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TONiC™ UHV incremental encoder system with RELM linear scale


  • Readhead size: 35 x 13.5 x 10 mm
  • Resolutions to 1 nm
  • Speed to 10 m/s
  • Analogue or digital outputs
  • Ultra-low Sub-Divisional Error (SDE): typically <±30 nm
  • Optical IN-TRAC™ reference mark


  • Ultra-High Vacuum (UHV)
  • Very high accuracy combined with near zero thermal expansion
  • Super-compact encoder with dynamic signal conditioning for improved motion control
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What is TONiC UHV?

TONiC UHV brings Renishaw's super-compact, non-contact encoder system to Ultra-High Vacuum applications offering customers improved motion control.
TONiC offers speeds up to 10 m/s and, combined with the Ti interface, resolutions down to 1 nm for both linear and rotary applications. TONiC systems are quick and simple to install with wide set-up tolerances and calibration at the push of a button. TONiC's dynamic signal processing gives improved signal stability with ultra-low Sub-Divisional Error of typically <±30 nm to help realise superior motion control performance.

What is RELM scale?

RELM is a spar scale manufactured from ZeroMet™, a low expansion nickel/iron alloy, featuring a 20 µm pitch. 
It is comparable to fine pitch glass scales and offers a total accuracy (including slope and linearity) better than ±1 µm over a 1.5 m length. ZeroMet has a thermal expansion coefficient of approximately 0.6 µm/m/°C over the temperature range of 0 °C to 30 °C.
System designers can choose between specially formulated UHV compatible 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?

Ultra-High Vacuum (UHV)

TONiC UHV readheads take standard TONiC outstanding performance and deliver it in a readhead that has been designed and constructed using UHV compatible materials and processes making it suitable for UHV conditions down to 10 -10 Torr.
The range of TONiC UHV encoders and accessories are constructed from vacuum-compatible materials and adhesives to give low outgassing rates and proven clean residual gas analysis (RGA) making them suitable for many applications including wafer handling / testing, scientific instruments, spectroscopy, vacuum inspection equipment and many more.

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.

Ultimate reliability and performance in a compact size

For ultimate reliability and consistent performance TONiC readheads incorporate third-generation filtering optics, tuned for even lower noise (jitter) and now further enhanced by dynamic signal processing including Auto Gain Control and Auto Offset Control. This combination – all incorporated inside the readhead - provides signals of unrivalled purity and ultra-low Sub-Divisional Error of just ±30 nm. The result is smoother velocity control for improved scanning performance, increased positional stability which in turn helps minimise the heat build-up in motors inside the vacuum; essential parameters for vacuum applications all in a compact readhead.

Quicker and easier installation

A set-up LED on the readhead gives a visual indication of signal size and an optional diagnostic kit allows remote checking of the system performance when the readhead is concealed within the machine. Calibration of the reference mark and incremental signals is done at the push of a button with no mechanical adjustment or additional diagnostic tools. The IN-TRAC customer-selectable optical reference mark is embedded in the incremental scale for compact dimensions and simplified alignment. This yields a reference mark output that is bi-directionally repeatable to unit of resolution over the full operating temperature and speed range.

Interface options

TD (dual resolution) interface

  • Selectable dual-resolutions quadrature output. Ti interface (square)
  • Ideal for applications that require high speed movement combined with finer precision motion.

DOP (dual output) interface

  • Provides simultaneous digital quadrature and 1 Vpp signals.
  • Designed for applications requiring one or more operations to be synchronised with a motion axis.TONiC Dual Output (DOP) interface

Optional diagnostic kit

TONiC™ diagnostic kit (software and hardware)

TONiC diagnostic software version 1.0 (released March 2015) can be used to optimise the installation of TONiC encoders and provide a quick and comprehensive system calibration. The software must be used in conjunction with the TONiC diagnostic hardware which can be purchased from Renishaw using part number A-9411-0011. The hardware is connected to the PC via the USB cable (provided in the kit) or in-line with the customers' electronics.

Find out all about the TONiC diagnostic kit.

Technical specifications

Measuring standard

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

Scale pitch

20 μm

Thermal expansion coefficient

~0.6 μm/m/°C (0 °C to 30 °C)

<1.4 μm/m/°C (30 °C to 100 °C)

Accuracy grade at 20 °C

Certified to ±1 μm, calibration traceable to international standards

Reference mark

IN-TRAC reference mark

Various reference mark position options, see data sheet for details

Limit switches

Dual or single limits (select at time of order)

Scale length

20 mm to 1 500 mm

Maximum speed



(See data sheet for details)

Up to 10 m/s at -3 dB

Up to 10 m/s

Sub-Divisional Error (SDE)

Typically <±30 nm

Dynamic signal control

Real time signal conditioning including Auto Gain Control (AGC) and Auto Offset Control (AOC) for optimised performance during operation

Incremental signals



1 Vpp (20 μm period)

Resolutions from 5 μm to 1 nm

Electrical connection

0.5 m, 1 m, 1.5 m, 3 m, 5 m and 10 m cable lengths with mini connector (connects direct to TONiC interface)

Power supply

5 V ±10%, <100 mA (analogue system), <200 mA (digital systems) (unterminated)

Readhead power consumption< 100 mA

Vibration (operating)

100 m/s2  max @ 55 Hz to 2 000 Hz

Shock (non-operating)

1 000 m/s2, 6 ms, ½ sine

Operating temperature (system)

0 °C to +70 °C

Bake-out temperature (non-operating)

120 °C (Readhead and scale only)


Readhead: IP20

Interface: IP20

Cable construction

Tinned copper braided single screen, FEP core insulation

Refer to data sheets for full details.



Data sheets


  • TONiC™ diagnostic software version 1.0

Technical drawings

How it works

TONiC 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 <±30 nm.

This evolution of filtering optics, combined with carefully-selected electronics, provide incremental signals with wide bandwidth achieving a maximum speed of 10 m/s with the lowest positional jitter (noise) of any encoder in its class. Interpolation is by CORDIC algorithm within the TONiC Ti interface, with fine resolution versions being further augmented by additional noise-reducing electronics to achieve jitter of just 0.5 nm RMS.

TONiC™ optical scheme with annotations

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. Yielding a reference mark output that is bi-directionally repeatable to unit of resolution at all speeds. This unique arrangement also benefits from an automatic calibration routine that electronically phases the reference mark and optimises the dynamic signal conditioning