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 Maximum DC Voltage Optical Technology Terminal Type Light Source IP Rating Maximum Current Interface Response Time
RS stock no. 729-5117
BrandRS PRO
R 1,062.13
Each
units
Barrel Retroreflective 0.05 → 7 m PNP 4-Wire Cable 2m - 30V - - LED IP67 100 mA - <=0.5 ms
RS stock no. 729-5113
BrandRS PRO
R 1,108.56
Each
units
Barrel Retroreflective 0.05 → 7 m PNP 4-Pin M12 Connector - 30V - - LED IP67 100 mA - <=0.5 ms
RS stock no. 729-5148
BrandRS PRO
R 1,314.49
Each
units
Block Diffuse 40 → 1000 mm PNP 4-Pin M12 Connector - 30V - - LED IP67 100 mA - <=2.5 ms
RS stock no. 729-5167
BrandRS PRO
R 2,073.97
Each
units
Block Through Beam (Emitter) 20 m PNP 4-Pin M12 Connector - 30V - - LED IP67 100 mA - 2.5 ms
RS stock no. 729-5185
BrandRS PRO
R 1,587.69
Each
units
Block Background Suppression 5 → 250 mm PNP 4-Pin M8 Connector - 24V - - LED IP67 100 mA - <625 μs
RS stock no. 729-5173
BrandRS PRO
R 1,587.94
Each
units
Block Background Suppression 5 → 250 mm NPN 4-Pin M8 Connector - 24V - - LED IP67 100 mA - <625 μs
RS stock no. 729-5094
BrandRS PRO
R 1,067.37
Each
units
Barrel Background Suppression 1 → 140 mm NPN 4-Wire Cable 2m - 30V - - LED IP67 100 mA - <=0.5 ms
RS stock no. 729-5151
BrandRS PRO
R 1,535.56
Each
units
Block Retroreflective 0.15 → 10 m PNP 4-Wire Cable 2m - 30V - - LED IP67 100 mA - 2.5 ms
RS stock no. 377-8419
BrandRS PRO
R 4,339.34
Each
units
Fork Through Beam (Fork) 2 mm PNP 4-Wire Cable 2m - 30V - - LED IP67 100 mA - 0.5 ms
RS stock no. 729-5145
BrandRS PRO
R 1,409.16
Each
units
Block Retroreflective 0.15 → 10 m NPN 4-Pin M12 Connector - 30V - - LED IP67 100 mA - 2.5 ms
RS stock no. 729-5214
BrandRS PRO
R 1,622.05
Each
units
Block Through Beam (Emitter) 15 m PNP Cable - 24V - - LED IP67 500 mA - <500 μs
RS stock no. 729-5205
BrandRS PRO
R 1,112.23
Each
units
Block Retroreflective 7.2 m PNP 3-Wire Cable 2m - 24V - - LED IP67 100 mA - <625 μs
RS stock no. 285-885
BrandRS PRO
R 2,784.83
Each
units
Block Diffuse 700 mm Relay 4-Terminal Screw 250V 240V - Screw Infrared LED IP66 2 A - 5 ms
RS stock no. 729-5090
BrandRS PRO
R 1,096.18
Each
units
Barrel Background Suppression 1 → 140 mm NPN 4-Pin M12 Connector - 30V - - LED IP67 100 mA - <=0.5 ms
RS stock no. 729-5110
BrandRS PRO
R 1,081.90
Each
units
Barrel Retroreflective 0.05 → 7 m NPN 4-Wire Cable 2m - 30V - - LED IP67 100 mA - <=0.5 ms
RS stock no. 285-891
BrandRS PRO
R 3,334.05
Each
units
Block Through Beam (Emitter and Receiver) 10 m Relay 4-Terminal Screw 250V 240V - Screw LED IP66 2 A - 5 ms
RS stock no. 729-5189
BrandRS PRO
R 1,589.71
Each
units
Block Background Suppression 5 → 250 mm PNP Cable - 24V - - LED IP67 100 mA - <625 μs
RS stock no. 729-5123
BrandRS PRO
R 1,653.56
Each
units
Barrel Through Beam (Emitter) 28 m PNP 4-Pin M12 Connector - 30V - - LED IP67 100 mA - <=0.5 ms
RS stock no. 729-5107
BrandRS PRO
R 1,099.08
Each
units
Barrel Background Suppression 1 → 140 mm PNP 4-Wire Cable 2m - 30V - - LED IP67 100 mA - <=0.5 ms
RS stock no. 729-5176
BrandRS PRO
R 2,151.70
Each
units
Block Through Beam (Emitter) 20 m PNP Cable - 30V - - LED IP67 100 mA - 2.5 ms