An illumination detection system includes an excitation radiation source and associated radiation processing arrangement for focusing the excitation radiation from the radiation processing arrangement onto an analysis region of a sample. A radiation collection arrangement collects radiation from the analysis region of the sample resulting from the excitation, and a detector detects the collected radiation. The focused excitation radiation includes an excitation line which is evanescent in the sample. This combines the advantages of line scanning (reduced analysis time) and evanescent excitation (reduced background signal) and therewith enables increase measurement speed and precision for point of care application.