Length-Section Light Scanner
Discrete Part Length Measurement

Optical Micrometer for the final measurement of discrete parts during lengthwise transport

μMETER-SLM product series is used for the non-contact final measurement of discrete parts lengths in the production process, while transporting the discrete parts in longitudinal direction. The highly accurate measurement of the optical light scanner generally serves the production optimization, the good/bad sorting as well as the documentation of the delivery condition of discrete parts. The SLM product series is based on a worldwide unique LED length-section light scanner measurement technology called Optical Micrometer/Measuring Light Scanner. SLM systems are maintenance-free, permanently calibrated and measure largely independent of material. SLM systems are used for the highly accurate, non-contact length measurement of profiles, tubes, plates, beams, bolts, struts, hubs made out of a wide variety of materials. SLM  length-section light scanner for discrete part length measurement are available in two versions. By the standard SLM system, discrete parts up to approx. 5 m in length can currently be measured, depending on the system length. The two-parted SLM/2 systems are used for the re-measurement of discrete parts with a length longer than 5 m, or when no continuous SLM measuring arrays can be used.

Non-contact discrete part length measurement

Product Types – Length-Section Light Scanner Discrete Part Length Measurement System


Standard SLM systems with continuous transmitter and receiver arrays for a highly precise final measurement of discrete parts being transported in longitudinal direction – measurement of plates, profiles, tubes, beams, bolts, rolls, … up to a maximum of 5 m length

  • Length-Section Light Scanner Discrete Part Length Measurement Systems
  • LED-based transmitted light sensor consisting of light transmitting array and light receiving array
  • Currently for measurement material lengths of 10 mm to a maximum of 5 m
  • Typical measurement accuracy of +/- 0,1 mm per meter measurement length
  • Measurement in material flow up to 240 m/min
  • Maintenance-free, permanently calibrated
  • Easy integration in existing conveyor technology
  • Sorting control – optional
  • Sorting mechanism – optional
  • Conveyor technology – optional


SLM System with two-parted transmitter and receiver arrays for a highly accurate final measurement of discrete parts up to 15 m being transported in longitudinal direction

  • SLM/2 is used for discrete parts with lengths between 5 m and 15 m
  • SLM/2 is used for machines in which a continuous sensor arrays can’t be put into operation
  • SLM/2 is also used, if an inexpensive but nonetheless accurate solution for discrete parts with different lengths is required and if the user is willing to move a sensor part to the estimated target length
  • Several SLM/2 systems can also be operated in series to increase the measuring range


Technical Data – Length-Section Light Scanner Discrete Part Length Measurement Systems

System Components Transmitter and Receiver Arrays Transmitter and Receiver Arrays Two-Parted Transmitter and Two-Parted Receiver
Types shortest SLM System longest currently available SLM System Measurement Range of max. 4,5 m (e.g. for part lengths of 10 m to 14,5 m)
Measurement Material Length 10 mm to 126 mm 10 mm to 4.860 mm Based on the Project
Systematical Measurement Accuracy ± 0,1 mm/m ± 0,1 mm/m typically: ± 0,1 mm/m  (Based on the Project)
Repetitive Accuracy ± 0,03 mm (confidence interval 1σ)
SLM Arrangement of Transmitter and Receiver to each other horizontal, vertical or diagonal
V-Measurement Range 0,1 m/min → 250 m/min 0,1 m/min → 100 m/min (higher Vmax on request) Depending on Sensor Length and Module Distance
Measurement Distance between Transmitter and Receiver Array 150 mm to 1.000 mm
Interfaces 1 x RS-485
I/Os Input: Start, Gate, Calibration
Output: Status
I/O Type RS‐422 Gauge
Available Data Speed, Length, Signal Quality, Status, Valid Measurement
Feldbus Optional:
Profibus-DP, ProfiNet‐RT, Ethernet‐IP, …
Protection Class Sensor Lines: IP50
Sensor Lines: 30x30mm Profil cross section, Bosch-Rexroth, Length depending on maximum measurement material length
Power Supply 12 – 24 VDC
Weight Sensor Lines: Depending on length – ca. 1 kg per meter of gauge array
LED Data 5mW, Infrared
Ambient Temperature 5 to 55°C ‐ not condensing, outside of temperature range external cooling / heating required
Humidity Environment should be dry

Accessories for Length-Section Light Scanner Discrete Part Length Measurement Systems

Standard Interface

Interface Box for PC Operation


Interface box for connecting the SLM system to a PC or laptop. Allows for easy connection and supply of the SLM sensor. With RS485 output interface and plug-in power supply.

Sensor Cable

Shielded Cables

SLM-K3, K10

Sensor cable for connecting the two SLM sensor lines with each other and for connection to an interface such as SLM box or bus module, a controller or a display.

Displays and Control Units

Length Display


Interface box with length display for connecting the SLM system to a PC or laptop. Box with RS485 output interface and plug-in power supply.
Control/Control Unit


Display and Control Unit for the SLM sensors provide the following features:

  • Display of all measurement values
  • Display of sensor status
  • Input of preselection lengths
  • Reset of current length
  • Cutting contact, pre-contact output
  • Sensor parameterization
Sorting Control


The SPS sorting control for the SLM sensors provide the following features:

  • Operation via Touch-Screen
  • Display of all measurement values
  • Input of nominal lengths
  • Input of low and high tolerance values
  • Output of sorting signals
  • Product data management
  • Measurement data storage

Mobile Equipment

Measurement Tripod


The shorter SLM sensors are lightweight and therefore very well suited for mobile measurement in conjunction with the ELOVIS tripods (TRI). The TRI tripod consists of: tripod, boom with joint, sensor attachment to the boom with ball head and sensor mounting plate.


PC Software


The CMS configuration and monitoring software is used for SLM operation, adjustment of setpoint and tolerance values as well as the display and storage of measurement values on a PC, laptop or tablet computer. The CMS software is mainly used for manual measurements.

Feldbus and Communication Modules

Profibus-DP, ProfiNet-RT, Ethernet-IP


Standard bus interface modules with the following output: Length (in m) , speed (in m/s), status signal (valid/invalid)

Protective Casing

Casing for Air Purge


The stainless steel casing SLM-HSEe serves to protect the sensor lines from contamination and inappropriate ambient temperatures. The HSEe must be kept clean with suitable scavenging air.
Quick-Change Protective Foil



The quick-change protective foil μSPEED-QCF (Quick-Change Foil) is designed for use in harsh environments with heavily polluted ambient air. The QCF allows the replacement of an older protective foil in minutes and prevents the need to clean the actual glass of the sensor system.

Conveyor Technology and Sorting Technology

Conveyor Technology and Sorting Technology Conveyor technology, conveyor belts, carriages, slide rails, push-out devices and sorting machines are offered together with experienced partner companies.

Length-Section Light Scanner Discrete Part Length Measurement Systems

The discrete part to be measured passes through the SLM System without stopping in longitudinal direction. As soon as the discrete part is located completely between both sensor arrays (a light transmitter array and a receiver array), a measurement is automatically triggered. To ensure that the measurement takes place with high accuracy, the discrete part already has to be separated while in supply, however, a distance between two subsequent discrete parts of only 10 mm to 50 mm is sufficient. In addition, the measurement object should pass the SLM system as straight as possible. Because the SLM system measures the shadowing of the measurement object in the transmitted light, if the measurement object is twisted or inclined, the measured projection can cause a measurement error. Furthermore, it is beneficial if the edges of the measurement object are cut at right angles and there are no ridges, cutting waste or chips left over on the front surface. The active measurement light line is only 2 mm high and is located in the middle of the sensor profile, which has a cross-section of 30 x 30 mm. The sensors are called “optical micrometer” or “measuring light scanner” for non-contact discrete part length measurement.

SLM/2 – Measurement Principle (Sideview):

Videos – Length-Section Light Scanner Discrete Part Length Measurement Systems

Application Video – SLM

Length-Section Light Scanner Part Length Measurement Systems

Measurement of film sheet length after cutting, before sorting/packaging

Application Video – SLM

Length-Section Light Scanner Part Length Measurement Systems

Part Length Measurement on short plastic profiles at high speeds

Application Video – SLM

Length-Section Light Scanner Part Length Measurement Systems

Part Length Measurement of 354 mm long plastic profiles after extrusion and cut

Application Video – SLM

Length-Section Light Scanner Part Length Measurement Systems

Small tubes in manual part guidance

Downloads – Length Section Light Scanner Discrete Part Length Measurement System

SLM – Product Overview


Measure piece lengths up to 5m
in transmitted light

Do you still measure piece lengths by hand in samples? Incoming and outgoing material edges ensure increased wear and...

Measure part length up to approximately 15 m
in transmitted light

The final measurement of very large parts is complex, staff-intensive, but still prone to error. If the maximum measu...

Length Measurement of long parts
in reflection

The measurement situation prevents the use of a transmitted light system for part length measurement? The space avail...

Measure part lengths
with free-form edges

You want to measure the length of parts with free-form edges? ... With the μVIS based 2D and 3D sensors a variety of ...


Length Measurement of profiles after cutting

High demands of the automotive, furniture, electronics or medical industry on the cutting accuracy of profiles make t...

Highly accurate contact free part length measurement during part feeding. Measurement of fixed length, sections and cut parts, pipe sections, tubes and hoses.

Length Measurement of pipes after cutting

The final measurement of all tubes after the cutting allows a shortening of the setup time of the cutting system and ...

Test station for final part length measurement

If discrete part lengths are to be measured quickly and reliably and the measurement length has to be documented, the...

Length Measurement of sheets and plates

Metal sheets and boards are cut and then palletized. A final measurement is often done manually on the pallet stack. ...

Length Measurement of window profiles

Window profiles with lengths between 2.5 m and 7 m should be cut as precisely as possible and checked directly after ...

Measure the length of wood and chipboard

The woodworking industry is now confronted with high accuracy requirements. In order to make a profit, it is importan...

Width of paper rolls on the chain conveyor

Paper rolls are transported to the warehouse via chain conveyors after wrapping. Prior to storage, the rolls of paper...

Length of transparent plastic profiles

Even the final length measurement of translucent plastic profiles is easily and accurately possible with the non-cont...

Measure the length of metal parts, pipes, bolts, slugs

Metal parts such as pipes, bolts, rods, slugs should have the correct part length. When operating presses and forging...

Weerth - cutting and measuring precision pipes and tubes

Weerth Handling Systeme manufactures systems for the non-cutting and burr-free cutting of metal pipes and tubes. For ...

ROBUST - Foil cutting machine with part length measurement

ROBUST is specialized in slitting machines and winding technology. The product range includes roll slitting and windi...

EXTRUDEX - extruder with guillotine and measuring unit

EXTRUDEX is a manufacturer of extruders and cutting devices. EXTRUDEX extruders are mainly used in the automotive and...

Always available for you:
Bernd Engelsdorf


Karl-Friedrich-Straße 14-18
76133 Karlsruhe, Germany

T +49 721 933823-0
F +49 721 933823-23


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