. Electroanal. Chem. 378, 85-92. 

A typical plot of third-order IM-free DR for a Mach-Zehnder biased at V /2 is shown in Fig. 9.60. Although the data in this plot were taken at 60 MHz, they should be valid at any frequency. This is because for a modulator, unlike the diode laser, the shape of the electrical-to-optical transfer function is independent of RF frequency. This has been experimentally demonstrated up to 20 GHz (Betts, Cox and Ray, 1990). A directional coupler modulator, when biased where the second-order distortion is zero, has almost identical third-order IM-free DR. 

Calculations of the twist structure resolution in a nonuniform field are very cumbersome and, for this reason, have not been attempted until recently [173, 174]. The direct minimization algorithm of the free energy functional proposed by Levov et al. stimulated progress in this field [174]. The idea of the calculations is as follows. A twist cell is considered as a linear optical unit for the corresponding values of voltages when the transmission-voltage curve is linear [2]. It enables us to determine the Optical Transfer Function (OTF) of a twist cell which characterizes the transformation of a spatially nonuniform field at the input of the cell to the corresponding variation of the optical transmission at the output (Fig. 5.33). OTF is defined as the... 

FIGURE 5.33. A liquid crystal twist cell, as a linear optical unit [174, 175]. Resolution /r is defined as the half-width of the normahzed Optical Transfer Function (OTF). The solid hne denotes experiment and the dashed line denotes calculations. 

Fig. 7 Normalized human contrast sensitivity (Data from Campbell and Robson [12]) and normalized optical transfer function with a pupil diameter of 2 mm (Data from Ijspeert et al. [13]). The decline in human spatial sensitivity is much steeper than the optical decline. Thus, spatial sensitivity is driven by neuronal processing capacities...

Mirrors reflect colours very well For CMS the image fidelity is determined by the optical-electrical-optical transfer function. The colour range of a CMS is limited. Colours can be perceived differently by changing the angle of view on the monitor. Artifacts can affect the depiction and perception of colours... 

The Electro-optic Transfer Function in Nematic Liquids Alan Sussman... 

When an electric field is applied across transparent plane-parallel electrodes containing mesomorphic liquids, many complex phenomena occur that depend on the optical, dielectric, and elastic properties of the liquid, the geometry of the test situation, and the nature of the electrical signal/ The electro-optic transfer function is a way of specifying such optical changes. An ever increasing interest in liquid-... 

Fig. 3—Influence of geometrical parameters on scattering electro-optic transfer function measurements. Three cases are illustrated, with their corresponding electro-optic transfer functions (highly schematic).

The electro-optic transfer function at a fixed angle between crossed polarizers is shown in Fig. 5. By swinging between two voltages, it is possible to modulate the color equivalent to a phase retardation at one wavelength (first voltage) to produce a color equivalent to a different wavelength (second voltage). This is the basis for a matrix-... 

Fig. 7—Electro-optic transfer function of twisted structure. Above threshold, increasing the voltage casuses the structure to lose the ability to rotate the plane of polarized light eventually, the optical behavior of the structure approaches that of a perpendicular home-otropic nematic. The difference (e,), however, is still finite at three times threshold. ...

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