How to Specify Fiber-Optic Sensors

Sensing part presence in machines, in fixtures, and on conveyors is an important component of industrial automation. Error-proofing assembly and controlling sequence based on presence or absence of a part is often required.

Many types of sensors are available, including inductive, magnetic, capacitive, and photoelectric. Each has its own strengths and weaknesses depending on the application. Photoelectric sensors, however, have the broadest offering of types and technologies, and the widest range of applications.

Photoelectric sensors come with a variety of light-emission types (infrared, visible red, laser Class 1 and 2), sensing technologies (diffuse, background suppression, reflective, through-beam), and housing configurations (photo eye or fiber optic).

This article focuses on specifying and applying fiber-optic sensors. Fiber-optic sensors include two devices that are typically specified separately: the amplifier and the fiber-optic cable, which includes the optic sensor head and the fiber cable that transmits light to and from the amplifier.

Fiber-optic sensors work well in tight spots and in applications with a high degree of electrical noise, such as with such as automated welding, variable frequency drives, and motors.

Another very common application is small part assembly. These operations tend to be fully automated, and thus require multiple sensors to confirm part placement (seated) and assembly verification to confirm completion of an operation.

>>Read more detail by Andrew Waugh, Machine Design, September 22, 2016