Optical sensors
Advantages for you
- Flexible implementation: Complete series with all operating principles, each in identical and installation-compatible housings. Depending on the respective application, it is possible to choose between throughbeam photoelectric sensors, retro-reflective photoelectric sensors and diffuse sensors
- Housing: New, compact housing (dimensions W x H x L: 11 mm x 32.4 mm x 20 mm) – installation-compatible with previous series – ideal for tight installation spaces. Certified with degree of protection IP 67 and ECOLAB
- Attachment and mounting: Fast attachment and easy mounting thanks to metal inserts with M3 thread
- Commissioning: All-around visible 360° indicator LEDs for easy installation and status display. Fast alignment thanks to homogeneous and easily visible light spot
- Optimal configuration: Easy alignment and adjustment to the application thanks to a user-friendly potentiometer
- Safe detection of depolarizing objects: Optimized performance for the detection of reflective, shrink-wrapped, and shiny objects
- Electrical connection: Adaptation to individual customer requirements thanks to different connection options (e.g., cable, M8 connector, pigtail,...)
- Switching frequency: Improved switching frequency for throughbeam photoelectric sensors with up to 900 Hz and for diffuse sensors up to 1000 Hz for high performance and function reserve
- Tamper protection: Light/dark switching takes place in a tamperproof manner through polarity reversal of the (cable) wiring
Available operating principles:

Retro-reflective photoelectric sensor

Throughbeam photoelectric sensor

Diffuse sensor
Highlights

Cost effective mounting
The larger the number of sensors to be mounted on a conveyor line is, the more important the cost effectiveness aspect becomes with respect to the time and cost of mounting and commissioning.
The intelligent and simple fastening concept with two convenient M3 metal threads facilitates fast mounting for the user.
The small and compact housing design also makes installation in small spaces easier.
Depending on your individual preference or local installation situation, various connection types are available, e.g., with M8 connector, cable, or pigtail connector.

Fast and simple commissioning and alignment
360° indicator LEDs ensure easy installation and a clearly discernible status display. Simple alignment of the sensor through the easily visible light spot results in an additional time saving and therefore in a reduction in costs for the user. The new 5B series is also available as a model with potentiometer for better fine adjustment of the sensor. The sensor can thus be quickly and easily adapted to new application conditions.
Moreover, the light/dark switching of the switching output can be performed in a tamperproof manner via the wiring.

Reliable detection even with depolarizing objects
In conveyor and storage systems, it is often the case that pallets, cardboard boxes and other containers are wrapped in film, which can be challenging for the sensor system. With the new 5B series, we offer optimized models especially for this area of application. These sensors guarantee safe switching even with shrink-wrapped or shiny objects.
Application

Presence control in intralogistics using retro-reflective photoelectric sensors
Requirement:
In a logistics center, various containers and cardboard boxes are to be transported on roller conveyors that are positioned closely to each another. In addition, some cardboard boxes are shrink-wrapped in film. All objects must be reliably detected. During commissioning, the sensor must be fast and simple to install, align, and adjust. The light spot must be easy to see.
Solution:
With their compact, space-saving housing, the new 5B series sensors can be mounted directly on roller conveyors that are positioned closely to each other. The sensors are installed and securely mounted using convenient metal inserts with M3 thread. They are aligned quickly and easily using a homogeneous and clearly visible light spot as well as 360° indicator LEDs. Adjustment is user-friendly by means of a potentiometer. Performance optimized for the detection of shrink-wrapped and glossy objects ensures that they can be reliably detected.

Presence control in packaging systems using throughbeam photoelectric sensors
Requirement:
At a food manufacturer's plant, potato chips are packed in primary packaging. The packages are then transported further on a conveyor line where they are to be reliably detected. The light spot must be visible. The sensor state should also be visible from a distance of 2 m.
Solution:
The new sensor of the 5B series can also be mounted horizontally on the conveyor line, and the light spot is easy to see. Thanks to the bright 360° indicator LEDs, the sensor state is visible at all times, even at some distance away from the conveyor line. The advantage of the throughbeam photoelectric sensor is the very high function reserve. This ensures reliable detection even in very demanding environmental conditions, and it reduces the risk of system downtimes. Furthermore, the new 5B series has an optimized switching frequency of 900 Hz.

Presence control in intralogistics using a diffuse sensor
Requirement:
Packages are transported on a conveyor belt in a distribution system. A sensor is to check whether the packages are filled properly. Underfilled or overfilled cartons are to be removed.
Solution:
The HT 5B diffuse sensor looks down onto the conveyor belt and detects the cartons and their contents with rapid switching behavior of up to 1000 Hz. Alignment and fine adjustment are user-friendly by means of a potentiometer. Background suppression of the sensors ensures that only the object is detected and the conveyor belt is blanked out.

Detection of foil tears in battery cell production using a diffuse sensor
Requirement:
During the production of lithium-ion battery cells, rolls of copper or aluminum foil are compressed in a complex process (calendering). High and irregular speeds can cause tears in the foil sheet. If a tear occurs, sensors are to stop the process immediately in order to prevent damage to the machine.
Solution:
The HT 5B diffuse sensor with background suppression monitors the presence of the foil continuously and detects a film tear immediately. The sensor also detects very glossy or dark surfaces reliably and, thanks to its compact design, is suitable for installation in extremely confined spaces.
Technical properties
Parameters | Retro-reflective photoelectric sensors | Throughbeam photoelectric sensors | Diffuse sensors |
Switching frequency | 500 Hz | 900 Hz | 1,000 Hz |
Operating range | 6.5 m | 15 m | 700 mm |
Light source | Highly visible red light | Highly visible red light, infrared light | Highly visible red light, infrared light |
Operational control | Potentiometer | - | Potentiometer |
Housing dimensions | 11 x 32.4 x 20 mm | ||
Housing material | Plastic | ||
Degree of protection | IP 67 | ||
Compatibility of materials | ECOLAB | ||
Connection | M8 / cable / Pigtail |
Advantages for you
- Two complete series with all operating principles: throughbeam photoelectric sensors, retro-reflective photoelectric sensors and sensors for specific application areas and tasks
- Two housing designs for use in wet applications (Wash-Down) and hygiene applications (Hygienic Design)
- High-quality V4A (AISI 316L) stainless steel housing with smooth surface and the glass-free optics cover made of PMMA+ with special scratch-resistant coating prevent bacterial carry-overs
- Degree of protection IP69K for reliable functional capability and absolute leak tightness of the housing
- Thermal and chemical resistance (inspected and certified in accordance with ECOLAB, CleanProof+, JohnsonDiversey)
- FDA-compliant housing materials allow the sensor to be used in applications that come into direct contact with food
- Simple configuration and condition monitoring through IO-Link interface and variants with electronic range adjustment and measurement value output via IO-Link
Highlights

All components of the stainless steel sensors are especially designed for use in hygiene-sensitive areas. The conditions here are harsh, specially for electronic components. The regular cleaning of the systems with high-pressure cleaners and aggressive cleaning agents plays an important role. Changing between productive shifts and cleaning shifts also results in large temperature fluctuations that must not affect the functionality of the sensors.
- The stainless steel sensors made of V4A (AISI 316L) are absolutely dust-proof and waterproof and achieve degrees of protection IP67, IP68 and IP69K
- Especially smooth stainless steel surfaces with approximately 0.8 Ra prevent bacterial carry-overs
- The glass-free optics cover (scratch-resistant and non-diffusive plastic screen (PMMA+) with Indium protective coating) withstands harsh cleaning cycles and ensures reliable function
- The newly developed operational control is absolutely leak- and gap-free
- All materials are approved for direct contact with foods (FDA complaint)
- Chemical and thermal resistance, tested and certified by ECOLAB, CleanProof+ and JohnsonDiversey

The 55C series in Wash-Down design is suitable for use in the wet areas of production lines. With the special design, it is possible to thoroughly clean the entire system with all common cleaning agents and processes. The non-diffusive and chemically-stable materials of optics and operational controls in combination with the gapless design thereby prevent bacterial carry-overs. The closed housing technology and expanded temperature range guarantee that the systems will function properly for years to come.
The 53C series sensors in Hygienic Design are designed for use in sensitive hygienic applications such as pharmaceutical, cosmetic and food applications.
Building upon the base elements of the 55C series, this special development in housing design is even more systematically geared toward preventing bacterial carry-overs. The smooth housing contours without fastening holes thereby eliminate any deposits. The unique fastening concept ensures a gas-tight connection between sensor and machine.

The two sensor series in stainless steel miniature housing cover all operating principles: throughbeam photoelectric sensors, retro-reflective photoelectric sensors and diffuse sensors. The various models were developed for specific areas of application and provide ideal, reliable and economical solutions to challenges in production and packaging processes.
Our product highlights for special applications:
- Retro-reflective photoelectric sensors for glass and PET detection or film detection
- Laser retro-reflective photoelectric sensors for the detection of small parts
- Throughbeam photoelectric sensors for the detection of aqueous liquids and for fill level monitoring
- Diffuse sensors with background suppression with small light spot for the detection of glossy objects and objects with colored structure
- Diffuse sensors with background suppression with elongated linear light spot for the detection of transparent objects and of objects with openings, holes and punchings
- Diffuse sensors with background suppression with electronic range adjustment and measurement value output via IO-Link
- Diffuse sensors with background suppression with special V-optics for the detection of transparent, planar, reflective and high-gloss objects and of the top layers of trays of syringes or ampoules

The sensors of the 55C and 53C series are equipped with an IO-Link interface, whereby innovative machine concepts with remote maintenance, diagnostics or sensor configuration can be realized. The sensors can be configured, operated and maintained (condition monitoring) via IO-Link. Format changes can also be implemented much more flexibly and economically with IO-Link.
Special sensor models can be adjusted electronically and are equipped with a measurement value transmission function for monitoring a certain window area. The operating range can be numerically adjusted via IO-Link (Remote Set Distance). The device calibration enables a high level of accuracy when adjusting via remote. When exchanging a defective sensor, the presettings can be transferred loss-free to the new device via IO-Link without having to repeat the teach.
Cables and reflectors for hygienic applications
For applications in the food and pharmaceutical industries, we offer appropriate cable solutions and reflectors for our 55C and 53C series sensors.
The special connection cables are made of FDA-compliant materials (thermoplastic elastomers (TPE) and V4A stainless steel) and are, thus, approved for direct contact with food.
If the cables are mounted with a tightening torque of 0.4 Nm or 0.6 Nm, respectively, they achieve degree of protection IP69. The cable solutions thereby prevent the penetration of liquids, dust or vapor and can also withstand intensive cleaning processes with high-pressure cleaners. The ECOLAB certification confirms the resistance of the cables to aggressive cleaning agents. The cables can be used in a temperature range from -40 °C to +105 °C.
The range of cables for use in hygienically demanding industrial applications includes M8 and M12 as well as cable lengths of 2, 5 and 10 meters.

Application

Loading check of a sausage cutting machine
Requirement:
In the food industry, sausage is delivered in large bars and cut into thin slices in a cutting machine. The product must be reliably detected in the infeed of the machine so that the gripper can uniformly push the material towards the knife and so that all cut slices have the required thickness.
Solution:
Our HT53C.S diffuse sensor in Hygienic Design reliably monitors the product infeed at the sausage cutting machine. If enough material is present for operating the machine, the system starts up automatically. The especially small light spot is characterized by very good performance, particularly with objects with colored structure; the background suppression of the sensor ensures reliable, color-independent detection of products.

Detection of the the leading edges of cut-good products
Requirement:
In an industrial cutting machine, cut goods are cut into small stacks and pre-portioned for the subsequent packaging in trays. The challenge for the sensor system is that the front edge of the cut goods must be reliably detected at the same switching point – regardless of whether they are located on the conveyor belt with a slight lateral offset. The sensors are mounted directly above the conveyor belt. In this application, it must be ensured that no cleaning agent residues drip onto the cheese or cut goods.
Solution:
The HT53CL1.X diffuse sensor with background suppression is specially optimized for the detection of the front edge of products thanks to a long laser light spot. With the linear light spot, cut goods are also reliably detected at the same switching point even with lateral offset on the conveyor belt. This guarantees clean positioning of the cut goods when loading into the tray packaging and ensures that the edge of the tray is not touched by the food, thereby preventing traces of fat from affecting the subsequent, hygienically perfect sealing of the trays. The housing construction of the 53C series was designed in Hygienic Design without drilled holes and is suitable for areas of application with direct contact with food.

Level detection when filling liquids
Requirement:
In the beverage industry, water is filled in 3 liter bottles in a filler. The fill level must be exactly the same in all bottles – underfilling of bottles should be prevented. Reliably detecting the fill level of aqueous liquids in all types of containers is one of the most challenging detection tasks for sensor systems and requires extremely powerful sensor solutions.
Solution:
The LS55C.H2O and LE55C.H2O throughbeam photoelectric sensors were developed for the detection of aqueous liquids as well as for fill-level monitoring and reliably stop the filling process. The transmitter and receiver system of the 55C stainless-steel series in Wash-Down design has a high radiation capacity and can also be used with colored containers and containers with plastic labels.
This solution can replace an expensive fill-level monitoring system, such as a scale or a flow measurement, and is easy to set up: aside from the precise alignment of the optical axis, no other settings via an operational control are necessary.

Presence control in bottle filling applications in the transfer star
Requirement:
Bottle filling is characterized by very high speeds. For a smooth process, it must be ensured prior to filling that all positions of the transfer star are occupied with bottles.
Solution:
The HT55C diffuse sensor with background suppression reliably detects containers in bottle filling applications and does so without reflectors. The sensors are designed for wet areas and can also withstand intensive cleaning processes. An ECOLAB certification as well as our expanded CleanProof+ long-term cleaning agent test ensures the reliable functionality of the sensor even under harsh conditions.

Bottle detection during transport
Requirement:
In a filling system for milk bottles, the position of the bottles must be reliably and precisely detected on the conveyor belt for the subsequent packaging steps in the system.
Solution:
The PRK55C.TT3 retro-reflective photoelectric sensor also reliably detects transparent containers. The sensitivity adjustment can be actuated via the teach button. The integrated tracking function automatically compensates for soiling on the reflector or sensor. This extends the cleaning intervals and reduces system downtime. With the highest degree of protection IP69K, the stainless steel housing in Wash-Down design is very robust. Resistance to cleaning agents commonly used on the market is confirmed by the ECOLAB certification, the Leuze CleanProof+ test as well as tests in accordance with JohnsonDiversey.

Precise positioning of vials
Requirement:
For the filling of vaccines and other liquids, vials made of transparent glass must be precisely detected and positioned.
Solution:
In combination with a small stainless steel reflector, the PRK53CL1.T3 retro-reflective photoelectric sensor with a small laser light spot enables the highly precise detection and positioning of vials. The sensor with miniature housing can also easily be integrated in constrained spaces. Both the sensor and the reflector have a hygienic design.

Detection and positioning of transparent vials
Requirement:
In a pharmaceutical packaging system, vials are filled on multi-track packaging lines. The position of the transparent vials must be precisely detected prior to filling. One challenge is that the vials are very flat and the photoelectric sensors must be precisely directed at the reflector.
Solution:
Our PRK53C.T3 retro-reflective photoelectric sensors of the 53C series are used with the MTKS 14x23.P pharmaceutical micro-triad-type reflectors, specially developed for the pharmaceutical industry. The stainless steel sensors in Hygienic Design are precisely directed at the reflector and ensure reliable detection of the vials.
Overview of our stainless steel sensors
Parameters | PRK53C / PRK55C | LS/LE53C / LS/LE55C | HT53C / HT55C | ODT53C /ODT55C |
Operating principle | Retro-reflective photoelectric sensor | Throughbeam photoelectric sensor | Diffuse sensors with background suppression | Distance diffuse sensor with background suppression |
Housing design and dimensions (WxHxD) | 53C series: Hygienic design (14.0 x 35.4 x 20.4 mm) 55C series: Wash-Down design (14.0 x 35.4 x 25.0 mm) | |||
Housing material | V4A stainless steel (AISI 316L) | V4A stainless steel (AISI 316L) | V4A stainless steel (AISI 316L) | V4A stainless steel (AISI 316L) |
Light sources | Red light (645 nm) Laser, red (650 nm; laser class 1) | Red light (645 nm) Infrared (1450 nm) | Red light (645 nm) Infrared (860 nm) Laser, red (650 nm; laser class 1) | Red light (645 nm) |
Switching frequency | 1,500 Hz (red light) 3,000 Hz (laser, red) | 1,000 Hz (red light) 350 Hz (infrared) | 1,000 Hz (red light and infrared) 3,000 Hz (laser, red) | 750 Hz (red light) |
Operating range | 0.1 … 5 m (two-lens) 0 … 4 m (autocollimation) 0 … 3 m (detection of transparent objects) 0 … 2 m (laser: autocollimation) 0 … 0.4 m (laser: detection of transparent objects) | 0.05 … 8.5 m (red light) 0 … 64 m (infrared) | 5 ... 600 mm (infrared) 5 ... 450 mm (red light) 5 … 200 mm (small light spot) 5 … 100 mm (long light spot) 15 ... 400 mm (laser) | 10 … 150 mm 10 … 80 mm (small light spot) |
IO-Link | V1.1 (COM2) | V1.1 (COM2) | V1.1 (COM2) | V1.1 (COM3) |
Operation | Teach button | - | Multiturn potentiometer | Teach button |
Temperature range | -40 … +70°C | -40 … +70°C | -40 … +70°C | -40 … +70°C |
Degree of protection | IP 67, IP 68, IP 69 K | IP 67, IP 68, IP 69 K | IP 67, IP 68, IP 69 K | IP 67, IP 68, IP 69 K |
Certifications | CE, UL, ECOLAB, CleanProof+, JohnsonDiversey | CE, UL, ECOLAB, CleanProof+, JohnsonDiversey | CE, UL, ECOLAB, CleanProof+, JohnsonDiversey | CE, UL, ECOLAB, CleanProof+, JohnsonDiversey |
Connection | M8, cable, M12 pigtail cable | M8, cable, M12 pigtail cable | M8, cable, M12 pigtail cable | M8 |
Advantages for you
- Extremely large operating ranges result in a large function reserve and therefore in a reliable detection rate, even in the case of critical applications
- Availability with your preferred operating principle:
- Sensors with background suppression with max. 2500 mm operating range
- Retro-reflective photoelectric sensors with max. 17 m operating range (optionally also for detecting objects with depolarizing properties)
- Throughbeam photoelectric sensors with max. 80 m operating range
- Outstanding price/performance ratio
- All common switching logics supported: NPN and PNP switching, light and dark switching
- Diverse connection possibilities enable easy integration (cable, M12 connector or cable with M12 connector)
- Mounting compatibility with 46 series sensors

Application

Detection of film-wrapped pallets.
Requirement:
To secure pallets for transport, they are often wrapped in film. Conventional retro-reflective photoelectric sensors are unable to detect these pallets reliably owing to the depolarizing properties of the tensioned film. As this method of transport safeguarding is widely used, the sensor must detect these special objects with absolute reliability. At the same time, a cost-effective solution needs to be found to enable scaling of this application.
Solution:
The new PRK36.D retro-reflective photoelectric sensor has special optics to enable depolarizing objects to be detected with absolute reliability. An improved design provides a cost benefit over sensors currently available on the market.

Detection of outer packaging in the food industry
Requirement:
In the food industry, identical products are generally bundled into larger packages in order to optimize and automate handling and logistical processes. A key requirement for a high level of automation are high-performance sensors which detect packages reliably – even in the case of changing products and outer packaging. To monitor these processes closely, a multitude of economically attractive sensors are required.
Solution:
With our new 36 series, we offer retro-reflective photoelectric sensors which, thanks to their very high function reserve, reliably detect different packaging units. An improved design provides a cost benefit over sensors currently available on the market.

Safeguarding material availability in production systems
Requirement:
On the one hand, highly automated production systems require high process reliability. On the other hand, the safeguarding of material availability and material tracking are essential. Sensor systems which reliably ensure that different assembly materials are present and therefore available are key components here. At the same time, sensors must be integrated flexibly in different installation situations.
Solution:
Thanks to the different operating principles, variance with respect to light color and the extremely high detection rate, our new range of 36 series sensors are ideal for detecting a wide variety of objects in production systems and therefore assessing the presence or absence of assembly materials. A broad range of mounting technology as well as diverse connection variants allow easy integration. The outstanding price/performance ratio allows scaling in large and complex production systems.
Technical properties
Feature | HT36 | PRK36 | PRK36.D | LS/LE36 |
Operating principle | Diffuse sensors with background suppression | Retro-reflective photoelectric sensor | Polarized retro-reflective photoelectric sensor | Throughbeam photoelectric sensor |
Operating range | 2500 mm | 17 m | 11 m | 80 m |
Light source | Red light, infrared | Red light | Red light | Red light |
Switching frequency | 250 Hz | 300 Hz | 300 Hz | 300 Hz |
Switching output | PNP, NPN Each with light and dark switching | PNP, NPN Each with light and dark switching | PNP, NPN Each with light and dark switching | PNP, NPN Each with light and dark switching |
Operation | Spindle | - | - | Potentiometer |
Degree of protection | IP 67 | IP 67 | IP 67 | IP 67 |
Certifications | CE, UL, ECOLAB | CE, UL, ECOLAB | CE, UL, ECOLAB | CE, UL, ECOLAB |
Connection | M12 and cable variants | M12 and cable variants | M12 and cable variants | M12 and cable variants |