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.