Photo Sensors

Photo Sensors

A sensor is any device which can be used to measure a physical quantity and produces a signal for comprehension by the instrument or person who observes it. It finds a number of applications such as machines, robotics, cars, manufacturing and even medicine.

These devices can be effectively used in the manufacturing line to increase the productivity of factories. The sensitivity is measured based on the signals received and response provided to even minute deflections and variations. With the rise in technological innovations, different types of sensors are being introduced such as biometric sensors, photoelectric sensor, ultrasonic sensors, transducers etc.

Ultrasonic sensors are used to generate high frequency sound waves and the echo received back is evaluated. These types of transducers are also called transceivers. The working principle is also similar to sonar or radar. The electrical signals are transmitted by converting to sound signals and the echo is converted into electrical signals again by means of a transducer.

A photo sensor is an electronic device that can be used for detecting the presence of visible light, ultraviolet radiations and infrared radiations. The major component of such sensors is a semiconductor which possesses the property photo conductivity. These sensors are similar to bipolar junction transistor, diodes and field effect transistors. The only difference is the presence of transparent windows that allow the radiations to enter the semiconductor junction. This sensor is often referred to as photo electric sensor.

Photo sensors are classified into three types- opposed (through beam), retro reflective and proximity-sensing (diffused) type of photo electric sensors. In the opposed (through beam) type of photo electric sensors, the light beam is blocked from getting into the receiver from the transmitter and the objects are sensed.

The retro reflective sensor arrangement consists of the transmitter and receiver at the same side and the light from transmitter is bounced back onto the receiver. The sensing of objects takes place when the path of the light beam is obstructed. The proximity sensing photo sensor works on the principle of reflection of transmitted light off the object and reaches the receiver.

The operation of photo sensors is either light or dark. The light operation happens when the transmitter signal is received. The operation of dark operate photo eyes happen whenever the signal is not received by the receiver.

The operation of photo electric sensor requires only a power source. The concepts of optics and electronics are combined together in this device. It performs several operations such as amplification, demodulation, modulation etc.

The advantage of such sensors is the lesser space it consumes. The technological advances have led to the manufacture of more such smaller photo electric sensors.