Method and apparatus for fixing a location

An apparatus for displaying a magnitude (54) obtained from an examination field (9), comprising:

• a sightline detecting device (35) adapted to detect a sightline of a user which is directed to the examination field (9);
• an input device (63) for receiving a request (65, 73) made by the user;
• means (21, 23, 35, 37) for fixing at least one location (59, 55) in the examination field (9) with respect to a coordinate system (13) and for providing a coordinate set (x, y, z) which is allocated to coordinates of the at least one location (59, 55) in the examination field (9) to which the eyes of the user are directed when the request (65, 73) is received;
• and
• a display (51) for displaying at least one magnitude (54) determined dependent upon the coordinate set in the field of view (47) of the user such that the display (54) and the examination field (9) are simultaneously in the field of view (47) of the user.

An apparatus for fixing at least one location in an examination field (9) with respect to a coordinate system (13), comprising:

• a targeting device (35) for determining a first location (59) within the examination field (9) with respect to the coordinate system (13) and for providing coordinates of the first location (59) as a first coordinate set (x, y, z) allocated to the first location (59);
• a topology recording device (37) for obtaining a recording of topological data (69) in a spatially extended area around the first location in the examination field;
• and
• means for comparing (19) at least two recordings of topological data, the means for comparing adapted to determine a displacement (Δx, Δy, Δz) of the examination field with respect to the coordinate system (13), the means for comparing adapted to change the coordinates of the first coordinate set (x, y, z) depending upon the determined displacement (Δx, Δy, Δz) such that the changed coordinates substantially correspond to the coordinates of the first location (59) within the examination field (9) after the displacement thereof.