Vertical Gravity Gradient Measurement Sensor Based on Atom Interference Effect

Abstract

The invention discloses a vertical gravity gradient measuring sensor based on an atom interference effect, and belongs to the technical field of gravity surveying. The sensor comprises a first unit device (A) and a second unit device (B) of the same structures, and is characterized in that a first vacuum container (1.1) and a second vacuum container (1.2) are connected end to end in the mode that central axes are overlapped in the gravity direction to form a vacuum container (1), and the hollow part inside the first vacuum container (1.1) and the hollow part inside the second vacuum container (1.2) are communicated into a whole; two Raman laser beam emitters (7) are respectively arranged on the vacuum container (1) along the central axis of the gravity field direction, and the Raman laser beam emitters (7) carry out opposite emitting and point to the preparation regions of cold atomic groups (c), and the two unit devices share the pair of Raman laser beam emitters (7). The vertical gravity gradient measuring sensor enables noise and deviation from environment and Raman laser phase positions to be offset in a common-mode mode, and reduces the complexity, the size, the mass and the power consumption of a physical system.

Description

technical field [0001] The invention belongs to the technical field of gravity survey, in particular to a vertical gravity gradient measurement sensor based on atomic interference effect. Background technique [0002] The distribution characteristics of mass and density below the surface can be obtained by inversion of the first-order derivative (gravity acceleration) and second-order derivative (gravity gradient) of the gravitational potential. Therefore, the gravity survey method has been playing a very important role in the fields of resource exploration, geological structure analysis and geophysical research. [0003] Compared with the gravity acceleration signal, the gravity gradient signal has higher spatial resolution and sensitivity; and has 9 spatial tensor components (5 of which are independent components), which can be used for stereo imaging; in addition, a series of gravity gradient signals The differential measurement scheme can greatly suppress the negative i...

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Problems solved by technology

However, the measuring device is actually two separate gravimeters, mainly because the physical devices of the two gravimeters are independent in space, which makes it difficult to guarantee the stability of their relative distances, and is susceptible to vibration and vibration. The impact of environmental noise; on the other hand, although the two gravimeters share a pair of Raman lasers, the time synchronization of the measurement is realized, and part of the environmental noise is suppressed, but there are two glasses between the two atomic groups inside the two gravimeters. window and a section of air, which allows the Raman laser to pass through two glass windows after interacting with atoms in the first (upper or lower) gravimeter and before interacting with atoms in the second (lower or upper) gravimeter And a section of air in the middle, so the surface deviation, smoothness, parallelism of the glass window and the vibration, flow and air pressure changes of the air will cause the inconsistency and inhomogeneity of the relative phase of the Raman laser that interacts with the two groups of atoms

As mentioned above, the phase of the Raman laser is the direct source of the phase of the atomic interference fringes, and the gravitational acceleration information is directly extracted from the phase difference of the atomic interference fringes, so the phase noise of the Raman laser is the measurement noise of the gravitational acceleration The main source of the two glass windows and the air in the middle make the measurement noise from the Raman laser unable to effectively eliminate the common mode, which makes it difficult to further improve the sensitivity and accuracy of the gravity gradient measurement of the measurement device; again, Due to the use of two separate gravimeters, two independent vacuum pump groups must be used to respectively achieve and maintain the vacuum degree of the two gravimeter vacuum containers, which forces the volume, weight and power consumption of the entire measuring device to be maintained at one higher level

[0006] It can be seen that the prior art utilizes two discrete gravimeters to carry out gravity gradient measurement, and there is a problem of stability of the relative position between the two gravimeters and the problem of system deviation and noise introduced by the glass window and the air gap, and the measuring device overly complex issues

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