There are three rotation axes in GMS-2000 goniophotometer. A precision reflecting mirror rotates around the horizontal axle and the tested luminaire rotates in the prescribed burning position and around the vertical axle, meanwhile, a synchronous axle will rotate toward the opposite direction synchronously. The combined motion of the luminaire and mirror permit light measurement at the direction of any horizontal or vertical angle without tilting the tested luminaire, therefore, the luminous intensity will be more stable. The photometer head located at a fixed position of the required photometric distance in front of the reflecting mirror to detect luminous intensity in each direction.