| abstract |
The invention relates to an optical device for measuring the position of an object along a first axis, the object being subjected to light radiations emitted by a light source. The optical device comprises: an imaging system comprising an objective for collecting light radiations diffused by the object, the imaging system having an optical axis extending parallel to the first axis; a transmission mask having at least a first aperture and a second aperture, the first aperture and second aperture being spaced from each other along a second axis, perpendicular to the first axis, the transmission mask being arranged so as to let a first part of the radiations and a second part of the radiations which are diffused by the object pass through the first aperture and the second aperture respectively, while blocking a part of the radiations emitted by the light source which is not diffused by the object; and a detector adapted for generating an image including a first spot and a second spot representative of the first part and second part of the radiations impacting the detector plane, wherein variation of the position of the object relative to the object plane of the imaging system along the first axis causes variation of a position of the first spot and of the second spot relative to each other along the second axis. |