Define what is measured, how results are recorded and which documents accompany the part. Inspection equipment and repair methods are covered in the manufacturing process pages.
A tolerance is useful only when the measured feature, reference and conditions are clear. The following distinctions prevent a process value from being mistaken for a finished-part specification.
| Control area | What to evaluate | How to define the result |
|---|---|---|
| Substrate geometry | Dimensions, thickness, flatness, parallelism and edges | Identify the measurement aperture and datums. For flatness in wavelengths, state the test wavelength as well as the permitted value. |
| Pattern geometry | Line width, pitch, location and registration | Keep critical-dimension error separate from pitch error and pattern-to-part alignment. Define sampling positions and the datum used for each result. |
| Optical behaviour | Transmission, reflectance, optical density and contrast | Record wavelength and measurement conditions. Film optical density alone does not describe the contrast delivered by a complete encoder or imaging system. |
| Pattern defects | Pinholes, breaks, excess chromium and contamination | Define defect type, size and location within the active field. Identify excluded edge regions and whether a repaired area needs separate approval. |
Classify an opaque defect as unwanted chromium in a clear region, and a clear defect as missing opacity in a dark region. Repair suitability depends on feature geometry and defect location. Record the inspected area and review it again after correction.
Inspection equipment and repair methodsDefine the drawing revision, lot or part identifier, inspection items and reporting format. Where numerical results are required, include units, measurement conditions and the acceptance limit. Specify any material certificate or calibration document explicitly.
Put acceptance requirements in the drawingAcceptance and delivery records connect the component to its drawing revision, batch and inspection requirements. Line width, position, substrate geometry, defects and optical contrast are separate checks.
Define functional and edge inspection regions, the datum for each measurement and the dimensional records or images required with delivery.
Identify the part and drawing revision, measured feature, units, datum, conditions, result and acceptance criterion. List any material documentation or other required evidence as order deliverables.