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. 361-5554
Mfr. Part No.EX-14A-PN
BrandPanasonic
TWD3,342.00
Each
units
Block Retroreflective 2 25 mm PNP 3-Wire Cable 2m - 24V - LED IP67 50 mA - <=0.5 ms PET
RS Stock No. 530-0888
Mfr. Part No.WTB27-3P2441
BrandSick
TWD12,000.00
Each
units
Block Diffuse 30 1100 mm PNP 4-Pin M12 Connector - 30V - LED IP69K 100 mA - <=1.5 ms ABS
RS Stock No. 786-5851
Mfr. Part No.WL260-S270
BrandSick
TWD5,300.00
Each
units
Block Retroreflective 0.01 15 m Relay 5-Terminal Screw 240V 240V - LED IP67 3 A - 20 ms ABS
RS Stock No. 198-0480
Mfr. Part No.E3SCT61
BrandOmron
TWD11,725.00
Each
units
Block Through Beam (Emitter and Receiver) 30 m PNP Pre-Wired Cable - 30V - Infrared IP67 100 mA - 1 ms Die Cast Zinc
RS Stock No. 818-1520
Mfr. Part No.EE-SPY411
BrandOmron
TWD1,460.00
Each
units
Block Convergent 2 5 mm NPN - - 24V Connector Infrared IP50 50 mA - - PC
RS Stock No. 307-913
Mfr. Part No.OPB704
BrandOptek
TWD84.00
Each
units
Block Retroreflective 3.8 mm NPN - - - Wire Lead Infrared - - - - Plastic
RS Stock No. 908-7087
Mfr. Part No.OPB700ALZ
BrandOptek
TWD344.00
Each
units
- - - - - - - - - - - - - -
RS Stock No. 909-2881
Mfr. Part No.Q4XTBLAF300-Q8
BrandBanner
TWD14,313.00
Each
units
Barrel Diffuse 25 300 mm Bipolar NPN/PNP M12 Connector - 30V M12 Laser Light IP67, IP68, IP69K - - 50 ms Stainless Steel
RS Stock No. 909-2869
Mfr. Part No.Q3XTBLD-Q8
BrandBanner
TWD8,373.00
Each
units
Barrel Diffuse 0 300 mm Bipolar NPN/PNP M12 Connector - 30V M12 Laser Light IP67, IP68, IP69K <28 mA - 5 ms Nickel Plated Metal
RS Stock No. 786-5933
Mfr. Part No.WL27-3P2451
BrandSick
TWD6,784.00
Each
units
Block Retroreflective 0.1 15 m PNP 4-Pin M12 Connector - 30V - LED IP69K 100 mA - 500 μs ABS, Plastic
RS Stock No. 493-7316
Mfr. Part No.WF2-40B410
BrandSick
TWD6,500.00
Each
units
Fork Through Beam (Fork) 2 mm NPN/PNP 4-Pin M8 Connector - 30V - Infrared IP65 100 mA - 100 μs Aluminium
RS Stock No. 786-5927
Mfr. Part No.WT24-2B410
BrandSick
TWD13,400.00
Each
units
Block Background Suppression 100 2500 mm NPN/PNP 4-Pin M12 Connector - 30V - Infrared IP69K 100 mA - 500 μs Die Cast Zinc
RS Stock No. 425-8411
Mfr. Part No.OJ5036
TWD7,185.00
Each
units
Block Retroreflective 8 m PNP M8 Connector - 30V - LED IP67 200 mA - - ABS
RS Stock No. 339-0003
Mfr. Part No.FPAM 18P3151/S14
BrandBaumer
TWD5,066.00
Each
units
Barrel Retroreflective 3.2 m PNP 4-Pin M12 Connector - 30V - LED IP67 200 mA - <1 ms Brass Nickel Plated PC
RS Stock No. 124-0334
Mfr. Part No.OBT300-R101-2EP-IO-V31-L
TWD5,721.00
Each
units
Block Background Suppression 7 300 mm NPN/PNP 4-Pin M8 Connector - 30V 4-Pin Connector Laser Light IP67, IP69, IP69K 100 mA IO-Link 300 μs PC
RS Stock No. 902-7186
Mfr. Part No.BOS 21M-PA-PK10-S4
BrandBALLUFF
TWD8,376.00
Each
units
Block Retroreflective 0 4 m PNP M12 Connector - 30V Connector LED IP67 100 mA - 0.5 ms Aluminium, GD-Zn
RS Stock No. 818-1576
Mfr. Part No.EE-SX670P
BrandOmron
TWD739.00
Each
units
Fork Through Beam (Fork) Maximum of 5 mm PNP 4-Pin Connector - 24V Connector Infrared IP50 12 mA - - PBT
RS Stock No. 125-4543
Mfr. Part No.PM-L45
BrandPanasonic
TWD680.00
Each
units
Fork Through Beam (Fork) 6 mm NPN 1m Cable - 24V Cable Infrared IP64 50 (Sink Current) mA - 20 (Received) μs, 80 (Interrupted) μs PBT (Enclosure), Polycarbonate (Display Section)
RS Stock No. 745-2186
Mfr. Part No.E3ZLS66
BrandOmron
TWD3,391.00
Each
units
Block Background Suppression 20 200 mm NPN M8 Connector - 24V - LED IP67 100 mA - 1 ms PBT
RS Stock No. 493-7287
Mfr. Part No.WL18-3P430
BrandSick
TWD6,600.00
Each
units
Block Retroreflective 7 m PNP 4-Pin M12 Connector - 30V - LED IP65, IP67 100 mA - 500 μs ABS