ATOM™ incremental encoder system with RCDM rotary (angle) disc
- 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
- Miniature package
- Filtering optics design enabling high dirt immunity
- Disc encoder for compact rotary applications
- Assured quality
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.
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.
ATOM comes with a variety of interface options which allows greater flexibility to integrate the encoder within your system design.
- 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.
- 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.
- 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.
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.
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
20 μm and 40 µm
Thermal expansion coefficient
Ring outer diameter
40 µm: 17 mm to 108 mm
20 µm: 30 mm to 108 mm
For larger sizes contact Renishaw
40 µm: 1 024 to 8 192
Single reference mark
± 0.5 µm
(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
Cable readhead: Interboard connector compatible with the Ri, Ti and ACi interfaces or 15 way, D-type connector
5 V ± 10% <50 mA (readhead),<200 mA (with Ti interface), <100 mA (with Ri interface), <100 mA (with ACi interface) (unterminated)
100 m/s² max @ 55 Hz to 2000 Hz
1 000 m/s², 6 ms, ½ sine
0 °C to +70 °C
Cable variant: IP40 Ri interface IP20
Ri/Ti interface: IP20
ACi interface: IP00
Refer to data sheets for full details.
- Installation drawing: 20 µm FPC ATOM readhead and RCDM glass disc
- Installation drawing: 20 µm cabled ATOM readhead and RCDM glass disc
- Installation drawing: 40 µm FPC ATOM readhead and RCDM glass disc
- Installation drawing: 40 µm cabled ATOM readhead and RCDM glass disc
- Installation drawing: DSi
- 3D model: ATOM side mount bracket
- 3D model: ATOM L bracket
- 3D model: ATOM cable interface connector
- 3D model: ATOM Slim Applicator
- 3D model: ATOM Top Mount Applicator
- 3D model: ATOM Side Mount Applicator
- 3D model: Ri interface
- 3D model: DSi (Dual Signal Interface)
- 3D model: ACi interface FPC variant
- 3D model: ACi interface cabled variant
- 3D model: ATOM 20um FPC
- 3D model: ATOM 20um cabled
- 3D model: ATOM 40um FPC
- 3D model: ATOM 40um cabled
- 3D model: ATOM_40um_readhead_with_cable
- 3D model: ATOM 20um, 30mm disc
- 3D model: ATOM 20um, 36mm disc
- 3D model: ATOM 20um, 56mm disc
- 3D model: ATOM 20um, 68mm disc
- 3D model: ATOM 20um, 108mm disc
- 3D model: ATOM 40um, 17mm disc
- 3D model: ATOM 40um, 20mm disc
- 3D model: ATOM 40um, 27mm disc
- 3D model: ATOM 40um, 30mm disc
- 3D model: ATOM 40um, 36mm disc
- 3D model: ATOM 40um, 50mm disc
- 3D model: ATOM 40um, 56mm disc
- 3D model: ATOM 40um, 68mm disc
- 3D model: ATOM 40um, 108mm disc
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.