Hemoglobin detector

An apparatus for photometrically investigating substances according to a two wavelength-method, in particular, for determining hemoglobin and other colored substance content in a substance specimen of blood plasma and blood serum, the apparatus comprising:

• a first light source having a first wavelength of emission within a first range of absorption levels of the substance specimen;
• a second light source having a second wavelength of emission within a second range of absorption levels of the substance specimen;
• means for alternatingly activating said first and second light sources, said activating means including a first switch-over device and a second switch-over device;
• a measuring photodetector means and a reference detector means, said measuring photodetector means and said reference photodetector means each for detecting emissions from both said first light source and said second light source, said measuring detector means for detecting light transmitted through the substance specimen and said reference photodetector means for detecting light directly from said first light source and said second light source;
• and
• evaluation means coupled to said measuring and said reference photodetector means for determining the different absorption typical for the substance specimen, in both the first light wavelength and the second light wavelength, including means for determining exposure of light respectively transmitted by the first and second light sources to establish a first switch-over point in time for said first switch-over device for controlling said first light source upon attainment of a first predetermined exposure of light and to establish a second switch-over point in time for said second switch-over device for controlling said second light source upon attainment of a second predetermined exposure of light.