Angle Graticule Calibration(Certified Angle References)
Calibration of angle graticules and screen protractor charts used on profile projectors — line angles verified against certified angle references with stated uncertainty.
What is Angle Graticule Calibration?
Angle graticules — the etched overlay charts used on profile projectors for thread angles, chamfers and taper checks — are reference artefacts themselves, and referencing an unverified chart just moves the error one layer down. Their etched angles must be verified against higher-accuracy certified references at defined intervals.
Global Lab calibrates graticules by comparison against certified angle gauge references on a calibrated optical stage, verifying the marked angles across the chart's working set, reporting deviation and uncertainty per line, and certifying fit-for-use against the user's tolerance under our ISO/IEC 17025 system.
How the Angle Graticule Calibration is Conducted
- 1
Chart Condition Inspection
The graticule is inspected for scratches, edge damage and clarity that would impair reading. - 2
Setup on Calibrated Stage
The graticule is mounted on a verified optical stage/projector with certified angle references. - 3
Angle Comparison
Each marked working angle is compared against the certified reference and deviation recorded. - 4
Uncertainty Evaluation
Measurement uncertainty is computed for the comparison chain. - 5
Certification
Per-angle deviations and verdicts are issued via Autovity QLMS.
Applicable Test Standards
| Standard | Title | Scope | Type |
|---|---|---|---|
| ISO/IEC 17025:2017 | Competence of Testing and Calibration Laboratories | Calibration System | International |
| NPLI-Traceable Artefacts | Certified Angle Gauges and Optical References | Reference Standards | Traceability |