面向绝对重力仪的光束垂直性快速调节
|
摘要
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1μGal(1μGal=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 freefall 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 than1μGal(1μGal=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 gradualchange in beam verticality during the measurement.
To reduce the influence of beam verticality on the accuracy of gravity measurement for freefall 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 than1μGal(1μGal=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 gradualchange in beam verticality during the measurement.
引文
[1] TAN Y J,SHAO C G,LI J,et al..A general relativistic model for free-fall absolute gravimeters[J].Metrologia,2016,53(2):846-852.
[2]江颖,李辉,刘子维,等.利用连续重力观测约束2014智利Iquique地震的震源机制解[J].地球物理学报,2016,59(3):941-951.JIANG Y,LI H,LIU Z W,et al..Constraining the focal mechanism of the Iquique earthquake with observations of the continuous gravity stations[J].Chinese J.Geophys,2016,59(3):941-951.(in Chinese)
[3] MUSSO C,BRESSON A,BIDEL Y,et al..Absolute gravimeter for terrain-aided navigation[C].Proceedings of the 20th International Conference on Information Fusion(Fusion),Xi′an,P.R.China,2017:1-7.
[4]HEES A,BAILEY Q,BOURGOIN A,et al..Tests of Lorentz symmetry in the gravitational sector[J].Universe,2016,2(4):30-70.
[5] SCHWARZ J P,ROBERTSON D S,NIEBAUER T M,et al..A new determination of the Newtonian constant of gravity using the free fall method[J].Measurement Science and Technology,1999,10(6):478-486.
[6] WU S,ZHANG Z,LI C,et al..Preliminary result of accurate gravimetry at NIM Joule balance site[C].Proceedings of Conference on Precision Electromagnetic Measurements(CPEM2016),Ottawa,ON,Canada,2016:75406841-2.
[7]姜永涛,王丽美,郭广猛,等.川滇地区震间期断层运动引起的重力变化[J].地球物理学进展,2018,33(1):25-29.JIANG Y T,WANG L M,GUO G M,et al..Research on the inter-seismic gravity change due to the fault movements in Sichuan-Yunnan region[J].Progress in Geophysics,2018,33(1):25-29.(in Chinese)
[8] CHEN S,LIU M,XING L L,et al..Gravity increase before the 2015 Mw 7.8 Nepal earthquake[J].Geophysical Research Letters,2016,43(1):111-117.
[9] ROTHLEITNER C,SVITLOV S,MERIMECHE H,et al..Development of new free-fall absolute gravimeters[J].Metrologia,2009,46(3):283-297.
[10]胡华,伍康,申磊,等.新型高精度绝对重力仪[J].物理学报,2012,61(9):542-549.HU H,WU K,SHEN L,et al..A new high precision absolute gravimeter[J].Acta Physica.Sinica,2012,61(9):542-549.(in Chinese)
[11]滕云田,吴琼,郭有光,等.基于激光干涉的新型高精度绝对重力仪[J].地球物理学进展,2013,28(4):2141-2147.TENG Y T,WU Q,GUO Y G,et al..New type of high-precision absolute gravimeter base on laser interference[J].Progress in Geophysics,2013,28(4):2141-2147.(in Chinese)
[12]冯金扬,吴书清,李春剑,等.基于双干涉仪的自由落体绝对重力测量[J].光学精密工程,2015,23(10):2740-2746.FENG J Y,WU SH Q,LI CH J,et al..Free-fall absolute gravity measurement based on double interferometers[J].Opt.Precision Eng.,2015,23(10):2740-2746.(in Chinese)
[13] FALLER J E.Thirty years of progress in absolute gravimetry:a scientific capability implemented by technological advances[J].Metrologia,2002,39(5):425-428.
[14] HU Z K,SUN B L,DUAN X C,et al..Demonstration of an ultrahigh-sensitivity atom-interferometry absolute gravimeter[J].Physical Review A,2013,88(4):43610.
[15] WU B,WANG Z,CHENG B,et al..The investigation of aμGal-level cold atom gravimeter for field applications[J].Metrologia,2014,51(5):452-458.
[16] NIEBAUER T M,SASAGAWA G S,FALLER J E,et al..A new generation of absolute gravimeters[J].Metrologia,1995,32(3):159-180.
[17] WESTRUM D,NIEBAUER T M.The diffraction correction for absolute gravimeters[J].Metrologia,2003,40(5):258-263.
[2]江颖,李辉,刘子维,等.利用连续重力观测约束2014智利Iquique地震的震源机制解[J].地球物理学报,2016,59(3):941-951.JIANG Y,LI H,LIU Z W,et al..Constraining the focal mechanism of the Iquique earthquake with observations of the continuous gravity stations[J].Chinese J.Geophys,2016,59(3):941-951.(in Chinese)
[3] MUSSO C,BRESSON A,BIDEL Y,et al..Absolute gravimeter for terrain-aided navigation[C].Proceedings of the 20th International Conference on Information Fusion(Fusion),Xi′an,P.R.China,2017:1-7.
[4]HEES A,BAILEY Q,BOURGOIN A,et al..Tests of Lorentz symmetry in the gravitational sector[J].Universe,2016,2(4):30-70.
[5] SCHWARZ J P,ROBERTSON D S,NIEBAUER T M,et al..A new determination of the Newtonian constant of gravity using the free fall method[J].Measurement Science and Technology,1999,10(6):478-486.
[6] WU S,ZHANG Z,LI C,et al..Preliminary result of accurate gravimetry at NIM Joule balance site[C].Proceedings of Conference on Precision Electromagnetic Measurements(CPEM2016),Ottawa,ON,Canada,2016:75406841-2.
[7]姜永涛,王丽美,郭广猛,等.川滇地区震间期断层运动引起的重力变化[J].地球物理学进展,2018,33(1):25-29.JIANG Y T,WANG L M,GUO G M,et al..Research on the inter-seismic gravity change due to the fault movements in Sichuan-Yunnan region[J].Progress in Geophysics,2018,33(1):25-29.(in Chinese)
[8] CHEN S,LIU M,XING L L,et al..Gravity increase before the 2015 Mw 7.8 Nepal earthquake[J].Geophysical Research Letters,2016,43(1):111-117.
[9] ROTHLEITNER C,SVITLOV S,MERIMECHE H,et al..Development of new free-fall absolute gravimeters[J].Metrologia,2009,46(3):283-297.
[10]胡华,伍康,申磊,等.新型高精度绝对重力仪[J].物理学报,2012,61(9):542-549.HU H,WU K,SHEN L,et al..A new high precision absolute gravimeter[J].Acta Physica.Sinica,2012,61(9):542-549.(in Chinese)
[11]滕云田,吴琼,郭有光,等.基于激光干涉的新型高精度绝对重力仪[J].地球物理学进展,2013,28(4):2141-2147.TENG Y T,WU Q,GUO Y G,et al..New type of high-precision absolute gravimeter base on laser interference[J].Progress in Geophysics,2013,28(4):2141-2147.(in Chinese)
[12]冯金扬,吴书清,李春剑,等.基于双干涉仪的自由落体绝对重力测量[J].光学精密工程,2015,23(10):2740-2746.FENG J Y,WU SH Q,LI CH J,et al..Free-fall absolute gravity measurement based on double interferometers[J].Opt.Precision Eng.,2015,23(10):2740-2746.(in Chinese)
[13] FALLER J E.Thirty years of progress in absolute gravimetry:a scientific capability implemented by technological advances[J].Metrologia,2002,39(5):425-428.
[14] HU Z K,SUN B L,DUAN X C,et al..Demonstration of an ultrahigh-sensitivity atom-interferometry absolute gravimeter[J].Physical Review A,2013,88(4):43610.
[15] WU B,WANG Z,CHENG B,et al..The investigation of aμGal-level cold atom gravimeter for field applications[J].Metrologia,2014,51(5):452-458.
[16] NIEBAUER T M,SASAGAWA G S,FALLER J E,et al..A new generation of absolute gravimeters[J].Metrologia,1995,32(3):159-180.
[17] WESTRUM D,NIEBAUER T M.The diffraction correction for absolute gravimeters[J].Metrologia,2003,40(5):258-263.