A Faster, More Accurate Way of Characterizing Cube Beamsplitters

Significance of the Topic

Cube beamsplitters enable precise division of light into reflected and transmitted beams for applications ranging from consumer optics and fiber telecommunications to interferometric nanopositioning. Accurate spectral characterization of transmission reflection and absorptance is critical to optical design validation and quality control however conventional methods often introduce measurement artefacts due to sample movement and angle of incidence variations.

Aims and Overview of the Study

This application note demonstrates an in situ automated approach using the Agilent Cary 7000 universal measurement spectrophotometer UMS to obtain reflection transmission and absorptance data on cube beamsplitters without relocating the sample. The study aims to eliminate artefacts simplify operation and support high throughput QA QC.

Methodology and Instrumentation

• Sample 25 mm TiO2 SiO2 coated cube beamsplitter with antireflection coated outer faces and optical adhesive bonding
• Instrument Agilent Cary 7000 UMS featuring independent motorized control of incidence angle and detector position
• Measurement setup Transmission recorded at 0° incidence reflection at 90° in a static configuration sample remains fixed during measurement
• Spectral parameters 500 to 720 nm range 1 nm step size 5 nm bandwidth and 0.5 second integration time

Main Results and Discussion

• S polarization at 633 nm 99.34 percent reflectance and 0.04 percent transmittance meeting the specification of less than 0.2 percent transmittance
• P polarization at 633 nm 98.19 percent transmittance and 0.11 percent reflectance meeting the specification of greater than 98 percent transmittance
• Absorptance Low total losses below 0.3 percent calculated as A equals one minus transmission minus reflection illustrating minimal absorption and scattering
• Data integrity Simultaneous transmission and reflection measurement at the same location removes artefacts from angle of incidence and coating thickness nonuniformity

Benefits and Practical Applications

• Automated unattended operation enhances QA QC throughput and reproducibility in optical component manufacturing
• Detailed spectral data guide coating design and support final performance testing of beamsplitters used in laser and interferometric systems

Future Trends and Potential Applications

• Integration of UMS systems into production lines for real time process monitoring and inline quality assessment
• Extension of measurement capabilities to UV and NIR ranges and advanced polarization analyses
• Development of software for automated defect detection and predictive maintenance in optical manufacturing

Conclusion

The Agilent Cary 7000 UMS enables artifact free high precision characterization of cube beamsplitters by measuring transmission reflection and absorptance at the same sample location. Its automation and flexibility make it an ideal tool for both research and development coating optimization and high volume QA QC environments.

Reference

1. Amotchkina TV et al. Oscillations in Spectral Behavior of Total Losses (1 minus R minus T) in Thin Dielectric Films Optics Express 2012 20 14 16129 16144.