A method for measuring the total sperm concentration (TSC) in a sample is described and includes: (i) placing the sample in a transparent container between a synchronically pulsed light source and a photodetector; and (ii) measuring the optical absorbance of the sample in the range of 800-1000 nm, the TSC of the sample being proportional to the absorbance. Also described is a sampling device for use in optically analyzing a biological fluid, a method for measuring motile sperm concentration (MSC) in a semen sample, a method of determining the average velocity (AV) of sperm cells and a system for analyzing semen quality including means for measuring TSC, means for measuring MSC; and a video visualization system.