Improving Absorption Measurements through Light Source Selection

Summary

Stray light limits the maximum absorbance level achievable in a spectral measurement. Once the stray light limit is reached, sample dilution or a shorter pathlength is required to measure more concentrated samples. In this Application Note, we show the impact of stray light on absorbance levels and describe how optimizing the choice of light source can minimize stray light and increase the maximum absorbance measured.

Introduction

The maximum absorbance level achievable with a spectrometer is limited, in part, by stray light. Stray light is undesired light of any wavelength that reaches the detector, including light that reaches the detector from an unintended source (reflection and scatter from optical bench components). Since the detector cannot distinguish stray light from light coming from the intended light path, the system’s dynamic range is lessened and the maximum achievable absorbance measurement level is reduced.