Multicapillary electrophoresis systems

Multicapillary electrophoresis system comprising a plurality of juxtaposed capillaries, at least one source configured for the emission of a light beam intended to excite molecules lying in its path and inside the capillaries and means for detecting the fluorescence of the molecules excited by said light beam, wherein said means are arranged so as to detect light which emerges at the exit of said capillaries and which propagates along the direction in which said capillaries extend, the resolution of the detection means is high enough to distinguish light which emerges at the exit of each of the capillaries, a first liquid is disposed outside of the capillaries, and a second liquid is disposed inside of the capillaries, the first liquid has a first refractive index and the second liquid has a second refractive index, wherein said first refractive index is equal to or superior to said second refractive index, and a mirror is facing the at least one source on the side of the capillaries which is opposed to said source.