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 Terminal Type Light Source IP Rating Maximum Current Interface Response Time Housing Material
RS Stock No. 814-0361
Mfr. Part No.OID200
HK$1,478.99
Each
units
Barrel Background Suppression 0.03 2 m NPN/PNP M12 Connector - 30V Wire Lead LED IP65, IP67 <75 mA @ 24 V dc IO-Link - Stainless Steel
RS Stock No. 739-6664
Mfr. Part No.OJ5052
HK$1,588.22
Each
units
Block Diffuse 15 200 mm PNP 4-Pin M8 Connector - 30V - LED IP67 200 mA - - ABS
RS Stock No. 191-9911
Mfr. Part No.OF5014
HK$1,010.00
Each
units
Barrel Retroreflective 0.05 2 m PNP Cable - 36V - Infrared IP67 200 mA - - Nickel Plated Brass
RS Stock No. 739-6673
Mfr. Part No.O1D100
HK$3,150.48
Each
units
Block Diffuse 0.2 10 m Analogue, PNP M12 Connector - 30V - Laser Light IP67 200 mA - - Die Cast Zinc
RS Stock No. 191-9933
Mfr. Part No.OF5012
HK$1,212.00
Each
units
Barrel Diffuse 1 200 mm PNP M12 Connector - 36V - Infrared IP65 200 mA - - Nickel Plated Brass
RS Stock No. 191-9949
Mfr. Part No.OF5027
HK$1,154.43
Each
units
Barrel Diffuse 1 400 mm PNP M12 Connector - 36V - Infrared IP65 200 mA - - Optalloy Plated Brass
RS Stock No. 136-5401
Mfr. Part No.OPU204
HK$2,193.11
Each
units
Fork Through Beam (Fork) 0.5 (Smallest) mm PNP 3-Pin M8 Connector - 35V Quick Disconnect LED IP67 30 mA - - Die Cast Zinc
RS Stock No. 425-8146
Mfr. Part No.OJ5026
HK$1,130.89
Each
units
Block Retroreflective 2 m PNP M8 Connector - 30V - LED IP67 200 mA - - ABS
RS Stock No. 488-122
Mfr. Part No.O5H500
HK$1,373.60
Each
units
Block Diffuse 50 1800 mm PNP M12 Connector - 36V - LED IP67 200 mA - - Polyamide
RS Stock No. 425-8231
Mfr. Part No.OJ5022
HK$1,047.13
Each
units
Block Diffuse 1 600 mm PNP M8 Connector - 30V - LED IP67 200 mA - - ABS
RS Stock No. 488-126
Mfr. Part No.O5H200
HK$989.80
Each
units
Block Diffuse 50 1400 mm PNP M12 Connector - 36V - LED IP65 200 mA - - Polyamide
RS Stock No. 144-3582
Mfr. Part No.O8H208
HK$1,196.62
Each
units
Block Diffuse 1 30 mm PNP M8 Connector - 30V M8 Connector LED IP65, IP67 20 mA IO-Link - ABS, Stainless Steel
RS Stock No. 136-5402
Mfr. Part No.OPU205
HK$2,226.83
Each
units
Fork Through Beam (Fork) 0.8 (Smallest) mm PNP 3-Pin M8 Connector - 35V Quick Disconnect LED IP67 30 mA - - Die Cast Zinc
RS Stock No. 144-3585
Mfr. Part No.O8P200
HK$983.15
Each
units
Block Retroreflective 20 1800 mm PNP Cable - 30V Cable LED IP65, IP67 20 mA IO-Link - ABS, Stainless Steel
RS Stock No. 739-6639
Mfr. Part No.O4P500
HK$1,090.80
Each
units
Block Retroreflective 0.3 22 m PNP M12 Connector - 36V - LED IP67 200 mA - - Polyamide
RS Stock No. 191-9927
Mfr. Part No.OF5024
HK$1,020.10
Each
units
Barrel Retroreflective 0.2 0.8 m PNP Cable - 36V - LED IP67 200 mA - - Nickel Plated Brass
RS Stock No. 425-8398
Mfr. Part No.OJ5038
HK$1,148.98
Each
units
Block Through Beam (Emitter) 15 m PNP M8 Connector - 30V - LED IP67 200 mA - - ABS
RS Stock No. 425-8411
Mfr. Part No.OJ5036
HK$1,526.40
Each
units
Block Retroreflective 8 m PNP M8 Connector - 30V - LED IP67 200 mA - - ABS
RS Stock No. 487-898
Mfr. Part No.O1D106
HK$4,006.32
Each
units
Block Background Suppression 1 75 m PNP M12 Connector - 30V - Laser Light IP67 200 mA - - Die Cast Zinc
RS Stock No. 814-0345
Mfr. Part No.OGH500
HK$1,129.51
Each
units
Barrel Diffuse 15 300 mm PNP M12 Connector - 36V Wire Lead LED IP67 25 mA - - Stainless Steel