Diffraciton Grating Flashcards
When the central maxima of one image falls on the first minimum of another image, the images are said to be just resolved. This limiting condition of resolution is known as
Rayleigh’s Criterion
Rayleigh’s criterion equation?
Theta=1.22 lambda/d
Smallest resolvable angle
Limiting angle of resolution
Snellen acuity is equal to the what?
Reciprocal of the minimum resolvable angular detail, expressed in minutes
How do you convert angles to minutes
X 180, divide by pi
According to ISO standard, R. E. > ________ is an acceptable image quality standard for industry product release
60%
To remove the rings around the central maxima and concentrate energy in the central maxima is called __________
Apodization
At the center of the anodized circular pupil, the intensity transmission is ______
100%
Diffraction pattern and apodization
For a clear circular pattern, airy’s disk contains 84% of the intensity in the diffraction pattern
Gaussian filter
86% of the intensity is inside the circle
-there are no rings, only smooth illumination fall off
What kind of filters do pupils act like?
Gaussian filters (apodized)
What is the stile crawford effect?
The luminous efficiency of rays entering at the center of the eye pupil is greater than the luminous efficiency of the rays entering through the edge of the pupil
Despite its retinal origins, the stiles crawford effect is sometimes modeled optically as a filter placed in front of the eye, in which the density of the filter increases from the center toward the edge of the filter, this is known as _________
Apodization
What influences the VA and visual performance of the human eye?
Stiles crawford apodization
Distance between maxima and 1st order minima is ________. This number also tells us how many maxima there are as well
D-2
A _____________ consists of many slits with a very small slit separation
Diffraction grating
Efficiency drops with ___________ number of slits
Higher
Transmission grating
- acts a laser beam splitter
- less sensitive to polarization
- less sensitive to alignment
- efficiency reduces with higher wavelength
CDs are an example of what?
Reflection diffraction grating
A diffraction grating that is designed to channel light away from the central maximum (oth order) into 1st or 2nd order maximums
Blazed grating
Angle at which the efficiency is maximum
Blazing angle
Optical device that blocks alternate zones
Zone plate
Diffraction image grating creates inwardly bending spherical diffracted wave
Point image
Central order (0th) goes though
Straight
1st order posting image is at
F2
2nd order point image is at
F2/2
3rd order point image is at
F2/3
Fresnel zone plate blocks wave that contribute to destructive interference at the diffraction max, making the image formation much _______
Dimmer
