Help needed with Polarisation (Rotated Waveplates)

  • Thread starter Thread starter catedral3000
  • Start date Start date
catedral3000
Messages
2
Reaction score
0
Homework Statement
a) Plot, as a function of time, the horizontal and vertical components of
E(0,t) for 0 ≤ ωt ≤ 2π. Plot the trajectory of the point (Ex,Ey) for a constant z as a function of time.
A_H = 1, A_V = 1, ϕ_H = 0, ϕ_V = π/4
b) How would you convert the polarization pattern in part (a) to horizontal using
one half-and one quarter-wave plates? What should be the angles of both plates?
Relevant Equations
n/a
(a) The polarisation pattern is elliptical with maximum (1,1) and minimum (-1,-1), and anticlockwise in direction.

(b) I know the solution is a quarter-wave plate oriented π/4, and half-wave plate at π/16, but don't understand how to reach there. I've obtained the polarisation vector (cos π/8, isin π/8) so far.

I can't find much online guidance or textbook material working through this topic, so I'd appreciate any help I can get. Also, if anyone could let me know where I can get more practice on these kinds of problems that'd be great!
 
Physics news on Phys.org
Can you plot the trajectory of point (Ex,Ey) as suggested in part (a)? What shape do you get?
If so, can you do the same for for part (b)? What shape do you get in this case?

Also, please provide the statement of the problem as was given to you. What comes before parts (a) and (b)?
 
kuruman said:
Can you plot the trajectory of point (Ex,Ey) as suggested in part (a)? What shape do you get?
If so, can you do the same for for part (b)? What shape do you get in this case?

Also, please provide the statement of the problem as was given to you. What comes before parts (a) and (b)?
I've now edited the original problem so it is complete - that all the information given though!

For part (a) I get an elliptical shape with maximum (1,1) and minimum (-1,-1), and anticlockwise in direction.
1764600804923.webp


Part (b) is asking to convert this to horizontal polarisation using 1/2 and 1/4 wave plates.
 
Last edited:
You know that the phase difference between the two components is ##\frac{\pi}{4}.##
  1. What phase difference do you need in order to get linear polarization?
  2. What does a half-wave plate do to the phase difference? How would it change the trajectory?
  3. What does a quarter-wave plate do to the phase difference? How would it change the trajectory?
  4. What does combining the two plates do to the phase difference?
 
I want to find the solution to the integral ##\theta = \int_0^{\theta}\frac{du}{\sqrt{(c-u^2 +2u^3)}}## I can see that ##\frac{d^2u}{d\theta^2} = A +Bu+Cu^2## is a Weierstrass elliptic function, which can be generated from ##\Large(\normalsize\frac{du}{d\theta}\Large)\normalsize^2 = c-u^2 +2u^3## (A = 0, B=-1, C=3) So does this make my integral an elliptic integral? I haven't been able to find a table of integrals anywhere which contains an integral of this form so I'm a bit stuck. TerryW

Similar threads

  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 8 ·
Replies
8
Views
3K
  • · Replies 1 ·
Replies
1
Views
2K
Replies
80
Views
7K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 5 ·
Replies
5
Views
4K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 12 ·
Replies
12
Views
9K
  • · Replies 10 ·
Replies
10
Views
2K