Question

Two parallel plane-polarized beams of light of equal intensity whose oscillation planes N1 and N2 form a small angle φ between them (Fig. 5.30) fall on a Nicol prism. To equalize the intensities of the beams emerging behind the prism, its principal direction N must be aligned along the bisecting line A or B. Find the value of the angle φ at which the rotation of the Nicol prism through a small angle δφ << φ from the position A results in the fractional change of intensities of the beams ΔI/I by the value η = 100 times exceeding that resulting due to rotation through the same angle from the position B.

Answer 1

If the principal direction N o f the Nicol is along A or B , the intensity of light transmitted is the same whether the light incident is one with oscillation plane N1 or one with N2 . If N makes an angle δφ with A as shown then the fractional difference in intensity transmitted (when the light incident is N or N ) is