Abstract: System making it possible to analyze electrical or other transients with the aid of an easily displaceable, miniature, passive, electrically insulated sensor. It comprises a monomode laser source connected by an optical fibre to an optical transient analyzer. The sensor is formed by a circuit receiving the signal to be analyzed and making it possible to modulate the light intensity in the fibre by means of an integrated optics modulating circuit and which receives the signal in electrical form. An adapting circuit at the input makes it possible to convert the signal to be analyzed into an electrical signal, where necessary. It is constituted by a coil in the case of a magnetic field, an antenna in the case of an electrical field, a quartz in the case of a force, etc.