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Detection of Transparent Objects

The detection of transparent objects can often be a real challenge due to their light transmission. Different technologies may work better under certain conditions or may prove more effective for specific materials. An overview of possible sensor solutions is provided here.

The Biggest Challenges in Detecting Transparent Objects

Transparent glass container in the pharmaceutical industry

Transmission Rate of Transparent Objects

Challenge: Transparent objects have a high degree of transmission, which causes the light emitted by the sensor to pass through objects. This minimal absorption of the light intensity makes detection more difficult for the sensor.

Solution:

Retro-reflex sensors for transparent objects, laser distance sensors ToF and fork sensors enable reliable detection even in fast applications due to their high sensitivity and switching frequency
Ultrasonic distance sensors and ultrasonic fork sensors for label detection detect the object regardless of transparency or color

Resistance to Contamination

Challenge: Dust and contamination affect sensor reliability in industrial production environments. This results in recurring maintenance intervals and the sensors having to be taught in again.

Solution:

Thanks to the dynamic readjustment of the switching threshold, taught-in retro-reflex sensors for transparent objects and reflex light barriers continuously adapt to varying ambient conditions
For applications in particularly dusty environments, ultrasonic distance sensors are suitable.

Medical ampoules in a pharmaceutical factory

Interference Effects with Irregularly Shaped Objects

Challenge: Irregular shapes and surfaces can cause interference, especially with moving objects with shiny surfaces, curves or edges. This can lead to uncontrolled light reflection and transmission and can impair the sensor system.

Solution:

Retro-reflex sensors for transparent objects are suitable for glossy surfaces due to their single-lens optics
The sonic cone of ultrasonic distance sensors detects large areas and also reliably detects irregular shapes

Discover our portfolio of reflectors, including those with recommended microstructure for detecting transparent objects!

Ultrasonic Sensors

Ultrasonic sensors use high-frequency sound waves. They determine the time interval between the emitted and received signal of ultrasonic pulses to calculate the distance to the target object. They can reliably detect objects, from dark to transparent, thanks to color-independent sound reflection. This makes them versatile, especially for applications that require precise object detection.

Presence check of glass bottles with retro-reflex sensor

Retro-Reflex Sensors for Transparent Objects

Retro-reflex sensors for transparent objects work with red light to detect even weak absorption of the signal level by the object. They have a function for dynamic readjustment of the switching threshold, which is automatically adjusted in the event of contamination, temperature fluctuations or aging.

Through-Beam Sensor for PET Selection

Through-beam sensor for PET selection distinguish transparent PET from other transparent materials, such as glass and opaque objects. This is made possible by measuring the material-dependent signal strength of polarized and unpolarized light, which can be used to reliably identify different objects.

Reflex Light Barriers

Reflex light barriers use red light to detect objects by detecting the intensity of the backscattered light, as well as the distance to a previously taught-in reference background. It is advisable to use a static reference background, such as a fixed stainless steel machine part, for the application of reflex light barriers.

Clearance check using laser distance sensor time-of-flight

Laser Distance Sensors Time-of-Flight

The latest generation of wintec laser distance sensors uses Dynamic Sensitivity (DS) technology. The sensor delivers precise distance values to the object by emitting very short laser light pulses in the nanosecond range and through statistical evaluation of the signals. This method allows reliable results even with weak signals.

Fork Sensors

Fork sensors rely on laser light using the through-beam principle. Even small changes in intensity can be detected by the receiver thanks to the precisely focused light beam and high detection accuracy. This enables reliable detection of clear glass, while remaining insensitive to ambient light.

Wide Range of Applications for All Challenges

Note: Simply click the relevant icon to learn more about the application.

Food industry

Pharmaceuticals industry

Packaging technology

Cosmetics industry

Logistics

Deposit return machines

Beverages industry

Electric Mobility

Functional Principles for Detecting Transparent Objects

	Functional principle	Benefits	Products
	Ultrasonic distance sensors	Adjustable sonic cone width for detecting transparent objects with complex shapes Material and color independent Resistant to contamination
	Ultrasonic fork sensor for label detection	The emitter and receiver are in the same housing Material and color independent Resistant to contamination
	Retro-reflex sensors for transparent objects	Reliable detection of transparent objects Reliable process thanks to dynamic readjustment of the switching threshold
	Fork sensors	The emitter and receiver are in the same housing Reliable detection of even the smallest objects and clear glass Ideally aligned transmitter-receiver axis at the factory
	Through-beam sensor for PET selection	Distinguishing clear PET from other transparent materials and opaque objects Two switching outputs for outputting the relevant switching states

Functional principle
Ultrasonic distance sensors	Ultrasonic fork sensor for label detection	Retro-reflex sensors for transparent objects	Fork sensors	Through-beam sensor for PET selection
Benefits
Adjustable sonic cone width for detecting transparent objects with complex shapes Material and color independent Resistant to contamination	The emitter and receiver are in the same housing Material and color independent Resistant to contamination	Reliable detection of transparent objects Reliable process thanks to dynamic readjustment of the switching threshold	The emitter and receiver are in the same housing Reliable detection of even the smallest objects and clear glass Ideally aligned transmitter-receiver axis at the factory	Distinguishing clear PET from other transparent materials and opaque objects Two switching outputs for outputting the relevant switching states
Products

Functional Principles for Detecting Semi-Transparent Objects

	Functional principle	Benefits	Products
	Reflex light barriers	Saves time and costs during installation as no reflector is required Enables applications where reflector mounting is not possible for process-related reasons Reliable process thanks to dynamic readjustment of the switching threshold
	Laser distance sensors ToF	For applications with a large working range Precise edge and object detection using a compact laser light spot Bright laser light spot for simplified alignment and initial start-up Saves time and costs during installation as no reflector is required

Functional principle
Reflex light barriers	Laser distance sensors ToF
Benefits
Saves time and costs during installation as no reflector is required Enables applications where reflector mounting is not possible for process-related reasons Reliable process thanks to dynamic readjustment of the switching threshold	For applications with a large working range Precise edge and object detection using a compact laser light spot Bright laser light spot for simplified alignment and initial start-up Saves time and costs during installation as no reflector is required
Products

Downloads for Transparent Object Detection

Ultrasonic Sensors Product Flyer (976 KB)

This document contains the product flyer for the ultrasonic sensors.

der wintec. Brochure (3 MB)

This document contains the brochure on long-range laser distance sensors with wintec (wenglor interference-free technology).

PNG//smart Product Flyer (1 MB)

This document contains the PNG//smart sensors product flyer. Photoelectronic Next Generation stands for a new age of smart photoelectronic sensors.

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