Single Slit Diffraction Flashcards
Change in direction of propagation of light NOT due to reflection of refraction
Diffraction
The deviation from rectilinear propagation that occurs when light advances beyond an obstruction
Phenomenon of diffraction
Can we use snellls law to predict diffraction
No
Diffraction at the edge of an aperture does what to images
Blurs images of objects
What proved light is a wave?
Diffraction
What is Huygens principle
All points on a wavefront can be considered as point sources for the production of spherical secondary wavelets, and at any later time the new wavefront position in the envelope (or surface of tangency) to these secondary wavefronts
What is fresenels expansion on Huygens principle
For light in the same bundle (waves from the same point source) the secondary wavelets undergo mutual interference. Interfere constructively and destructively
What is the ripple effect in the diffraction pattern due to?
The constructive and destructive interference of the secondary wavelets
When a single slit is vertical, the waves are diffracted _______
Horizontally
When a single slit is horizontal, the waves are diffracted ______
Vertically
When a vertical slit is placed against a horizontal slit of the same width, the combo forms ________
A square aperture
When a circular aperture is illuminated by a monochromatic plane wave, the waves are diffracted_________
Equally in all directions
Wavelength of spruce equal to or larger than width of the slit (lambda > a), forms _________
Diffraction pattern
For diffraction to occur, what is the relationship of d and a?
D should be larger than a
Path difference in single slit diffraction
asin(theta)=m(lambda)
What are the two types of diffraction?
- fresnel (near field) diffraction
- Fraunhofer (far-field) diffraction
Fresnel (near field) diffraction
The source of light and the screen are at finite distance from the diffraction aperture
Can be converging or diverging, but not collimated
Fraunhofer (far field) diffraction
The source of light and the screen are at an infinite distance from the diffraction aperture
Can be collimated
Which type of diffraction is easy to observe and calculate the intensity distribution
Fraunhofer (far field) diffraction
Bright in the center of a shadow, ex. Floaters in the eye
Poisson spot
Near field diffraction
Fresnel diffraction
Far field diffraction
Fraunhofer diffraction
Finite distance from slit to screen
Fresnel diffraction
Infinite distance from slit to screen
Fraunhofer diffraction
Converging or diverging wave
Fresnel difffraction
Plane waves
Fraunhofer diffraction
Difficult to observe and calculate
Fresnel diffraction
Easy to observe and calculate
Fraunhofer diffraction
Diffraction patterns vary with distance (slit to screen)
Fresnel diffraction
Insensitive to distance changes (maintains same angular relationship)
Fraunhofer diffraction
Which type of diffraction yields a poisson spot?
Fresnel diffraction
Combined effect of 2 slits and single slit interference
With 2 slits, not only will you see diffraction patterns due to individual single slits, but also interference patterns due to the waves coming from different slits
The diffraction pattern acts as ________–, that _____________
- Envelope
- that controls the intensity of the regularly spaced interference maxima
