The present invention relates to a detection device comprising a proximal end and a light- transmitting portion, wherein the proximal end comprises a light detection means and the light-transmitting portion comprises means for transmitting light along a path from a surface of interest to the Hghi detection means, characterised in that the light transmitting portion is optimised for use in detecting a low light signal generated by fluorescence or luminescence in conditions of ambient light； and wherein the device is adapted to detect the presence of a disclosing substance which has been applied to a surface of interest.
