RCU10 real-time quadrature compensation system

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. This is because the principle of interferometry is dependant 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 result in a 1 ppm variance in laser wavelength.

To compensate for environmental variations, Renishaw offer the RCU10 real-time quadrature compensation system.  RCU10 system components include:

• RCU10 compensation units; available with or without an integral pressure sensor (RCU10-PX-XX and RCU10-XX-XX respectively)
• Air temperature sensors
• Material temperature sensors
• Sundry optional components

For multi-axis systems, up to six RCU10s can be linked via a high-speed serial communications link. If used as part of a multi-axis system, only one RCU10-PX-XX is required.

The RCU10 part number generator allows you to determine the part number of the compensation system required for your individual application. Simply enter data into the grey cells and the program will automatically calculate the necessary system part number which can then be used to request a quotation or place an order.

Features and benefits

• Accuracy
  Refractive index compensation for laser encoders using air pressure and temperarure 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
  Can provide compensation for many laser and scale encoders that provide digital quadrature feedback signals.

Specifications

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.

A number of optional extras is 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-VA-XX	Sensor vacuum accessory kit
A-9904-1711	Sensor vacuum connector assembly
A-9904-1712	Sensor vacuum seal kit (spare x 5)