Detecting Clear and Reflective Targets
Detecting transparent or shiny objects is one of the most challenging sensor applications. Variations in target shape, size, material, color, and translucence can complicate accurate detection. For example, the light from the sensor can burn through a target or be reflected away erratically.
Furthermore, not all clear and reflective materials attenuate light in the same way; for example, a glass bottle will attenuate light differently than a plastic bottle, and variations in the contours and grooves of a target can also cause light to reflect in unpredictable ways.
In addition, high speed conveyors and harsh washdown environments found in many clear object detection applications present additional challenges.
Two common technologies for clear object detection are: laser distance sensors and retro-reflective photoelectric sensors (photo-eyes).
Laser distance sensors are an extremely effective solution for clear object detection, including detecting small targets. Laser measurement sensors with dual mode can detect changes in both distance and light intensity to reliably identify clear objects; these sensors do not require a reflector or receiver unit, which allows for flexible mounting as well as reduced inventory and maintenance costs. In addition, laser sensors are available with response speeds as fast as 0.5 ms for detecting fast-moving targets.
Depending on your application, you might also consider retro-reflective photoelectric sensors. A photoelectric sensor designed for clear object detection is often a cost-effective solution for detecting larger clear objects with larger gaps between them, where the precision of a laser sensor is not necessary. Similar to laser sensors, photoelectric sensors are capable of very fast response times for high speed applications. It is important to consider, however, that these sensors do require mounting a reflector.
Choose Laser Distance Sensors With Dual Mode
A premier solution for clear and reflective object detection is a laser measurement sensor with dual mode. The small, visible laser spot allows for easier sensor alignment, greater precision, detection of smaller objects, and detection of smaller gaps between objects compared to an LED-based sensor. In addition, laser sensors with dual mode do not require a reflector for more flexible mounting and reduced inventory and maintenance costs.
In addition to measuring distance, laser sensors with dual mode also detect changes in light intensity from a stable background condition. In other words, a laser distance sensor with dual mode can detect not only when the target is present within a certain distance but also when it returns a certain amount of light to the receiver.
For this to work, a stable reference surface must be taught, and the distance and intensity of the reference surface are recorded and used as a baseline. The presence of a transparent or highly reflective object entering the sensing range of the beam alters the perceived distance and light intensity from the background condition.
Choose Photoelectric Sensors with Polarized Coaxial Optics
Retro-reflective sensors are the most commonly used LED-based photoelectric sensor in clear object detection applications. Each sensor houses an emitter and a receiver. The emitter directs a beam of light to a reflector which redirects the light beam back to the receiver. An object passing between the sensor and reflector will either block or attenuate a perceivable percentage of the emitted light.
Retro-reflective photoelectric sensors with a coaxial optical design emit and receive light along a single narrow axis. This optimizes clear object detection by dramatically reducing the risk of false detection from reflected light. Sensors using this technology have a small bright spot that simplifies sensor alignment and enables precise leading edge detection.
Photoelectric sensors with polarizing filters will emit and detect light waves of a specific polarization, ignoring all other light waves. This further reduces the risk of false detection caused by reflected light. Learn more about polarized coaxial optics for detecting transparent objects.
Choose Sensors Rated IP69K
Many clear object detection applications occur in food and beverage processing applications, which are often subjected to frequent high pressure, high temperature washdown and/or chemical clean-in-place processes to ensure a safe food chain.
Sensors rated IP69K are ideal for these environments, as they have been tested to ensure reliable operation even when subjected to frequent cleaning. A rugged, stainless steel sensor is a popular choice, and in some applications, a sensor made with food-grade materials may be required. Learn more about IP ratings and what they mean.
In some cases, plastic sensors can also be used, as long as they are properly sealed. In addition, some photoelectric sensors can see through an aperature, which allows them to be shielded for use in washdown and hygienic environments.
IP69K Laser Distance Sensor, 25-610 mm Range
I sensori laser di distanza, robusti e versatili, offrono prestazioni eccellenti e sono in grado di rilevare a distanza variazioni inferiori al millimetro.
- Disponibili nei modelli digitale, analogico (da 0 a 10 V o da 4 a 20 mA), oggetti trasparenti e IO-Link
- Campo di misura affidabile da 25 mm a 610 mm
- Rileva bersagli in un'ampia varietà di colori, materiali e superfici, in base alla distanza
- Con la doppia modalità TEACH (intensità + distanza), è l'ideale per applicazioni di verifica errori e consente il rilevamento di oggetti trasparenti senza catarifrangenti
- Robusta custodia con grado di protezione IP69K e acciaio inossidabile con approvazione FDA
Laser Distance Sensor, 9.5 cm - 2 m Range
Il laser di soppressione dello sfondo Q5X è un sensore potente con funzionalità di risoluzione dei problemi, racchiuso in un dispositivo conveniente con custodia rettangolare in linea con gli standard del settore.
- La portata va da 9,5 cm a 2 m
- L'eccesso di guadagno eccezionalmente alto permette al sensore di rilevare in modo affidabile gli oggetti più scuri (bersagli neri con riflettanza
- Rilevamento affidabile di bersagli neri su sfondo nero, bersagli neri su sfondo in metallo lucido, oggetti riflettenti e trasparenti, imballaggi multicolori e bersagli di tutti i colori
- La modalità DUAL TEACH consente la misurazione contemporanea di distanza e intensità luminosa, per risolvere le applicazioni più complesse
Photoelectric Sensor for Clear Object Detection
La custodia universale con ottica filettata di 18 mm è il ricambio ideale per centinaia di sensori di tipo diverso. I modelli per il rilevamento di oggetti trasparenti utilizzano l'algoritmo "Clear Tracking" che compensa automaticamente gli effetti dell'accumulo di polveri e delle variazioni di temperatura ambientale, aumentando l'affidabilità e la durata del sensore.
- Custodia universale, con ottica filettata da 18 mm o supporti laterali
- Valida alternativa a centinaia di altri sensori
- Grado di protezione IP67, conforme a NEMA 6 per condizioni ambientali difficili
- Portate fino a 20 m
- Presenta un LED brillante per l'indicazione dello stato
- Modelli COD (Clear Object Detection) specificatamente progettati per il rilevamento di oggetti trasparenti.
