Metrology & Inspection
Measuring optical surfaces and verifying component performance.
Optical Metrology & Quality Verification
Optical metrology connects drawing requirements with measurable results, from surface geometry and finish to spectral performance. Strahl Optics coordinates inspection methods according to the component, specified tolerances, and acceptance criteria. The inspection scope and reporting requirements are established for each project.
Surface Figure & Wavefront Testing
Interferometric testing compares light from the test surface or component with a reference wavefront. The resulting interference pattern is analyzed to map surface figure or wavefront errors across the measured aperture.
These measurements reveal departures from the intended optical form, with results reported using parameters such as peak-to-valley (PV) and RMS under defined testing conditions. For optical components such as optical prisms, transmitted wavefront testing evaluates the distortion introduced as light passes through the component.
Surface Roughness & Topography
Non-contact optical profiling captures local surface height variations to characterize roughness and microscopic features. This complements overall surface figure measurements by examining texture at a finer scale.
The measured area, spatial filtering, and reporting parameters are defined for the inspection task, allowing surface finish to be assessed against the specified requirements.
Spectral Measurement
Spectrophotometry measures transmission across the ultraviolet, visible, and near-infrared regions, with reflectance measurements supported by suitable accessories.
The resulting spectra show how transmission or reflection varies with wavelength, allowing coating response, passbands, and spectral edges to be evaluated. The measurement range and relevant conditions, including angle of incidence and polarization, are defined according to the specified optical requirements.
Quality Assurance Review
Inspection results are reviewed against the drawing, purchase specifications, and agreed acceptance criteria. The review checks whether the required characteristics have been evaluated and whether the records identify the relevant parts or batch.
Any discrepancies are addressed before release, with inspection documentation prepared according to the project’s reporting requirements.
Inspection Workflow
01
Specification Review
Confirm the drawing, material, tolerances, test conditions, and acceptance criteria before processing.
02
Incoming Material Verification
Verify material identification, supporting documentation, blank dimensions, and visible condition.
03
Shaping & Grinding Checks
Check preliminary dimensions, thickness, and curvature where applicable, maintaining sufficient allowance for subsequent processing.
04
Surface Check
Evaluate surface figure, wavefront error, and roughness using suitable interferometric and profiling methods. Recheck thickness as needed.
05
Centering & Edge Inspection
Verify final outer dimensions, bevels, and edge condition, together with applicable centration, parallelism, or angular requirements.
06
Pre-Coating Inspection
Inspect polished surfaces for scratches, digs, contamination, and other defects before coating, where required.
07
Post-Coating Verification
Check spectral performance and coating appearance. For parts cut after coating, also verify finished dimensions and edge condition.
08
Final Inspection & Documentation
Confirm that all required inspection stages are complete and finalize the inspection report.
Inspection stages and sampling plans depend on the component and processing route. Relevant measurements may be repeated during production and final verification.
Have an Optical Component Drawing?
Send us your drawing or specifications. Strahl Optics will review the material, geometry, and tolerances to confirm a suitable fabrication approach for your project.