2. IR Sensor
This device emits and/or detects infrared radiation to sense a particular phase in the environment. Generally, thermal radiation is emitted by all the objects in the infrared spectrum. The infrared sensor detects this type of radiation which is not visible to human eye.
· Easy for interfacing
· Readily available in market
· Disturbed by noises in the surrounding such as radiations, ambient light etc.
The basic idea is to make use of IR LEDs to send the infrared waves to the object. Another IR diode of the same type is to be used to detect the reflected wave from the object. The diagram is shown below.
When IR receiver is subjected to infrared light, a voltage difference is produced across the leads. Less voltage which is produced can be hardly detected and hence operational amplifiers (Op-amps) are used to detect the low voltages accurately.
Measuring the distance of the object from the receiver sensor: The electrical property of IR sensor components can be used to measure the distance of an object. The fact when IR receiver is subjected to light, a potential difference is produced across the leads.
· Thermography – According to the black body radiation law, it is possible to view the environment with or without visible illumination using thermography
· Heating – Infrared can be used to cook and heat food items. They can take away ice from the wings of an aircraft. They are popular in industrial field such as, print dying, forming plastics, and plastic welding.
· Spectroscopy – This technique is used to identify the molecules by analysing the constituent bonds. This technique uses light radiation to study organic compounds.
· Meteorology – Cloud heights, calculate land and surface temperature is possible when weather satellites are equipped with scanning radiometers.
· Photobiomodulation – This is used for chemotherapy in cancer patients. This is used to treat anti herpes virus.
· Climatology – Monitoring the energy exchange between the atmosphere and earth.
· Communications – Infra red laser provide light for optical fibre communication. These radiations are also used for short range communications among mobiles and computer peripherals.