Photoelectric Sensors

Photoelectric sensors detect and measure physical objects or quantities by emitting a field or beam of electromagnetic radiation, an object is detected by measuring alterations in the return signal. There are 3 main types of photoelectric sensors which provide reliable detection, these are through-beam, retro-reflective and diffuse. The basic function of each is to detect the presence or absence of objects or measure the distance to the object.

Through-beam Sensors

Through-beam sensors (aka thru-beam) rely on two separate housings, one for the transmitter and one for the receiver, with the transmitter providing a continuous beam of light to the receiver. Each time an object passes through the beam this interrupts the signal between the transmitter and receiver, which in turn causes the receiver to send an electrical signal to the output. Through-beam sensors are suited to long-distance sensing and are capable of detecting almost any object, irrespective of colour or angular motion.

Retro-reflective Sensors

Retro-reflective photoelectric sensors (retroreflective) have both the transmitter and receiver contained within the same housing but require a reflector opposite to the sensor. The reflector bounces the light beam back to the transmitter until an object breaks the beam. Objects which are highly reflective such as aluminium require sensors with polarising filters. The filter allows the sensor to acknowledge that the reflected light from reflecting materials is different from the reflector.

Diffuse Sensors

Diffuse sensors (proximity sensor) are easier to install as only one device has to be mounted. This is because the transmitter and receiver are contained within one housing. Diffuse sensors use the reflection from the target object within a predetermined sensing range. The transmitter sends out a continuous beam of light, once this hits the target it is diffused in all directions, a part of this light is reflected back and recognised by the receiver, the receiver then sends an electrical signal to the output.

A special type of diffused mode is background suppression which enables the user to precisely control the sensing range. A diffuse mode sensor with background suppression is less sensitive to the target colour. They can also use a visible red light or infrared light sources.


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Description Price Sensor Style Detection Type Detection Range Output Type Electrical Connection Maximum AC Voltage Communication Protocol Maximum DC Voltage Terminal Type Light Source IP Rating Maximum Current Interface Response Time
RS Stock No. 729-5101
BrandRS PRO
PHP5,121.40
Each
units
Barrel Retro-Reflective 0.05 → 7 m NPN 4-Pin M12 Connector - - 30V - LED IP67 100 mA - <=0.5 ms
RS Stock No. 729-5117
BrandRS PRO
PHP4,444.96
Each
units
Barrel Retro-Reflective 0.05 → 7 m PNP Cable - - 30V - LED IP67 100 mA - <=0.5 ms
RS Stock No. 903-3927
BrandRS PRO
PHP4,214.98
Each
units
Fork Through Beam (Fork) 30 mm NPN/PNP 4-Wire Cable 2m - - 30V Pre-Wired Infrared IP67 15 mA - <1 ms
RS Stock No. 903-3939
BrandRS PRO
PHP4,214.98
Each
units
Fork Through Beam (Fork) 30 mm NPN/PNP 4-Wire Cable 2m - - 30V Pre-Wired Infrared IP67 15 mA - <1 ms
RS Stock No. 729-5157
BrandRS PRO
PHP5,834.25
Each
units
Block Retroreflective 0.15 → 10 m PNP 4-Pin M12 Connector - - 30V - LED IP67 100 mA - 2.5 ms
RS Stock No. 729-5182
BrandRS PRO
PHP7,344.59
Each
units
Block Background Suppression 10 → 140 mm NPN 2-Wire Cable 2m - - 24V - LED IP67 100 mA - <625 μs
RS Stock No. 729-5145
BrandRS PRO
PHP7,140.52
Each
units
Block Retroreflective 0.15 → 10 m NPN 4-Pin M12 Connector - - 30V - LED IP67 100 mA - 2.5 ms
RS Stock No. 903-3936
BrandRS PRO
PHP4,379.58
Each
units
Fork Through Beam (Fork) 30 mm PNP 4-Wire Cable 2m - - 30V Pre-Wired Infrared IP67 15 mA - <1 ms
RS Stock No. 729-5185
BrandRS PRO
PHP6,828.84
Each
units
Block Background Suppression 5 → 250 mm PNP 4-Pin M8 Connector - - 24V - LED IP67 100 mA - <625 μs
RS Stock No. 903-3942
BrandRS PRO
PHP2,267.04
Each
units
Fork Through Beam (Fork) 7 mm PNP Cable - - 30V Pre-Wired Infrared IP64 15 mA - <1 ms
RS Stock No. 440-5639
BrandRS PRO
PHP5,533.79
Each
units
Barrel Diffuse 100 mm PNP M12 Connector - - 30V - Infrared IP67 100 mA - -
RS Stock No. 903-3958
BrandRS PRO
PHP3,809.99
Each
units
Fork Through Beam (Fork) 15 mm PNP Cable - - 30V Pre-Wired Infrared IP64 15 mA - <1 ms
RS Stock No. 729-5135
BrandRS PRO
PHP5,053.10
Each
units
Block Diffuse 40 → 1000 mm NPN 4-Pin M12 Connector - - 30V - LED IP67 100 mA - <=2.5 ms
RS Stock No. 729-5094
BrandRS PRO
PHP4,126.66
Each
units
Barrel Background Suppression 1 → 140 mm NPN 4-Wire Cable 2m - - 30V - LED IP67 100 mA - <=0.5 ms
RS Stock No. 729-5113
BrandRS PRO
PHP4,444.96
Each
units
Barrel Retro-Reflective 0.05 → 7 m PNP 4-Pin M12 Connector - - 30V - LED IP67 100 mA - <=0.5 ms
RS Stock No. 729-5107
BrandRS PRO
PHP5,284.29
Each
units
Barrel Background Suppression 1 → 140 mm PNP Cable - - 30V - LED IP67 100 mA - <=0.5 ms
RS Stock No. 729-5195
BrandRS PRO
PHP4,155.12
Each
units
Block Retro-Reflective 7.2 m PNP 4-Pin M8 Connector - - 24V - LED IP67 100 mA - <625 μs
RS Stock No. 903-3945
BrandRS PRO
PHP3,809.99
Each
units
Fork Through Beam (Fork) 7 mm PNP Cable - - 30V Pre-Wired Infrared IP64 15 mA - <1 ms
RS Stock No. 729-5189
BrandRS PRO
PHP6,828.84
Each
units
Block Background Suppression 5 → 250 mm PNP Cable - - 24V - LED IP67 100 mA - <625 μs
RS Stock No. 729-5191
BrandRS PRO
PHP4,155.12
Each
units
Block Retroreflective 7.2 m NPN Cable - - 24V - LED IP67 100 mA - <625 μs