VIONiCplus™ incremental encoder system with RELM linear scale - available from August 2016
- Digital output direct from the readhead
- Readhead size: 35 x 13.5 x 10 mm
- Resolutions to 2.5 nm
- Speed to 3.63 m/s
- Ultra-low Sub-Divisional Error (SDE): typically <±10 nm
- Optical IN‑TRAC™ reference mark
- Dual limits
- No separate interface required
- Advanced Diagnostic Tool for easy fault finding, challenging installations and servicing
- Very high accuracy combined with near zero thermal expansion
- High dirt immunity
What is VIONiCplus?
VIONiCplus integrates Renishaw's filtering optics design and interpolation technology to create a high performance, super-compact, digital all-in-one incremental open optical encoder. It offers resolutions down to 2.5 nm and a wide range of configurations to optimise the speed of your motion control system. VIONiCplus systems are quick and simple to install with wide set-up tolerances and automatic calibration. VIONiCplus implements our latest interpolation algorithms and signal processing techniques to achieve a typical Sub-Divisional Error of <±10 nm. This is world-leading performance from a 20 µm pitch incremental encoder system.
The Advanced Diagnostics Tool aids fault finding and servicing, and assists optimisation of system setup for challenging installations.
What is RELM scale?
RELM is a spar scale manufactured from ZeroMet™, a low expansion nickel/iron alloy, featuring 20 µm pitch incremental graduations.
It is comparable to fine pitch glass scales and offers a total accuracy (including slope and linearity) better than ±1.5 µm over a 1.5 m length. ZeroMet has a thermal expansion coefficient of 0.75 ±0.35 µm/m/°C at 20 °C.
System designers can choose between specially formulated adhesive tape or mechanical clips to suit mounting requirements. Both mounting methods allow for independent thermal expansion to that of the substrate.
Why choose this encoder system?
World-leading performance from a 20 µm pitch incremental encoder system
VIONiCplus, using our latest interpolation algorithms and signal processing techniques, can achieve a Sub-Divisional Error (SDE) as low as ±10 nm. Low SDE directly equates to low velocity ripple which is important for constant velocity applications, such as scanning measurement systems. VIONiCplus' intelligent interpolation chip can achieve 8 000 x interpolation which equates to 2.5 nm resolution directly out of the readhead. This system is used when precision and repeatability is of paramount importance.
Easy fault finding and servicing
The Advanced Diagnostic Tool is available for comprehensive encoder feedback . This can be used for challenging installlations and fault finding. It provides:
- Remote calibration functions
- Signal optimisation over axis length
- Readhead pitch indication
- Limit and reference mark indicators
- DRO and lissajous outputs.
Ease of handling
The RELM ZeroMet low thermal expansion scale has a much smaller cross section than typical glass scales and allows easier handling and installation without risk of breakage, making it ideal for the most demanding precision applications.
Optional Advanced Diagnostic Tool
The Advanced Diagnostic Tool (ADT) includes user software that allows control and monitoring of VIONiC's set-up and calibration routines. This set-up tool is ideal for factory production-line installation as it allows remote, advanced calibration features.
Find out more about the Advanced Diagnostic Tool.
RELM: high accuracy ZeroMet spar scale with mid reference mark
Also available with end reference mark as RELE
Readhead size (LxWxH)
35 mm x 13.5 mm x 10 mm
Thermal expansion coefficient at 20 °C
0.75 ±0.35 μm/m/°C
Accuracy grade at 20 °C
Certified to ±1 μm per m, calibration traceable to International Standards
IN-TRAC reference mark
Various reference mark position options, see data sheet for details
20 mm to 1 500 mm
Up to 3.63 m/s
(See data sheet for details)
Sub-Divisional Error (SDE)
Typically <±10 nm
Dynamic signal control
Real time signal conditioning including Auto Gain Control (AGC), Auto Balance Control (ABC) and Auto Offset Control (AOC) for optimised performance across a range of operating conditions
0.1 μm to 2.5 nm resolution
(See data sheet for details)
0.5 m, 1 m, 1.5 m, 2 m and 3 m cable lengths with D-type connectors (9 and 15 pin) or circular in-line connector (12 pin)
5 V -5%/+10%, typically <200 mA fully terminated
100 m/s2 max @ 55 Hz to 2 000 Hz
500 m/s2, 11 ms, ½ sine, 3 axes
Operating temperature (system)
0 °C to +70 °
Refer to data sheets for full details.
How it works
VIONiCplus features the third generation of Renishaw's unique filtering optics that average the contributions from many scale periods and effectively filter out non-periodic features such as dirt. The nominally square-wave scale pattern is also filtered to leave a pure sinusoidal fringe field at the detector. Here, a multiple finger structure is employed, fine enough to produce photocurrents in the form of four symmetrically phased signals. These are combined to remove DC components and produce sine and cosine signal outputs with high spectral purity and low offset while maintaining bandwidth to beyond 500 kHz.
Fully integrated advanced dynamic signal conditioning, Auto Gain , Auto Balance and Auto Offset Controls combine to ensure ultra-low Sub-Divisional Error (SDE) of typically <±10 nm.
This evolution of filtering optics, combined with carefully-selected electronics, provide incremental signals with wide bandwidth achieving a maximum speed of 12 m/s with the lowest positional jitter (noise) of any encoder in its class. Interpolation is within the readhead, with fine resolution versions being further augmented by additional noise-reducing electronics to achieve jitter of just 1.6 nm RMS.
The IN-TRAC reference mark is fully-integrated in the incremental scale and is detected by a split photodetector within the readhead. As the diagram shows, the reference mark split detector is embedded directly into the centre of the incremental channel linear photodiode array ensuring greater immunity from yaw-dephasing. This unique arrangement also benefits from an automatic calibration routine that electronically phases the reference mark and optimises the incremental signals.