Method and apparatus for measuring the coordinates of a surveyed point

An apparatus for measuring coordinates of a survey point comprising:

• reflecting sheet prism means for reflecting transmitted light and being located at two points present on a line extending through the survey point, the two points being separated from the survey point at predetermined distances, said reflecting sheet prism means having a plate on which said reflecting sheet prism means is mounted, the plate having cross graduations for collimation formed thereon;
• a tachymeter for transmitting light to said reflecting sheet prism means and for receiving light from the two points as reflected by said reflecting sheet prism means resulting from light transmitted from said tachymeter such that receiving light generates a received signal for each of the two points in said tachymeter, said tachymeter determining distances to the two points at which said reflecting sheet prism means is locatable, a horizontal plane angle and a vertical plane angle relative to said tachymeter and the two points, the distances to said reflecting sheet prism means being based on a phase difference between the received signals and a reference signal;
• first calculating means connected to said tachymeter for calculating coordinate values of the two points at which said reflecting sheet prism means is locatable from the horizontal plane angle and the vertical plane angle;
• second calculating means connected to said first calculating means for calculating a coordinate value of the survey point from the coordinate values calculated for the two points at which said reflecting sheet prism means is locatable;
• and
• a support member for supporting said reflecting sheet prism means.

An apparatus for measuring coordinates of a survey point comprising:

• reflecting sheet prism means having at least one reflecting sheet prism for reflecting transmitted light and locatable at two points present on a line extending through the survey point, the two points being separated from the survey point at predetermined distances, said reflecting sheet prism means having plate on which said reflecting sheet prism means is mounted, the plate having cross graduations for collimation formed thereon;
• a tachymeter for transmitting light to said reflecting sheet prism means and for receiving light from said reflecting sheet prism resulting from light transmitted from said tachymeter such that receiving light generates a received signal for the two points in said tachymeter, said tachymeter determining distances to the two points at which said reflecting sheet prism means is locatable, a horizontal plane angle and a vertical plane angle relative to said tachymeter and said reflecting sheet prism, the distances to said reflecting sheet prism being based on a phase difference between the received signal and a reference signal;
• first calculating means for calculating coordinate values of the two points at which said reflecting sheet prism means is locatable from the horizontal plane angle and the vertical plane angle;
• second calculating means for calculating a coordinate value of the survey point from the coordinate values calculated for the two points at which said reflecting sheet prism means is locatable;
• and
• a support member for supporting said reflecting sheet prism means.

A reflecting sheet prism device for reflecting transmitted light in an apparatus for measuring coordinates at a survey point and positioned at the survey point comprising:

• reflecting sheet prism means locatable or located at two points present on a line extending through the survey point, the two points being separated from the survey point at predetermined distances, said reflecting sheet prism means having a plate on which said reflecting sheet prism means is mounted, the plate having cross graduations for collimation formed thereon;
• a support member for supporting said reflecting sheet prism means;
• and
• mounting means for mounting said reflecting sheet prism means in said support member at the survey point.