Transcript Resolution

Resolution
Resolution:
Refers to the sharpness and
clarity of an image. The term is
most often used to describe
monitors, printers, and bitmapped graphic images. In the
case of dot-matrix and laser
printers, the resolution
indicates the number of dots
per inch.
The display resolution of a digital television or computer display
typically refers to the number of distinct pixels in each dimension
that can be displayed. It can be an ambiguous term especially as
the displayed resolution is controlled by all different factors in
cathode ray tube (CRT) and flat panel or projection displays using
fixed picture-element (pixel) arrays.
Two red stars
Just resolved
Not resolved
The Rayleigh Criterion
The Rayleigh criterion is the generally accepted criterion for
the minimum resolvable detail - the imaging process is said to
be diffraction-limited when the first diffraction minimum of
the image of one source point coincides with the maximum of
another.
A simple practical test is called Rayleigh’s criterion
Sine of the angular separation of two sources
OR
Sine
b
Wavelength of the wave,
Width of the gap,b
A car’s headlights are 1.5m apart, and give out light of average wavelength 500
nm . You are 5.0 km away and the diameter of the pupil of your eye is 3.0 mm.
would you see two separate headlights or just a patch of light?
This small angle approximation:
sin
=
= 1.5
5.0
Also,
=
b
500
3.0
= 1.5
= 0.00030 Radians
5000
= 500x10^-9 = 0.00017
3.0x10^-3
two source interference
Two sources a distance d apart are sending out
identical waves in phase. We observe an
interference pattern with lines of constructive
interference at particular angles and lines of
destructive interference at other angles.
young's equation :
In 1801, this experiment was performed for the first time by
Thomas Young. Young expanded the mathematical model presented
above by relating the wavelength of light to observable and
measurable distances. Today, an experimental setup similar to that
of Thomas Young's is commonly used in a Physics classroom to
repeat the experiment and to measure the wavelength of light. In
the experiment as it is commonly performed today, light from a
laser beam is passed through two narrowly-spaced slits in a slide or
sheet of paper. The light diffracts through the slits and interfere
in the space beyond the slits. Thus, the slits serve as the two
sources. The interference pattern is then projected onto a screen,
paper or a whiteboard located several meters away. The spatial
separation of nodes and antinodes on the screen is clearly seen.
Here is a Java applet which can be used as an aid to
understanding the patterns which are produced when two
circular periodic waves interfere. This is often termed a two
source interference pattern.
Basic operation:
The 'Small', 'Medium', and 'Large' radio buttons control the
size of the waves.
young's equation
Diffraction grating
In optics, a diffraction grating is an optical component with
a regular pattern, which splits (diffracts) light into several
beams travelling in different directions. The directions of
these beams depend on the spacing of the grating and the
wavelength of the light so that the grating acts as a
dispersive element. Because of this, gratings are commonly
used in monochromators and spectrometers.
Diffraction grating
http://www.youtube.com/watch?v=gxgfthefKbg
Hessa Abdullah
Ghayda Al-khater
11A
Al-wakra independent secondary School for Girls