Detection sensors and contrast sensors

Detection sensors and contrast sensors detect and recognize colors, grayscale and luminescence printed matter. This includes color-coding or labels on an object. When a contrast sensor passes the set teach-in point between the background and print mark, color coding or label, the contrast sensor or detection sensor recognizes this and indicates the precise position of the print mark, color-coded or label.

Precise position determination

Contrast sensors and detection sensors are used for accurate positioning in printing presses, packaging machines, labeling machines and in the beverage, pharmaceutical and food industries. Contrast sensors are characterized by the low contrast resolution, high switching reliability with small contrast differences, fast response times and insensitivity to fluctuations.

Contrast sensors and color sensors

Where contrast sensors function on the basis of a similar principle, color sensors have a high reliability with multi-colored backgrounds. A color sensor is set via the teach-in function and detects RGB color channels based on the set values.

Principles of contrast sensors:


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Contrast sensors - F 25-series - SensoPart
FT 25-RA-series sensors - SensoPart

Detection sensor F 25-series for every application

F 25: For every application the right sensor

Colour sensors work according to the principle of energetic reflection, in which the partial spectra of red, green and blue are evaluated separately. The three colors are transmitted one after the other and the amount of light that is reflected by the target object is registered individually at the FT 25-C sensor.

Contrast sensors

Contrast sensors work according to the principle of energetic reflection and detect gray scale differences on matt, glossy or transparent objects and surfaces. The F 25-series photocells are convincing not only by the wide range of variations, but also by many useful details that make the difference in an application. All F 25 sensors from SensoPart are available as laser and LED versions.


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Detection sensor for reflective and shiny objects

The FT 25-RHD is equipped with an ASIC microchip for very high accuracy and unique background suppression. Even a reflective or glossy background has no effect on the detection of an object by this sensor. This guarantees very stable operation of the machine.

Detection up to 400 mm

Despite the compact design, the FT 25-RHD detection sensor is able to detect materials or products at distances up to 400 mm! This makes the detection sensor extremely suitable for difficult conditions with limited installation space.

Minimal link hysteresis

What makes the FT 25-RHD absolutely unique is the minimum link hysteresis on black compared to white. This makes the sensor easy to use, even in places where a large variety of colors occurs and where precise switching is required. At a distance of 100 mm, for example, this sensor has a complete color-independent switching point. This sensor beats all other sensors with ease.


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Detection with detection sensor FT 25-RHD - SensoPart
Analog sensors for distance measurement - SensoPart

Detection sensor for distance measurement

In addition to an analog voltage output 1… 10 V, the compact distance sensor FT 25-RLA also has a switching output with two adjustable switching points as a window mode for two-point control. Thanks to the compact design 34 x 12 x 20 and the simple teach-in operation, the sensors are very suitable for simple measurement and control tasks at distances up to 200 mm (20-100 mm FT 25-RLA / 20-200 mm FT 25-RA ) with a resolution from 0.12 mm. The FT 25-RLA sensors are available in both LED and laser versions. Read more about analog sensors for distance measurement.

Areas of application: FT 25-RLA distance sensors:

  • Control of sag monitoring (LED/laser)
  • Determination of the roll diameter of an unwinding machine (LED/laser)
  • Stack height measurement, double layer detection and height measurements in the wood processing, packaging and processing industry (LED/laser)
  • Distance measurement and positioning on robot grippers in "Pick & place" applications (LED/laser)
  • Small partial measurement, e.g. O-rings and electronic components (laser)
  • Measurement on multicolored and high-contrast objects, e.g. packages (laser)


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Presence check and object detection - Photocell without reflector - SensoPart FT 25-RV

Vision and sensors - SensoPart

More then 100 models!

There are editions with adjustable and fixed switching distance. Because of the different connection and switching distance like I/O-link and auto-detect-editions, there are more than 100 models available. All models have a compact housing form.


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F 25 series sensors with io link

IO-link is the first standardized IO technology (IEC 61131-9) worldwide for communication with sensors and actuators. The SensoPart series F 25 LED is now equipped with IO-Link as standard.

With IO-link it is possible to read product parameters from the sensor to a higher level. These can be parameters such as measured value, switching status, signal quality or operating hours. Read more about IO-link.

Sensors and photocells with IO-Link - SensoPart
F 25-series sensor - SensoPart

Miniature housing, maximum performance

The FT 25-W contrast sensor uses white light and has a very small and accurate rectangular light spot (1 x 4 mm²). This also makes it possible to detect very small printed markings and colored objects with weak contrast differences. The sensor can be parameterized during running machines and during the teach-in process, the switching threshold automatically adjusts to the object, color and background.

High switching frequency 25 kHz

Due to the high switching frequency (25 kHz) of the FT 25-W and FT 25-RGB contrast sensors, the front edges of printed markings are very precisely detected and achieve maximum positional accuracy. This also ensures reliable sensor switching behavior, even at very high processing speeds. The FT 25-RGB contrast sensor has three different transmissions LEDs (red, green and blue). During teach-in, the sensor evaluates the taught-in contrast and then automatically selects the ideal transmission color (red, green or blue) for the contrast present. As a result, even extremely low contrast differences can be reliably detected.


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Features F 25-series sensors

  • Detection of objects, color, contrast and measuring distance.
  • Easy in use because of tech-in-principal or fixed settings
  • Reliable because of suspression of envoirement light.
  • Clear LED-designation (visible from each side)
  • Many connection options (M8, M12 pigtail, fixed cable


FT 25-RV miniature sensor | SensoPart

F25 series Proximity switch background suppression