Method and apparatus for positioning an object

Device to permit positioning of an object or a body in space reproducibly, comprising:

• a television camera adapted to furnish a video signal corresponding to the object,
• a television monitor coupled to the camera to show the captured image,
• a synchronization clock adapted to furnish time reference signals particularly to control the electronic sweep of the camera,
• a photosensitive sensor, provided to be able to be displaced on the screen of the monitor and adapted to deliver a signal characteristic of the luminance of the zone opposite which it is placed,
• a threshold detector, connected to the photosensitive sensor to receive the signal furnished by the sensor and adapted to deliver an impulse when this signal exceeds a determined threshold,
• a frame positioning circuit, connected to the threshold detector and to the synchronization clock, and adapted to deliver a control signal, set off in relation to the received impulse at vision frequency in order to center a frame around the zone opposite which the photosensitive sensor is placed,
• a frame generator, connected to the positioning circuit and adapted to furnish a frame signal which can have two values, the one corresponding to a limited zone, called a frame, the other corresponding to zones outside the limited zone,
• a set-off index circuit, controlled by the frame positioning circuit and adapted to deliver a set-off signal in relation to the signal issued from the frame positioning circuit, at vision frequency, in order to position an index on the outside of the frame in constant position in relation to the frame,
• an index generator, connected to the set-off index circuit and adapted to furnish an index signal characterizing an image point,
• a video mixer connected to the camera and to the frame generator and to the aforementioned index generator, and this mixer is connected at its output to the television monitor to furnish it with a video signal representing the image of the plane on which are superimposed the frame and the index, and said video mixer is adapted to confer a predetermined luminance on said frame,
• a measuring assembly, connected to the index generator and to the clock to receive the signal issued from the index generator as well as the reference signals from the clock, and this assembly is adapted to measure the time separating the arrival of the index signals and reference signals, and said assembly furnishes signals characteristic of the position of the points in coincidence with the index,
• a manually controlled selector, having two sets of inputs and one set of outputs and adapted to connect, according to the state of its manual control, its set of outputs to one of the sets of inputs, and one of these sets of inputs is connected to the measuring assembly to receive the signals issuing from it,
• a storage which is adapted to store the coordinates of at least one point, and this storage has a set of outputs connected to the other set of inputs of the selector,
• a buffer which is adapted to store the coordinates of at least one point and having an entry control with manual release, and this storage is connected to the set of outputs from the selector and is provided with a set of outputs for each point to be stored,
• at least one point synthesizer receiving the clock signals and the signals from one set of outputs from the buffer and this synthesizer is adapted to deliver, at vision frequency, impulses characterizing the relevant point, and these impulses are received by the video mixer to be added to the video signal and to generate a superimposition on the monitor screen of at least one luminous zone of small dimensions.