Optical properties of biochemical compositions of microalgae within
spectral range from 300 to 1700 nm
A combination method (DOPTM-EM) using both DOPTM (double optical
pathlength transmission method) and EM (ellipsometry method) is used to
acquire the optical constants of protein, lipid and carbohydrate of
Haematococcus pluvialis, Nannochloropsis sp. and Spirulina in both solid
and solution state within the visible and near-infrared spectral range.
For different types of microalgae, the refractive index of protein and
carbohydrate in solid state are similar to each other, but show an
observed difference from lipid in solid state. The refractive index of
protein and carbohydrate in solution state presents a visible
distinction in the researched spectral range. The absorption index of
protein, lipid and carbohydrate in solid state for these three types of
microalgae are close to each other in the spectral range 300-500 nm.
However, an observed difference is shown in the spectral range 500-1700
nm. For ease of application, the refractive index of biochemical
composition of microalgae was fitted based on the Sellmeier equation.