为了减小自由落体式光学干涉型绝对重力仪中光束垂直度对重力测量准确度的影响, 提出了一种基于双层液体光楔对光束的可变偏折实现光束垂直性自校正的快速调节方法。当光束偏离铅锤方向时, 利用液面天然水平的特性, 使液体在重力的作用下形成可变液体光楔, 自上而下的光束经双层液体光楔时光束传播方向发生偏转, 合理地匹配双层液体的折射率, 使它偏离铅锤方向的夹角得到实时修正。搭建光束垂直性自校正装置并进行实验验证, 结果表明, 装置的角度抑制比优于18.0, 当装置倾斜角度不大于2.7′时, 出射光束偏离铅锤方向不超过9.0″, 对应于重力加速度的测量误差小于1 μGal (1 μGal=10-8 m/s2)。将本方案用于自由落体式的重力加速度测量, 仅通过条式水平仪调平便可实现光束垂直性的快速准确调节, 同时还能抑制测量过程中光束垂直性缓变带来的影响。

To reduce the influence of beam verticality on the accuracy of gravity measurement for free-fall absolute gravimeters based on optical interferometry, a fast alignment method based on the adjustable deflection of the laser beam by two liquid-filled optical wedges to realize the self-correction of beam verticality was proposed. When the direction of the laser beam deviates from the plumb line, the liquid forms variable optical wedges under the force of gravity due to the nature of the liquid level. The laser beam is deflected when it passes through a double layer liquid-filled optical wedge from top to bottom. The deviation angle of the laser beam from the plumb line is corrected in real time by adjusting the refractive index of the liquid appropriately. A self-correcting device for beam verticality was built and verified experimentally. The results indicate that the angle rejection ratio of the device is better than 18.0. When the tilt angle of the device does not exceed 2.7′, the deviation of the output beam from the plumb line does not exceed 9.0″, corresponding to an error of g measurement less than 1 μGal (1 μGal = 10-8 m/s2). Assuming that this solution is used for free-fall gravitational acceleration measurement, it is expected that the beam verticality can be aligned quickly and accurately only by leveling with a tubular spirit level. Furthermore, it can also inhibit the influence of the gradual change in beam verticality during the measurement.