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2. (75 points) Consider a crystal on the stage of a polarized light microscope. The microscope is set up according to DIN standards, the same as what is used in the Criminalistics laboratory. A 40X dry objective of 0.75 NA is used for this work. The crystal has the general shape of an elongated flattened hexagonal plate and is mounted, under a coverglass, in Meltmount 1.539, with the planes of its largest faces parallel to the surface of the microscope slide. Two independent measurements of the thickness of the crystal reveal it to be 53.0 um. The crystal is examined conoscopically, and a well-centered biaxial interference figure is observed; 10 orders of isochromes can be seen between the melatopes, with each isochrome corresponding to one wavelength of retardation as seen with the first order red plate. It is found, in correlating conoscopic and orthoscopic views, that the trace of the OAP corresponds to the direction of the long axis of the crystal. Additionally, when it is viewed orthoscopically with the analyzer removed, the crystal vanishes when its long axis is oriented E-W. The contrast is much greater if the crystal is oriented N-S. In the N-S orientation Becke lines are seen to move in on upward focusing. d. Determine the sign of elongation of the crystal. Explain how you arrived at your