Establish an instrument for measuring the height difference between two points on the ground with horizontal line of sight. The main components are telescope, pipe level (or compensator), vertical shaft, base and anchor screw. According to the structure, it is divided into micro-tilt level, automatic level, laser level and digital level (also known as electronic level). According to the accuracy, it is divided into precision level and ordinary level. Application classification of grades:
The level meter is suitable for leveling instruments. At present, according to the precision index of the accidental median error of height difference measured per kilometer, China divides the level into four grades.
Grade models all start with DS, which are the Chinese phonetic letters of "Dida" and "Grade" respectively. Usually, the letter d is omitted. Numbers such as 05 ",1", 3 "and 10" indicate the accuracy of the instrument. S3 level and S 10 level are also called ordinary level, which are used for national third and fourth level and ordinary level in China, and S05 level and S 1 level are called precision level, which are used for national first and second precision level:
Level model DS05DS 1DS3D 10
The median accidental median error of kilometer round trip height difference is ≤ 0.5mm ≤1mm ≤ 3mm ≤10mm.
Main uses: national first-class leveling and earthquake monitoring, national second-class leveling and precision leveling, national third-and fourth-class leveling and general engineering leveling.
The axis of the circular level is parallel to the vertical axis (l' l'//vv);
(2) The transverse wire of the crosshair is perpendicular to the vertical axis;
(3) The horizontal axis of the tube is parallel to the collimation axis (LL//CC).
Level belongs to precision measuring equipment, which requires high calibration of instruments, so these axis relationships should be satisfied. It is not easy to discuss which is the most important. I don't think it makes sense. Take (1) as an example, the circular level is directly related to the roughness of the instrument. If something goes wrong with this relationship, the instrument cannot be leveled. How do we start the measurement? . Crosshair Crosshair affects reading, so we need to get data through reading. It is meaningless for the instrument to over-calibrate the reading, so (2) try to be as accurate as possible. One-sided view of (3) may cause a relatively large error, but it can be completely eliminated by equidistant front and rear feet.