Alternative Measurement Configurations for Extracting Bulk Optical Properties Using an Integrating Sphere Setup.

Area of Science:

• Optical Physics
• Spectroscopy
• Materials Science

Background:

• Integrating sphere setups typically use collimated transmittance (Tc), total transmittance (Td), and diffuse reflectance (Rd) for bulk optical property estimation.
• Accurate Tc measurement is challenging for highly scattering samples due to forward-scattered light contamination.

Purpose of the Study:

• To investigate alternative integrating sphere measurement strategies that avoid Tc.
• To potentially extend the measurable concentration range for bulk optical properties in suspensions.
• To improve accuracy in the visible-near-infrared (Vis-NIR) spectrum for challenging samples.

Main Methods:

• Replacing Tc with reflectance measurements at varying sample thicknesses.
• Replacing both Tc and Td with multiple reflectance measurements.
• Analyzing the impact of these substitutions on bulk scattering and absorption coefficient estimations.
• Comparing two- vs. three-measurement strategies.

Main Results:

• Replacing Tc with reflectance measurements reduces errors in bulk scattering properties for highly scattering samples.
• Using only multiple reflectance measurements yields good optical property estimates for low-absorption samples.
• The effectiveness of measurement strategies depends on sample optical properties and absorption levels.

Conclusions:

• Alternative integrating sphere measurement sets can overcome limitations of traditional methods, especially for turbid media.
• The proposed methods offer a pathway to more accurate bulk optical property determination in chemical and biological suspensions.
• Careful selection of measurement modes is crucial for reliable optical characterization across diverse sample types.