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2 D 10683

Determine the separation between the coherent sources formed by a biprism whose inclined faces
make angles of 2° with its base and the slit is 0.1 m away from the biprism. Given, the refractive
index of the material of the prism is 1.5.

Calculate the radius of the first dark ring of the Fraunhofer diffraction pattern produced by a
circular aperture of radius 0.02 cm at the focal plane of a convex lens of focal length 20 cm. Assume
that the wavelength of light used is 600 nm.

Consider a Fresnel zone plate with radii r, = 0.1 Vn cm. For 2 = 5 x 10> cm, calculate the
positions of the foci.

Determine the thickness of a half-wave plate of quartz for a wavelength 500 nm. Given, the
refractive indices of the extra-ordinary and ordinary rays are yp, = 1.553 and யூ = 1.544,
respectively.

Discuss the applications of holography.

Calculate the numerical aperture and hence the acceptance angle of an optical fiber having core
and cladding refractive indices 1.45 and 1.40 respectively.

(5 x 5 = 25 marks)
Section C (Essay Type)

Answer any one question.
The question carries 11 marks.

Discuss the interference by a plane parallel film when illuminated by a plane wave and obtain the
conditions for maxima and minima.

Obtain an expression for the intensity distribution for the Fraunhofer diffraction due to a single
slit.

(1 x 11 = 11 marks)

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