Measuring diffuse refl ectance of solid samples with the Agilent Cary 60 UV-Vis

Importance of the Topic

Measuring diffuse reflectance of solid materials is crucial in applications where samples cannot be removed or altered, such as quality control of painted surfaces and non‐invasive analysis of cultural heritage objects. Remote measurement extends analytical reach and preserves sample integrity.

Study Objectives and Overview

This application note evaluates the Agilent Cary 60 UV‐Vis spectrophotometer equipped with a Remote Diffuse Reflectance Accessory (DRA). The primary aims are to assess spectral quality, noise performance, and measurement reproducibility on colored PTFE standards over the wavelength range 360 to 830 nm.

Methodology

Measurements were performed using the Cary 60 with remote DRA and Cary WinUV software. A 100% reflectance baseline was recorded on a white PTFE reference. Diffuse reflectance spectra for white, yellow, red, blue, and green PTFE samples were collected, each corrected against baseline. Reproducibility was tested by performing ten consecutive scans on the blue PTFE sample and evaluating signal consistency.

Used Instrumentation

• Agilent Cary 60 UV‐Vis spectrophotometer
• Remote Diffuse Reflectance Accessory
• Fiber optic coupler (up to 1.5 m length)
• Cary WinUV data acquisition software

Key Results and Discussion

The collected reflectance spectra exhibited clear, low‐noise profiles typical of PTFE pigments. Measurement noise remained minimal across all colors. Reproducibility testing on the blue PTFE sample yielded an average standard deviation of 0.053 %R, with extremes of 0.007 %R and 0.213 %R between 460 and 500 nm. The high coupling efficiency and focused beam of the Cary 60 ensured consistent photometric performance.

Benefits and Practical Applications

The Cary 60 with remote DRA offers:

• Non‐destructive measurement of large or fixed samples
• High light throughput and low noise via optimized fiber coupling
• Accurate sample positioning aided by integrated video camera
• Room‐light immunity for field or on‐site measurements

This technology is valuable in art restoration, automotive and paint quality control, and any scenario requiring remote or intact sample analysis.

Future Trends and Possibilities

Advancements may include integration with hyperspectral imaging for spatially resolved reflectance mapping, extension to other solid matrices beyond PTFE, and deployment in harsh or inaccessible environments. Combining remote DRA with automation and machine learning algorithms could further streamline color and material characterization workflows.

Conclusion

The Agilent Cary 60 UV‐Vis spectrophotometer with remote DRA accessory delivers rapid, accurate, and reproducible diffuse reflectance measurements of solid samples without the need for destructive sampling. Its superior light coupling, video‐guided placement, and room‐light tolerance make it a versatile tool for diverse analytical challenges.

References

1. Marco Leona, Francesca Casadio, Mauro Bacci & Marcello Picollo Identifi cation Of The Pre‐Columbian Pigment Maya Blue On Works Of Art By Noninvasive UV‐Vis And Raman Spectroscopic Techniques JAIC 2004 43(1) 39–54
2. Dan Drollette Spectrophotometer Finds Cure for Edo Blues Photonics Online 2006