Sensing unit provided with separated detection light guiding

A process for determining an analyte by using an optical sensing unit comprising at least one sample measurement cell, at least one excitation light source, a photoelectric detector array, and an array of waveguides or channels, said process comprising:

• introducing a liquid sample into the at least one sample measurement cell;
• directing excitation light from the at least one excitation light source into the at least one measurement cell to establish at least one sensor field defining an array of measurement fields;
• guiding luminescence light emitted from each of the array of measurement fields to a respective portion of the photoelectric detector array via the array of waveguides or channels which have separate beam guiding of excitation light and emission light;
• and
• detecting an intensity of light emitted by each of the array of measurement fields with the photoelectric detector array.