水准仪

A level consists of a telescope for focusing on objects, a spirit level bubble for centering, and leveling screws for manual adjustment. Automatic levels use a suspended compensator for precise automatic leveling after rough manual setup. Electronic digital levels perform automatic leveling and take readings electronically by sighting bar codes on the level rod.

Level rods are graduated rods made of wood, fiberglass, or metal, available in one or more pieces that fold or slide together. Graduations start from zero at the bottom and are represented in feet or meters depending on the region. The rod's sole has a metal plate for durability, and readings are sighted through the level's telescope.

Automatic levels use a suspended compensator to automatically orient the line of sight once roughly leveled with leveling screws and a circular spirit level. Electronic digital levels function similarly with a pendulum compensator for optical leveling but also process bar-code rod images electronically to measure distances and compute point elevation with one-button operation.

A sliding vernier scale placed on the rod or an optical micrometer mounted on the telescope helps take readings smaller than the rod's least count. These precision tools allow surveyors to obtain measurements more accurate than the rod's basic graduations, improving the overall accuracy of leveling measurements.

Leveling measures vertical distances relative to a horizontal line of sight, requiring the level's telescope to establish a truly horizontal reference. The spirit level bubble and leveling mechanism ensure the line of sight remains horizontal when centered, which is critical for accurate vertical distance measurements in surveying applications.

Beyond automatic and electronic digital levels, laser levels, tilting levels, total stations, and transit theodolites can be used as levels for surveying work. Each instrument offers different capabilities and precision levels depending on project requirements and field conditions encountered during surveys.

The level's high-powered telescope focuses on the level rod to enable precise sighting and reading of graduations from a distance. The telescope magnifies the rod's markings, allowing surveyors to accurately read vertical measurements and detect small variations in elevation across surveying projects.