A NEW METHOD OF DETERMINING THE ISOCLINIC PARAMETER

The isoclinic parameter can be determined from points of intersection of two systems of characteristic lines called secondary isochromatics. These lines, along which the light intensity is a minimum, can be observed in monochromatic light in an originally linear polariscope with two crossed quarter-wave plates in which the polarizer and analyser have been rotated through small angles in opposite directions. The theory of the polariscope, based on Jones’s metric equations, is given and the influence of imperfect quarter-wave plates is discussed. The effect of light of incorrect wave-length on the resulting error is con-sidered. A disc loaded by two opposite compression forces is used for demonstration of the methods