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Ultrasonic vs Infrared-Difference between Ultrasonic and Infrared

This page compares Ultrasonic vs Infrared and mentions difference between Ultrasonic and Infrared frequencies and sensors. Ultrasound is synonym term for ultrasonic.

Both of these frequencies fall within electromagnetic (EM) spectrum. Ultrasonic frequencies use spectrum above 20 KHz. Infrared frequencies range from 430 THz down to 300 GHz (not shown). They are used for various applications.

Ultrasound or ultrasonic frequency range Electromagnetic spectrum showing infrared range

The figure-1 and 2 depicts ultrasonic and infrared frequencies.

Ultrasonic or Ultrasound sensors or devices

Ultrasonic Sensor

• As mentioned ultrasonic frequencies fall above 20KHz in EM spectrum. The device which uses ultasonic frequencies is known as ultrasonic sensor.
• Ultrasonic sensors are used for various applications viz. distance measurement, automatic car parking system, humanoid robot design, sonography (i.e. medical imaging), ultrasonic flaw detector etc.
• There are two parts in ultrasonic sensor viz. transmitter and receiver. Transmitter converts electrical energy into sound waves and transmits it into the air (usually 40 kHz) . The receiver receives echo of reflected sound waves from the object and converts the same into electrical energy back. Based on this it does various calculations as per applications of use.
• Refer advantages and disadvantages of Ultrasonic sensor >>.

Infrared sensors or devices

Infrared sensor

• As mentioned infrared frequencies fall between 430 THz to 300 GHz in EM spectrum. It uses wavelengths from 700 nm to 1 mm.
• The device which uses infrared frequencies is known as infrared sensor.
• There are two parts in infrared sensor viz. transmitter and receiver. Whenever voltage is applied to IR LED of transmitter it generates infrared waves. The infrared transmitter transmits infrared waves to a few distance. The receiver detects reflected infrared waves and produces voltage accordingly. If there is no object in the vicinity of infrared sensors then there will not be any reflected infrared waves and hence there is no voltage output of infrared receiver. If object presents, it receives reflected wave and produces voltages accordingly. This voltage levels are compared using comparators or microcontrollers for further processing. This is the way Infrared sensor works.
• Refer advantages and disadvantages of Infrared Sensor >> .

Following table-1 mentions difference between ultrasonic and infrared sensors. SHARP part no. GP2Y0A21YKOF is taken as infrared sensor and Multicomp HC SR-04 is taken as ultrasinic sensor for comparison.

difference between ultrasonic and infrared sensors

Following table-2 compares ultrasonic vs infrared devices and mentions generic difference between ultrasonic sensor and infrared sensor devices.

Features Ultrasonic sensor Infrared sensor
Detection range • Suitable to detect objects which are more than 1 meter away.
• capable to place objects within 5 mm more accurately.
• Some ultrasonic sensors detect objects with max. range of 20 meters.
• The object detection depends on shape, size and orientation.
• More appropriate for targets which are closer than 10 mm
Ability to measure distance to soft objects • Not easily detected • Easily detected
Interference from light sources (e.g. sunlight, fluorescent tubes etc.) • Unaffected • affected
Frequency range • Ultrasonic/ultrasound devices operate from 20 kHz upto several GHz. • 430 THz down to 300 GHz
Wavelength range • ultrasonic waves use wavelengths of about 1.9 cm or less. • 700 nm to 1 mm

Ultrasonic sensor and Infrared sensor related links

•  Infrared sensor basics and working operation
•  Advantages and disadvantages of Infrared Sensor
•  Ultrasonic sensor basics and working operation
•  Advantages and disadvantages of Ultrasonic sensor

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