A prism cut from fused silica has an apex angle of

PHYSICS · Multi-part · Fermi University Physics · Optics & Photonics · Geometrical optics and imaging · Wave propagation and light in media

Optics and Photonics, Ch Light as an electromagnetic wave in matter

Problem

45.0^\circ

. Its refractive index follows the Cauchy fit

n = A + B/\lambda^2

with

A = 1.4580

and

B = 3540\ \text{nm}^2

(with

\lambda

in nanometres). ((a)) Find

n

at 410 nm and at 660 nm from the fit. ((b)) At minimum deviation the ray inside the prism makes an angle with the normal equal to half the apex angle at each face. Using Snell's law

n_1\sin\theta_1 = n_2\sin\theta_2

(Chapter 1) with

n_1 = 1.00

for air, find the angle of incidence at the first face for each wavelength, and hence the deviation (twice the angle of incidence, less the apex angle) at minimum deviation. ((c)) State the angular spread between the two deviations.

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