Confocal optical scanning device designed to allow visualization of an object to be observed (1107) and comprising: an optical system designed, on the one hand, to focus an illuminating beam (FX) coming from a light source on to at least one illuminating point (FXO) intended to illuminate a point of the object to be observed (1107) and, on the other hand, to focus a light beam (FE) coming from the illuminated point of the object (1107) on to a luminous point (FEO) in a first image plane (P1), at least one rotatably mounted mobile mirror (1104) on which are reflected, on the one hand, the illuminating beam (FX) to allow the scanning of the object to be observed (1107) along an observed plane and, on the other hand, the light beam (FE) to bring the luminous point (FEO) on to a fixed point on the first image plane, a first spatial filtering system (1203) arranged in the first image plane and designed to filter the luminous point (FEO) to obtain a beam to be detected (FD). The optical system and the first spatial filtering system (1203) are designed to send back the beam to be detected (FD) on to said rotatably mounted mobile mirror (1104), the optical system is also designed to focus said beam to be detected (FD), on to a point to be detected (FDO) in a second image plane (P2) to obtain, in said second image plane, a movement of said point to be detected proportional to the movement of the illuminated point in the observed plane of the object.