Photoelectric sensors (sometimes known as "Photo Sensors") are an incredibly useful bit of kit. They work incredibly simply yet can be deployed in numerous ways for various industries - with excellent levels of accuracy. Essentially, a photoelectric sensor detects the distance, presence or absence of a physical object by emitting an electromagnetic field or beam. This is then picked up by a receiver which detects if anything has changed. An alteration in the return signal alerts the sensor to whether an object is or isn't present or if other required criteria is different. An everyday example would be the sensor on an automatic door – when an object is near the door it breaks the signal between the transmitter and the receiver and so the door opens.

Photoelectric sensors can also be used to:

• Check conveyor belts to detect errors.
• Count small objects for sorting and packing.
• Manage the movements of pick and place machinery in warehouses.
• Detect colours for printing and sorting.

Multiple sensors can be used to monitor wide spaces to detect the absence or presence of an item or triangulate movement and distance – perfect for public transportation or assembly lines.

Why Choose an OMRON Photo Electric Sensor?

Although known for their work in many areas, OMRON are specialists in both electrical components and industrial automation. They have a wealth of experience supplying not just parts, but whole solutions for the manufacturing and processing industries. They continue to innovate, develop and work closely with the food and beverage, automotive and medical sectors. When choosing a photoelectric sensor for your needs OMRON are the way to go.

There are three main types of photoelectric sensor and OMRON can supply all of them with various configurations.

Through-Beam Sensors

Through-beam (sometimes written as thru-beam) sensors use two separate parts – a transmitter and a receiver – positioned either side of the area to be detected. If the beam between the two modules is broken the sensor knows an object is present. Through-beam sensors can be used over very small distances. For example, the OMRON "EE" series has a detection range of just 5mm – perfect for technical applications such as component mounting or use in semiconductor production. On the other side of the scale "E3Z" sensors have a range up to 60m. As one of the most widely used series of photoelectric sensors in the world, "E3Z" sensors are ideal for food processing, manufacturing and packing applications.

Retro Reflective Sensors

Retroreflective sensors have the transmitter and receiver in the same housing but use a separate reflective module to bounce the beam back. This makes them easy to install as usually only one element needs to be wired in. However, they shouldn't be used to detect highly reflective items. The "E3Z" series includes several retroreflective options for use in large areas while the "E3S" range can be used to detect transparent objects such as plastic bottles. The OMRON "EE" series includes photomicrosensors with a detection range as low as 1mm.

Diffuse Reflective Sensors

Diffuse sensors work in a similar way to retroreflective sensors, but instead of needing a separate reflective unit rely on the light reflected by the object detected. Usually, a diffuse sensor would not expect to have any light reflected back at it. These sensors are not suitable for every application as they need the objects detected to produce sufficient light – however they are easy to install and work well over shorter or mid-range distances. OMRON "E3F" sensors offer non-stop detection with a range of up to 1m. They are often used for logistics or manufacturing purposes. You will also find them deployed in food and beverage, textile and ceramics production.

When considering which photoelectric sensor you need think about whether background suppression is needed. This feature enables the sensor to isolate detected objects from their surroundings. This is especially useful in locations with a high degree of reflection, which might otherwise affect the sensor's ability to detect.