The present invention relates to an apparatus and a method for detecting the fluorescence of a sample, wherein the apparatus comprises excitation light source located on the same side of the sample as the detecting means. The apparatus may be constructed as a single-sided as well as a double-sided system, wherein the double-sided system comprises double-sided excitation system and/or double-sided detecting system. The double-sided system may also be a combination of fluorescence system and conventional microscopy. The apparatus may be used for analysis of various types of biological material, liquid as well as solid material, and various other types of material suitable being analysed through fluorescence studies.