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ATOM™ incremental encoder system with RCDM rotary (angle) disc

Features

  • Readhead size: 8.35 x 12.7 x 20.5 mm (7.3 x 12.7 x 20.5 mm for FPC version)
  • Resolutions down to 1 nm
  • Speed up to 20 m/s
  • Analogue or digital outputs
  • Low Sub-Divisional Error (SDE) of <±120 nm for 40 µm version, and <±75 nm for 20 µm version

Benefits

  • Miniature package
  • Filtering optics design enabling high dirt immunity
  • Disc encoder for compact rotary applications
  • Assured quality
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What is ATOM?

ATOM is Renishaw's miniature non-contact optical incremental linear and rotary encoder system. Its innovative design combines miniaturisation with leading-edge signal stability, dirt immunity and reliability. This combination is unique in the market place and represents a significant advance in the performance and reliability of miniature encoders.

ATOM is supplied in hi-flex cable and Flexible-Printed Circuit (FPC) variants with either 20 µm or 40 µm scale options.

A range of interfaces is available including the standard Ri, a high-performance Ti and the compact open ACi interface.

What is RCDM disc?

RCDM is a one-piece glass disc featuring graduations marked directly onto its face and a single reference mark position and optical alignment ring. The optical alignment ring can be used to minimise angular alignment errors and improve installed accuracy.

Two versions are available, either 20 µm pitch or 40 µm pitch, in a range of sizes (20 µm: Ø30 mm to Ø108 mm, 40 µm: Ø17 mm to Ø108 mm)

The non-contact format eliminates backlash, shaft wind-up (torsion) and other mechanical hysteresis errors that are inherent in traditional enclosed encoders.

Why choose this encoder system?

Miniature encoder where space is at a premium

ATOM, available in sizes as small as 7.3 mm x 20.5 mm x 12.7 mm, allows for integration in the tightest of spaces. There are a number of options to choose from including both cabled and component FPC versions.

High reliability and system performance

ATOM is the world's first miniature encoder system incorporating Renishaw's unique filtering optics design. This is further enhanced by dynamic signal processing within the readhead including Auto Gain Control and Auto Offset Control. This combination allows ATOM to have higher dirt immunity and signal purity which is comparable to, if not better, than our standard size readheads with SDE's as low as ±75 nm on 20 µm readheads and ±120 nm on 40 µm readheads. The result is smoother velocity control for improved scanning performance and increased positional stability, essential parameters for many motion control applications.

Assured quality

Quality is assured with ATOM's automated production line and fast delivery. ATOM has a number of quality controls including temperature and humidity testing, vibration testing, ISO9001, static discharge testing, radiated interference testing, conducted interference testing, LED burn-in and 100% inspection.

Interface options

ATOM comes with a variety of interface options which allows greater flexibility to integrate the encoder within your system design.

Ri interface

  • Ri interfaces offer analogue 1 Vpp or digital interpolation outputs down to 50 nm (clocked) and 0.5 μm (non-clocked) in a compact low cost package.
  • This is contained within an industry standard 15 way D-type connector shell, including CAL button.
Ri interface (square)

Ti interface

  • Ti interfaces are designed for applications that require higher speed, lower SDE and digital interpolation down to 1nm and include a CAL button.
  • Clocked outputs have been optimised for speed and performance at all resolutions for industry-standard controllers.
  • Analogue variants are also available.Ti interface (square)

ACi interface

  • ACi interfaces are a range of high performance, miniature, open interpolator subsystems.
  • They bring unparalleled price-performance benefits to today's motion systems that need fine resolution coupled to high speed performance in an ultra compact, open format, small footprint solution and have provision for calibrating the system.
  • Digital interpolation down to 10 nm at up to 40 MHz clocked output is available.
  • FPC or cable input versions available.
Website: ACi for ATOM readhead

Optional diagnostic kit

ATOM™ diagnostic kit (software and hardware)

ATOM diagnostic software version 1.0 (released March 2015) can be used to optimise the installation of ATOM encoders and provide a quick and comprehensive system calibration. The software must be used in conjunction with the ATOM 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 ATOM diagnostic kit.

Technical specifications

Measuring standard

RCDM: glass disc

Readhead size (LxWxH)

Cable variant: 20.5 mm x 12.7 mm x 8.35 mm

FPC variant: 20.5 mm x 12.7 mm x 7.3 mm

Scale pitch

20 μm and 40 µm

Thermal expansion coefficient

~8 µm/m/°C

Ring outer diameter

40 µm: 17 mm to 108 mm

20 µm: 30 mm to 108 mm

For larger sizes contact Renishaw

Line count

40 µm: 1 024 to 8 192
20 µm: 4 096 to 16 384

Reference mark

Single reference mark


Graduation accuracy

± 0.5 µm

Maximum speed 
                          Analogue


                                Digital

(see data sheet for details)

40 µm: up to 20 m/s

20 µm: up to 10 m/s

Dependent on interface type, see data sheet for details

40 µm: up to 20 m/s

20 µm: up to 10 m/s

Sub-Divisional Error (SDE)

40 µm version: Typically <±120 nm

20 µm version: Typically <±75 nm

Dynamic signal control

Real time signal conditioning including Auto Gain Control (AGC) and Auto Offset Control (AOC) for optimised performance across a range of operating conditions

Incremental signals 
                           Analogue 
                                  Digital


1 Vpp
Resolutions from 10 µm to 1 nm

Electrical connection

Cable readhead: Interboard connector compatible with the Ri, Ti and ACi interfaces or 15 way, D-type connector
FPC readhead: 16 core, 0.5 mm pitch, compatible with ACi

Power supply

5 V ± 10% <50 mA (readhead),<200 mA (with Ti interface), <100 mA (with Ri interface), <100 mA (with ACi interface) (unterminated)

Vibration (operating)

100 m/s² max @ 55 Hz to 2000 Hz

Shock (non-operating)

1 000 m/s², 6 ms, ½ sine

Operating temperature

0 °C to +70 °C

Sealing

Cable variant: IP40 Ri interface IP20
FPC variant: IP20 (with lid fitted)

Ri/Ti interface: IP20

ACi interface: IP00

Refer to data sheets for full details.

Downloads

Data sheet

Software

  • ATOM™ diagnostic software version 1.0

Technical drawings

How it works

ATOM uses a non-collimated LED located centrally between the incremental and reference mark sensors. This high divergence LED produces a low profile height with a footprint at the scale that is much larger than the LED, enabling illumination of incremental and reference mark regions.

ATOM employs the same filtering optics scheme as used in all Renishaw's incremental encoders. The incoherent LED produces a signal of high harmonic purity allowing high resolution interpolation. Efficient photometry also produces a low jitter signal. A further benefit of the filtering optics scheme is that ATOM does not generate measurement errors due to scale contamination and undulations.

ATOM uses a large single feature off-track optical reference mark for good contamination immunity. Phasing of the reference mark is as simple an operation as with TONiC.

ATOM™ optical scheme with annotations