We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What are Photoelectric Sensors?

By Phil Shepley
Updated May 17, 2024
Our promise to you
WiseGeek is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At WiseGeek, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject-matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

Photoelectric sensors, also known as photoeyes, are electronic devices that are used to sense the presence or absence of an object, or to measure the distance to the object, sometimes simultaneously, and do so for a wide variety of applications. They utilize light that is usually in the infrared spectrum to do so, which is sent through a light transmitter and is sometimes sensed by a photoelectric receiver, but the latter component is not always necessary. There are many different uses for different types of photoelectric sensors, for example they are used commonly in automated manufacturing, transportation, aerospace technologies, the health care industry and more.

A common type of photoeye is the self-contained photoelectric sensor, which does not use a receiver, and can have a counting display, can be integrated into a specific machine to help control its functions, or can also be built with an array of specialized features. An example of its use would be on an assembly line where it could be set up to sense the presence of objects moving down the belt to count them, determine defects, establish the rate at which items are being produced, and more. Another common place for self-contained photoelectric sensors is above automatic doors to detect the presence of people walking in and to open the door for them.

In high-speed manufacturing, photoelectric eyes are also used as safety devices that can shut a machine off automatically if production stops, or if they detect the presence of foreign objects or people around components that are dangerous or could cause serious malfunctions. Often, machine designs incorporate photoeyes that will not even allow the equipment to operate at all if anything is blocking light from the sensor.

Security photoelectric sensors can trigger alarms if a person, animal, or object crosses their infrared beam. The photoeyes can utilize the photoelectric receiver, which is placed opposite the transmitter to create an infrared beam of light that will set off the alarm the moment the transmitter senses that the light is not being reflected back. There are smoke alarms that are built with photoelectric sensors, which operate on the same principle. When smoke enters the alarm, it scatters the infrared beam and sets it off. Photoeyes can also be designed to operate in an opposite manner, so that they will be set off only when the light is allowed to travel from the transmitter to the receiver and back.

WiseGeek is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Discussion Comments
By David09 — On Aug 15, 2011

@SkyWhisperer - Yeah, but I don’t think that would cover every scenario. I believe the object would need to be near the garage door bottom to trip the sensor. If you had something which did not protrude out of the bottom (like a broom through the back window, maybe) then I don’t think it would trip.

Personally, I wish they had a sensor that would detect when your car is backing up if the garage door is down. In my old house, I had the garage door half way down and then I backed up – bang, I made a big dent in the garage door.

Nothing tripped; the door didn’t rise to get out of my way. I just had forgotten that it was half way down. There’s no technology to fix dumb I guess.

By SkyWhisperer — On Aug 14, 2011

I believe that we have a photoelectric sensor in our home – or in our garage, to be more specific.

I think that the garage door opener has such a sensor at the floor of the garage. The sensors uses a beam to make sure that nothing is blocking the garage door when it closes.

I think this would work in most scenarios that you can imagine. For example, if car wasn’t completely enclosed in the garage and its bumper was sticking out, then it would trip the sensor.

WiseGeek, in your inbox

Our latest articles, guides, and more, delivered daily.

WiseGeek, in your inbox

Our latest articles, guides, and more, delivered daily.