Immagini

DESCRIPTION

Exhibit 440 is a direct vision spectroscope formed by five prisms of alternating flint (2) and crown (3) glass with opposite orientations to obtain overall null average deviation of the green color and maximum dispersion of the extreme colors, red and violet. This spectroscope is a direct vision instrument in that the result of the light dispersion, due to the particular disposition of the prisms, can be observed in the same direction as that of the incident light source. The dispersive element is a set of five prisms, glued together, three crown glass and two flint glass with the refraction angles opposed as shown in design 2. The glue used is Canada balsam which has an index of refraction of 1.55 which minimizes the intensity loss between the prisms. This configuration was invented by G.B.Amici and first realized with three prisms. Here the dispersive effect is increased with the use of five prisms.

BIBLIOGRAPHY

• [1] Jenkins and White, "Fundamentals of Optics", McGRAW-HILL Book Company, INC. New York, 1957.
• [2] D.N. Vasudeva, "A Text Book of LIGHT", Atma Ram & Sons, Delhi, IV Edition, 1959, pag. 117

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