L11 Flashcards
Helmholtz Equation
add actual equation?
Helmholtz equation describes the propagation of waves under certain conditions.
Paraxial Approximation
Approximation where spherical wave is approximated by a paraboloidal wave.
This describes the Fresnel approximation. The paraxial approximation sai
Fresnel Principle
- Each point on a wavefront generates spherical waves;
- envelope constitutes new wavefront.
Fourier Transform in Far Field
Fourier component separation occurs naturally at sufficiently long distances.
Fraunhofer Diffraction
- Interference pattern of light observed in the far field
- Many wavelengths away from object.
Dynamic Light Scattering (DLS)
Light scattering used as a tool for nanoparticle sizing.
Huygens-Fresnel Principle
Every solution of the paraxial wave equation can be written as a Fresnel diffraction integral.
Sounds wrong
Airy Disk
Pattern produced by single aperture diffraction; central bright spot surrounded by rings.
Speckle Pattern
Random interference pattern from dynamic light scattering.
Fresnel Lens
Lens with reduced material; divided into concentric annular sections.
Diffraction Grating
Separates light into various wavelengths by diffraction.
ABCD Law
add context or delete
Describes ray transfer matrices in Gaussian beam optics.
Stokes-Einstein Relation
Relates diffusion coefficient (D) with temperature and viscosity to find particle radius.
Fraunhofer Approximation
Used when distance from aperture to observation point is very large (far-field).
Constructive Interference
Occurs when waves combine to form a wave with larger amplitude.
