FAQs on Fiber-Optic Sensors
Fiber-optic sensors detect objects by directing light to the test object via a fiber-optic cable and analyzing the change in light intensity reflected by the object.
They are highly resistant to extreme conditions such as high temperatures, humidity and aggressive chemicals, making them ideal for demanding industrial environments.
A fiber-optic sensor consists of a fiber-optic amplifier that contains the light source and processing unit, as well as sensor heads and fiber-optic cables that transmit and receive the light.
Plastic fiber-optic cables are particularly suitable for use in confined spaces, as they are more flexible and save space. Glass fiber-optic cables, on the other hand, are more resistant to high temperatures and harsh chemicals, making them more suited for more demanding environments.
Multi unit mode allows several sensors to be connected to each other and their evaluation to be coordinated without affecting each other. Only the master requires a power supply. This simplifies installation and improves efficiency.
The alignment mode helps to accurately align the fiber-optic cables by visualizing signal strength by pulsing the transmitting light. Similar to parking sensors in the car, the pulse frequency increases the stronger the signal received. This enables efficient and precise setup even with greater distances between the emitter and receiver.
The aperture angle determines how much light is scattered after exiting the fiber-optic cable. A large aperture angle allows detection of nearby objects, but reduces the range. In this case, lenses can be used to focus the light and thus increase the range or detect the smallest parts.
A fiber-optic amplifier amplifies light signals transmitted by fiber-optic cables and records physical variables such as pressure, temperature and position of test objects. In industrial automation, it evaluates the amount of light received and checks whether a switching condition is in place.
Excessive bending or kinking of a fiber-optic cable can damage the fiber optic in the fiber-optic cable. These microcracks in the fiber core can cause increased attenuation or even total loss of the light signal, resulting in sensor malfunction. Dynamic readjustment makes it possible to compensate for these effects to a certain extent.
The length of the fiber-optic cable has no influence on the switching speed, as this is determined by the light speed. However, a longer cable length may affect detection performance as it may result in slightly increased signal attenuation.
An optical fiber is a fiber-optic cable that transmits light through total reflection within a light-conducting core. It consists of a core that conducts light, a coating to optimize light refraction, and a jacket to protect the core from external influences.
Dynamic readjustment uses a quasi-fixed threshold value, which is adjusted to compensate for contamination or changes. In contrast, jump detection evaluates signal changes without a fixed threshold value, which makes it particularly suitable for variable or changing objects.
There are jacket materials in plastic PVC, stainless steel and silicone. PVC is a cost-effective option for standard applications, stainless steel offers high protection against mechanical stress, and silicone is particularly resistant to aggressive media with maximum leak-tightness.
A larger diameter of the light-conducting core allows more light to pass through the cable. This improves the sensor’s range and ability to reliably detect even deep black objects.
Yes, fiber-optic sensors are ideal for areas with strict EMC requirements, as they transmit their signals between the amplifier unit and the interrogation position purely optically and are therefore not affected by electromagnetic interference.
Fiber-optic sensors are always energetic sensors that react to received light. Various measures are taken to ensure that sources of interference are largely suppressed. Sensors of the same family can influence each other if the query points are positioned in an unfavorable orientation or closely together. For this reason, wenglor offers different technologies to reduce or eliminate this mutual interference.
