A novel dual-axis optoelectronic level with refraction principle

Levels are fundamental metrological tools for machine leveling and angle measurements. Current levels are all based on the pendulum principle and bubble vial principle. The former is precise but complicated, while the latter is not precise enough. This paper presents a novel, simple and precise optoelectronic level. It is based on the principle of light refraction in the transparent and viscous fluid. The fluid surface is always in leveling condition regardless whether the ground is level or not. Measuring the refraction angle with precise dual-axis autocollimator can directly reflect the inclined angle of the level. A leakage prevention design is also proposed to allow the level to be placed in any pose. Calibrated by an angular interferometer, the error of the dual-axis optoelectronic level is better than ±0.7 arcsec in the measuring range of ±100 arcsec, and better than ±0.4 arcsec for the range of ±30 arcsec, for both axes. Without the need of a pendulum mechanism, this is a simpler design for precision level. (paper)