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. 219-033
Mfr. Part No.DT20-P254B
BrandSick
HK$7,482.62
Each
units
Block Background Suppression 50 → 150 mm PNP 5-Pin M12 Connector - 30V - Laser Light IP65 100 mA - 2.8 ms Metal
RS Stock No. 219-2319
Mfr. Part No.EE-SPX303N
BrandOmron
HK$353.90
Each
units
Fork Through Beam (Fork) 13 mm NPN Non-Solder Connector - 24V - Infrared IP50 80 mA - - PC
RS Stock No. 218-989
Mfr. Part No.WT100L-F2241
BrandSick
HK$1,206.30
Each
units
Block Diffuse 450 mm PNP 4-Pin M8 Connector - 30V - Laser Light IP65 100 mA - <0.25 ms ABS, PMMA
RS Stock No. 821-0044
Mfr. Part No.E3Z-G62-M3J
BrandOmron
HK$1,215.77
Each
units
Fork Through Beam (Fork) 25 mm NPN Pre-Wired Cable - 24V 4-Pin Connector Infrared IP64 25 mA - 1 ms ABS
RS Stock No. 768-9464
Mfr. Part No.WL9-3P1162
BrandSick
HK$1,334.62
Each
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Block Retroreflective 0 → 0.4 m PNP - - 30V - LED IP66, IP67, IP69K 100 mA - <0.5 ms Al2O3
RS Stock No. 121-2722
Mfr. Part No.WTB11-2P2461
BrandSick
HK$1,334.62
Each
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Block Background Suppression 30 → 1100 mm PNP 4-Pin M12 Connector - 30V M12 LED IP66, IP67, IP69K 30 mA - 2.5 ms ABS Plastic
RS Stock No. 191-9933
Mfr. Part No.OF5012
HK$1,212.00
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Barrel Diffuse 1 → 200 mm PNP M12 Connector - 36V - Infrared IP65 200 mA - - Nickel Plated Brass
RS Stock No. 891-9514
Mfr. Part No.RLK31-8-2500-IR/31/115
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Block Diffuse 0 → 2500 mm Relay 5-Wire Cable 2m 240V 240V - Infrared IP67 40 mA - 25 ms PC
RS Stock No. 463-8801
Mfr. Part No.VL12-2P132
BrandSick
HK$1,119.19
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Barrel Retroreflective 0.03 → 2.8 m PNP 4-Wire Cable 2m - 30V - LED IP67 100 mA - <=1.25 ms Metal
RS Stock No. 361-5532
Mfr. Part No.EX-13EA-PN
BrandPanasonic
HK$863.85
Each
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Block Through Beam (Emitter and Receiver) 500 mm PNP 3-Wire Cable 2m - 24V - LED IP67 50 mA - <=0.5 ms PET
RS Stock No. 901-2910
Mfr. Part No.EX-11A-PN
BrandPanasonic
HK$991.22
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Block Through Beam (Emitter and Receiver) Maximum of 150 mm PNP Cable - 24V Wire Lead LED IP67 10 mA - 0.5 ms PET
RS Stock No. 444-3625
Mfr. Part No.XUX0ARCTT16T
HK$669.55
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Block Through Beam (Emitter) 40 m - 3-Terminal Screw 240V 240V - Infrared IP65, IP67 3 A, 500 mA - <25 ms PBT
RS Stock No. 111-3700
Mfr. Part No.WLG4SC-3P2232A71
BrandSick
HK$1,815.96
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Block Retroreflective 0 → 5 m PNP 4-Pin M8 Connector - 30V 4-Pin M8 Connector LED IP66, IP67 100 mA IO-Link 300 → 450 μs ABS Plastic
RS Stock No. 786-5918
Mfr. Part No.WL12L-2B530
BrandSick
HK$4,769.62
Each
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Block Retroreflective 0 → 18 m NPN/PNP 5-Pin M12 Connector - 30V - Laser Light IP67, IP69K 100 mA - 200 μs Die Cast Zinc
RS Stock No. 701-8803
Mfr. Part No.WLG4S-3P2232V
BrandSick
HK$1,916.41
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Block Retroreflective 5 m PNP 4-Pin M8 Connector - 30V - LED IP69K 100 mA - <=0.5 ms Stainless Steel
RS Stock No. 752-5073
Mfr. Part No.XUB0BKSWL2T
HK$398.00
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Barrel Through Beam (Emitter) 10 m Solid State Cable - 24V - Infrared IP65, IP67 100 mA - <2 ms Nickel Plated Brass
RS Stock No. 878-7948
Mfr. Part No.XUK1ARCNL2H60
HK$1,391.37
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Compact Retroreflective Maximum of 10 m Relay 5-Wire Cable 2m 240V 240V Cable LED IP65 3 A - - PBT
RS Stock No. 289-2491
Mfr. Part No.WL150-P430
BrandSick
HK$1,198.80
Each
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Block Retro-Reflective 2.4 m PNP 4-Pin M8 Connector - 30V - LED IP67 100 mA - <=0.5 ms ABS, PMMA
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Mfr. Part No.XUK0AKSAL2
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Compact Through Beam (Emitter) 0.28 m, 0.8 m, 4 m, 30 m PNP 3-Wire Cable 2m - 24V - Infrared IP65 100 mA - <2 ms PBT
RS Stock No. 617-0739
Mfr. Part No.E3ZM-LS87H
BrandOmron
HK$1,613.17
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Block Retroreflective 10 → 150 mm PNP 4-Pin M8 Connector - 30V - LED IP69K 100 mA - 1 ms Stainless Steel