Diffractive Optics And Iridescence Flashcards
An optical device that blocks alternate zones is called a ___________
Zone plate
A diffraction grating that creates inwardly bending spherical diffracted wave forms a _________
Point image
The focal length of the plate is give by…
F2=r^2/mlambda
Fresnel zone plate blocks wave that contribute to destructive interference at the diffraction maximum, making the image formation much ________
Dimmer
Instead of blocking these waves, they are ________________.
Phase shifted by 180
After phase shift of 180, the phase shifted waves would be ___________ with the axial wave, and would contribute to the constructive interference at the diffraction maximum, making the image much _________.
What is this called?
- in phase
- brighter
Phase plate or phase reversal zone plate
A zone plate with kinoform shaped grooves is referred to as a ______________
Diffractive lens
What is the benefit of the kenoform shaped grooves on an ophthalmic diffractive lens?
It makes it much thinner
A single refractive lens with a phase plate embedded on one side of its surfaces
Hybrid lens
Multifocal
The original bulk of the dashed lens is reduced, leaving a thin lens whose surface slopes match the original lens. This example has __________
Equal step heights
A Fresnel lens with ______________. A fresnel lens is always a mono-focal lens.
Equal zone widths
What does the power in the M=0 come from?
The base curve power
1st order in contact lens
Near vision
0th order in contact lens
Distance vision
Local grating _________ determines ray direction (add power). Spacing gets progressively smaller from center to its edge
Spacing
