Optical Measurement

Calibrated Optical Encoder

Precision optical angular measurement built around a divisionally characterized code disk and precision analog front end, calibrated as a complete sensing system rather than treated as an ideal geometric device.

Calibrated optical encoder
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If you are interested in purchasing a calibrated optical encoder, or would like to discuss a different sensing configuration, contact us to discuss your requirements.

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Optical Angular Measurement

Calibration as part of the sensing system

The encoder combines an optical code disk with a precision analog front end that resolves the disk's angular signal. Rather than assuming perfect geometric spacing across the code disk, the calibration process characterizes the actual angular response of the sensing system.

This approach separates the nominal resolution of the encoder from the accuracy and repeatability of its measured angular response. Calibration data then characterizes the encoder as an individual measurement device.

Sensing Architecture

Code disk, analog front end, and calibration

The sensing system combines the optical pattern, analog signal conditioning, angular reconstruction, and calibration process into one measurement architecture.

Characterized Code Disk

The optical code disk provides the angular pattern from which the encoder reconstructs shaft position. Calibration characterizes the actual disk rather than relying solely on nominal geometry.

Precision Analog Front End

The analog front end converts the optical encoder signals into measurement data suitable for precise angular reconstruction and digital processing.

Calibrated Angular Measurement

The calibration process produces a characterized angular response that the control system can use when reconstructing shaft position.

Calibration

Interferometric angular calibration

Ångström Droids calibrates optical encoders using a common-path polarization interferometer called the Geometric Phase Angular Calibrator, or GPAC. The system provides an angular reference for characterizing the encoder's response.

GPAC Geometric Phase Angular Calibrator provides the interferometric angular reference used during encoder calibration.
Common-Path Interferometry The calibration architecture uses a common optical path to establish a precise angular measurement reference.
System Characterization The calibration process characterizes the complete optical sensing chain rather than treating the code disk as geometrically perfect.
Specifications

Encoder specifications

Current specifications describe established encoder performance and the absolute-accuracy target.

Measurement type Optical angular measurement
Sensing architecture Code disk + precision analog front end
Calibration method GPAC interferometric calibration
Precision ~0.25 arcsecond
Repeatability ~0.25 arcsecond
Absolute accuracy 1 arcsecond target
Configuration

Standard encoders and configured sensing systems

The encoder platform combines optical geometry, analog signal conditioning, and calibration into a single measurement system. Customers can select encoder configurations around the mechanical and measurement requirements of their application.

If you have a specific encoder application or sensing configuration in mind, contact us to discuss the requirements.