Ernst Leitz Wetzlar, petrographic microscope, 1909
This is a Petrographic microscope made in 1909 by E. Leitz Wetzlar. It consists of a microscope body supported by a brass limb. The limb floats on a triangular pillar for fine focus via the top screw. Coarse focus is by rack & pinion. The microscope is supported by a heavy brass base painted with black lacquer. The support is hinged just below the insertion of the rotating stage to allow the instrument to be tilted. The polarizing condenser is centered by a locating pin. It has a leaf iris for contrast control. Inside the condenser is the single Nicol prism polarizer. Sample illumination is provided by the substage mirror. The microscope body consists of two tubes: the draw tube and body tube. The top, draw tube is calibrated for 170-190mm optical tube length objectives. The body tube has several slots and cutouts to allow placement of PLM-specific components: an Amici-Bertrand lens (for observation of interference fringes), a Tube Analyzer (upper Nicol), and a compensator slider. The objective is held in place by a spring-loaded quick release mechanism: the objective clutch. The objective mount has two screws to center the objective. The eyepiece is a Huygenian type, but with a focusing mechanism for a crosshair or reticle.