The invention concerns a device for heating an object (6) in an intense magnetic field, comprising:—a light source (1), an optic fiber (2) for transporting the light emitted by said light source (1) and emitting a beam of light in the direction of the object (6) to be heated, a converging optical system (3), a diaphragm (4) positioned at the focusing point of the optical system (3),—a reflector (5), whereof the inner wall is defined by the revolution of a semi-parabola around an axis perpendicular to the optical axis of the parabola and passing through the focal point of said parabola, the optical axis of said reflector (5) coinciding with the optical axis (A) of the optical system (3) and the focal point (F″) of said reflector coinciding with the focusing point of said optical system (3).