The invention discloses a method for measuring the content of
free hemoglobin in a blood bag by a multiple-position modulated
light source. The method comprises the following steps: modulating a
light source by a modulation device, allowing the light exit port of the
light source and the entrance slit of a spectrum receiving device to cling to the blood bag, controlling the light source to move to multiple positions by a displacement platform in order to transmit a blood sample, and acquiring the transmission spectrum by the spectrum receiving device; transforming the
time sequence of every
wavelength in the acquired transmission spectrum into a
frequency domain, constructing a transmission spectrum in the
frequency domain based on the fundamental wave component of every
wavelength, carrying out normalization
processing, comparing the obtained result with existing chemical analysis results, and establishing a
mathematical model; and acquiring the transmission spectrum in the
frequency domain of an unknown blood sample through using above steps, normalizing the obtained transmission spectrum, and substituting the normalization result into the
mathematical model in order to obtain the content of the
free hemoglobin. The method eliminates the influences brought by spectral background noises and scattering, increases the information content of all components in the blood, and improves the precision of the
free hemoglobin content analysis.