Measurement of Absorption and Scattering With an Integrating Sphere Detector: Application to Microalgae.

Area of Science:

• Spectroscopy
• Optical Physics
• Biophysics

Background:

• Distinguishing light scattering from molecular absorption is crucial for accurate optical analysis.
• Traditional methods often struggle to decouple these two phenomena, especially in complex biological samples.

Purpose of the Study:

• To develop and validate a measurement protocol for separating scattering and molecular absorption contributions using an integrating sphere (IS) spectrometer.
• To apply this method to characterize optical properties of microsphere and microalgae suspensions.

Main Methods:

• Utilized a spectrometer with an integrating sphere (IS) detector.
• Implemented a two-measurement approach: one in the standard position and another near the IS aperture.
• Tested the method with known solutions (microspheres with fluorescein and holmium oxide) and microalgae suspensions.

Main Results:

• The two-measurement strategy successfully separated scattering and molecular absorption.
• The model showed good agreement with expected responses for known solutions.
• Microalgae measurements revealed spectral structure in scattering inversely related to molecular absorption.

Conclusions:

• The proposed method effectively distinguishes scattering and molecular absorption.
• This technique provides independent insights into chlorophyll status and chloroplast structure in microalgae.
• The findings have implications for optical characterization in biological and material sciences.