The lab was designed by and uses equipment provided by Professor Eric Szarmes.
We will learn techniques of modern optics and measure polarization phenomena including the Brewster angle, extinction ratio for polarized light (Malus’s Law) and birefringence.
1. Observation of polarization phenomena:
- polarization of reflected light from dielectric surfaces.
- polarization of scattered light from the blue sky (understand why the light is polarized).
- reflection of light at the Brewster angle (determine refractive index n)
- (*** Report: Measure theta_B and the observed polarization. Compare theta_B to the expected value for BK7.)
2. Polarizing components and systems
- transmission through crossed polarizers (Malus’ Law)
- (*** Report: Plot your data and verify Malus’ Law. Use Malus’ Law to check for photodiode saturation. Also report your measured extinction ratio.)
3. Production and measurement of various states of polarization
- relative phase shift of linearly polarized light upon external reflection from dielectric surfaces.
- relative phase shift of linearly polarized light upon reflection from metal mirrors
- (*** Report: Include these measurements and a brief explanation)
4. Birefringence of sapphire
- observation of birefringence in sapphire
- measurement of the orientation of the crystal c-axis in a sapphire plate
- (*** Report: Plot your data and explain the features we discussed. Determine the angle of the crystal c-axis.) Hint: Find the minimum angle in I_min versus theta curve. Use Snell’s Law to find the angle phi and then use phi to determine alpha.
Self-study questions
1. Why is the sky blue ? Why are sunsets red ? Why is scattered sunlight polarized ?
2. What is Malus’ Law ? How can you determine whether a helium-neon laser is polarized ?
3. Suppose two linear polarizers are oriented with their polarization axes perpindicular, how much light is transmitted ? Suppose a third polarizer is inserted with its polarization axis at 45^0, now what happens ?
4. What are Jones matrices ? What are Jones vectors ? How can they be used to predict intensity ratios ?
5. What is the Brewster angle ? Why is reflected light polarized at the Brewster angle ?
6. What is the phase shift on reflection from a dielectric ? What is the phase shift from a metal surface ?
7. What is total internal reflection ? What is the phase shift of reflected light in total internal reflection ?
8. What is birefringence ? What is the ordinary ray and extraordinary ray ?
9. What are Fresnel coefficients ? What are the values of the Fresnel coefficients at the Brewster angle ?
Last updated: November, 2016
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