What is the error of theodolite used for measurement?

Theodolite is used to measure instrument error and environmental error.

The line-of-sight error refers to the situation that the line-of-sight of the goniometer is not on the optical axis of the camera. The line-of-sight error will affect the measurement angle and direction, leading to the deviation of the measurement results. Return error is a common error of cycloidal theodolite, which means that when the instrument measures in the same position and direction, the measurement results tend to increase or decrease gradually. This kind of error is usually caused by structural relaxation or friction of cycloidal structure.

Spherical error is caused by incomplete rotation of theodolite parts or incomplete vertical to the ground during measurement, which will affect the measurement results. The sensitivity of infrared detector and other components of theodolite will change at different ambient temperatures, which will lead to measurement errors.

Function of theodolite

When measuring, put the theodolite on a tripod, aim the center of the instrument at the ground station with a vertical ball or optical collimator, level the instrument with a level instrument, aim the measuring target with a telescope, and measure the horizontal angle and vertical angle with a level dial and a vertical dial. According to accuracy, it can be divided into precision theodolite and ordinary theodolite, according to reading equipment, it can be divided into optical theodolite and vernier theodolite, and according to shafting structure, it can be divided into retest theodolite and direction theodolite.

In addition, there is a coded dial theodolite, which can automatically record dial readings according to coded perforations. An automatic tracking theodolite that can continuously and automatically aim at air targets, a gyro theodolite and a laser theodolite that can quickly and autonomously determine the orientation of ground points by using the gyro orientation principle. All-round theodolite with three functions of theodolite, meridian instrument and zenith instrument for astronomical observation, and phototheodolite with camera and theodolite for ground photogrammetry, etc.

Reference to the above content: Baidu Encyclopedia-Theodolite