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. 194-4018
Mfr. Part No.OPB608A
BrandOptek
TWD55.00
Each
units
Block Retroreflective 1.27 → 9.525 mm NPN - - - - Wire Lead Infrared - - - -
RS Stock No. 908-7087
Mfr. Part No.OPB700ALZ
BrandOptek
TWD350.00
Each
units
- - - - - - - - - - - - - -
RS Stock No. 307-913
Mfr. Part No.OPB704
BrandOptek
TWD95.00
Each
units
Block Retroreflective 3.8 mm NPN - - - - Wire Lead Infrared - - - -
RS Stock No. 170-0724
Mfr. Part No.OPB704W-Z
BrandOptek
TWD136.90
Each (In a Bag of 100)
units
Block Retroreflective 3.8 mm NPN 4-Wire Cable 0.61m - - - - Infrared - - - -
RS Stock No. 627-6556
Mfr. Part No.OPB704W-Z
BrandOptek
TWD142.00
Each
units
Block Retroreflective 3.8 mm NPN 4-Wire Cable 0.61m - - - - Infrared - - - -
RS Stock No. 908-7129
Mfr. Part No.OPB750T
BrandOptek
TWD160.00
Each
units
- - - - - - - - - - - - - -
RS Stock No. 908-7110
Mfr. Part No.OPB745
BrandOptek
TWD104.00
Each
units
- - - - - - - - - - - - - -
RS Stock No. 627-8388
Mfr. Part No.OPB715-Z
BrandOptek
TWD239.00
Each
units
Block Retroreflective 12.7 mm - - - - 5.25V Wire Lead LED - - - -
RS Stock No. 170-0725
Mfr. Part No.OPB715-Z
BrandOptek
TWD233.60
Each (In a Bag of 25)
units
Block Retroreflective 12.7 mm - - - - 5.25V Wire Lead LED - - - -
RS Stock No. 908-7021
Mfr. Part No.OP506A
BrandOptek
TWD27.80
Each (In a Pack of 50)
units
- - - - - - - - - - - - - -
RS Stock No. 908-7116
Mfr. Part No.OPB733TR
BrandOptek
TWD103.00
Each
units
- - - - - - - - - - - - - -
RS Stock No. 908-7126
Mfr. Part No.OPB771TZ
BrandOptek
TWD259.00
Each
units
Barrel Diffuse 2.03 → 5.59 mm TTL Wire - - 1.8V Wire Lead LED - 40 mA - -
RS Stock No. 908-7163
Mfr. Part No.OPB829DZ
BrandOptek
TWD131.00
Each
units
Block Through Beam (Fork) 3.18 → 8 mm Phototransistor Wire - - 1.7V Wire Lead LED - 50 mA - -
RS Stock No. 301-606
Mfr. Part No.OPB706B
BrandOptek
TWD73.00
Each
units
Block Retroreflective 1.27 mm NPN - - - - Wire Lead Infrared - - - -
RS Stock No. 908-7090
Mfr. Part No.OPB701ALZ
BrandOptek
TWD357.00
Each
units
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