Skip navigation

RESOLUTE™ optical absolute encoder series

The RESOLUTE optical absolute encoder is a high-speed fine-resolution position measurement system. Learn how position is found immediately on start-up, without needing any motion, offering smooth velocity control and dependable positional stability.

High-performance absolute position measurement

The RESOLUTE optical absolute encoder measures absolute position with fine resolutions down to 1 nm and high speeds up to 100 m/s. Advanced optics and innovative position determination algorithms deliver exceptional metrology performance. Low Sub-Divisional Error (SDE) and ultra-low noise (jitter) makes it suitable for demanding motion control challenges.

Application-specific variants include RESOLUTE Ultra-High Vacuum (UHV), RESOLUTE Extended Temperature Range (ETR) and RESOLUTE Functional Safety (FS).

Optional Advanced Diagnostic Tools and ADT View software acquire comprehensive real-time encoder data allowing optimisation and in-field fault finding.

Datasheets and technical documents

Further information about the technical specifications of the RESOLUTE encoder series, such as datasheets and installation guides, are available from our technical downloads section.

Serial interfaces

RESOLUTE encoders are available with linear, rotary and partial arc scales with a variety of serial interfaces:

  • BiSS® C (unidirectional) with compatible controllers
  • BiSS Safety (unidirectional)
  • FANUC (α and αi)
  • Mitsubishi (J4 and J5 series of servo drives, and the MDS-D2/DH2/DM2/DJ drives for machine tool applications)
  • Panasonic (A5 and A6 series of drivers)
  • Siemens DRIVE-CLiQ®
  • Yaskawa (Sigma-5 and Sigma-7 SERVOPACKs)

Watch our introduction to RESOLUTE absolute encoders

Key benefits

Illustration representing absolute encoder scales

True-absolute

Position is acquired immediately on start-up without requiring any motion.

Illustration of speedometer

High speed

Measurement of absolute position with high speeds up to 100 m/s (36 000 rpm) and fine resolutions down to 1 nm.

Illustration representing Sub-Divisional Error (SDE)

Metrology performance

Low Sub-Divisional Error (SDE) of ±40 nm and ultra-low noise (jitter) of less than 10 nm RMS.

What form of motion do you need to measure?

Linear (including UHV, FS)

Scale type

Scale name

Accuracy

Scale pitch

Coefficient of thermal expansion at 20 °C

Supplied length

Other variants

Stainless steel tape

RTLA linear scale

RTLA30±5 µm/m30 µm10.1 ±0.2 µm/m/°CUp to 21 mUltra-High Vacuum, Functional Safety

Stainless steel tape with track option

RTLA FASTRACK linear scale


RTLA30 with optional FASTRACK™

±5 µm/m

30 µm

10.1 ±0.2 µm/m/°C

Up to 21 m


Ultra-High Vacuum, Functional Safety

ZeroMet™ spar

RELA linear scale

RELA30

±1 µm for up to 1 m, then ±1 µm/m

30 µm

0.75 ±0.35 µm/m/°C

Up to 1.5 m Ultra-High Vacuum, Functional Safety

Stainless steel spar

RSLA linear scale

RSLA30 ±1.5 µm up to 1 m, ±2.25 µm up to 2 m, ±3 µm up to 3 m, ±4 µm up to 5 m

30 µm

10.1 ±0.2 µm/m/°C

Up to 5 mUltra-High Vacuum, Functional Safety

Narrow stainless steel tape

RTLA linear scale

RKLA30-S

±5 µm/m

30 µm

Matched to substrate material when scale ends are fixed with end clamps Up to 21 m

Partial arc

Scale type

Scale name

Accuracy

Scale pitch

Coefficient of thermal expansion at 20 °C

Supplied length

Narrow stainless steel partial arc tape

RKLA partial arc scale

RKLA30-S

±5 μm/m


30 µm

10.1 ±0.2 μm/m/°C

Up to 21 m

Rotary (including UHV, FS, ETR)

Scale type

Scale name


Accuracy

(depending on ring diameter)

Scale pitch

Coefficient of thermal expansion at 20 °C

Ring diameter

Other variants

Stainless steel ring

RESA rotary scale

RESA30


Graduation accuracy: 4 to 0.4 arc seconds

30 µm

15.5 ±0.5 µm/m/°C

52 to 550 mm


Ultra-High Vacuum, Functional Safety, Extended Temperature Range

Ultra-high accuracy stainless steel ring

REXA rotary scale

REXA30

Installed accuracy:

(≥100 mm diameter)

±1 arc second
(75 mm diameter)

±1.5 arc seconds
(≤57 mm diameter)

±2 arc seconds

30 µm

15.5 ±0.5 µm/m/°C

52 to 417 mm

Ultra-High Vacuum, Functional Safety, Extended Temperature Range

We exclusively use RESOLUTE encoders in our radar products, the line-of-sight and SATCOM antennas and high-power microwave products. We have chosen these encoders for their high accuracy and high resolution, which we can use in our control loops.

Pacific Antenna Systems (USA)

Optional Advanced Diagnostic Tool ADTa-100

Advanced Diagnostic Tool ADTa-100

RESOLUTE encoder readheads (marked with the ADT symbol) are compatible with the Advanced Diagnostic Tool ADTa-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
  • Digital readout of encoder position (relative to the scale)
  • Exporting and saving data
  • Setting zero

How RESOLUTE encoders work

RESOLUTE communicates bi-directionally in purely serial format, using a variety of industry-standard protocols, of both proprietary and open standard.

The process begins...

The controller initiates operation by sending a demand message to the readhead, instructing it to capture the absolute position on the linear or rotary scale at that instant. The head responds by flashing a high-power LED source to illuminate the scale. The flash duration is as brief as 100 ns to minimise image blur on moving axes. Crucially its timing is controlled within a few nanoseconds to preserve the relationship between demanded and reported position, one of the essential features that makes RESOLUTE ideally suited to very high specification motion systems.

Single track scale

The scale is essentially a single track of full-width contrasting lines, based on a nominal period of 30 m. The absence of multiple parallel tracks gives important immunity from yaw errors and much more lateral tolerance in head position.

Image acquisition

The scale is imaged, via an aspheric lens which minimises distortion, onto a custom detector array designed specifically for RESOLUTE. The optical arrangement, with a folded illumination path but direct imaging, is highly compact yet stable thus assuring the fidelity essential for excellent metrology.

Data decoding and analysis

Once captured by the detector, the image is transferred via an analogue-to-digital converter (ADC) to a powerful Digital Signal Processor (DSP). Specially developed algorithms then obtain a true absolute, but relatively coarse position from the code embedded in the scale. This process is checked, and corrections are made by further algorithms in the DSP which exploit redundancy and intentional restrictions in the scale code. Meanwhile other routines calculate a very high resolution fine position, which is then combined with the coarse position to provide a truly absolute and very high resolution location.

Final checks and data output

After final error checking procedures this information is uploaded in the appropriate protocol to the controller as a pure serial word representing position to within 1 nm. Protection against electrical noise disturbance is provided by addition of a Cyclic Redundancy Check (CRC). The entire process can take as little as a few microseconds and be repeated up to 25 000 times per second. By a variety of techniques, including adjusting the light flash duration to the axis speed, this performance is achieved at up to 100 m/s while, crucially, preserving exceptionally low positional jitter at lower operating speeds.

And the result is...

An encoder with generous installation tolerances: RESOLUTE allows 0.5 in yaw, pitch and roll and an impressive 150 m in rideheight. Meanwhile the generous optical footprint and advanced error correcting procedures confer excellent immunity to optical contamination, both particulate and greasy smears. All this while maintaining 1 nm resolution at 100 m/s: RESOLUTE is the answer to the toughest absolute challenge.

Discover our range of open optical encoders designed to meet your industrial automation needs.