Pepperl+fuchs Phototalk

Small light spot size: In this episode, we get back to the basics and discuss photoelectric sensors with a small light spot. --Photoelectric sensors with a laser emitter are very common in the industrial sensor world. They typically produce a very focused and small light spot. --What are the advantages and disadvantages of a small light spot?

Distance Measurement with light: PRT (Pulse Ranging Technology) is a distance measurement technology from Pepperl+Fuchs. But does PRT share similarities with other technology terms like LiDAR, LaDAR, time-of-flight, etc…? --What is time-of-flight? --Is PRT this type of technology? --Where does the term LiDAR and LaDAR come from? --Is Pulse Ranging Technology this type of technology? View Lidar image recorded using the R2000 distance measurement sensor.

Fiber optic sensors consist of a sensing amplifier and small fiber optics cables.  The amplifier houses the emitter, receiver and are where any adjustments are made.  The fiber optic cables connect to the amplifier and guide emitted light from the amplifier to the sensing area.  Because of their small size and variety of sensing tips, fiber optic cables are perfect for applications where conventional sensors don’t fit. --Fiber optic cables are available in both diffuse and thru-beam styles --Fiber optic cables can withstand extreme heat and harsh environments --Large variety of sensing tips available

Divergent mode sensors and clear object retroreflective sensors are two photoelectric sensor types used to detect clear or opaque objects.  Divergent sensors have a wide light spot that spreads out over the object rather than burning through the clear or opaque objects.  Clear object retroreflective sensors are taught the light level to a reflector with no object present.  A special low hysteresis circuit in the sensor detects small changes in the light level when a clear or opaque object is present. --Divergent sensors have a much larger light spot compared to a standard diffuse type --Many clear object retroreflective sensors have 3 adjustable contrast or sensitivity levels --Clear object retroreflective sensors can function just like a standard polarized retroreflective sensor

Background suppression sensors contain an emitter and two receiver elements, a near receiver and far receiver, all in the same housing. Based on triangulation, objects in the foreground are detected when emitted light is reflected onto the near receiver and background objects are suppressed when emitted light is reflected onto the far receiver.  Because objects are detected based on which receiver the light is reflected on, black and white targets are detected at virtually the same distance.  Background evaluation sensors function just the opposite and use the background as a reference.  Objects are detected when they pass between the sensor and background and light is reflected onto the near receiver or in the case of curved surfaces, on neither receiver. --Background suppression sensors detect objects based on triangulation --Background suppression sensors detect black and white at almost the same range --Background evaluation sensors can accurately detect irregular shaped objects

Diffuse mode sensors contain both an emitter and receiver in the same housing.  Objects are detected when emitted light reflects off an object and is returned to the sensor.  If the returned light is above a certain threshold, the output switches.  Two variations of diffuse mode sensors are convergent and divergent. Convergent mode sensors are more efficient than a standard diffuse sensor because the emitter and receiver are focused at an exact point in front of the sensor.  Convergent mode sensors are able to detect objects at this focus point plus or minus some distance.  Divergent sensors function just like a standard diffuse but have a large light spot.  The large light spot is particularly good for sensing clear and opaque objects because the light spot spreads out over the object rather than burning through. --Diffuse sensors are greatly affected by a targets surface and color --Convergent sensors have a high amount of excess gain at their focal point --Divergent sensors

Contrast Sensors vs. Color Sensors: In this episode, Helge and Michael note that even though a contrast sensor and color sensor are both special variations of a diffuse mode sensor, the fundamental principles of operation between the two are drastically different. --A contrast sensor is built for speed. They contain superfast hardware for high switching speeds and lightning-fast response times --A color sensor is built for detecting minute color variations between multiple color samples

In this episode, Helge and Michael give an overview of color sensors. A color sensor separates light reflected from a sample into several portions of the visible spectrum and returns an intensity value for each of these sub-spectra. The distribution of these values reveals the spectral properties—and thus the color—of the target. --A color sensor can differentiate between multiple colors with high precision --Commonly referred to as a Color-Mark Sensor --A color sensor is capable of detecting very minute color variations

In this episode, Helge and Michael discuss contrast sensors. A contrast sensor is a special type of diffuse mode photoelectric sensor used to detect a difference between two colors. These 2 colors are commonly referred to as mark and background. The detection process evaluates the brightness, or light level received, from a sample presented to the contrast sensor. For each new sample presented, the contrast sensor compares the new sample value to what it was taught, to determine if it is more like the mark or more like the background. --High-efficiency sensor used to detect a difference in brightness between 2 colors - Mark and Background --Commonly referred to as a Print-Mark Sensor --Contrast sensors provide lightning fast response times

Pulse Ranging Technology (PRT) is a true time-of-flight distance measurement technology. Photoelectric sensors with PRT emit short, intense pulses of light and measure object distance based on the time-of-flight of the reflected light pulses. The intensity of a PRT light pulse provides many key advantages over other distance measurement technologies. -True time-of-flight distance measurement technology -High intensity light pulses emitted up to 250k times / second -High operating range and noise immunity

A photoelectric sensor with Multi-Pixel Technology (MPT) is a diffuse mode sensor with a measuring core. Photoelectric sensors with MPT measure the distance to an object based on the triangulation angle of the reflected light to a large array of internal receiver elements. This array of receiver elements or pixels allows the sensor to detect objects within a defined distance with very high precision while still ignoring anything outside of this area: -Diffuse mode sensor with a measuring core -Triangulation of reflected light a receiver array -Objects outside of a user-defined sensing area are effectively suppressed

Pepperl+Fuchs’ 4-in-1 photoelectric sensors provide 4 output possibilities in just one device.  Each photoelectric sensor provides one or two outputs that detect the connected load and sinks (NPN) or sources (PNP) current automatically. This reduces inventory costs and wiring time as one sensor can operate as normally open (N.O.) or normally closed (N.C.) NPN or PNP. -Output automatically selects NPN or PNP -One sensor - 4 possibilities: NPN or PNP, N.O. or N.C. -Reduces inventory costs and wiring time

The two most common light source types for photoelectric sensors are LED and laser.  Both LEDs and lasers are available in visible red or infrared types.  Additionally, lasers are divided into different classes based on their power and wavelength.  With photoelectric sensors, the advantages of using laser light sources over LED are: --Small, concentrated light spot --Long ranges as compared to LED --High burn-through ability

A photoelectric sensor uses an oscillator to modulate its light source.  The modulated light source transmits infrared or visible red light.  The light is returned or reflected back to the sensor and is detected by the receiver.  If the returned light is above a certain threshold, the sensor’s output changes states.  The output of a 4-in-1 sensor can be either: --PNP light on --PNP dark on --NPN light on --NPN dark on

In this first episode of PhotoTalk, the basics of photoelectric sensors are covered, starting with: What is a photoelectric sensor?  A photoelectric sensor is a device that detects the presence or absence of light.  Not just ordinary room or sun light, but its own transmitted infrared or visible red light.  Photoelectric sensors are available in the following light source types: - Visible red LED - Infrared LED - Visible red laser - Infrared laser