An analysation instrument including: a first reflector having a partial ellipsoidal shape; a near focal point of the partial ellipsoidal shape of the first reflector; a distant focal point of the partial ellipsoidal shape of the first reflector; a central axis of the partial ellipsoidal shape defined by the near focal point and distant focal point of the partial ellipsoidal shape of the first reflector; a source of electromagnetic radiation disposed at the near focal point of the partial ellipsoidal shape capable of emitting electromagnetic radiation toward the first reflector; a second reflector having a partial ellipsoidal shape oriented relative to the first reflector so as to be capable of receiving electromagnetic radiation reflected by the first reflector; a near focal point of the partial ellipsoidal shape of the second reflector; a distant focal point of the partial ellipsoidal shape of the second reflector; a central axis of the partial ellipsoidal shape defined by the near focal point and distant focal point of the partial ellipsoidal shape of the second reflector; a flow source to produce a flow of particles to be analysed; and wherein an inspection zone of the flow of particles located at the near focal point of the partial ellipsoidal shape of the second reflector to receive electromagnetic radiation reflected by the second reflector to illuminate the flow of particles, wherein the second reflector is also adapted to collect at least a portion of the electromagnetic radiation produced as a result of illumination of the flow of particles and to reflect at least the portion of the electromagnetic radiation produced as a result of illumination of the flow of particles for processing to determine predetermined information relating to the particles; an aperture in the second reflector for outward passage of the stream; a correlator to correlate the information with an associated particle downstream of the aperture; and a sorting apparatus to sort particles based on the information with an associated particle downstream of the aperture. a first reflector having a partial ellipsoidal shape; a near focal point of the partial ellipsoidal shape of the first reflector; a distant focal point of the partial ellipsoidal shape of the first reflector; a central axis of the partial ellipsoidal shape defined by the near focal point and distant focal point of the partial ellipsoidal shape of the first reflector; a source of electromagnetic radiation disposed at the near focal point of the partial ellipsoidal shape capable of emitting electromagnetic radiation toward the first reflector; a second reflector having a partial ellipsoidal shape oriented relative to the first reflector so as to be capable of receiving electromagnetic radiation reflected by the first reflector; a near focal point of the partial ellipsoidal shape of the second reflector; a distant focal point of the partial ellipsoidal shape of the second reflector; a central axis of the partial ellipsoidal shape defined by the near focal point and distant focal point of the partial ellipsoidal shape of the second reflector; a flow source to produce a flow of particles to be analysed; and wherein an inspection zone of the flow of particles located at the near focal point of the partial ellipsoidal shape of the second reflector to receive electromagnetic radiation reflected by the second reflector to illuminate the flow of particles, wherein the second reflector is also adapted to collect at least a portion of the electromagnetic radiation produced as a result of illumination of the flow of particles and to reflect at least the portion of the electromagnetic radiation produced as a result of illumination of the flow of particles for processing to determine predetermined information relating to the particles; an aperture in the second reflector for outward passage of the stream; a correlator to correlate the information with an associated particle downstream of the aperture; and a sorting apparatus to sort particles based on the information with an associated particle downstream of the aperture.