. Elementary chemical microscopy. Microscopy; Microchemistry. ULTRAMICROSCOPES 111 After passing through the slit the light rays enter the lens C2, having a focal length of 55 millimeters, whose function is to project a reduced image of the slit into the condenser-objective C3. Since both slit and lens C2 are movable forward and back upon the optical bench, the lens C2 serves a double purpose, projection and adjustment of the magnitude of the light beam entering C3. The objective C3 projects into the preparation contained in the cell of black glass U a tiny conical beam of light at right angle
. Elementary chemical microscopy. Microscopy; Microchemistry. ULTRAMICROSCOPES 111 After passing through the slit the light rays enter the lens C2, having a focal length of 55 millimeters, whose function is to project a reduced image of the slit into the condenser-objective C3. Since both slit and lens C2 are movable forward and back upon the optical bench, the lens C2 serves a double purpose, projection and adjustment of the magnitude of the light beam entering C3. The objective C3 projects into the preparation contained in the cell of black glass U a tiny conical beam of light at right angles to the optic axis of the microscope M. To prevent any side light from entering the preparation, lenses Ci and C2 are small and are mounted in blackened metal screens; as a further precaution a large metal screen D with tubular opening or adjustable diaphragm is introduced between the radiant and Ci. The objective C3 screws into a tube fitting into the sleeve T and may be slid forward and back for coarse adjust- ment. A very sensitive forward and back movement is further provided by the fine adjustment screw Vi. A second fine adjust- ment to the right and left for accurately centering the illumi- nating cone of light is obtained by the screw V2. By means of these two screws it is possible to adjust the tiny beam entering the material to be studied, in such a manner as to ensure the focal point of the condensing objective C3 falling in the line of the optic axis of the observing microscope M, and therefore have the whole of the tiny beam lying across the exact center of the field of view. To the lower end of the body tube of the microscope is at- tached an adapter Fig. 52. Biltz Cell. A with centering screws a, a, providing a device for accurately centering the objective O. The liquid containing suspensoids is conveniently placed for examination in a Biltz cell, Fig. 52, or, when the short piece of rubber tubing which is attached to the end of the tube is objec- tionable becaus
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectmicroscopy, bookyear1
