What the component does
The code disc or ring provides a repeatable reference around the rotation axis, with the readhead mounted to a stable mechanical datum.
Precision Rotary Stages & Angle Measurement
Reference a rotary platform directly to its measurement axis for repeatable positioning and angular inspection.
Where the component works
Measure rotation at the platform axis
- Rotating platform
- Disc coupled to the platform axis
- Readhead attached to the base
Direct platform measurement can observe output rotation rather than infer it only from a drive motor.
Read and compare angular position
- Pattern defines angular divisions
- Reader detects relative movement
- Positioning or measurement controller
Pattern resolution, mounting accuracy and system calibration contribute differently to the final result.
How the system works together
Centre location, track radius and axial clearance connect the optical pattern to the bearing and platform. Some systems use multiple readers to manage selected errors.
What an unsuitable choice changes
More divisions improve nominal reading resolution but do not remove eccentricity or bearing errors. Evaluate repeatability and absolute angle error separately.
Components for this application
Optical Encoder Discs
Fine-pattern disc example with an interactive view of the code track.
Incremental Encoder Discs
Periodic angular divisions with a defined index.
Gray Code Encoder Discs
Absolute code tracks for compatible angular readout systems.
Other relevant products and configurations
Glass Encoder Discs
Annular-pattern example for rotary rings and central-clearance layouts.
Principles and selection details
System context
A circular scale gives a rotary stage a physical angle reference. Large reading radii can provide more distance along a code track for each angular interval, while a central bore leaves space for a bearing, shaft or optical path. The sensor arrangement and installation determine how scale errors appear in the final measurement.
Selection considerations
Specify the required angular placement accuracy and track-to-bore concentricity separately from line count. Multiple-readhead systems can compensate for some eccentricity effects, but the pattern, mounting datums and electronics still need a shared error budget.
Measurement during indexing and scanning
An indexing table needs repeatable angular locations; a scanning stage also needs useful readout throughout movement. Choose the reference architecture around that task and keep the optical track accessible through the required travel and mechanical arrangement.
Related applications
Planning your project
Rotary stages use glass encoder discs or rings coupled to the axis as angular references.
Reading radius, centring and readhead placement influence installed performance. Specify component geometry separately from full-system angular accuracy.
Does a larger reading radius guarantee higher accuracy?
The same angle spans a longer arc at a larger radius, changing feature geometry and installation space. Radius alone does not determine system accuracy.