Dual-axis optoelectronic level based on laser auto-collimation and liquid surface reflection

Abstract

This paper presents a novel dual-axis optoelectronic level that can simultaneously measure the dual-axis inclined angles. Viscous liquid is employed as the reference to gravity. Whether the level is horizontal or not, the liquid surface keeps horizontal under the influence of gravity. The single-mode fiber-coupled laser provides the stable illumination beam as the light source, which is divided into two beams after passing through the splitter. One of the beams is transformed into the level angle by the auto-collimation structure, using the liquid surface. And the other beam is processed by the compensation structure, which can prevent the angular drift of the emitted laser. The experiment results revealed that the designed level worked well. Its angle error was less than ±2 arcsec in the range of ±1000 arcsec and less than ±0.3 arcsec in the range of ±100 arcsec. The peak to peak resolution of the final data was about 0.1 arcsec and the response time was less than 3 s. Furthermore, the drift of the level was about 0.1 arcsec in 1 h, which showed good stability in long-term.