- 1 (40.16 KiB) Viewed 17 times
600 nm and optical power 1 mW, is incident on an instrument made
of: a linear polariser (P1) with its direction of transmission at
45 degrees with respect to the r-direction. a quarter-wave plate
(WP) of thickness L and a second linear polariser (P2) oriented in
the same way as P1. The Jones (2x2) matrix associated with the 2
polarisers is.
1/2 J_45= 1 1
1 1
WP is rotated in such a way that its eigenaxes are parallel to
the r and y-direction. The birefringent material used for WP has
refractive indices associated with its eigenaxes, 2.201 and 2.202.
The incident beam of light is linearly polarised at 60 degrees with
respect to the r-direction.
(a) Derive an expression for the Jones vector describing the
state of polarisation of the incident beam..
(b) After WP, light is circularly polarised. Use Jones calculus
to find out the thickness of WP.
(c) Determine the state of polarisation after each component.
Comment on how the optical power is changed by Pi, WP and P₂.
(d) P1 is replaced by a linear polariser with its transmission
along the r-direction whereas WP is replaced by an optically active
medium characterised by a Jones (2x2) matrix,
J_OA= cosp -sinp
sinp
cosp
The rotatory power p, is the angle by which the active medium
changes the polarisation direction of the incident, linearly
polarised beam of light. Use Jones calculus to find p for which
there is no light after P2.
(e) Demonstrate that any linearly polarised state can be
decomposed into a sum of right and left circularly polarised states
of equal amplitudes. Write the expressions of the Jones vectors for
the two circularly polarised states, in which a linearly polarised
state in the x-direction can be decomposed.
y 。 60° X H WP P. 1 P。 2 江