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Fiber Optic Sensors

Fiber Optic Sensors offer a compact and versatile solution for presence/absence detection. Regardless of environment or mounting style, KEYENCE Fiber Optics can be used anywhere.

Fiber Optic Sensors Product Lineup

Discontinued Series:
  • Digital Fiber Optic SensorsFS-N40 series

    FS-N40 series - Digital Fiber Optic Sensors

    This series is able to detect virtually anything, in any environment with high power and a variety of head options. An OLED display provides clear and detailed information greatly reducing setup time. Integration is also made easy through reduced wiring options and fiber optics with integrated status indicators.

    Features
    Worlds Smartest Fiber Heads

    Fiber optics with Built-In Indicators now allow for a quick status or alignment check by simply looking at the fiber head.

    Easy to Read OLED Display

    The OLED display is easy to read and the menu structure is incredibly simple, featuring intuitive navigation and easily understandable messages.

  • Fiber UnitFU series

    FU series - Fiber Unit

    This is a series of fiber optic sensor heads designed to be connected to a fiber optic sensor amplifier. The FU Series offers a wide variety of options including thrubeam, reflective, retro-reflective and definite reflective sensing heads. Additional options include those with high environmental resistance, integrated brackets, and those designed specifically to detect difficult targets.

    Features
    Hex-shaped Heads

    Hex-shaped sensor head

    Easy, trouble-free mounting. Unbreakable fiber exits the housing at a right angle, like a periscope.

    ToughFlex Heads

    Toughflex sensor head

    A flexible stainless steel jacket protects the fiber from daily wear.

  • Digital Fiber Optic SensorsFS-N series

    FS-N series - Digital Fiber Optic Sensors
    Features
    Complete Setup in Just One Click

    Complete Setup in Just One Click

    An entirely new concept in setup ease. Just one click calibrates the sensitivity and resets the display.

    Automatic Maintenance

    Automatic Maintenance

    The automatic maintenance function detects light intensity reduction due to dirt or misalignment, and returns the sensor to its original display state. This feature can cancel the effects of the ambient environment, enabling the sensor to continue to perform highly accurate detections.

  • Digital Fiber Optic SensorsFS-V30 series

    FS-V30 series - Digital Fiber Optic Sensors
    Features
    Product Features

    Fiber Optic Sensor Features

    High power optic sensors for stable detection in harsh environments. Amazing response speed of 33μs.

  • Manual-Calibration Fiberoptic SensorFS-V/T/M series

    FS-V/T/M series - Manual-Calibration Fiberoptic Sensor
    Features
    Product Features

    FS01 Series: With Dual monitoring system

    Dual monitoring system utilizing a digital LED indicator and bar LED. Available in 3 calibration variations: Manual, automatic and hybrid calibration type.

    Product Applications

    FS01 Fiber optic sensor applications

    Superb amplifier and sensor setup resulting in enhanced stability for previously difficult detection applications.

Discontinued Series

What is a Fiber Optic Sensor?

A fiber optic sensor is an instrument that measures light from an LED (or other device) for detection purposes. These devices are most commonly used in factory automation environments.
Fiber optics feature two distinct components, an amplifier and sensor heads. The amplifier contains "the brains" of the sensor as well as the light source. The fiber optic cables/heads are used solely to transmit and receive the light.
Because there are no electronic components in the sensing heads, fiber optic sensors are commonly used in tight spaces, harsh environments, or simply where other sensors cannot be used.

Principles of fiberoptic sensors

Fiber optic sensors detect target conditions by transmitting light onto or across a target and measuring the increase or decrease of light returned.

Optical principles of fiberoptic sensors

The properties of light include straightness, refraction, and reflection. Fiberoptic sensors utilize these properties to enable various types of detection.

Specular reflection and retro-reflection
Specular reflection is reflection where the angle of incidence and angle of reflection of light are the same on a flat surface such as a mirror or glass. Retro-reflection is reflection where light projected at two reflective surfaces mounted at right angles is reflected off both surfaces and travels in the opposite direction of the incident light.

Refraction
Light normally travels straight through air or water. However, if the light passes through a boundary surface between materials with different refractive indices, the direction of travel changes. This phenomenon is referred to as refraction.

Polarization
Light waves normally oscillate in a variety of directions. Polarization is when oscillation is limited to one direction. Devices that restrict the oscillation direction are called polarizing filters. However, polarizing filters that restrict oscillation in a specific direction will block light with oscillation restricted in the perpendicular direction.

Detection principles of fiberoptic sensors

There are several types of fiber optic sensors. Detection methods include thrubeam, reflective, retro-reflective, and definite-reflective. Each method is used for different applications and targets.

Thrubeam models
Thrubeam models include a transmitter and receiver installed opposite each other. As the target passes between the transmitter and receiver, light is blocked, and detection is performed by determining the decrease in the received light intensity. Detecting distances range from a couple inches to several feet. Stability is achieved with high resistance to dirt and dust. Opaque targets can be detected regardless of reflectance, color, or material.

Reflective models
With reflective models, light emitted from a transmitter hits the target and the reflected light is returned to the receiver. Target detection is based on the amount of reflected light returned to the receiver. Because the detecting distances range from a couple inches to several meters, adjustment during installation is incredibly easy. Detection is possible even for small targets.

Retro-reflective models
Retro-reflective models detect the amount of light returned from a reflector installed opposite of the transmitter. The light from the reflector is blocked as a target passes through, reducing the amount of received light. Targets are detected by measuring this reduction. Installation is easy with detecting distances ranging from a couple inches to several feet. Detection is also less likely to be affected by target color or angle, and opaque targets can be detected regardless of shape, color, or material.

Definite-reflective models
In definite-reflective models, light is sent and received at a specific angle creating an intersecting point at a fixed distance. This ensures detection is performed only where the optical axes intersect. These models are often used when the target is relatively close and background suppression is important.

Diffuse reflective models
With diffuse reflective models, light is emitted and the target is used to reflect light back to the sensor. The transmitter and receiver or housed together, eliminating the need for a separate receiver or reflector. Any reflective target can be detected and colors can also be differentiated.

Benefits of Fiber Optic Sensors

Benefit 1 of Fiber Optic Sensors: Highly flexible installation

Fiber optic sensors are compact because the detection circuit is located in the amplifier, allowing for detection even in narrow spaces. Installation and adjustment are easy and the devices have high environmental resistance—just a few of the advantages offered by fiber optic sensors.

Fiber optic heads are compact and ideal for mounting in tight spaces. Additionally, the cable connecting the fiber optic heads are highly flexible, allowing for the cable to be easily routed. For example, mounting on a robotic arm is common for fiber optics.
Also, because the fiber units do not house any electrical circuits, they are resistant to temperature, humidity, vibration, impacts, and fluids. This ensures high operation reliability even in locations where electrical noise is generated.

Benefit 2 of Fiber Optic Sensors: Detection regardless of target material, with fast response times

Most fiber optic sensors use light from an LED to detect targets, enabling detection of a wide variety of materials. This also allows for faster response times compared to other sensors.

A wide variety of target materials can be detected including metal, glass, plastic, wood, and even liquid. Stable detection is also possible for low-reflectivity target materials such as rubber and sponges. This is achieved by increasing the amount of emitted light. Some models also include a switch for adjusting the light intensity to help solve light intensity saturation problems caused by too much light. Light is emitted from the fiber unit at high speeds, and the fiber optic sensor has no moving parts, significantly reducing both operation and response times.

Benefit 3 of Fiber Optic Sensors: Detection methods for specific targets

There are several types of detection methods with fiber optic sensors, including thrubeam, reflective, retro-reflective, and definite-reflective. Each method uses an LED or other light source for non-contact detection. This prevents damage to both the target and the sensor.

There are several types of detection methods with fiber optic sensors, including thrubeam, reflective, retro-reflective, and definite-reflective. Each method uses an LED or other light source for non-contact detection. Non-contact measurement ensures targets are not damaged while also protecting the sensor.
Some fiber optic sensors are also capable of long-range detection by increasing the power of emitted light, while still having fast response times. This range of sensing options allow users to choose the right combination to best suit their specific needs.

Fiber Optic Sensor Case Studies

Target detection in high-temperature environments

In high-temperature environments such as drying rooms, sensors with detection circuits may be damaged as the detection circuit heats up. FU Series fiber units, however, do not have detection circuits in the sensing head. Heat-resistant fiber units can handle temperatures of up to about 300°C (572°F).
The high-output FS-N40, with its newly developed NEO Parabolic LED, offers 7.5 times the received light intensity of conventional models. Meanwhile, the TERA power mode offers 220 times more power with the flick of a switch. These features enable long-range detection with no influence from heat.

Product drop detection

When using a sensor to detect the number of dropped steel balls (or something similar) the position of the targets will not be consistent. Changes in light intensity due to dust or dirt can also result in false detections. Only sudden light intensity changes caused by a passing target should be detected.
The FU-E40 Fiber Unit (FU Series) uses an area light to detect targets passing in various positions. The amplifier makes it possible to ignore gradual changes in light intensity caused by dust or dirt, ensuring that only sudden light intensity changes caused by a passing target are detected. Also, because the light is focused, this sensor can be used in crowded or tight spaces.

Frequently Asked Questions About Fiber Optic Sensors

Photoelectric sensors use light to detect the presence or absence of targets. Such sensors usually use an LED as the light source and consist of two parts: a light transmitter and a light receiver. As the target passes between the transmitter and the receiver, the reflected or blocked light is converted into an electrical signal and output.
Although fiber optic sensors detect targets in basically the same way, the amplifier and the head are connected by a fiber unit. Because the amplifier that outputs the light and the transmitter and receiver are separated, these devices can be combined in various ways, so detection can be performed in various environments. The fiber unit is also incredibly thin and compact, so installation is possible in a wider variety of locations.

Detection errors are more likely when detecting small targets. Slower response speeds may also prevent detection of small, dropped targets.
To prevent such errors, select a thrubeam sensor with a small optical axis or use a slit to reduce the optical axis when detecting small targets. Doing so will stabilize detection while still providing an area large enough to capture the target.
The FU-E40 Fiber Unit (FU Series) uses an area light to detect targets passing in various positions. The amplifier makes it possible to ignore gradual changes in light intensity caused by dust or dirt, ensuring that only sudden light intensity changes caused by a passing target are detected. Also, because the light is focused, this sensor can be used in crowded or tight spaces.

Knowledge About Fiber Optic Sensors

This site provides basic information to better understand sensors. Nine varieties of sensors are highlighted based on operating principle, structure, characteristics, and variations. Learn all about sensors starting from the basics.

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