Optical determination of white blood cell concentration in fluids

An optical detection apparatus for determining a concentration of white blood cells in a fluid, said apparatus comprising:

• a light emitting arrangement, which is configured to generate a first light beam with a wavelength within a range of 350-575 nanometers (nm) and arranged to direct the first light beam along a first main direction into a first region in the fluid;
• a light detection arrangement, which is arranged to detect first scattered light originating from the first light beam in the first region and provide a first signal that represents the first scattered light as a function of time;
• and
• a computing apparatus operably coupled to at least the light detection arrangement and configured to:
• determine, based on the first signal, a plurality of first properties representing the first scattered light, and
• operate a first calculation function on the plurality of first properties to estimate the concentration of white blood cells in the fluid.