RCU10 real-time quadrature compensator

Compensation systems for real-time quadrature positional feedback.

When any laser interferometer system is used in a non-vacuum environment, some form of environmental compensation is required to maintain accuracy under varying environmental conditions. The principle of interferometry is dependent on the wavelength of the laser light, a figure which fractionally varies depending on the refractive index of the air through which it travels.

Environmental changes of ±1 °C in air temperature, ±3.3 mbar in air pressure, or 50% variance in relative humidity would generate a 1 ppm variance in laser wavelength and resulting measurements.

The input and output parameters for an RCU10 unit are configured with the Renishaw Configuration Software (RCU-CS).  This can be downloaded from the link at the bottom of this page.

Features and benefits

  • Accuracy – refractive index compensation for laser encoders using air pressure and temperature sensors, improves accuracy to within ±1 ppm.
  • Yield enhancement – thermal expansion compensation of workpiece and machine structures, using material temperature sensors, dramatically improves process repeatability.
  • Flexibility – RCU10 can also be used for compensation with many other laser and scale encoders that provide digital quadrature feedback signals.


Features Refractive index compensation
Material expansion compensation
Accuracy ±1 ppm*
Data format Digital – RS422 quadrature
Analogue – 1 Vpp sine / cosine
Resolution Digital – variable to 10 nm
Analogue – variable to 20 µm
Velocity Up to 5 m/s

* plus the greater of 3 input counts and 1 output count for digital outputs and a further velocity dependant error for some analogue outputs.

Optional extras

A number of optional extras are also available for use with the RCU10 real-time quadrature compensation unit.

A-8014-0670 Serial / USB adaptor
RCU10-DB-XX Sensor distribution box
RCU10-AC-X5 Armoured sensor cable (5 m length)
RCU10-AT-XX  Air temperature transmitter
RCU10-MT-XX  Material temperature transmitter
RCU10 real-time quadrature compensator