Infrared Light Infrared Light Electromagnetic waves whose frequency range is above that of microwaves, but below that of the visible spectrum. Electromagnetic waves whose frequency range is above that of microwaves, but below that of the visible spectrum. region of the electromagnetic spectrum that includes wavelengths from 0.7 to 1000 microns. region of the electromagnetic spectrum that includes wavelengths from 0.7 to 1000 microns. Infrared are invisible radiation, sensed as heat. Infrared are invisible radiation, sensed as heat.

Regions in the infra-red : Regions in the infra-red : 1. Near infra-red NIR ( 0.7 – 1.4 µm in wavelength) 2. Short wavelength IR SWIR ( 1.4 – 3 µm in wavelength) 3. Mid wavelength IR MWIR (3 – 8 µm in wavelength) 4. Long wavelength IR LWIR (8 – 15 µm in wavelength) 5. Far infrared FIR ( µm in wavelength)

IR vs RF  The frequency of radio waves is from 3 kHz to about 300,000 Mhz while IR has wavelength longer than visible light but shorter than RF.  For long distance communication RF is the best choice while IR is a good choice for movie theaters, court rooms etc.  RF transmission requires more electrical power than the infrared type.  IR systems are also immune to radio inter-ference so receiver management is easier than that in RF.

Infra-red Modulation:

Infra-red transmitter Two diodes are used at the base of transistor in fig.2 to avoid the disadvantage of reduced control distance due to the variation in battery voltage

IRCDM - Infrared Remote Control Development Module IRCDM - Infrared Remote Control Development Module

Construction of bi-phase coding: Transformation of NRZ into bi-phase is done by combining the signal with clock in an EX-OR gate

Applications : Control motors using infrared remote control Control motors using infrared remote control Control non-infrared computer systems (serial, RS-232) with a handheld remote control Control non-infrared computer systems (serial, RS-232) with a handheld remote control Increase the distance of operation and flexibility of computerized systems Increase the distance of operation and flexibility of computerized systems

 In blood flow vascular scan & cancer research A Thermal Image of the Human Hand using IR Scanning

 In the detection of concealed weapons.  In night vision systems to see an object when there is insufficient visible light. Privacy is more in IR wireless than in RF wireless Privacy is more in IR wireless than in RF wireless Final Slide

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