Optical Disc

A 500 mm diam. the disc marked every 5° is mounted on a heavy stand and is rotatable around its center. It can be held in any desired position. The lamphouse, with a 12V 24 W special filament lamp has rotatable slots to provide light beams of varying widths and also narrow single, double and triple beams. Attached to the lamphouse is an adjustable lens carrier with a lens to provide diverging, parallel, or converging light beams that are clearly visible in the classroom. The lamp house can be held in any desired position around the disc. Optical elements are two 50 x 25 mm plane glass mirrors, and a metallic cylindrical mirror, each mounted in a holder, for reflection. For refraction, 20 mm thick acrylic semi-circular block, biconvex lens, bi-concave lens each 140 mm long, and a trapezium with 125 mm base is provided. Each of these elements has embedded magnets to hold on to the disc.