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


  • Digital output direct from the readhead
  • Readhead size: 20.5 x 12.7 x 10.85 mm (20.5 x 12.7 x 7.85 mm for top exit variant)
  • Resolutions down to 2.5 nm
  • Speed up to 20 m/s


  • Miniature package
  • No separate interface required
  • Filtering optics design enabling high dirt immunity
  • Advanced Diagnostic Tool for easy fault finding, challenging installations and servicing
  • Disc encoder for compact rotary applications
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What is ATOM DX?

The ATOM DX encoder series is Renishaw's smallest incremental optical encoder with digital output direct from the readhead. It provides positional feedback, onboard interpolation and filtering optics all in a miniature package.

Detailed diagnostic information can be accessed by using the optional Advanced Diagnostic Tool ADTi‑100 and ADT View software for in‑field diagnostics, fault finding and to aid optimisation of encoder set-up in even the most demanding applications.

The ATOM DX encoder also offers resolutions down to 2.5 nm with a wide range of configurations.

ATOM DX is supplied in cabled and top exit variants with either 20 µm or 40 µm scale options.

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 band. The optical alignment band can be used to minimise alignment errors and improve installed accuracy.

Two versions are available, with either 20 µm pitch or 40 µm pitch incremental graduations, 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 for space critical applications

ATOM DX, available in sizes as small as 20.5 mm x 12.7 mm x 7.85 mm, allows for integration in the tightest of spaces. There are a number of options to choose from, including both cabled and top exit versions.

Easy fault finding and servicing

The Advanced Diagnostic Tool acquires comprehensive real-time data from ATOM DX encoder readheads. The information is displayed via the user-friendly ADT View software interface. Whilst in most cases the integral set-up LED on the encoder is sufficient for setting up the system, the ADT can be used to aid more challenging installations. The ADT can also report on encoder performance and assist system fault finding to avoid lengthy machine downtime.

High performance

With resolutions down to 2.5 nm, low SDE and low jitter, the ATOM DX encoder series is a high performance encoder. Combining digital quadrature output direct from the readhead and Renishaw's proven filtering optics, ATOM DX encoders are a powerful building block for a modern motion control system.

Optional Advanced Diagnostic Tool ADTi-100

Advanced Diagnostic Tool ADTi-100

The ATOM DX encoder system is compatible with the Advanced Diagnostic Tool ADTi-100 and ADT View software. They provide comprehensive real-time encoder data feedback to aid more challenging installations and diagnostics. The intuitive software interface can be used for:

  • Remote calibration
  • Signal optimisation over the entire axis length
  • Reference mark indication
  • Digital readout of encoder position (relative to the scale)
  • Monitoring the velocity against time graph
  • Exporting and saving data

Technical specifications

Measuring standard

Glass disc

Readhead size (LxWxH)

Cabled variant: 20.5 mm x 12.7 mm x 10.85 mm

Top exit variant: 20.5 mm x 12.7 mm x 7.85 mm

Scale pitch

20 μm and 40 µm

Thermal expansion coefficient

~8 µm/m/°C

Disc outer diameter

20 µm: 30 mm to 108 mm

40 µm: 17 mm to 108 mm

For larger sizes contact Renishaw

Line count

20 µm: 4 096 to 16 384

40 µm: 1 024 to 8 192

Reference mark

Single reference mark

Graduation accuracy

±0.5 µm (disc ø up to 100 mm)

±0.7 µm (disc ø over 100 mm)

Maximum speed

Up to 20 m/s

(See data sheet for details)

Sub-Divisional Error (SDE)

20 µm version: typically < ±75 nm

40 µm version: typically < ±120 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

10 µm to 2.5 nm resolution

(See data sheet for details)

Electrical connection

Cabled variant: 0.2 m, 0.5 m, 1 m, 1.5 m, 2 m and 3 m cable lengths with D-type connectors (9 and 15 way)
0.5 m, 1 m, 3 m cable lengths with 10-way JST connector
Top exit variant: readhead with 10-way JST connector

Power supply

5 V -5/+10% typically < 200 mA fully terminated, 3 axes

Vibration (operating)

100 m/s² max @ 55 Hz to 2000 Hz, 3 axes

Shock (operating)

1 000 m/s², 6 ms, ½ sine, 3 axes

Operating temperature

0 °C to +70 °C



Refer to data sheets for full details.