Tomsk State University. Physical Department.
Laboratory of training physics experiment
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Conoscope   for   demonstrations Обратно   Далее  
Earlier, to show an interference of polarized rays the special device by Duboscq were used. They included many optical elements, that resulted the beam aperture to be considerably restricted and, hence, the picture brightness and its sizes to be small.
We have designed very simple and convenient device - demonstration conoscope and have implanted it to practice. On a miniature optical bench there are three movable stands that may be fixed on it. On the first of them the incandescent bulb of 170 W is set up. Two others support polaroid-polarizer and polaroid-analyzer of diameter 8 cm. Both are easy to turn. Between them planar specimens are placed (quartz, aragonite, and polymer films).
There are no any focusing elements in this device, because to form the demonstrational conoscope picture is sufficient the divergent light beam from the lamp to pass through the birefringence specimen. The main advantage of this device is that all above elements may be put close to each other, furnishing large aperture angles up to 90 degrees.
. Conoscope pictures are projected either on a dull screen, placed at the distance of 1m., or on a big one in the lecture room. The conoscope makes it possible to demonstrate the picture of lemniscates family produced by a slice of mica. As a lamina of mica is thin, and the angle between optical axes is large, the conoscope picture may be as great as 3x3 m of a good brightness.
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