Laser encoders overview

Renishaw has been active in the field of homodyne interferometry since 1985. 

Our first laser encoder product, the HS10 long-range laser scale, was launched in 1994 after specific requests for a laser feedback solution. Field proven in harsh production environments worldwide, the HS10 became the interferometer solution of choice for a wide range of long-axis machine tool applications.

To extend application suitability to smaller geometry machines, the RLE laser encoder was developed, based on the principle of combining interferometer performance levels with encoder simplicity. The first generation RLE10 was launched in 2001, with additional laser sources, interferometer configurations and interfaces introduced since.

RLE laser encoder

The Renishaw RLE laser interferometer-based encoder system provides the positioning performance expected from an interferometer, with the ease of use associated with traditional tape or glass scale based encoders.

Simple system architecture is achieved using a fibre optic laser delivery system that enables the laser beam to be delivered directly to the measurement axis, eliminating multiple beam benders, splitters and mounts. This transformation of interferometer system architecture provides a system that can be installed in minutes, with a smaller footprint and at lower cost.

Each RLE system comprises two main parts - the RLU laser unit and the RLD10 detector head. These core components are available in various, user selectable configurations. Renishaw also supplies retroreflectors for integration with single pass detectors, and can provide mirrors and mounts for double pass applications.

RLU laser units

Available in single or dual axis configurations, the RLU laser unit contains a HeNe (Helium / Neon) laser source, stabilisation electronics, fibre optic launch and axis position feedback electronics. RLU laser units are available with two frequency stability specifications: the RLU10, with a laser frequency stability of ±50 ppb over any one hour period, which is used within all RLE10 systems, and the RLU20, with a laser frequency stability of ±2 ppb over any one hour period, which is used within all RLE20 systems.

Standard systems have a 3 m fibre optic umbilical connecting the RLD10 detector head to the RLU laser unit. RLE10 systems are also available with a 6 m umbilical on request.

 

RLD10 0° launch detector head

Contains either a single or double pass interferometer (for retroreflector or plane mirror applications respectively), a unique, multi-channel fringe detection system, laser shutter and integral beam steerer.

A second varient of 0° launch detector head is available with no internal interferometer. This configuration allows an RLE system to be used with the linear, angular and straightness optics available from the calibration division.

 

RLD10 90° launch detector head

Contains either a single or double pass interferometer (for retroreflector or plane mirror applications respectively), a unique, multi-channel fringe detection system, laser shutter and integral beam steerer. This detector head can be mounted on either top or bottom face, to provide 90° or 270° beam launch orientation.

 

RLD10 DI (differential interferometer) detector head

Contains differential (column reference) interferometer optics, a unique, multi-channel fringe detection system and integral beam steerers, which provide independent pitch and yaw adjustment of measurement and reference beams.

 

RPI20 parallel interface

Accepts differential analogue 1 Vpp sine / cosine signals and interpolates by 4096 to provide a 36-bit parallel format output with resolution capability of 38.6 picometres at 1 m/s.

 

RCU10 real-time quadrature compensation system

Utilises environmental sensors to monitor a machine's ambient environment and provides real-time compensation of the position feedback signals.