CN113466958B - Single-beam atomic gravity gradient sensor based on complementary reflector - Google Patents
Single-beam atomic gravity gradient sensor based on complementary reflector Download PDFInfo
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Abstract
The invention discloses a single-beam atomic gravity gradient sensor based on a complementary reflector, and relates to the field of measuring gravity gradient by an atomic interference technology. The invention comprises a 1 st cold atom interference device (A) and a 2 nd cold atom interference device (B) which are connected end to end and have the same structure; each cold atom interference device comprises a vacuum container (1), a 1 st laser beam emitter (2), a vacuum pump (3), an alkali metal sample (4), a vacuum separator (5), a complementary reflector (6), a 2 nd laser beam emitter (7), a three-dimensional magneto-optical trap reverse magnetic field coil pair (8), a bias magnetic field coil (9) and a photoelectric detector (10). The invention simplifies the physical system and the optical system of the sensor from complexity to simplicity, improves the reliability, has good long-term stability, promotes the miniaturization and the application of the atomic gravity gradiometer, and plays an important role in the aspects of resource exploration, environment monitoring, basic physical research and the like.
Description
Technical Field
The invention relates to the field of measuring gravity gradient by an atomic interference technology, in particular to a single-beam atomic gravity gradient sensor based on a complementary reflector.
Background
Gravity gradient is a physical quantity describing the rate of change of gravity space, caused by inhomogeneities or discontinuities in the geological structure and material density distribution at the earth's surface. The anomaly of the gravity gradient is often related to the motion change of oil and gas, mineral deposits or substances in the earth surface, and the like, and scientists can invert the distribution characteristics of local geological structures and substance densities through the measurement data of the gravity gradient. Therefore, high-precision gravity gradient measurement plays an important role in geological exploration, geoscience, space science, and inertial navigation.
Currently, well established gravity gradient measurement solutions include the rotary accelerometer solution of Bell Aerospace, usa, the superconducting solution of ARKeX, uk, and the electrostatic accelerometer solution of the french national Aerospace research institute (ONERA). The three schemes all adopt macroscopic test quality, adverse environmental factors cannot be effectively isolated, and the measurement accuracy is limited. The cold atom interference scheme is the most potential technical scheme for gravity gradient measurement. The scheme adopts cold atoms in vacuum as test mass, minimizes adverse environmental factors influencing gravity measurement, has high measurement precision, and can simultaneously measure absolute gravity and gravity gradient. The measurement of the gravity gradient of the first three schemes belongs to relative measurement, long-term drift exists, and the measurement baseline of the gravity gradient is limited by a mechanical structure. The gravity gradient measurement of the cold atom interference scheme belongs to absolute measurement, no long-term drift exists, a measurement base line is determined by Raman light, the theoretical limitation is not realized, the dynamic range is large, and the atoms are operated by using light beams, so that the maintenance is easy. In a word, the cold atom interference scheme can simultaneously measure absolute gravity and gravity gradient, has high measurement precision, good long-term stability, large dynamic range and easy maintenance, and is the technical direction for future development of the gravity gradient measuring instrument.
The cold atom interference scheme is to measure the gravity gradient by using two identical cold atom interferometers, wherein each atom interferometer measures an absolute gravity, and interference signals of the two atom interferometers are fitted by an ellipse to obtain the gravity gradient. The two atomic interferometers in the scheme do not work completely independently, but inhibit vibration noise through a bundle of shared Raman light, so that the measurement accuracy and the environmental adaptability of the gravity gradiometer are improved. In 1998, the group m.a. kaservich first demonstrated a gravity gradiometer of the diatomic interferometer configuration. Compared with the traditional scheme, the scheme is absolute measurement for measuring the gravity gradient, has good long-term stability, is not limited by a mechanical structure on a measurement base line, is easy to maintain and is widely concerned by people. However, the vacuum system of the gravity gradiometer is large and heavy, the laser system is too complex, stability and reliability are affected, and the gravity gradiometer is not suitable for working on a mobile platform. To this end, the m.a. kaservich group explored a technique for making the vacuum chamber of a cold atom interferometer using glass ceramics (Zerodur). Compared with a titanium metal vacuum cavity, the microcrystalline glass (Zerodur) vacuum cavity is transparent, and does not need to be independently perforated for cooling laser beams, so that the size and the weight of the vacuum cavity are greatly reduced. However, two atomic interferometers require 12 cooling lasers, 1 raman laser, 2 probing lasers and 2 pumping back lasers, and corresponding frequency and power control systems, so that the laser system is still complex and low in reliability. In order to enable a gravity gradient sensor based on a cold atom interference scheme to be moved out of the laboratory, working on a moving platform, miniaturization of the physical system and simplification of the laser system must be done simultaneously.
Disclosure of Invention
The invention provides a single-beam atomic gravity gradient sensor based on a complementary reflector for the first time, aims to overcome the defects and shortcomings in the prior art, is beneficial to miniaturization and engineering of the atomic gravity gradient sensor, and promotes wide application of the atomic gravity sensor on a mobile platform.
The problems solved are in particular:
the existing three-dimensional magneto-optical trap technology usually adopts a polyhedral (such as a 14-surface body) vacuum container to reserve windows for 6 beams of cooling light and other purposes, and adds a beam collimator, so that a cold atom gravity gradient sensor with two three-dimensional magneto-optical traps is large in size, heavy, high in cost and difficult to miniaturize.
② the existing three-dimensional magneto-optical trap technology usually needs 6 cooling laser beams to cool atoms. The cooling light beam is generally transmitted from the optical platform to the cold atom interference device by adopting optical fibers, the coupling efficiency of each optical fiber is about 60-80%, and in addition, the light splitting optical path and the loss thereof are added, the optical system is complex, and the laser power loss is large. To ensure sufficient laser power, additional laser power amplifiers and multiple lasers are required, making laser systems with atomic gravity gradient sensors with two three-dimensional magneto-optical traps complex, long-term stable, and less reliable.
The purpose of the invention is realized as follows:
the sensor comprises a 1 st cold atom interference device and a 2 nd cold atom interference device which are connected end to end and have the same structure;
each cold atom interference device comprises a vacuum container, a vacuum pump, an alkali metal sample, a vacuum separator, a complementary reflector, a three-dimensional magneto-optical trap reverse magnetic field coil pair, a bias magnetic field coil, a photoelectric detector, a 1 st laser beam emitter and a 2 nd laser beam emitter;
the position and the communication relation are as follows:
an alkali metal sample, a three-dimensional magneto-optical trap reverse magnetic field coil pair, a bias magnetic field coil, a vacuum pump 3 and a photoelectric detector are sequentially arranged on the outer wall of the vacuum container 1 from top to bottom;
the vacuum container is divided into a three-dimensional magneto-optical trap and a cold atom interference area by a vacuum separator with a hole in the center, wherein the vacuum degree difference is about 10 times; the complementary reflector is arranged in the three-dimensional magneto-optical trap, the central axis of the complementary reflector is superposed with the central axis of the vacuum container, and the optical center of the complementary reflector is superposed with the zero point of the quadrupole magnetic field generated by the three-dimensional magneto-optical trap reverse magnetic field coil;
the vacuum containers of the 1 st cold atom interference device and the 2 nd cold atom interference device are connected end to end along the vertical direction, and the central axes of the first cold atom interference device and the second cold atom interference device are coincident along the vertical direction;
the difference between the reflecting mirror surfaces of the two complementary reflecting mirrors is 45 degrees along the central axis, and the two complementary reflecting mirrors form complementation in space;
when the vertical shaft is seen downwards, the eight mirror surfaces are staggered in space, are not shielded, and are provided with a regular octagonal small hole in the middle;
a1 st laser beam emitter and a 2 nd laser beam emitter are respectively arranged at the top and the bottom of the sensor, a 1 st cooling laser beam and a 2 nd cooling laser beam are respectively emitted in an atom cooling stage, and a Raman beam is emitted in an atom interference stage.
The invention has the following advantages and positive effects:
the complementary reflector is utilized, the cooling light beams required by the two three-dimensional magneto-optical traps can be realized only by using a single cooling light beam, windows do not need to be reserved for other light beams, more light beam collimators are not needed, and a vacuum container of the three-dimensional magneto-optical traps is simplified into a simple cylinder from an original polyhedron, so that the atomic gravity gradient sensor with the two three-dimensional magneto-optical traps has the advantages of small volume, light weight, simple structure and low cost.
And cutting the single cooling laser beam into cooling light of three-dimensional magneto-optical traps of two same cold atom interference devices by adopting a complementary reflector. Originally, each three-dimensional magneto-optical trap needs 6 beams of cooling light, two cooling lights need 12 beams of cooling light, and only one beam of cooling light is needed after a complementary reflector is adopted, so that the light path is greatly simplified, and devices needed for controlling the light path are greatly reduced. In addition, the cooling light beam is generally transmitted from the optical platform to the cold atom interference device by adopting optical fibers, 6 optical fibers are needed for 6 cooling light beams, and the transmission efficiency of each optical fiber is about 60-80 percent, so that the optical power loss is greatly reduced and the efficiency is improved by adopting a single cooling light beam and only using one optical fiber, and the laser with various frequencies and powers needed by the atom interference device can be provided by using a single semiconductor laser. Therefore, the laser system has the advantages of greatly simplified optical path and circuit, improved reliability and stability, reduced cost, and contribution to miniaturization and wide application of the atomic gravity gradient sensor on a mobile platform.
The three-dimensional magneto-optical trap and the cold atom interference region are connected through the differential hole, so that the vacuum degree of the cold atom interference region is about 10 times higher than that of the three-dimensional magneto-optical trap, and enough alkali metal atoms in the three-dimensional magneto-optical trap are captured while the high vacuum degree of the cold atom interference region is ensured, so that the capture rate is improved.
And fourthly, the two cold atom interference devices inhibit common-mode phase noise, particularly vibration noise, introduced through the optical path by sharing the same Raman light, so that the atom gravity gradient sensor can work on a mobile platform with larger vibration noise.
The cooling laser and Raman laser beam co-beam technology is adopted, the beam centers of the cooling laser beam and the Raman laser beam are overlapped and are generated by the 1 st and 2 nd laser beam emitters, the beam diameter of the cooling laser is large, a three-dimensional magneto-optical trap formed after the cooling laser can be cut by the complementary reflector has a large cooling volume, the beam diameter of the Raman laser is small, the Raman laser can completely pass through the center of the complementary reflector and is not cut, and the Raman laser beam has high optical power.
In a word, the invention simplifies the physical system and the optical system of the sensor from complexity to simplicity, improves the reliability, has good long-term stability, promotes the miniaturization and the application of the atomic gravity gradiometer, and plays an important role in resource exploration, environment monitoring, basic physical research and the like.
Drawings
FIG. 1 is a schematic structural diagram of the present sensor;
FIG. 2 is a schematic structural diagram of a complementary mirror;
FIG. 3 is a schematic diagram showing relative positions of the No. 1 and No. 2 complementary mirrors and cutting of the cooling beam.
Wherein:
a-1 st cold atom interference device; b-2 nd cold atom interference device;
1-a vacuum container, wherein,
1.1-three-dimensional magneto-optical trap (MOT), 1.2-cold atom interference region;
2-1 st laser beam emitter;
3-a vacuum pump;
4-alkali metal sample;
5-a vacuum separator;
6-complementary mirror;
7-2 nd laser beam emitter;
8-three-dimensional magneto-optical trap reverse magnetic field coil pair;
9-bias magnetic field coil;
10-a photodetector;
a-a cold radical;
c 1-cooling laser beam 1;
c 2-2 nd cooling laser beam.
Detailed Description
The following detailed description is made with reference to the accompanying drawings and examples:
a, a whole
Referring to fig. 1, the sensor comprises a 1 st cold atom interference device a and a 2 nd cold atom interference device B which are connected end to end and have the same structure;
each cold atom interference device comprises a vacuum container 1, a vacuum pump 3, an alkali metal sample 4, a vacuum separator 5, a complementary reflector 6, a three-dimensional magneto-optical trap reverse magnetic field coil pair 8, a bias magnetic field coil 9, a photoelectric detector 10, a 1 st laser beam emitter 2 and a 2 nd laser beam emitter 7;
the position and the communication relation are as follows:
an alkali metal sample 4, a three-dimensional magneto-optical trap reverse magnetic field coil pair 8, a bias magnetic field coil 9, a vacuum pump 3 and a photoelectric detector 10 are sequentially arranged on the outer wall of the vacuum container 1 from top to bottom;
the vacuum container 1 is divided into a three-dimensional magneto-optical trap 1.1 and a cold atom interference region 1.2 by a vacuum separator 5 with a hole in the center, wherein the vacuum degrees of the three-dimensional magneto-optical trap and the cold atom interference region are different by about 10 times; the complementary reflector 6 is arranged in the three-dimensional magneto-optical trap 1.1, the central axis of the complementary reflector coincides with the central axis of the vacuum container 1, and the optical center of the complementary reflector coincides with the zero point of the quadrupole magnetic field generated by the three-dimensional magneto-optical trap reverse magnetic field coil pair 8;
the vacuum containers 1 of the 1 st cold atom interference device A and the 2 nd cold atom interference device B are connected end to end along the vertical direction, and the central axes of the vacuum containers are along the vertical direction and are overlapped;
the difference between the reflecting mirror surfaces of the two complementary reflecting mirrors 6 along the central axis is 45 degrees, and the complementary reflecting mirrors are formed in space;
when the vertical shaft is seen downwards, the eight mirror surfaces are staggered in space, are not shielded, and are provided with a regular octagonal small hole in the middle;
the 1 st and 2 nd laser beam emitters 2 and 7 are respectively provided on the top and bottom of the sensor, and emit the 1 st and 2 nd cooling laser beams (c1 and c2) respectively during the atomic cooling phase and the raman beam during the atomic interference phase.
The working mechanism is as follows:
1. the 1 st cooling light beam c1 emitted by the 1 st laser beam emitter 2 is downwards incident along a vertical axis, two pairs of cooling light beams which are oppositely emitted along a horizontal direction and are mutually vertical are formed by the mirror reflection of the complementary reflector of the 1 st cold atom interference device A, two pairs of cooling light beams which are oppositely emitted along the horizontal direction and are mutually vertical are formed by the cooling light which is not reflected after the mirror reflection of the complementary reflector of the 2 nd cold atom interference device B, the intermediate light beam returns along the original path after being reflected by the mirror surface of the reflector of the 2 nd laser beam emitter 7, and the intermediate light beam and the incident light beam form two oppositely emitted cooling light beams of the vertical direction of the three-dimensional magnetic light trap; thus, a single beam of cooling light is incident, and three-dimensional magneto-optical traps can be formed at the optical centers of the two complementary mirrors respectively.
The effect is as follows:
1) the complementary reflector is utilized, the cooling light beams required by the two three-dimensional magneto-optical traps 1.1 can be realized only by using a single cooling light beam, windows do not need to be reserved for other light beams, more light beam collimators are not needed, and a vacuum container of the three-dimensional magneto-optical traps 1.1 is simplified into a simple cylinder from an original polyhedron, so that the atomic gravity gradient sensor with the two three-dimensional magneto-optical traps has the advantages of small volume, light weight, simple structure and low cost.
2) Cutting a single cooling laser beam into cooling light of three-dimensional magneto-optical traps of two same cold atom interference devices by adopting a complementary reflector 6; originally, each three-dimensional magneto-optical trap 1.1 needs 6 beams of cooling light, two need 12 beams of cooling light, only need a beam of cooling light after adopting complementary mirror 6, make the light path simplify greatly, the required device of control light path reduces greatly. In addition, the cooling light beam is generally transmitted to the cold atom interference device from the optical platform by adopting optical fibers, 6 optical fibers are needed for 6 cooling light beams, and the transmission efficiency of each optical fiber is about 60-80 percent, so that the single cooling light beam is adopted, only one optical fiber is used, the optical power loss is greatly reduced, the efficiency is improved, and the laser with various frequencies and powers needed by the atom interference device can be provided by only using a single semiconductor laser; therefore, the laser system has the advantages of greatly simplified optical path and circuit, improved reliability and stability, reduced cost, and contribution to miniaturization and wide application of the atomic gravity gradient sensor on a mobile platform.
2. The 1 st laser beam emitter 2 emits cooling beams in a cold atom sample preparation stage and emits Raman beams in a cold atom interference stage; the centers of the two light beams are superposed, the diameter of the cooling light beam is large, and partial light is reflected by the complementary reflector 6 to form cooling light in the horizontal direction; the Raman light beam has small diameter and directly passes through the middle regular octagonal small hole to enter the No. 2 laser beam emitter 7; the 2 nd laser beam emitter 7 mainly consists of a glass slide and a reflecting mirror and is used for reflecting the 1 st cooling laser beam c1 of the 1 st laser beam emitter 2 back according to the original path to form a vertical opposite beam.
The effect is as follows:
1) the same pair of beam transmitters is used for outputting laser frequency and power required by different stages, so that the optical path is further simplified, the loss is reduced, and the single laser is used for providing the laser frequency and power required by all stages of the atomic gravity gradient sensor;
2) the two cold atom interference devices share a pair of Raman lasers, so that common-mode phase noise, particularly vibration noise, introduced by a Raman optical path can be suppressed, and the atom gravity gradient sensor can work on a mobile platform with large vibration noise;
3) the diameter of the cooling laser is large, the diameter of the Raman laser is small, and the problem that the three-dimensional magneto-optical trap 1.1 needs a large cooling volume and the Raman laser needs high power under the condition that a single laser is used for providing unchanged optical power is solved.
3. The vacuum container 1 is made of titanium metal material or full glass structure
The effect is as follows: the titanium metal material can greatly reduce phase noise interference generated by residual magnetism, and has higher strength; the all-glass material has almost no remanence and light weight.
Two, functional unit
1. Vacuum vessel 1
As shown in fig. 1, a vacuum container 1 is a long cylinder made of titanium metal or full glass, and a window is arranged on the side wall of the long cylinder and communicated with a vacuum pump 3; the upper end surface and the lower end surface are sealed by glass windows; the inside of the cylinder is divided into a three-dimensional magneto-optical trap 1.1 and a cold atom interference area 1.2 by a vacuum separator 5, wherein the vacuum degrees of the three-dimensional magneto-optical trap and the cold atom interference area are different by about 10 times;
the vacuum degree of the three-dimensional magneto-optical trap 1.1 is better than 10 -6 Pa；
The vacuum degree of the cold atom interference zone 1.2 is better than 10 -7 Pa。
2. Vacuum pump 3
The vacuum pump 3 is a general vacuum obtaining device, and is selected from a molecular pump, an ion pump or a getter pump.
3. Alkali Metal sample 4
The alkali metal sample 4 is one or two of alkali metal elements such as lithium, sodium, potassium, rubidium, cesium and the like.
4. A vacuum separator 5;
the vacuum separator 5 is a circular optical device which is made of glass material and has a central opening and is transparent to laser, and divides the vacuum container 1 into a three-dimensional magneto-optical trap 1.1 and a cold atom interference region 1.2 which have different vacuum degrees, and the difference of the vacuum degrees of the two regions is determined by the size of the central opening.
5. Complementary mirror 6
As shown in fig. 2, the complementary reflector 6 is composed of 4 isosceles trapezoid-shaped reflector surfaces with identical structures; the 4 reflecting mirror surfaces are exactly coincided with the side surfaces of 4 mutually nonadjacent isosceles trapezoid shapes of a regular octahedral funnel-shaped geometric surface completely, form an included angle of 45 degrees with a vertical shaft, and are formed by processing glass materials or assembling 4 same isosceles trapezoid-shaped reflecting mirror surfaces.
6. Three-dimensional magneto-optical trap reverse magnetic field coil pair 8
The three-dimensional magneto-optical trap opposing field coil pair 8 is a common coil, wound from a metal wire, or printed on a film.
7. Bias magnetic field coil 9
The bias field coil is a general purpose coil that is wound from a metal wire or printed on a film.
8. Photodetector 10
The photodetector 10 is a general fluorescence signal measuring device, and is a semiconductor photodiode or a photomultiplier tube.
9. 1 st, 2 nd laser beam emitter 2, 7
The transmitting terminal is formed by connecting a laser, an adjusting system and a transmission device, and the tail end of the transmitting terminal is an optical fiber collimating lens group or a reflector system.
The laser is semiconductor laser, the regulating system is composed of lens, prism, acousto-optic modulator and electro-optic modulator, and the transmission device is optical fiber.
Third, the working principle
The sensor comprises two cold atom interference devices with the same structure, wherein each cold atom interference device is used for measuring an absolute gravity, and interference signals of the two cold atom interference devices extract a gravity gradient by an ellipse fitting method so as to achieve the purpose of inhibiting vibration noise; each cold atom interference device measures gravity and comprises a cold atom sample preparation method, a free falling method, an initial state preparation method, a cold atom interference method, a final state detection method and an ellipse fitting method to extract a gravity gradient; the above-mentioned stages of the two cold atom interference devices are performed simultaneously at different positions but under the control of the same laser beam, so as to achieve the purpose of suppressing the common mode noise.
1) Cold atom sample preparation phase
As shown in fig. 1, the 1 st laser beam emitter 2 emits the 1 st cooling beam c1, which is reflected by the mirror surface of the complementary mirror 6 to form two pairs of oppositely oriented and mutually perpendicular horizontal cooling beams, as shown in fig. 3; the non-reflected cooling light is reflected by the 2 nd complementary reflector to form two pairs of oppositely-reflected and mutually-perpendicular cooling light beams in the horizontal direction; the middle part of the cooling light beam returns along the original path after being completely reflected by the reflecting mirror surface of the No. 2 light beam emitter 7, and forms a cooling light beam pair in the vertical direction of two three-dimensional magneto-optical traps with the incident light beam; the two pairs of horizontal cooling light beams of each cold atom interference device are intersected with the light beams in the vertical direction at the magnetic field zero point of the quadrupole magnetic field generated by the three-dimensional magneto-optical trap reverse magnetic field coil pair 8; and after being cooled by the cooling laser beam, alkali metal atoms in the three-dimensional magneto-optical trap 1.1 are imprisoned in the central area of the three-dimensional magneto-optical trap 1.1, namely near the zero point of the magnetic field, to form cold atomic groups a with the temperature of about tens of mu K, and the preparation of the cold atomic sample is finished.
2) Free fall phase
After the magnetic field of the magneto-optical trap is closed, the temperature of the cold atomic group is further reduced to be about several mu K by a polarization gradient cooling technology; after this, the cooling light is completely turned off, and the two cold radicals start to fall by gravity.
3) Initial state preparation stage
After the cold atomic groups freely fall into an interference region, a 1 st laser beam emitter 2 emits Raman beams to perform speed state selection, the temperature of the cold atomic groups is further reduced, and meanwhile, the cold atoms are prepared to be in a ground state lower energy level m F In the initial state, where the magnetic field is insensitive to 0, provision is made for atomic interference.
4) Cold atom interference phase
The 1 st laser beam emitter 2 emits a pi/2-pi/2 pulse sequence of Raman laser, and the pulse sequence acts on two cold atomic groups respectively to enable the two cold atomic groups to form synchronous atomic interference rings at different spatial positions respectively; the following processes take place simultaneously on two cold radicals, only the process of the pi/2-pi/2 pulse sequence acting on one of the cold radicals a being described for the sake of clarity; the 1 st pi/2 pulse enables atoms to be in a superposition state of a ground state lower energy level and a ground state upper energy level; the momentum of the atoms at the energy level above the ground state for absorbing photons is increased, the momentum of the atoms at the energy level below the ground state is unchanged, and then the atoms at different energy states are gradually separated in space; after the free evolution of the time T, the pi pulse acts on the atom, the two energy states of the atom are exchanged by the pi pulse, the atom which is originally at the energy level under the ground state absorbs photons, and the momentum is increased; the atoms at the energy level on the ground state emit photons, and the momentum is reduced; the atoms of the two energy states then gradually come together in space. And after the free evolution of T time, enabling the 2 nd pi/2 to act on atoms, and enabling the atoms in the same energy state to coincide in space to form an interference ring to generate interference.
5) End state detection stage
A photodetector 10 is provided at each end of the two interference rings to detect the probability of the cold atom being in one of the two ground state levels, and obtain an interference signal of the cold atom.
6) Gravity gradient extraction stage by ellipse fitting method
Cold atom interference signals output by the two photoelectric detectors are in a sine shape, but the initial phases are different; the two initial phases are respectively caused by the gravity acceleration at which the two interference rings are positioned, so that the difference of the two initial phases is caused by the gravity gradient at which the two cold atom interference devices are positioned; in order to suppress common-mode noise, an interference signal output by one detector is taken as an abscissa, an interference signal output by the other detector is taken as an ordinate, and data points of the two interference signals form an elliptical distribution in a plane; phase difference extraction by ellipse fitting
Thereby according to the relationship
Calculating a gravity gradient, where k eff Is the effective wave vector of the raman laser, T is the free evolution time of the atom, and L is the separation distance of two cold radicals, both of which are known quantities.
The sensor can realize gravity gradient measurement only by using a single laser beam by adopting the complementary reflector 6, greatly simplifies the sensor from two aspects of a vacuum system and a laser system, improves the reliability and the stability, promotes the miniaturization and the application of the atomic gravity gradiometer, and plays an important role in resource exploration, environment monitoring, basic physical research and the like.
Claims (3)
1. A single beam atomic gravity gradient sensor based on complementary reflectors is characterized in that:
comprises a 1 st cold atom interference device (A) and a 2 nd cold atom interference device (B) which are connected end to end and have the same structure;
each cold atom interference device comprises a vacuum container (1), a 1 st laser beam emitter (2), a vacuum pump (3), an alkali metal sample (4), a vacuum separator (5), a complementary reflector (6), a 2 nd laser beam emitter (7), a three-dimensional magneto-optical trap reverse magnetic field coil pair (8), a bias magnetic field coil (9), a vacuum pump (3) and a photoelectric detector (10);
the position and the communication relation are as follows:
an alkali metal sample (4), a three-dimensional magneto-optical trap reverse magnetic field coil pair (8), a bias magnetic field coil (9) and a photoelectric detector (10) are sequentially arranged on the outer wall of the vacuum container (1) from top to bottom;
the vacuum container (1) is divided into a three-dimensional magneto-optical trap (1.1) and a cold atom interference region (1.2) with the difference of 10 times of vacuum degrees by a vacuum separator (5) with a hole in the center; the complementary reflector (6) is arranged in the three-dimensional magneto-optical trap (1.1), the central axis of the complementary reflector coincides with the central axis of the vacuum container (1), and the optical center coincides with the magnetic field zero point of a quadrupole magnetic field generated by the three-dimensional magneto-optical trap reverse magnetic field coil pair (8);
the vacuum containers (1) of the 1 st cold atom interference device (A) and the 2 nd cold atom interference device (B) are connected end to end along the vertical direction, and the central axes of the vacuum containers are coincident along the vertical direction;
the reflecting mirror surfaces of the two complementary reflecting mirrors (6) have a difference of 45 degrees along the central axis, and form complementation in space;
when the vertical shaft is seen downwards, the eight mirror surfaces are staggered in space, are not shielded, and are provided with a regular octagonal small hole in the middle;
the complementary reflector 6 is composed of 4 isosceles trapezoid-shaped reflector surfaces with completely same structures; the 4 reflecting mirror surfaces are exactly superposed with 4 mutually non-adjacent isosceles trapezoid-shaped side surfaces of a regular octahedral funnel-shaped geometric surface, form an included angle of 45 degrees with a vertical axis, and are formed by processing glass materials or assembling 4 identical isosceles trapezoid-shaped reflecting mirror surfaces;
a1 st laser beam emitter (2) and a 2 nd laser beam emitter (7) are respectively arranged at the top and the bottom of the sensor, a 1 st cooling laser beam (c1) and a 2 nd cooling laser beam (c2) are respectively emitted in an atom cooling stage, and a Raman beam is emitted in an atom interference stage.
2. A single beam atomic gravity gradient sensor based on complementary mirrors, as defined in claim 1, wherein:
the vacuum container (1) is a long cylinder made of titanium metal or full glass, and the side wall of the vacuum container is provided with a window communicated with the vacuum pump (3); the upper end surface and the lower end surface are sealed by glass windows; the inside of the cylinder is divided into a three-dimensional magneto-optical trap (1.1) and a cold atom interference area (1.2) by a vacuum separator (5), wherein the difference of vacuum degrees is 10 times;
the vacuum degree of the three-dimensional magneto-optical trap (1.1) is better than 10 -6 Pa；
The vacuum degree of the cold atom interference zone (1.2) is better than 10 -7 Pa。
3. A single beam atomic gravity gradient sensor based on complementary mirrors, as defined in claim 1, wherein:
the vacuum separator (5) is a circular optical device which is made of glass materials and has a central hole and can transmit laser, and divides a vacuum container (1) into a three-dimensional magneto-optical trap (1.1) and a cold atom interference region (1.2) with different vacuum degrees, wherein the difference of the vacuum degrees of the two regions is determined by the size of the central hole.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102007371A (en) * | 2008-03-12 | 2011-04-06 | 国立科学研究中心 | Cold atom interferometry sensor |
| WO2014106811A2 (en) * | 2013-01-07 | 2014-07-10 | Muquans | Cold atom gravity gradiometer |
| WO2019116047A1 (en) * | 2017-12-15 | 2019-06-20 | The University Of Birmingham | Gravity gradiometer |
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| CN108279441B (en) * | 2017-12-25 | 2020-06-26 | 中国科学技术大学 | Vacuum structure suitable for miniaturized atom interferometer |
| CN109781088B (en) * | 2019-03-12 | 2020-11-06 | 中国计量大学 | Miniaturized atomic interference gyroscope device and measuring method |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102007371A (en) * | 2008-03-12 | 2011-04-06 | 国立科学研究中心 | Cold atom interferometry sensor |
| WO2014106811A2 (en) * | 2013-01-07 | 2014-07-10 | Muquans | Cold atom gravity gradiometer |
| WO2019116047A1 (en) * | 2017-12-15 | 2019-06-20 | The University Of Birmingham | Gravity gradiometer |
Non-Patent Citations (1)
| Title |
|---|
| "小型化原子重力仪及其应用研究";罗覃;《2020年中国地球科学联合学术年会论文集（二十一）》;20201018;第3178页 * |
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