Page 8 - Spec Tech Vol 1 Issue 03
P. 8
SPACE SENSORS
INFRARED SENSOR
An infrared sensor is a radiation-sensitive LED, and the receiver is an Infrared
opto-electronic component with a Photodiode. The infrared photodiode is
spectral sensitivity in the infrared wavelength activated by the infrared light produced by
780nm-50µm. IR sensors are now widely used an Infrared LED. The Photodiode’s
in building services to switch on lamps ir in resistance and the change in output voltage
alarm systems to detect unwelcome guests. In are proportional to the amount of infrared
a defined angle range, the sensor elements light obtained. This is the IR sensor’s
detect the heat radiation (IR radiation) that fundamental working Principle. There are
changes over time and space due to the wide range of applications which uses IR
movement if people. IR sensors are used in sensors. Some are Proximity sensor, Item
gas warning devices, gas analysers, medical counter, Burglar alarm, Radiation
gas measurement technology, flame detectors Thermometers, human body detection and
and in contactless precision Gas Analyzers.
temperature measurement of IR radiation in
defined spectral ranges.
FUN FACTS
The working of infrared sensor is based on the
Planck’s radiation law, Wein’s displacement Þ A CCD (charge-coupled
law and Stephen Boltzmann law. IR LED is device) has a grid of sensors
one kind of transmitter that emits infrared that react to light.
radiation. This LED has the appearance of a Þ Thermistor Is a temperature
standard LED, and the radiation by sensitive resistor that changes
infrared receivers. These infrared receivers its physical resistance with the
are available in photodiode form. IR change in temperature.
photodiodes are different from regular
photodiodes in that they only detect IR Þ Turbidity sensors measure
radiation. suspended solids in water,
typically it is used in river and
When used as an IR transmitter and receiver, stream gaging, wastewater and
the wavelength of the receiver must match that effluent measurement.
of the transmitter. The transmitter is an infrared
Space Explorer 2022 8
