Automatic focussing device for installation in a measuring device and for the determination of the focal distance between the measuring device and a a leveling pole on the basis of the division of the pattern markings of the a leveling pole

摘要

Automatic focussing device for installation in a a telescope (20) having a measuring device, wherein the telescope (20) is designed in such a way that it is an aiming a a leveling pole (1) with pattern markings (11), which to this with a same spacing between each mark are marked, wherein said automatic focussing device comprises:– a control device (4, 41), designed in such a way that it comprises a displacement of a focusing lens (21b) of the telescope (20) of one end in the direction of an opposite end of a shifting area of the focusing lens (21b), and specifically until in the case of a first focusing lenses position in accordance with the specific depth of modulation, a sufficiently clear image for the determination of the division of the pattern markings of the a leveling pole (1) on a photoelectric means (24) appears;– a division calculation a direction (3, 24) consisting of microcomputer (3) and a photoelectric means (24), designed in such a way that they the pitch of the pattern markings (11) of a leveling pole (1) with said photoelectric means (24) in the case of the first focusing lenses position is determined, in which the a leveling pole (1) has not yet being focused, and the microcomputer (3) on the basis of these specific pitch and a second focusing lenses position are calculated, in which the a leveling pole (1) is focused and the distance between the measuring device and the corresponding to a leveling pole (1), in that the distance of the a leveling pole (1) for measuring device from the average value of the distances between the respective center lines (cl) of the of the photoelectric means (24) in the case of the first focusing lenses position certain spacing of the pattern markings (11) of a leveling pole (1) on account of the dependence of the depending on the distance of the a leveling pole (1), which is caused to the measurement device, a reduced or increased unfocused representation of the pitch is determined, and– ''a fine adjusting means (3, 4, 41), designed in such a way that it comprises a displacement of the focusing lens (21b) on the second focusing lenses position causes.