Theodoliet

Theodoliet (English: theodolite) is a precision instrument used to measure horizontal and vertical angles in surveying, civil engineering, and geodesy. It provides essential angular data for determining directions, laying out lines, and controlling construction alignment. The instrument comprises a telescope mounted on two perpendicular axes: a horizontal axis for rotation in the horizontal plane and a vertical axis for tilt, with graduated circles or encoders, a stable tripod, and a leveling mechanism.

Historically, theodolites evolved from earlier angle-measuring devices and were refined into optical transit and non-transit forms. Traditional theodolites rely on optical readouts and micrometer screws, while modern variants use electronic displays and digital encoders for greater precision and faster readings. In recent decades, electronic theodolites and total stations have become standard, combining angle measurement with distance measurement and data storage.

Applications include establishing reference lines for construction and road or railway alignment, topographic surveying, and geodetic networks. Accuracy varies with instrument class, from high-precision devices capable of arcsecond-level readings to more rugged field instruments; modern total stations can achieve centimeter-level distance accuracy over substantial distances.

Maintenance and calibration are integral to reliable performance. Regular collimation checks, axis adjustments, and verification of circle flatness are recommended, along with careful cleaning and protection of optical components from dust and temperature fluctuations. Proper setup, leveling, and proper handling are essential for obtaining accurate measurements.