High Volume Optical Component Testing

Importance of the Topic

Multilayer optical coatings require precise characterization of reflectance and transmittance to ensure performance and quality assurance in industries such as telecommunications, aerospace, and consumer electronics. Traditional separate measurements of transmission and reflection can introduce alignment errors and reduce throughput, driving the need for efficient multi-angle photometric spectroscopy methods.

Objectives and Overview

This study demonstrates the use of the Agilent Cary 7000 Universal Measurement Spectrophotometer (UMS) equipped with a Solids Autosampler to enable high-volume, automated, multi-angle reflectance/transmission (R/T) measurements on fused silica samples without manual intervention or sample repositioning. The primary goals are to increase productivity, reduce QA/QC costs, and maintain measurement accuracy across multiple samples.

Methodology and Instrumentation

The key components and methodology include:

• Agilent Cary 7000 UMS covering 250–2500 nm, performing variable-angle transmission and absolute reflectance from the same sample patch.
• Solids Autosampler enabling unattended analysis of up to 32 one-inch diameter samples or similar sized plates with radial and rotational positioning.
• Measurement protocol involving S and P polarization at angles ±7° and ±45°, with automatic averaging of positive and negative angles and baseline correction prior to sample analysis.

Main Results and Discussion

• Single-sample analysis on 1 mm thick fused silica showed close agreement with Fresnel equation predictions for reflectance and transmittance up to 82° angle of incidence, with negligible absorptance in the 500–2000 nm range.
• Multi-sample analysis of 11 fused silica plates (38 × 42.5 × 1 mm) produced 16 spectra per sample in under 40 minutes, and less than 8 hours for all samples in an unattended run.
• Residual errors relative to theoretical values at 1500 nm remained within ±0.17%, demonstrating high system stability, reproducibility, and optical symmetry.
• Factors influencing accuracy included sample mounting precision, system drift, and optical asymmetries mitigated by angle averaging and automated baseline collection.

Benefits and Practical Applications

• Significant reduction in QA/QC cycle time from days to hours through fully automated multi-angle spectroscopy.
• Lower cost per analysis enabling routine high-volume testing of optical components during production runs.
• Enhanced characterization fidelity supporting reverse engineering, coating validation, and design optimization for precision optics.

Future Trends and Prospects

Advances may include integration with rapid material sorting, expansion to diffuse and scattering surfaces via goniospectrophotometry, and application to emerging transparent materials. Automated multi-angle data combined with machine learning could further refine coating process control and predictive quality assurance.

Conclusion

The Agilent Cary 7000 UMS with Solids Autosampler delivers precise, unattended multi-angle R/T measurements, aligning closely with theoretical models and dramatically improving throughput for optical coating QA/QC. This approach enables cost-effective, reliable assessment of thin-film performance and supports advanced production workflows.

References

1. Death D.L., Francis R.J., Bricker C., Burt T., Colley C. The UMA: A new tool for Multi-angle Photometric Spectroscopy. Proceedings of the Optical Interference Coatings (OIC) OSA Topical Meeting, Canada, 2013.
2. Tikhonravov A.V., Amotchkina T.V., Trubetskov M.K., Francis R.J., Janicki V., Sancho-Parramon J., Zorc H., Pervak V. Optical characterization and reverse engineering based on multiangle spectroscopy. Applied Optics, 2012, 51, 245–254.
3. Amotchkina T.V., Trubetskov M.K., Tikhonravov A.V., Janicki V.J., Sancho-Parramon J., Razskazovskaya O., Pervak V. Oscillations in the spectral behavior of total losses (1 – T – R) in dielectric films. Optics Express, 2012, 20, 16129–16144.
4. Amotchkina T.V., Trubetskov M.K., Tikhonravov A.V., Schlichting S., Ehlers H., Ristau D., Death D., Francis J.J., Pervak V. Quality control of oblique incidence optical coatings based on normal incidence measurement data. Optics Express, 2013, 21, 21508–21522.