Riftek's Absolute Linear Position Sensors

RIFTEK has introduced absolute linear position sensors, also known as absolute linear encoders, engineered to quantify and check dimensions, displacements, surface profiles, run-outs, and deformations of engineered objects.

The RIFTEK absolute linear encoders come in two models:

  • RF251 for hard industrial environments;
  • RF256 sensors with a built-in display option for laboratory environments.

RF251 Series

  • ​Wide temperature range
  • IP57
Measuring ranges, mm: 3 and 25                       
Accuracy ,μm: ±1
Resolution, μm: 0,1: 0,5 and 1


        See detailed specifications

RF256 Series

  • Built display option
  • Batteries powered
Measuring ranges, mm: 15, 35 and 55        
Accuracy ,μm: ±1
Resolution, μm: 0,1: 0,5 and 1


  See detailed specifications



  MODEL RF251-3 MODEL RF251-25 MODEL RF256-15 MODEL RF256-35 MODEL RF256-55
Measured ID range, mm 3 25 15 35 55
Accuracy (at T=20 °C), μm ±2 - - - ±3
Resolution, μm 0.1 or 0.5 1 or 5 of 10 - - -
Output interface: digital RS422 (RS485 and SSI and RS232) and (EncD5 or EncD10-emulation of quadrature signals or incremental transducers)
Output interface: analog No 0...2 mA (<500 Om load) or 0...10 V -
Synchonization input No - Opsto-isolated - -
Logical outputs No Two outputs, NPM: 100 mA max; 40 V max -
Indication No - Two-color LED (red/green) -
Power supply, V 12 (without analog output) 15 (with analog output) -
Power consumption, W 0.75 - - - -
Enclosure rating IP57 IP50 - - -
Operating temperature, °C -40...+50 -10...+50 - - -
Weight (without cable), g 70 110 110 150 180



Operation of the sensors is based on the principle of photoelectric scanning of special scale, connected with a measurement tip of the sensor. Radiation of a LED 1 is collimated by a lens 2 and is directed on a scale 3. The image of area of the scale is examined by CMOS array 4 and is analyzed by signal processor which calculates position of the scale.

As compared with incremental sensors, absolute sensors have a number of advantages: the absolute position of the gauge plug is determined immediately after power is on and the necessity of search of the reference mark is excluded. 


Also excluded is the probability of accumulation or loss of count pulse signals in case of  impacts, vibrations and reverse motion.




  • Width measurements


  • Parts dimensions


  • Object and target displacements


  • Object deformation


  • Runout


  • Flatness

Absolute contact sensor RF25.avi


Find detailed information about this device here.

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