The London, Edinburgh and Dublin philosophical magazine and journal of science . ttT u I ! POSITION OF 11 iPRISM REFLECTION FOR U i WITHOUT PHASE REVERSAL ill! m In order to give some idea of the relative intensities of thefocal images produced by the plate with and without a phase-reversal, I photographed an incandescent lamp-filament, firstfrom the outside surface of the zones and then from theinside, by the arrangement shown in fig. 2. The time of and Diffraction Telescopes. 521 exposure and development was the same, and both were takenon the same plate. Reproductions of the two images ares
The London, Edinburgh and Dublin philosophical magazine and journal of science . ttT u I ! POSITION OF 11 iPRISM REFLECTION FOR U i WITHOUT PHASE REVERSAL ill! m In order to give some idea of the relative intensities of thefocal images produced by the plate with and without a phase-reversal, I photographed an incandescent lamp-filament, firstfrom the outside surface of the zones and then from theinside, by the arrangement shown in fig. 2. The time of and Diffraction Telescopes. 521 exposure and development was the same, and both were takenon the same plate. Reproductions of the two images areshown in fig. 3. It will be noted that the brilliant one Fiar. (or phase-reversal image) is larger than the other. This isdue to the increase in the focal leugth to wThich I havealluded, and, other things being equal, would make theillumination less. The image obtained from the outer surfaceof the plate is so faint that it is hardly perceptible. I have made a very cursory examination of these phase-reversal reflecting plates with polarized light, and find that ifthe light falling on the prism be plane-polarized, rotation ofthe nicol causes fluctuations in the brilliancy of the effect, however, varies with the angle of incidence; at anangle of 40° with the normal of the reflecting surface no effectis produced by rotating the nicol. When the angle is greaterthan this, partial extinction of the image is produced whenthe plane of polarization is perpendicular to the plane ofreflexion; when the angle is less than 40°, the reverse is the case. The field about the image grows bright when the © © © central image weakens, and vice versa. Th
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Keywords: ., bookcentury1800, bookdecade1840, booksubjectscience, bookyear1840
