A light directing assembly for use in an object analysis system, the light directing assembly including: a plurality of optical relay assemblies, each optical relay assembly including at least one optical element configured to: relay an interrogation beam from a light transmission system to an object; and relay a return beam from the object to the light transmission system, the return beam being generated by reflection or back scattering of the interrogation beam by the object, wherein each optical relay assembly defines: an interrogation angle at which the interrogation beam relayed by the optical relay assembly reaches the object, and an optical path length being the distance from the light transmission system to the object travelled by an interrogation beam via the optical relay assembly, and wherein the plurality of optical relay assemblies are further configured such that the optical path length for a given optical relay assembly has a predefined relationship with the optical path lengths of the other optical relay assemblies, wherein each of the plurality of the optical relay assemblies further includes a path length adjustment means (1304, 1310) for adjusting the optical path length of the optical relay assembly, characterized in that the path length adjustment means for a given optical relay assembly includes a pair of optical elements configured to adjust the path length of the optical relay assembly by deflecting the interrogation and return beams out of and back into an original beam axis. a plurality of optical relay assemblies, each optical relay assembly including at least one optical element configured to: relay an interrogation beam from a light transmission system to an object; and relay a return beam from the object to the light transmission system, the return beam being generated by reflection or back scattering of the interrogation beam by the object, relay an interrogation beam from a light transmission system to an object; and relay a return beam from the object to the light transmission system, the return beam being generated by reflection or back scattering of the interrogation beam by the object, wherein each optical relay assembly defines: an interrogation angle at which the interrogation beam relayed by the optical relay assembly reaches the object, and an optical path length being the distance from the light transmission system to the object travelled by an interrogation beam via the optical relay assembly, and wherein an interrogation angle at which the interrogation beam relayed by the optical relay assembly reaches the object, and an optical path length being the distance from the light transmission system to the object travelled by an interrogation beam via the optical relay assembly, and wherein the plurality of optical relay assemblies are further configured such that the optical path length for a given optical relay assembly has a predefined relationship with the optical path lengths of the other optical relay assemblies, wherein each of the plurality of the optical relay assemblies further includes a path length adjustment means (1304, 1310) for adjusting the optical path length of the optical relay assembly, characterized in that the path length adjustment means for a given optical relay assembly includes a pair of optical elements configured to adjust the path length of the optical relay assembly by deflecting the interrogation and return beams out of and back into an original beam axis.