What Are Photoelectric Sensors?

photoelectric sensor is a commonly used tool for measuring properties like surface conditions and detecting objects through emitting and receiving light. By the means of an emitter, photoelectric sensors cast light on the objects they sense. In turn, the object interrupts or reflects the light to a receiver, which detects the difference in light emitted versus received to create an electrical output. This output can be used across a myriad of applications to measure different variables in different ways. As photoelectric sensors are highly versatile and complex, this blog will provide an overview of their basic types and functions so you can better understand the significance of these popular devices.

Before we dive into the specifics of the various functions of photoelectric sensors, it is helpful to understand why photoelectricity works well for sensors. While proximity sensors and other devices may also be used to detect objects and surfaces, they are limited in their ability to detect certain objects like metals. On the other hand, photoelectric sensors have virtually no restrictions on the objects they are able to sense and some have the ability to detect objects up to 10 meters away. Furthermore, photoelectric sensors are quick, high-resolution sensors that make non-contact sensing easy and low-risk. 

Photoelectric sensors work on three main operating principles, those of which involve the properties of light, the light sources used, and triangulation. As photoelectric sensors manipulate light to detect readings, it is unsurprising that they depend on the properties of light; however, different types use different properties to function. For example, some sensors use the refraction of light to detect objects, while others use the reflection of light in different directions to detect objects. Still others use the polarization of light. Depending how and where the received light is manipulated, a sensor will require different light sources as well as different positioning. Typically, photoelectric sensors use pulse-modulated light meaning that they emit light at fixed intervals, but some sensors use non-modulated light which is an uninterrupted light source. The latter is less popular given its tendency forshort sensing distances and susceptibility to external light interference. The last working principle of light sensors is their dependency on triangulation which states that where the no beam is concentrated depends on the distance to the sensing object. In general, a photoelectric sensor, usually distance-settable sensors, will use three points of focus to detect objects nearby.

Because photoelectric sensors may conduct readings in a variety of ways, there are a few ways to categorize them. Whether by sensing method or configuration, organizing sensors into groups makes understanding their operating principles less confusing. For stable operation and long sensing distances, one might benefit from through-beam sensing, where the sensing object directly interrupts the light between the emitter and the receiver. However, a diffuse-reflective sensor receives intensified light from the sensing object, which makes this method sensitive to certain surface conditions. Retro-reflective sensors pass light through the sensing object twice, and this gives them the advantage of being able to detect transparent objects. Lastly, distance-settable sensors and limited-reflective sensors are other reliable options that receive light reflected from the sensing object to detect it.

Depending on what you need, photosensors are available with a variety of different features that make for easy use, such as built-in amplifiers, built-in power supplies, or area sensors. When you are in the market for reliable industrial part types you can use for applications with photoelectric sensors, turn to Industrial Part Sphere. Owned and operated by ASAP Semiconductor, we are a leading online distributor of electrical components for all uses. To get started procuring any part you need, submit a Request for Quote form to receive a custom quotation for your comparisons in 15 minutes or less. To learn more, contact us at any time via phone or email.


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