143
general agreement between theoretical and experimental results concerning both absorption
and total scattering is analyzed. Information about the angular scattering pattern and its
magnitude is provided for various particles, with particular emphasis on the possibilities
offered by theory in the quantitative interpretation of scattering signals as detected in flow
cytometry.
The last part deviates slightly from the main topic, to the extent that it does not strictly
coincide with the title of the Advance Study Institute (Individual Cell and Panicle Analysis
in Oceanography). In this last discussion, the cell-by-cellievel or the microscopic scale are
abandoned and the optical oceanography viewpoint is adopted. In principle, the formation of
the bulk optical properties of oceanic waters could be explained from the knowledge of the
optical role and contribution of each category of materials, as supposedly provided by the
analytical optics method. The solution of this problem is as yet out of reach: all types of
particles are not presently studied or even identified, their numerical abundance is not
sufficiently documented and so on. Therefore, this tentative discussion, which does not claim
to be exhaustive, mainly aims at putting forward some working hypotheses for future
research.
RELEVANT PHYSICAL CHARACTERISTICS OF PARTICLES
Among the physical characteristics of individual particles or of a population of particles, some
are of direct interest when dealing with the optical properties. The bulk index of refraction
and absorption capability of the material forming a single cell or particle is, along with its
size, the parameter which primarily governs its optical properties. Heterogeneities and internal
and external structures, as well as actual shape, are additional factors also to be taken into
account for detailed studies, requiring much more complex theoretical support and
computational effort. To the extent that marine particles are randomly oriented when their
optical properties are to be measured or predicted, or when they are producing the in-water
radiative field, the simplified approach of considering that they behave as quasi-spherical and
homogeneous bodies is an acceptable approximation, which at least allows the main features
to be understood and predicted.
general agreement between theoretical and experimental results concerning both absorption
and total scattering is analyzed. Information about the angular scattering pattern and its
magnitude is provided for various particles, with particular emphasis on the possibilities
offered by theory in the quantitative interpretation of scattering signals as detected in flow
cytometry.
The last part deviates slightly from the main topic, to the extent that it does not strictly
coincide with the title of the Advance Study Institute (Individual Cell and Panicle Analysis
in Oceanography). In this last discussion, the cell-by-cellievel or the microscopic scale are
abandoned and the optical oceanography viewpoint is adopted. In principle, the formation of
the bulk optical properties of oceanic waters could be explained from the knowledge of the
optical role and contribution of each category of materials, as supposedly provided by the
analytical optics method. The solution of this problem is as yet out of reach: all types of
particles are not presently studied or even identified, their numerical abundance is not
sufficiently documented and so on. Therefore, this tentative discussion, which does not claim
to be exhaustive, mainly aims at putting forward some working hypotheses for future
research.
RELEVANT PHYSICAL CHARACTERISTICS OF PARTICLES
Among the physical characteristics of individual particles or of a population of particles, some
are of direct interest when dealing with the optical properties. The bulk index of refraction
and absorption capability of the material forming a single cell or particle is, along with its
size, the parameter which primarily governs its optical properties. Heterogeneities and internal
and external structures, as well as actual shape, are additional factors also to be taken into
account for detailed studies, requiring much more complex theoretical support and
computational effort. To the extent that marine particles are randomly oriented when their
optical properties are to be measured or predicted, or when they are producing the in-water
radiative field, the simplified approach of considering that they behave as quasi-spherical and
homogeneous bodies is an acceptable approximation, which at least allows the main features
to be understood and predicted.