A crown-glass prism has apex angle and a Cauchy fit (with in nm) .

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

A crown-glass prism has apex angle 40∘40^\circ and a Cauchy fit (with λ\lambda in nm) n(λ)=1.5100+4800 nm2λ2n(\lambda) = 1.5100 + \dfrac{4800\ \text{nm}^2}{\lambda^2}. ((a)) Using Snell's law at minimum deviation (Chapter 1), find the deviation at λ1=450\lambda_1 = 450 nm and at λ2=650\lambda_2 = 650 nm, and the angular spread between them. ((b)) Find the group index and group velocity at λ0=589\lambda_0 = 589 nm from the Cauchy fit, then estimate the group velocity again by the two-point method of Chapter 4 using the indices at 584584 nm and 594594 nm. Compare the two results.

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