Pepperl+Fuchs Blog

Smaller Can Be Better with Fiber Optic Sensors

Posted by Tom Corbett on Fri, Jan 30, 2015

Fiber optic sensors sometimes get a bad reputation because of their small size or oddly shaped sensing tips. But, actually, it’s their size and shape that give them unique advantages over typical photoelectric sensors.


Not only can fiber optic sensors fit into tight spots and stand up to harsh environments, the sensing tips are offered in a variety of styles and sizes.

A fiber optic sensor consists of an amplifier and separate fiber optic cables.  The amplifier contains the emitter and receiver, along with any adjustments or controls.  When used with the appropriate fiber, the amplifier operates like a standard diffuse or thru-beam sensor.  Amplifiers range from low-cost basic models with very few features up to high-end models with built-in time delays, 4-in-1 output, 4-digit display, and much more.  Models with 4-digit displays usually have additional menu functions that can be selected, which include different sensing modes for high resolution or high-speed applications.

The fiber optic cables guide light from the amplifier to the sensing area through flexible transparent strands, or cores, of plastic or glass.  The cores are bundled together and covered in cladding, which helps the light bounce and travel through the core.  The plastic types have a smaller diameter and are only available with a PVC outer jacket, which helps protect the inner core and cladding from damage.  Plastic types are more flexible than glass and are even available in models offering a bend radius as tight as 0.5 mm.  Glass types are available with both PVC and stainless steel outer jackets.  The stainless steel jacket provides a higher degree of protection over PVC and allows glass models to withstand temperatures up to 900 °F.

The variety of sensing tips and styles that are available allow the fiber cables to be tailored to each application.  Fiber cables with a small diameter tip are perfect for sensing tiny objects while larger tips provide greater sensing range while still being able to fit into small spaces.  There are also fiber arrays which have the glass or plastic core spread out flat rather than bundled into a circular shape. Plus, the fiber cables are available in a variety of cable lengths, allowing the amplifier to be mounted remotely away from the application itself.  And plastic cables can be cut to size by the user with plastic fiber cutters that come with every plastic cable.


Fiber optic sensors are an excellent choice for applications such as PCB detection, web detection, small parts detection, position detection, and high-speed applications.  And they’re ideal for environments that are too harsh for standard sensors.

Free Download: Photoelectric  Fiber Optic Sensors and Cables

Topics: Photoelectric Sensors

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