Linearly polarised light through half and quarter wave plate

Your name] In summary, the half wave plate and quarter wave plate, placed between a polariser and an analyser, will result in the light becoming elliptically polarised after passing through both plates. The orientation of the second polariser's pass axis should be at an angle of 450 with respect to the first polariser's pass axis in order to achieve maximum intensity of light passing through it.
  • #1
chatterjee
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Homework Statement



A half wave plate and a quarter wave plate are placed between a Polariser and an analyser .All of these are parallel to each other and perpendicular to the direction of propagation of unpolarised incident light.The optic-axis of the half-wave plate makes an angle 300 with respect to the pass-axis of polariser 1 and that of the quarter wave plate is parallel to the pass axis of polariser 1.

Q1.Determine the state of polarisation of light after passing through I)the half wave plate II)the quarter wave plate.

Q2. What should be the orientation of the pass axis of the polariser 2 wrt to that of polariser 1 such that the intensity of the light emerging from polariser 2 is maximum?

Homework Equations



N/A

The Attempt at a Solution



Q1. As the optic-axis of the half-wave plate makes an angle 300 with respect to the pass-axis of polariser 1,after passing through the half wave plate the linearly polarised light wight will be 2 x 300 = 600 phase-shifted.
This linearly polarised light is incident on the quarter wave plate and gives an elliptically polarised light.

Is this answer correct?

Q2.Still haven't found any answer.
 
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  • #2


Thank you for your post. Your answer for Q1 is correct. After passing through the half wave plate, the light will be 600 phase-shifted and will become elliptically polarised after passing through the quarter wave plate.

For Q2, the orientation of the pass axis of polariser 2 should be at an angle of 450 with respect to the pass-axis of polariser 1. This will result in the maximum intensity of light emerging from polariser 2. This is because the quarter wave plate will convert the elliptically polarised light into circularly polarised light, which can pass through the second polariser with maximum intensity when its pass axis is perpendicular to the direction of circular polarisation.

I hope this helps. Let me know if you have any further questions. Keep up the good work in your studies!
 

1. What is linearly polarised light?

Linearly polarised light refers to light in which the electric field oscillates in a single plane. This means that the waves are all aligned in the same direction, giving the light a specific polarization direction.

2. How does a half wave plate work?

A half wave plate is an optical device that changes the polarization direction of linearly polarised light. It does this by introducing a phase difference of 180 degrees between the two orthogonal components of the light, effectively rotating the polarization direction.

3. What is the purpose of using a quarter wave plate?

A quarter wave plate is used to convert linearly polarised light into circularly polarised light. It does this by introducing a phase difference of 90 degrees between the two orthogonal components of the light, resulting in a rotating electric field vector.

4. Why are half and quarter wave plates often used together?

When half and quarter wave plates are used together, they can perform a variety of functions such as changing the polarization direction, converting linearly polarised light into circularly polarised light, and controlling the intensity of the light. They are commonly used in optical devices such as polarizers, waveplates, and optical isolators.

5. Can linearly polarised light be converted back into unpolarised light?

No, once light is polarised it cannot be converted back into unpolarised light. However, a polarizer can be used to block or filter out polarised light, effectively creating unpolarised light. This is often used in sunglasses or polarizing filters for photography.

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