Method and apparatus for position control of plant parts in a highly radioactive cell for an atomic plant

A method of monitoring the position of parts within a viewing field in a radioactive cell, and identifying changes in parts position at a subsequent time by repeating the monitoring steps and comparing the viewing fields so obtained, comprising the steps of

• (a) obtaining a first image of the viewing field by two spatially displaced optical imaging systems, each system having a high resolution objective field smaller than the viewing field, wherein the image is obtained by
• (i) simultaneously obtaining two objective field images from the two systems,
• (ii) displacing one system relative to the other by a predetermined distance,
• (iii) simultaneously obtaining two further objective field images, and
• (iv) repeating the steps (i-iii) until objective field image pairs have been obtained over the entire viewing field, and
• (v) forming the image of the viewing field by measuring the displacement of respective objective field image pairs over the entire viewing field;
• (b) obtaining a second image of the viewing field at a subsequent time, by repeating steps (a), and comparing the second image to the first image to identify changes in part position.

An apparatus for monitoring the positions of objects within a visual field, comprising

• a plurality of movable optical imaging devices,
• said optical imaging devices spatially displaced to image the visual field in sections,
• said visual field sections being imaged in pairs by separate ones of said optical imaging devices,
• said visual field section pairs containing a reference locus,
• a recording medium for recording the visual field sections and respective positions of the optical imaging devices,
• an evaluation device for comparing the recorded visual field sections and the positions of the optical imaging devices with a second set of imaged visual field sections and positions of the optical imaging devices.