Function Of Magnification Research Articles

Refracting Afocal Systems In Thermal Imagers

Afocal systems are frequently used in thermal imagers to match the field of view required by the user to that required for high scan efficiency. The limitation on performance of such telescopes due to chromatic aberrations and field curvature as a function of magnification, field angle, and f/number is discussed together with some methods for reducing these aberrations. A detailed scheme is given for the analytical correction of the primary monochromatic aberrations in telescope systems. Aberrations of the pupil in such telescope systems, and their control, are discussed with respect to the radiometry of thermal imagers. Finally a number of designs of telescope systems of various magnifications are discussed in some depth, from design philosophy to performance values. The designs include refracting and reflecting systems employing both spherical and aspheric surfaces.

High magnification unstable resonator excimer laser

High brightness performance has been achieved in a UV preionized transverse discharge KrF excimer laser by using a high magnification unstable resonator configuration. The properties of laser brightness as a function of resonator magnification are examined.

Visual Perception Limits In Angiography

The results of two types of visual detection experiments are presented and discussed. One set of experiments was done using single bar targets optically superimposed on a variety of backgrounds. The experiments were designed to determine functional relationships between the target contrast at the detection threshold and a number of variables. The variables include bar angular width, bar angular length, background noise level, and viewing distance. The second set of experiments was done using radiographs of aluminum wires. The radiographs were produced using a conventional neuro-angiography system with a 0.38 mm focus. The aluminum wire diameter at the detection threshold was determined as a function of geometric magnification for several screen-film combinations. The aim of the experiments is to determine how to calculate visual signal-to-noise ratios. Some progress has been made toward this goal.

Magnification in Striate Cortex and Retinal Ganglion Cell Layer of Owl Monkey: A Quantitative Comparison

Magnification, the relative size of the neural representation of a portion of the visual field, decreases more rapidly with increasing visual field eccentricity in striate cortex than in the retinal ganglion cell layer of the owl monkey (Aotus trivirgatus); the proportion of the cells in striate cortex devoted to central vision is much larger than the comparable proportion of retinal ganglion cells. Magnification in striate cortex is a power function of magnification in the retinal ganglion cell layer. A formula for convergence (ganglion cells to cortical neurons) follows from this relationship.

Composite one- and two-pass gain saturation in the geometric mode limit of unstable resonators

Design curves, of the geometric mode limit output power of gain-saturated confocal positive branch unstable resonators with mirror separation large compared to mirror diameters, are given as a function of mode magnification, ratio of mean cavity to small signal gain coefficients, and axial and transverse distributions of the small signal gain coefficient.

Resolution of fiber-optic faceplate image-intensifier tubes as a function of magnification

The resolution capability of image intensifiers is customarily assumed as proportional to the magnification of the tube. An equation is presented to calculate resolution a priori as a function of magnification, applicable to tubes with fiber-optic faceplates. in addition, a method is suggested to improve the resolution capability of multistage tubes.

Dependence of Spherical and Chromatic Aberration upon Magnification in an Immersion Lens

Spherical and chromatic aberration as functions of lens magnification have been computed for an immersion lens with a ``bell-shaped'' axial field distribution.

The optimum tilt angle for electron stereo-microscopy

Curves are given of the optimum tilt angle for stereo photographs as a function of foil thickness and magnification, to give a good stereo impression in a stereoviewer.

VISUAL FACTORS IN SIZE MEASUREMENT BY MICROSCOPY.

In estimating the size of an isolated object by visual observation of its image as formed by a microscope objective, the characteristics of the eye as well as the physical light intensity distribution in the image must be taken into account. Experiments are described in which the visual sizes of circular objects of known size are measured as a function of the instrumental magnification, the retinal illumination and the adaptation of the eye, these results being discussed in relation to the corresponding diffraction images and the properties of the eye.

An examination of visual acuity and depth perception as a function of magnification.

An examination of visual acuity and depth perception as a function of magnification.

Photographic granularity and graininess V A variable-magnification instrument for measuring graininess

An instrument has been built to measure graininess in terms of the reciprocal of the blending magnification of an image of the sample as viewed by binocular vision from a constant distance. This instrument is essentially an autofocus variable-magnification projector which forms an image of constant size and of a luminance which is proportional to the transmittance of the sample. The image is formed on a rear-projection screen which is part of the front wall of a special observation room. The blending magnification may be determined either by permitting the observer to vary the magnification continuously until graininess is just perceptible, or by the experimenter varying the magnification discontinuously and presenting the enlarged image of the sample to the observer at ten predetermined magnifications and having the observer judge only whether or not graininess is perceptible at each magnification. With the latter method, the image at each of the predetermined magnifications is repeatedly presented to the observer in a random order and the frequency of perception of graininess at each magnification of the image is plotted as a function of magnification. From this psychometric function the blending magnification is determined as that magnification at which the observer has perceived graininess during 50 percent of the observations.