Chapter 38 Diffraction patterns and polarization

What is a Faunhofer diffraction pattern?

(The diffraction pattern seen when the screen is placed FAR from the slit) (pg. 1161)

Malus's Law

(pg. 1177)

What are four ways to produce polarized light from unpolarized light?

1) Selective absorption 2) Reflection 3) Double refraction 4) Scattering (pg. 1176-81)

What is a second arc?

1/60th of 1 minute arc. That is, 1/3600th of one degree.

What is a diffraction pattern?

A series of light and dark bands resulting from light passing past the edge of an opaque body. It consists of a central maximum and secondary maxima/minima (pg. 1161)

What is a linearly polarized wave?

A wave whose electric field vibrates in the same direction at all times (pg. 1176) aka plane polarized light

What is meant by the direction of polarization of a light wave?

An indiviual light wave has an electrical component and a magnetic component. The direction of polarization is defined to be the direction in which the electric field is vibrating (pg. 1175)

Give the limiting angle of resolution for a circular aperature

D is the diameter of the aperature. The book doesn't show where this comes from.

Diffraction vs. Diffraction pattern

Diffraction refers to the general behavior of waves spreading out as they pass through a slit. We used diffraction in explaining the existence of an interference pattern in Chapter 37. A diffraction pattern is actually a misnomer, but is deeply entrenched in the language of physics. The diffraction pattern seen on a screen when a single slit is illuminated is actually another interference pattern. The interference is between parts of the incident light illuminating different regions of the slit (pitfall prevention 38.1 pg. 1162)

What is diffraction grating?

In optics, a diffraction grating is an optical component with a periodic structure, which splits and diffracts light into several beams travelling in different directions. A diffraction grating consists of a large number of equally spaced parallel slits (pg. 1169)

What is a minute arc?

It's a unit of angle measurement equal to 1/60th of 1 degree (pg. 1168)

What is unpolarized light?

Light that has waves that are polarized in many different directions (pg. 1175-6)

What is the polarizing angle? AKA Brewster's Angle (pg. 1178)

The angle at which an unpolarized light beam, upon reflecting off a surface, becomes polarized (pg. 1177-8)

Intensity of a single-slit Fraunhofer diffraction pattern

The book just gives this to us (pg. 1164)

Bragg's Law

The path length difference is 2dsinθ. When this is equal to an integer multiple of the wavelength, we get constructive interference. Thus we get constructive interference when 2dsinθ=mλ for m= 1,2,3,... (pg. 1175)

What is diffraction?

The process by which a beam of light or other system of waves is SPREAD OUT as a result of passing through a narrow aperture or across an edge, typically accompanied by interference between the wave forms produced (pg. 1160)

How do we get polarized light from absorption?

There exist materials that absorb light polarized in specific directions. So when unpolarized light passes through these materials all but light polarized parallel to the transmission axis is absorbed, producing polarized light. (pg. 1176)

Brewster's Law

This is obtained from Snell's law and figure 38.28 on pg. 1178

What is Rayleigh's Criterion?

When the central maximum of one image falls on the first minimum of another image, the images are said to be JUST RESOLVED. This is the limiting condition of resolution (pg. 1166)

Condition for interference maxima for a grating

dsinθbright = mλ for m=0, ±1, ±2, ±3, ±4. Where d is the distance between adjacent slits. Once again, dsinθ represents the path difference between different rays of light (pg. 1169). Notice this is the same equation for the two slit setup.

Condition for DESTRUCTIVE interference for a SINGLE SLIT

sinθdark = mλ/a for m=±1, ±2, ±3, ... This can be derived from figure 38.5 pg. 1163