Sperm densimeter

In an instrument for measuring sperm concentration of a semen specimen and calculating dose value and having an optical assembly with a light source, a specimen holder and a photodetector, a computation means and a display, the improvement comprising in combination:

• storage means for storing a concentration and calibration calculation equation in the form of a continuous multi-term polynomial obtained from a plurality of data points and directly relating measured sperm concentration and measured sperm transmittance value so that separate calibration of said light source is omitted;
• said computation means including means for calculating sperm concentration of a semen specimen independently of the optical absorbance of the semen specimen using said stored concentration and calibration calculation equation and a semen specimen transmittance value;
• said optical assembly including means for measuring transmission of said specimen holder while empty with said light source energized, TFS, sample transmission of said specimen holder with a semen specimen with said light source energized, TS, and dark cell output of said photodetector with said light source unenergized, TDC;
• said computation means including means for calculating actual percent transmission of the semen specimen in said specimen holder as follows (TS-TDC)/(TFS-TDC) to provide a transmittance value for the semen specimen;
• said means for measuring including means for making a plurality of said measurements and transmittance value calculations in sequence and calculating an average for said transmittance value.