Interference & Diffraction

1. Thin Film Interference

2. Double Slit Experiment

3. Single Slit Diffraction

4. Resolution

a. Of microscope

b. Of human eye

5. Contrast

Group Problem

1. Light of 500 nm falls on two parallel slits, each of 0.005 mm width, that are separated by 0.1 mm.a) If the screen is 10m away from the slits, find the distance to the first diffraction minimum from the center of the diffraction pattern (optic axis).b) Find the distance from the optic axis to the first minimum in the interference pattern.c) How many bright fringes are there in the central maximum?

Group Problem

• Using the wavelength of maximum sensitivity of the eye (550 nm) and a pupil size of 2 mm, find the minimum angular separation the eye can resolve according to the Rayleigh criterion.

• To what minimum separation distance does this correspond for two “point sources” of light 20 m away?

• Using a near point of 25 cm, what is the resolving power of the eye?

• To what separation on the retina does this correspond? Use a focal length of 2 cm for the eye.