A comparison is made between clad fibers and lens-like guides with parabolic index profiles, from several points of view: delay distortion, beam capacity per unit cross section, ability to negotiate bends, and deterioration of transmission due to imperfections. Theoretical and experimental quantitative comparisons are also presented.
Space astronomy, above the obscuring effects of the atmosphere, promises a quantum jump in knowledge of the universe comparable to the original invention of the telescope. The scientific community has recommended eventual orbiting of a 120 inch telescope to exploit the potential. The pacing problem is undoubtedly the primary mirror itself, which must hold microinch tolerances across the 10 foot diameter during manufacture, launch and operation.
A dye laser uses a fluorescent organic dye in liquid solution, or in a polymer, as the active medium. The device may be excited either by a flashlamp or with a giant-pulse solid-state laser. The broad fluorescence linewidth of a dye and the large variety of dyes available permit the construction of a tunable laser operating throughout the visible spectrum. Furthermore, use of a liquid active medium facilities cooling of the laser for operation at high repetition rates. The gain and power output performance of the dye laser is greater than that of the gas laser and is comparable to that obtained from solid-state lasers. Factors which influence the gain of the dye laser and the excitation power required to reach threshold are reviewed. Tuning by means of dispersive elements in the dye laser cavity is discussed. The results of mode-locking experiments are described. Also, consideration is given to the possibility of obtaining CW operation of the dye laser.
The usual practice in pattern recognition is first to adopt some working definition for the patterns of interest and then to expend most of the effort on the equipment and/or automated techniques required to find and recognize these patterns. This paper is concerned only with the first step; it outlines a strategy, based on psycho-physical methodology, for determining those features of the pattern which are most likely to be informative. The approach used is termed psychopictorics; this is defined as a subfield of psychophysics which is concerned with pictorial stimuli, and in which it is assumed that, in a picture, the information of significance to the human observer may be characterized and analyzed in terms of the properties of perceived objects. The analysis of these properties involves the measurement of many psychophysical variables while the observer is responding to repeated, controlled changes of the features of single objects in the picture. Thus psychopictorics is strongly dependent on the development of computer picture processing techniques which permit such controlled manipulations without unduly degrading the quality of the picture.
The airborne multichannel scanners at present in use in the University of Michigan's flying program will be described. This equipment provided eighteen parallel outputs from eighteen detectors each operating at fixed optical bandwidths distributed over the .35 to 13.5 micron region. The pattern recognition concepts used to create compositional maps on the basis of the information carried in the parallel channels will be described as will the electronic equipment used to implement these concepts. Examples of the parallel stripmaps obtained will be shown as will examples of compositional maps generated with the equipment described. The extension and applicability of these techniques to future airborne and orbital remote sensing programs will be discussed.