Light barriers – find manufacturers and suppliers

Light barriers are used to reliably detect objects, people or movements and operate contact-free and wear-free.

They are among the most frequently used optical sensors in industry, automation and safety technology. Thanks to their high switching speed, precision and robustness, photoelectric sensors are a central element of modern production, conveyor and safety systems.

Below you will find the mode of operation, the different types and the use and areas of application of light barriers, as well as an overview of their advantages and limitations.

How light barriers work:

A light barrier basically consists of a transmitter and a receiver, which are arranged opposite each other or in a common housing. The transmitter generates a light beam, usually in the infrared or visible range.
If the light beam hits the receiver, a defined state is present.
If the beam is interrupted or weakened by an object, the sensor detects this event and switches accordingly.

The main functional principles are:

1. Light generation:
   LEDs or lasers are used as the light source, depending on the range, precision and design.
2. Light transmission:
   The light beam is bundled or slightly fanned out and is aimed specifically at the receiver.
3. Signal processing:
   The receiver evaluates the intensity and timing of the light signal and converts it into an electrical switching signal.
4. Switching logic
   The light barrier reacts either when the light beam is interrupted or when it is restored.

As no mechanical contact is required, the light barrier works quickly, reliably and wear-free.

Types of light barriers:

1. Through-beam sensors:
   The transmitter and receiver are housed in separate enclosures. The object is detected when it interrupts the light beam.
   They offer long ranges, high functional reliability and low dependence on object color and surface
2. Retro-reflective sensors:
   Transmitter and receiver are located in one housing. The light is reflected by the object itself.
   This design is compact, but depends on the color, gloss and surface structure of the object.
3. Retro-reflective sensors with reflector:
   The light is reflected by a special reflector.
   An object interrupts the light path between the sensor and reflector.
   They offer greater ranges than pure reflection sensors, good detection reliability and less installation effort than through-beam sensors
4. Fork light barriers:
   The transmitter and receiver are integrated in a U-shaped housing.
   They are particularly suitable for small objects, high positioning accuracy and fast switching processes.
5. Fiber optic barriers:
   The light is guided via glass or plastic fibers.
   Ideal for tight installation spaces, high temperatures and dirty environments.
6. Laser light barriers:
   Use a highly focused laser beam.
   They enable very precise object detection, long ranges and detection of the smallest objects.

Use and application areas of light barriers:

1. Industrial automation:
Presence and position monitoring.
Counting tasks and process monitoring.

2. Conveying and packaging technology:
Package and product detection.
Jam and gap monitoring.
Belt speed control.

3. Mechanical engineering:
End position monitoring.
Tool and workpiece detection.

4. Safety technology:
Person detection.
Safeguarding of danger zones.
Access control.

5. Logistics:
Identification and sorting of goods.
Volume and height control.

6. Building and everyday technology:
Automatic doors.
Lighting control systems.
Presence detection.

Advantages of light barriers:

• Non-contact detection therefore no wear and long service life.
• High switching speed makes them suitable for fast processes and high cycle rates.
• High reliability, especially with through-beam sensors.
• Large operating ranges allow flexible installation.
• Versatile designs available for almost any installation situation.
• Simple integration thanks to standardized electrical interfaces.
• Gentle object detection. Ideal for sensitive or hot objects.

Limits and restrictions of light barriers:

• Dependence on soiling of the optics.
• Interference due to strong ambient light with simple systems.
• Limitations with transparent or very shiny objects.

These factors must be taken into account when making a selection.

Light barriers are robust, precise and versatile sensor solutions for non-contact object detection. Their mode of operation is based on the targeted interruption or reflection of light and enables fast, reliable switching processes. Different types - from through-beam sensors to laser and fork systems - allow photoelectric sensors to be optimally adapted to a wide range of applications. Their advantages in terms of speed, freedom from wear and flexibility make them an indispensable technology in modern automation and safety technology.

Here are the most important aspects to look out for when buying light barriers:

Although light barriers appear simple at first glance, their correct selection is crucial for process safety, reliability and system availability. Different designs, types of light and performance features make the market diverse, but also complex. Professional purchasing therefore requires a systematic evaluation of the application, the ambient conditions and the technical and economic requirements. The following overview shows the most important criteria for a well-founded selection decision.

• The first step is to precisely describe the task that the light barrier is to perform. The key questions are:
• Should an object merely be detected or counted?
• Is a high level of position accuracy required?
• Is it a safety-relevant application or pure process monitoring?
• A clear task description prevents the selection of an unsuitable or oversized system.
• Selecting the right type of photoelectric sensor. Different designs are suitable depending on the application.
• Through-beam sensors offer maximum reliability and long ranges.
• Retro-reflective sensors are compact, but react sensitively to object surfaces.
• Retro-reflective sensors with reflectors are a good compromise.
• Fork light barriers are suitable for precise switching points on small objects.
• Laser light barriers also enable very precise detection of small parts.
• Purchasing should check which design is functionally and economically sensible.
• The range must be suitable for the application and offer sufficient reserve. The following must be taken into account:
• Nominal range under ideal conditions.
• Decrease in range due to dust, dirt or ageing.
• Safety distance between maximum working distance and nominal range.
• A sufficient functional reserve significantly increases operational safety.
• Object characteristics have a strong influence on detection reliability. Important factors:
• Size and shape of the object.
• Color, gloss and transparency.
• Speed of movement.
• Transparent, very dark or highly reflective objects require special light barriers or filter technologies.
• The light source used influences precision and susceptibility to interference.
• Infrared light is inconspicuous and robust.
• Visible red light facilitates alignment.
• Laser light offers maximum precision.
• The optics also determine the beam shape and detection accuracy.
• The environment has a major influence on function and service life. Dust, dirt, oil or moisture must be taken into account:
• Dust, dirt, oil or moisture.
• Extraneous light, sunlight or reflections.
• Temperature range and temperature fluctuations.
• Vibrations and mechanical loads.
• Purchasers should pay attention to suitable types of protection, filters and robust housings.
• The switching frequency and response time are crucial in fast applications. The following must be checked:
• Maximum switching frequency.
• Delay between beam interruption and output signal.
• Suitability for high switching speeds.
• Not every photoelectric sensor is suitable for high-speed processes.
• Simple and stable installation is crucial for reliable operation. Important aspects:
• Design and dimensions.
• Mounting options and adjustability.
• Alignment tolerances.
• Standardized designs facilitate replacement and spare parts inventory.
• The electrical connection must match the control unit. Attention must be paid to
• Output types and logic.
• Supply voltage.
• Protection against reverse polarity and short circuit.
• Optional communication interfaces.
• Proper integration reduces commissioning time and errors.
• The cost of installation and operation influences the overall costs. Purchasing should take this into account:
• Simple adjustment and alignment.
• Teach-in functions.
• Status displays and diagnostic options.
• User-friendly sensors reduce downtimes.
• Light barriers are often used in continuous operation. Important criteria:
• Quality of the optics.
• Long-term stability of the electronics.
• Protection against ageing and soiling.
• Manufacturer experience and references.
• Reliable products reduce maintenance and downtime costs in the long term.
• Standards are particularly important for safety-relevant applications. The following must be observed:
• CE conformity.
• Safety standards for personal protection.
• Industry or country-specific requirements.
• Compliance with legal requirements is mandatory.
• The purchase price is only part of the consideration. A high-quality product is often more economical in the long term.

The professional purchase of light barriers requires a structured and holistic evaluation of technical, mechanical and economic aspects. The decisive factor is not the maximum range or the lowest price, but the reliable function under real operating conditions. Those who carefully consider the application, object characteristics, environmental conditions and integration requirements will obtain durable and stable solutions with high process reliability. A well-founded selection pays off through reduced downtimes, low maintenance costs and permanently reliable processes.

Light barriers can be purchased from various suppliers. You will find comprehensive information on manufacturers and suppliers of Light barriers around the world on Exportpages.