InteliSENS® SL mini Series

Speed & Length Measurement

This state-of the art InteliSENS mini Series provides the complete high-spec. solution for non-contact laser Doppler speed and length measurement. Its solid-state design ensures high-reliability without calibration drift and significantly reduced maintenance compared to contacting encoders. The comprehensive specifications, high-reliability and competitive price point combine together to make the InteliSENS mini-series a market leader, validated by thousands that are in continuous operation on many applications worldwide.

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  • Non-contact, high-speed, solid-state laser speed and length measurement with no slippage, drift, mechanical wear or maintenance compared with contact wheel / roller systems.
  • Wire optomized SL mini-W series version available for wire and cable applications
  • Unidirectional speed and length measurement.
  • Ultra-compact design with a footprint comparable to a smartphone.
  • Optimized for sheet material and converting applications.
  • UKAS-traceable calibration; accuracy better than 0.05% and repeatability better than 0.02%.
  • Rugged industrial design for use in factory environments.
  • Available fitted with industry-standard communcations interfaces for easy integration with PLCs and production line equipment.
  • Excellent value with low cost of ownership.


Proton Products InteliSENS® SL mini Series non-contact, unidirectional speed and length gauges provide extremely accurate speed and length measurements in almost any sheet material or converting application.

Production processes for web products, woven and non-woven materials, paper, plastic film, tapes, building materials, flooring and labelling can all be measured using the laser Doppler method.

Applications requiring a precise cut-to-length process benefit from the non-slip and highly accurate laser measurement technique which reduces scrap, increases uptime and improves material yield by eliminating product “Give Away” or “Short Length” claims.

InteliSENS® SL mini Series gauges are money-saving, direct replacements for traditional problematic and high-maintenance contact wheel and roller-type devices and are extremely easy to install and operate. Integration with production line controllers such as PLCs is eased by the availability of a wide variety of industry standard communications interfaces.

Operating principle – Laser surface velocimeter

Proton Products InteliSENS® SL mini Series speed and length gauges illuminate the measured surface with an interference pattern created by the intersection of two laser beams. The alternating bright and dark interference fringes modulate the light scattered by the object with a frequency proportional to the object speed. This scattered light is detected by a photodiode and the electrical signal digitally processed to determine the frequency and hence the speed. Object length is then calculated by integrating the speed measurement over time.

Operating Principle


ModelSL mini 1220SL mini 3060Units
Part number00050MC00100050MC002-
Stand-off distance120300mm
Minimum speed0.10.25m/min
Maximum speed20005000m/min

Internal measurement rate200kHz
Measurement output interval20µs
Laser spot diameter3mm
Operating temperature540°C
Ingress protectionIP67
Power supply152425VDC
Power consumption8W

*only valid if the measured object is positioned within the central 20% of the depth-of-field.

Measurement units
(end-user configurable)
Laser safety control inputsLaserExternal closed contact to ground enables laser diode.
ShutterExternal closed contact to ground opens laser shutter.
Shutter status outputElectricalN-channel MOSFET pull-down (for connection to user-supplied opto-isolated relay).
Maximum voltage: 30VDCMaximum current: 100mA
FunctionPulled to ground when laser shutter is open.
3×Logic inputs
(end-user configurable)
ElectricalMaximum input voltage: 24VDC
FunctionLength resetDisplay holdLength hold
Speed holdDirectionPause
2×Logic outputs
(end-user configurable)
ElectricalN-channel MOSFET pull-down (for connection to user-supplied opto-isolated relay).
Maximum voltage: 30VDCMaximum current: 100mA
FunctionGauge OKLaser at tempLaser on
MeasuringPreset Length 1Preset Length 2
2×Differential pair pulse outputs
(end-user configurable)
ElectricalOpto-isolated differential pair
Output voltage: 5V or user supplied (up to 24V)
Maximum frequency: 1MHz
FunctionIndependentQuadrature pair
CANbus communicationsConnects to an optional Proton Products CDi interface display unit
Serial communicationsRS-232
Ethernet communicationsModbus protocol
Optional communications (factory-installed, choice of one, replaces standard Ethernet interface)PROFIBUSEthernet/IPDeviceNET