Electro-Optical Sensors
Electro-optical sensors
are
electronics devices
that act in response to either light or any
electromagnetic wave in X-ray, Ultraviolet and infrared
bands to visible light band. Light is a form of
electromagnetic radiation and is similar to radio waves,
infrared waves, X rays and Ultraviolet Rays.
Wavelength=Velocity
of light/Frequency in hertz
Energy level
of each photon is expressed by
E=c*h/wavelength
where
h=Planck's
constant=6.62*10 to power-34
J-s
Photo emissive Sensors
These are type of a
Vacuum tubes that gives current as an output. The
photoelectric effect
was discovered in early to mid 19th century by
Albert Einstein.
Various Scientific experiments on primitive batteries
found that its working was more better when exposed to
light.
Energy expression for
photoelectric effect is:
1/2mV*V=HV-Ew
m-mass of electron
V-Velocity of fastest
emitted electrons
h is Planck's
constant(6.63*10 to power-27 erg-second)
v is frequency of
incident light
Ew-Energy in ergs
required to permit an electron to escape from photo
emissive surface.
Photovoltaic Cells
A Photovoltaic Cell is a
device in which an electrical
potential difference is
generated and then current is made to flow in a circuit
by giviing light onto its surface.
E.g "SOLAR CELL"
Photoconductive Cells
A photoconductive cell or
photo resistor is a device that changes electrical ohmic
resistance when light is given to it.
|
