Patent ID: 8244477

Claim:
A method for estimating a stage of growth of a selected algae, the method comprising: placing an algae, having a growth stage that may be unknown, in a chamber that also contains an ambient fluid, the chamber having one or more windows that are at least partly transparent to light in a selected wavelength range R; passing N light beams, numbered n=1, . . . , N (N≧2), having initial light beam intensities I 0 (n) and having wavelength sub-ranges λ1 n ≦λ≦λ2 n ., respectively, within the range R, through the one or more chamber windows, through the ambient fluid and through the algae, and allowing at least one of the ambient fluid, the one or more chamber windows and the algae to absorb a portion of at least one of the N light beams, to produce modified light beams, numbered n=1, . . . , N, in the respective wavelength sub-ranges, that have passed through the chamber; receiving the modified N light beams and estimating or measuring modified light beam intensities, I(n), numbered n=1, . . . , N, for the respective N modified light beams; providing N reference light beam intensities I(ref;n;g), numbered n=1, . . . , N, for each reference growth stage, numbered g=1, . . . , G (G≧2) for the selected algae; comparing the N modified light beam intensities I(n) with the corresponding N reference initial light beam intensities I(ref;n;g) for each reference growth stage g of the algae; computing an error value ε(g), based upon differences between the N modified light beam intensities I(n) and the respective N reference light beam intensities I(ref;n;g), for each growth stage g of the algae; and when, for a selected growth stage number g0, (1) the error value ε(g) for at least one growth stage, g−g0, is no greater than a value ε(g′), for any other growth stage g′, and (2) ε(g0) is no greater than a selected error threshold value ε(thr), interpreting these conditions as indicating that the algae is most likely in the growth stage g0.