Theodolite is an inclinometer precision instrument for measuring angles in the horizontal and vertical planes. Theodolites are mainly used for surveying applications, and have been adapted for specialized purposes in fields like meteorology and rocket launch technology. Theodolite will be used for general topographic surveying application and in particular for position fixing during discharge measurements on rivers and canals from boats.

Optical Reading Theodolites display the result in a mechanical gauge. Electronic Reading Theodolites offer decreased operating time and power consumption with long-lasting usage! Typically displaying counts with an LCD panel, an electronic theodolite gets the job done for practically any angular or weather condition. Digital theodolite is an optimal choice for surveyors looking for precise, direct horizontal and vertical readouts. Laser theodolite includes the superior functionality of top-quality electric theodolite, with grade-setting laser capabilities for superior accuracy.

A modern theodolite consists of a movable telescope mounted within two perpendicular axes β€” the horizontal or trunnion axis, and the vertical axis. When the telescope is pointed at a target object, the angle of each of these axes can be measured with great precision, typically to seconds of arc. The horizontal and vertical axes of a theodolite must be perpendicular, if not then a “horizontal axis error” exists. This can be tested by aligning the tubular spirit bubble parallel to a line between two footscrews and setting the bubble central.

Gyrotheodolite is used when the north-south reference bearing of the meridian is required in the absence of astronomical star sights. This mainly occurs in the underground mining industry and in tunnel engineering. The gyrotheodolite comprises a normal theodolite with an attachment that contains a gyroscope mounted so as to sense rotation of the Earth and from that the alignment of the meridian.