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.