Hollow-core optical fiber guide type cold atom inertia measurement system and use method

Abstract

The invention relates to a hollow-core optical fiber guide type cold atom inertia measurement system and a use method, and belongs to the technical field of cold atom interference measurement inertia. The hollow-core optical fiber guide type cold atom inertia measurement system comprises a vacuum cavity assembly, a laser coupling module I, a laser coupling module II, a cold atom group preparation module and a gravitational acceleration measurement module, according to the invention, a uniform light potential well is constructed by using the hollow-core optical fiber with low loss, high bandwidth and large core diameter, long-distance constraint and guidance are carried out on the cold atom ensemble, and a guide light field applies an optical fiber radial constraint force to the atom ensemble, so that the degree of freedom of motion of the atom ensemble in a non-measurement direction can be inhibited; gravity measurement in a dynamic environment and gravity component measurement in any vector direction are achieved, meanwhile, the size and power consumption of the system are reduced, and integration and engineering of the system are achieved.

Description

Technical Field

[0001] The present invention relates to the field of cold atom interferometric inertial measurement technology, and in particular to a hollow-core optical fiber guided cold atom inertial measurement system and a use method thereof. Background Art

[0002] Atom interferometer is a precision measuring instrument based on the principle of matter wave interference. At present, atomic fountain clocks, atomic gravimeters, atomic gravity gradient meters, atomic interferometer gyroscopes, etc. have been realized one after another, showing ultra-high measurement accuracy, sensitivity and long-term stability. Among them, the typical atomic gravimeter uses a free fall method to release the prepared cold atomic group and perform beam splitting-reflection-combination operations on the atomic matter wave through the "π / 2-π-π / 2" Raman light pulse sequence, and the atomic internal state coherently superimposes to form atomic matter wave interference, thereby realizing the measurement of gravitational acceleration.

[0003] However, traditional free-space cold atom gravimeters have the following problems: since the atomic clusters will undergo thermal expansion during free fall, in order to reduce the impact of laser light intensity non-uniformity, a larger diameter laser beam is needed to interact with the atoms, which increases the volume and power consumption of the system while also limiting the accuracy of gravitational acceleration measurement; during dynamic measurements, due to the movement of the carrier relative to the atoms, it is impossible to ensure that the atomic clusters are always located in the center area of ​​the laser, resulting in a decrease in measurement accuracy or even failure of the atomic interference mechanism; when measuring non-vertical gravitational acceleration components, since the direction of atomic free fall motion is inconsistent with the laser propagation direction, the movement of atoms in a direction perpendicular to the laser wave vector causes the required laser beam size and power to increase significantly, severely limiting the accuracy of the atomic gravimeter when performing vector measurements. Summary of the invention

[0004] In view of the above problems, the present invention provides a hollow-core fiber-guided cold atom inertial measurement system and a method of use, which utilizes low-loss, high-bandwidth, and large-core-diameter hollow-core optical fibers to construct a uniform optical potential well, and performs long-distance confinement and guidance on the cold atom ensemble. The guided light field exerts a radial constraint force of the optical fiber on the atomic ensemble, which can suppress its freedom of movement in non-measurement directions, realize gravity measurement in a dynamic environment and measurement of gravity components in any vector direction, and reduce the system volume and power consumption at the same time, which is conducive to the integration and engineering of the system.

[0005] The present invention provides a hollow-core optical fiber guided cold atom inertial measurement system, comprising:

[0006] Vacuum chamber assembly, laser coupling module 1, laser coupling module 2, cold atom group preparation module and gravity acceleration measurement module;

[0007] The vacuum chamber assembly includes a chamber frame 26 and a glass window assembly; the chamber frame 26 is connected to the glass window assembly;

[0008] The laser coupling module 1 and the laser coupling module 2 are respectively arranged at the outer ends of the vacuum chamber assembly;

[0009] The cold radical preparation module comprises an anti-Helmholtz coil assembly 13 and a lens barrel assembly; the anti-Helmholtz coil assembly 13 and the lens barrel assembly are respectively connected to the cavity assembly 26;

[0010] The vacuum chamber 26 is also connected to a vacuum pipe 35;

[0011] The gravity acceleration measurement module includes a bias magnetic field coil assembly, an atomic interference system and an atomic detection system;

[0012] The bias magnetic field coil assembly is coaxially arranged with the vacuum pipe 35;

[0013] The atomic interference system includes a Raman light pulse sequence coupled in a second optical fiber jumper 19 and an optical fiber internal cold atomic group 17;

[0014] The atom detection system includes detection light, pump light and a photodetector coupled in the second optical fiber jumper 19 .

[0015] Optionally, the vacuum chamber assembly further includes a rubidium atomic source 25; the rubidium atomic source 25 is connected to the chamber frame 26;

[0016] It can be understood that the cavity skeleton 26 is a cylindrical skeleton having a plurality of support members 26-1; the cavity skeleton includes a first end surface, a second end surface 26-3 and an outer peripheral surface;

[0017] The multiple support members 26-1 are arranged circumferentially, and one side of the multiple support members respectively penetrates the outer peripheral surface, wherein, on the side of each support member away from the center of the cavity frame 26, corresponding circumferential surface glass window grooves are formed between the two support members for connecting the corresponding glass windows; on the side of each support member close to the center of the cavity frame 26, a first end surface glass window groove and a second end surface glass window groove are formed, and the first end surface glass window groove and the second end surface glass window groove respectively penetrate the first end surface and the second end surface for connecting the corresponding glass windows;

[0018] Preferably, the cavity frame 26 has an ultra-high vacuum degree; the ultra-high vacuum degree is 10 -8 Pa;

[0019] The rubidium atomic source 25 is used to provide room temperature atomic gas;

[0020] Optionally, the laser coupling module 1 includes a first fiber jumper 1, a first fiber collimator 2, a first reflector 4-1, a second reflector 4-2, a dichroic mirror 5, a quarter wave plate 6 and a first focusing lens 7 which are sequentially arranged along the light beam transmission direction;

[0021] Optionally, the laser coupling module 2 includes a second optical fiber jumper 19, a second optical fiber collimator 20, a third reflector 22-1, a fourth reflector 22-2, a second focusing lens 23, a 1 / 2 wave plate 24 and a hollow core optical fiber 18;

[0022] The vacuum cavity 26 is also connected to the vacuum pipe 35; the hollow core optical fiber 18 is fixed to the inner wall of the vacuum pipe 35 by an optical fiber clamp;

[0023] Further, the glass window assembly includes a first glass window 8, a second glass window 9, a third glass window 10, a fourth glass window 11, a fifth glass window 27 and a sixth glass window 28;

[0024] Optionally, the cold radical preparation module includes an anti-Helmholtz coil assembly 13 and a lens barrel assembly;

[0025] Further, the lens barrel assembly includes a first lens barrel 14 - 1 , a second lens barrel 14 - 2 and a third lens barrel 14 - 3 ;

[0026] Further, the anti-Helmholtz coil assembly 13 includes an anti-Helmholtz coil 1 13 - 1 and an anti-Helmholtz coil 2 13 - 2 ;

[0027] The anti-Helmholtz coil 1 13-1 and the anti-Helmholtz coil 2 13-2 are respectively arranged coaxially with the fifth glass window and the sixth glass window, and are connected to the two end surfaces of the vacuum cavity; Figure 2 As shown (a cross-sectional view of the cavity skeleton along the yoz plane), a quadrupole gradient magnetic field is generated after power is turned on, and the atoms produce a first-order Zeeman frequency shift in the quadrupole gradient magnetic field to provide a position-related frequency shift, which ultimately binds the atoms to the zero point of the magnetic field;

[0028] Furthermore, the fiber axis of the hollow-core optical fiber 18 coincides with the y-axis; one end of the hollow-core optical fiber 18 is located below the center of the cavity skeleton 26; the hollow-core optical fiber 18 has the characteristics of high bandwidth, low loss, large core diameter, etc., and can ensure long-distance uniform transmission of the laser mode.

[0029] Furthermore, the rubidium atomic source 25, the first glass window 8, the second glass window 9, the third glass window 10, the fourth glass window 11, the first lens barrel 14-1 and the second lens barrel 14-2 are respectively arranged in corresponding circumferential glass window grooves; wherein the second glass window 9 is arranged opposite to the first lens barrel 14-1, the third glass window 10 is arranged opposite to the second lens barrel 14-2; the rubidium atomic source 25 is arranged opposite to the fourth glass window 11;

[0030] The fifth glass window 27 and the sixth glass window 28 are respectively arranged in the second end surface glass window groove and the first end surface glass window groove.

[0031] It can be understood that the second glass window 9 and the third glass window 10 are used to transmit the third collimated laser 12 - 1 and the fourth collimated laser 12 - 2 ;

[0032] The fifth glass window 27 is used to transmit the fifth collimated laser 12-3;

[0033] It can be understood that the third collimated laser 12-1, the fourth collimated laser 12-2 and the fifth collimated laser 12-3 all include cooling light and pumping light; the cooling light is used to cool the room temperature atomic gas, and the pumping light is used to re-pump the atoms that are detuned and excited outside the closed transition back to the closed transition energy level to ensure that the cycle of atomic cooling continues.

[0034] In one embodiment of the present invention, the third collimated laser 12-1 is incident perpendicularly to the second glass window 9 along the xo (-y) direction and is reflected by the first lens barrel 14-1 to obtain a first pair of circularly polarized cooling beams;

[0035] The fourth collimated laser 12-2 is incident perpendicularly to the third glass window 10 along the (-x)o(-y) direction, and is reflected by the second lens barrel 14-2 to obtain a second pair of circularly polarized cooling beams;

[0036] The fifth collimated laser 12-3 is incident from the fifth glass window 27 along the -z axis and reflected by the third lens barrel 14-3 to obtain a third pair of circularly polarized cooling beams;

[0037] Each pair of circularly polarized cooling beams is composed of two circularly polarized laser beams with opposite propagation directions and orthogonal polarization states, and the three pairs of cooling beams are perpendicular to each other;

[0038] The three pairs of circularly polarized cooling beams and the anti-Helmholtz coil group 13 form a magneto-optical trap; the magneto-optical trap cools and traps the room temperature atomic gas in the cavity skeleton 26 to form a cold atomic cluster 15 at the center of the cavity skeleton 26.

[0039] Optionally, the gravity acceleration measurement module includes a bias magnetic field coil assembly, an atomic interference system and an atomic detection system;

[0040] The bias magnetic field coil assembly includes a bias magnetic field coil 1 16-1 and a bias magnetic field coil 2 16-2; the bias magnetic field coil 1 16-1 and the bias magnetic field coil 2 16-2 are arranged outside the vacuum pipe 35 and are coaxial with the pipe;

[0041] It can be understood that the bias magnetic field coil assembly is used to define the quantization axis and simultaneously produce the splitting of the Zeeman energy level of the cold atoms in the optical fiber for conducting atomic state preparation experiments before interference;

[0042] Further, the atomic interference system includes Raman light coupled in the second optical fiber jumper 19, and the cold atomic group 17 in the optical fiber;

[0043] The atom detection system includes detection light, pump light and a photodetector; the detection light and pump light are coupled in the second optical fiber jumper 19, and the photodetector is used to detect the absorption of the detection light by atoms.

[0044] In one embodiment of the present invention, the first collimated laser 3 passes through the laser coupling module 1, the vacuum chamber assembly, the cold atom group preparation module and the gravity acceleration measurement module to output the first guide light 29 coupled from top to bottom; the second collimated laser 21 passes through the laser coupling module 2 and the gravity acceleration measurement module to output the second guide light 30 coupled from bottom to top; Figure 3 As shown, the first guided light 29 and the second guided light 30 have opposite transmission directions, the same power, and their polarization states are both linear polarization and have the same polarization direction;

[0045] The second collimated laser includes a second guide light 30, a third Raman pulse laser 33, a fourth Raman pulse laser 34, a resonance detection light and a pumping light;

[0046] The first collimated laser 3 includes a first guide light.

[0047] The first guided light 29 and the second guided light 30 form a movable optical lattice;

[0048] Atoms are loaded into the optical lattice at the position of the cold atomic group 15 , and the transmission speed v of the atoms entering the hollow-core optical fiber is further controlled by scanning the detuning amount of the first guiding light 29 and the second guiding light 30 .

[0049] Furthermore, the second collimated laser 21 includes a third Raman pulse laser 33 and a fourth Raman pulse laser 34; the third Raman pulse laser 33 and the fourth Raman pulse laser 34 are coupled from bottom to top into the hollow core optical fiber 18;

[0050] It can be understood that the third Raman pulse laser 33 and the fourth Raman pulse laser 34 are a pair of linearly polarized lasers with a frequency difference of 6.834 GHz, and the switching timing of the Raman light in the second collimated laser 21 is precisely controlled to obtain a Raman laser pulse sequence of "π / 2-π-π / 2", and the time interval between adjacent Raman pulse lasers is T, which is called the free evolution time;

[0051] The third Raman pulse laser 33 and the fourth Raman pulse laser 34 are output from the upper end face of the hollow core optical fiber 18, pass through the quarter wave plate 6 and are reflected by the dichroic mirror 5, and then pass through the quarter wave plate 6 again to form the first Raman pulse laser 31 and the second Raman pulse laser 32 which are reflected oppositely.

[0052] The third Raman pulse laser 33 and the second Raman pulse laser 32 form a counter-injection Raman light combination 1; the fourth Raman pulse laser 34 and the first Raman pulse laser 31 form a counter-injection Raman light combination 2; the counter-injection Raman light combination 1 or the counter-injection Raman light combination 2 is selected to act on the cold atomic group 17 in the hollow core optical fiber to realize the counter-injection Raman interference experiment; Figure 4 As shown;

[0053] It can be understood that the said opposite Raman light combination is a Doppler-sensitive opposite Raman light combination, wherein the propagation direction of the third Raman pulse laser 33 and the second Raman pulse laser 32 is opposite, and the frequency difference is 6.834 GHz;

[0054] The second counter-infrared Raman light combination is a Doppler-sensitive counter-infrared Raman light combination, wherein the fourth Raman pulse laser 34 and the first Raman pulse laser 31 have opposite propagation directions and a frequency difference of 6.834 GHz;

[0055] Another object of the present invention is to provide a method for using a hollow-core fiber-guided cold atom inertial measurement system, comprising:

[0056] Step 1, providing room temperature atomic gas to the vacuum chamber assembly through the rubidium atomic source 25;

[0057] The third collimated laser 12-1, the fourth collimated laser 12-2 and the fifth collimated laser 12-3 are respectively obtained and reflected by the lens barrel assembly to obtain the first pair, the second pair and the third pair of circularly polarized cooling beams respectively;

[0058] A cold atomic cluster 15 is obtained based on the first, second and third pairs of circularly polarized cooling beams and the anti-Helmholtz coil group 13;

[0059] Preferably, the specific steps of obtaining the cold atomic radicals in step 1 include:

[0060] A rubidium atom source 25 is used to provide room temperature atomic gas to obtain a third collimated laser 12 - 1 , a fourth collimated laser 12 - 2 , and a fifth collimated laser 12 - 3 ;

[0061] The cooling lights in the third collimated laser 12-1, the fourth collimated laser 12-2 and the fifth collimated laser 12-3 are respectively passed through the first lens barrel 14-1, the second lens barrel 14-2 and the third lens barrel group 14-3 to obtain the first pair, the second pair and the third pair of circularly polarized cooling light beams with opposite transmission directions and orthogonal polarizations.

[0062] The three pairs of circularly polarized cooling beams slow down the room temperature atomic gas;

[0063] The anti-Helmholtz coil group 13 is energized to generate a quadrupole gradient magnetic field, which together with three pairs of circularly polarized cooling beams form a magneto-optical trap, and the decelerated room temperature atomic gas is trapped at the geometric center of the magneto-optical trap to obtain a cold atomic group 15 with a temperature of μK;

[0064] Step 2, obtaining the first guide light 29 and the second guide light 30 in the first collimated laser 3 and the second collimated laser 21;

[0065] The first guided light 29 and the second guided light 30 respectively pass through the laser coupling module 1 and the laser coupling module 2 and then couple into the hollow core optical fiber 18 through the corresponding glass windows to interfere and form an optical lattice;

[0066] Setting a transport speed; the cold atomic group 15 is loaded into the optical lattice and transmitted into the hollow-core optical fiber 18 at the transport speed to form a cold atomic group 17 in the optical fiber;

[0067] Preferably, the specific steps of transmitting into the hollow core optical fiber 18 at the transport speed in step 2 to form the cold atomic group 17 in the optical fiber include: simultaneously turning on the first guide light 29 in the first collimated laser 3 and the second guide light 30 in the second collimated laser 21, such as Figure 2 As shown;

[0068] The first guide light 29 is reflected by the first reflector 4-1 and the second reflector 4-2, and then transmitted to the first focusing lens 7 through the dichroic mirror 5 and the quarter wave plate 6 for focusing, and is coupled into the hollow core optical fiber 18 from top to bottom through the first glass window 8;

[0069] The second guide light 30 is reflected by the third reflector 22-1 and the fourth reflector 22-2, and then focused by the second focusing lens 23 and transmitted to the 1 / 2 wave plate 24, and coupled into the hollow core optical fiber 18 from bottom to top through the sixth glass window 28;

[0070] An optical lattice is formed by the interference of the first guided light 29 and the second guided light 30;

[0071] The cold atomic clusters are bound in the optical lattice formed by the two guiding lights and are transmitted into the hollow core optical fiber 18 at the transmission speed to form cold atomic clusters 17 in the optical fiber. Figure 3 shown.

[0072] Furthermore, the specific steps of adjusting the transport speed of the cold atomic groups include:

[0073] Gradually reduce and turn off the current of the third collimated laser 12 - 1 , the fourth collimated laser 12 - 2 , the fifth collimated laser 12 - 3 and the anti-Helmholtz coil assembly 13 ;

[0074] By scanning the AOM driving signal frequencies corresponding to the first guide light 29 and the second guide light 30, the frequency detuning amount Δf between the two guide light beams is controlled to adjust the transport speed of the cold atomic clusters after entering the optical lattice, and the cold atomic clusters are manipulated to perform accelerated, uniform, or decelerated transport.

[0075] Furthermore, the expression of the transport velocity is:

[0076] v=Δfλ L / 2

[0077] Where Δf is the frequency detuning of the two guiding laser beams, λ L is the wavelength of the guided light, and v is the transport velocity of the optical lattice.

[0078] Step 3, energizing the bias magnetic field coil assembly 16 to generate a bias magnetic field and define a quantization axis;

[0079] The bias magnetic field splits the |F=1> energy level of the cold atomic group 17 in the hollow core optical fiber into |F=1,m F =0, ±1> three Zeeman sub-levels, atoms are evenly distributed on the three Zeeman sub-levels, m F represents the magnetic quantum number, F represents the angular momentum quantum number, and is the hyperfine energy level structure of the atom;

[0080] Turn on the pumping light in the second collimated laser 21,

[0081] will be evenly distributed in |F=1,m F =0,±1> all the cold atoms in the state are pumped to the magnetically insensitive state|F=1,m F =0>, eliminating the atomic interference phase shift caused by the ambient magnetic field;

[0082] Then the pumping light is turned off to complete the atomic state preparation;

[0083] Step 4, turning off the first guide light 29 in the first collimated laser 3, and only using the second guide light 30 in the second collimated laser 21 to transversely bind the cold atomic group 17 in the optical fiber;

[0084] The cold atomic group 17 in the optical fiber is freely released along the optical fiber axis at an initial velocity v0;

[0085] The third Raman pulse laser 33 and the fourth Raman pulse light 34 in the second collimated laser 21 are turned on. The lasers are reflected by the third reflector 22-1 and the fourth reflector 22-2, and then focused to the lower end face of the hollow core optical fiber 18 by the second focusing lens 23, and coupled into the hollow core optical fiber 18 from bottom to top.

[0086] After being output from the upper end face of the hollow core optical fiber, it is collimated by the first focusing lens 7, transmitted to the dichroic mirror 5 through the 1 / 4 wave plate 6 for reflection, and then transmitted to the 1 / 4 wave plate 6 again to form the first Raman pulse laser 31 and the second Raman pulse laser 32 transmitted from top to bottom, as shown in FIG. Figure 4 As shown; based on the first Raman pulse laser 31, the second Raman pulse laser 32, the third Raman pulse laser 33 and the fourth Raman pulse light 34, the opposite Raman light combination one and the opposite Raman light combination two are determined;

[0087] The first and second Raman light combinations act on the cold atomic group 17 in the optical fiber with a Raman pulse sequence of π / 2-π-π / 2 to perform atomic splitting, reflection, and beam combining operations, thereby realizing internal state interference of atoms in the two evolution paths;

[0088] The π / 2-π-π / 2 Raman pulse sequence includes a first group of π / 2 Raman pulse lasers, a second group of π Raman pulse lasers and a third group of π / 2 Raman pulse lasers;

[0089] Preferably, the specific steps of the atomic interference include:

[0090] At the initial moment, the atom is in the |F=1,p> state; where F represents the angular momentum quantum number, which is the hyperfine energy level structure of the atom, and p is the initial momentum of the atom;

[0091] After the π / 2 Raman pulse laser acts on the cold atomic group 17 in the optical fiber, the atomic matter wave is split, and the atoms are in the |F=1,p> state and The coherent superposition state of the state, and due to the two-photon recoil momentum The atoms in the coherent superposition state gradually separate in space and transmit along two paths; eff is the effective wave vector of the incident Raman light combination 1 and / or the incident Raman light combination 2, is the reduced Planck constant.

[0092] After a free evolution time T, the π Raman pulse laser pulse is used to act on the cold atomic group 17 in the optical fiber to achieve the inversion of the internal energy level of the atom and the transfer of the external momentum, that is, the atom in the |F=1,p> state transitions to state, and Then it transitions to the |F=1,p> state;

[0093] After a free evolution time T, it is in the state |F=1,p> and The atoms in the state gradually become bundled in space;

[0094] The third group of π / 2 Raman pulse laser acts on the cold atomic group 17 in the optical fiber, so that the |F=1,p> state and The atoms in the two internal states undergo another transition with a probability of half, and now half of the atoms in the two internal states come from two different evolutionary paths, ultimately achieving internal state interference of atoms.

[0095] Step 5, turn on the resonant detection light in the second collimated laser 21; the resonant detection light is output from the upper end face of the hollow core optical fiber 18, reflected by the dichroic mirror 5, returns to the second optical fiber collimator 20 along the original optical path, and is output by the second optical fiber jumper 19, and is transmitted to the photodetector through the specified spatial optical path for power detection, and then the second guide light 30 in the second collimated laser 21 is turned off, and the resonant detection light is turned off;

[0096] The internal state of the cold atomic group 17 in the hollow-core optical fiber after beam combination is detected by resonant detection light, and the probability of the atom being in the |F=2> state is obtained;

[0097] The gravitational acceleration component g along the optical fiber axis is obtained based on the probability calculation of atoms in the |F=2> state.

[0098] Preferably, the probability that the atom is in the |F=2> state is expressed as:

[0099]

[0100] Among them, k eff g 2 is the phase shift caused by the uniform gravitational acceleration component along the fiber axis, where k eff is the effective wave vector of the incident Raman light pulse combination, g is the gravitational acceleration component along the fiber axis, is the initial phase corresponding to the first group of π / 2 Raman pulse lasers, is the initial phase corresponding to the second group of π Raman pulse lasers, is the initial phase of the third group of π / 2 Raman pulse laser, P is the atomic transition probability, and T is the free evolution time.

[0101] After the present invention uses the optical lattice scheme to transport the cold atomic group 15 into the hollow core optical fiber, the uniform optical potential well constructed by the hollow core optical fiber can effectively limit the movement of the atomic group in the non-measurement direction. In addition to being sensitive to the component of gravitational acceleration in the axial direction of the optical fiber, it can also be sensitive to the component of the carrier inertial acceleration in the axial direction of the optical fiber.

[0102] The third object of the present invention is to provide an application of vector acceleration measurement, where the hollow-core fiber-guided cold atom inertial measurement system is used to construct a cold atom vector accelerometer to achieve inertial acceleration measurement.

[0103] Compared with the prior art, the present invention has at least the following beneficial effects:

[0104] (1) The hollow-core fiber-guided cold atom inertial measurement system of the present invention utilizes hollow-core fibers with high bandwidth, low loss, and large cores to ensure long-distance uniform transmission of laser modes, thereby achieving long-distance trapping or transmission of cold atom ensembles;

[0105] (2) The present invention applies a radial constraint force of the optical fiber to the atomic ensemble by guiding the light field, thereby suppressing its freedom of movement in the non-measurement direction, greatly reducing the sensitivity of the gravimeter to the thermal expansion of the atomic ensemble and the movement of the carrier, and improving the measurement capability of the inertial measurement system in dynamic measurement scenarios;

[0106] (3) In the present invention, the atomic ensemble is constrained by the guided light in the direction of the non-gravity sensitive axis, but its movement in the axial direction of the optical fiber is not affected. By changing the direction of the optical fiber axis, the measurement of the gravity component in any vector direction can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0107] The drawings are only for the purpose of illustrating particular embodiments and are not to be construed as limiting the invention.

[0108] Figure 1 Schematic diagram of a sensor head of a hollow-core optical fiber guided cold atom inertial measurement system in an embodiment of the present invention;

[0109] Figure 2 Schematic diagram of a cross-sectional view (yoz plane) of a hollow-core fiber-guided cold atom inertial measurement system sensor head in an embodiment of the present invention;

[0110] Figure 3 is a schematic diagram of an optical transmission belt in an embodiment of the present invention;

[0111] Figure 4 Schematic diagram of the combined incident Raman light in an embodiment of the present invention.

[0112] Reference numerals:

[0113] First fiber jumper 1, first fiber collimator 2, first collimated laser 3, first reflector 4-1, second reflector 4-2, dichroic mirror 5, 1 / 4 wave plate 6, first focusing lens 7, first glass window 8, second glass window 9, third glass window 10, fourth glass window 11, third collimated laser 12-1, fourth collimated laser 12-2, fifth collimated laser 12-3, anti-Helmholtz coil assembly 13, anti-Helmholtz coil 1 13-1, anti-Helmholtz coil 2 13-2, first lens barrel 14-1, second lens barrel 14-2, third lens barrel 14-3, cold atomic group 15, bias magnetic field coil 1 16-1, bias Magnetic field coil 2 16-2, cold atomic group 17 in optical fiber, hollow core optical fiber 18, second optical fiber jumper 19, second optical fiber collimator 20, second collimated laser 21, third reflector 22-1, fourth reflector 22-2, second focusing lens 23, 1 / 2 wave plate 24, rubidium atomic source 25, cavity skeleton 26, support 26-1, first end face 26-2, second end face 26-3, fifth glass window 27, sixth glass window 28, first guide light 29, second guide light 30, first Raman pulse laser 31, second Raman pulse laser 32, third Raman pulse laser 33, fourth Raman pulse laser 34, vacuum pipe 35. DETAILED DESCRIPTION

[0114] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. In addition, the present invention can also be implemented in other ways different from those described herein, and therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0115] A specific embodiment of the present invention, as Figure 1-4 , discloses a hollow-core fiber-guided cold-atom inertial measurement system and a method of using the same,

[0116] In order to illustrate the effectiveness of the method proposed in the present invention, the above technical solution of the present invention is described in detail below through a specific embodiment, and the specific implementation steps are as follows:

[0117] The present invention provides a hollow-core optical fiber guided cold atom inertial measurement system, comprising:

[0118] Vacuum chamber assembly, laser coupling module 1, laser coupling module 2, cold atom group preparation module and gravity acceleration measurement module;

[0119] The vacuum chamber assembly includes a chamber frame 26 and a glass window assembly; the chamber frame 26 is connected to the glass window assembly;

[0120] The laser coupling module 1 and the laser coupling module 2 are respectively arranged at the outer ends of the vacuum chamber assembly;

[0121] The cold radical preparation module comprises an anti-Helmholtz coil assembly 13 and a lens barrel assembly; the anti-Helmholtz coil assembly 13 and the lens barrel assembly are respectively connected to the cavity assembly 26;

[0122] The vacuum chamber 26 is also connected to a vacuum pipe 35;

[0123] The gravity acceleration measurement module includes a bias magnetic field coil assembly, an atomic interference system and an atomic detection system;

[0124] The bias magnetic field coil assembly is coaxial with the vacuum pipe 35;

[0125] The atomic interference system includes a Raman light pulse sequence coupled in a second optical fiber jumper 19 and an optical fiber internal cold atomic group 17;

[0126] The atom detection system includes detection light, pump light and a photodetector coupled in the second optical fiber jumper 19 .

[0127] Optionally, the vacuum chamber assembly further includes a rubidium atomic source 25; the rubidium atomic source 25 is connected to the chamber frame 26;

[0128] It can be understood that the cavity frame 26 is a columnar frame having a plurality of support members 26-1; the cavity frame includes a first end surface 26-2, a second end surface 26-3 and an outer peripheral surface;

[0129] The multiple support members 26-1 are arranged circumferentially, and one side of the multiple support members respectively penetrates the outer peripheral surface, wherein, on the side of each support member away from the center of the cavity frame 26, corresponding circumferential surface glass window grooves are formed between the two support members for connecting the corresponding glass windows; on the side of each support member close to the center of the cavity frame 26, a first end surface glass window groove and a second end surface glass window groove are formed, and the first end surface glass window groove and the second end surface glass window groove respectively penetrate the first end surface 26-2 and the second end surface 26-3, for connecting the corresponding glass windows;

[0130] Preferably, the cavity frame 26 has an ultra-high vacuum degree; the ultra-high vacuum degree is 10 -8 Pa;

[0131] The rubidium atomic source 25 is used to provide room temperature atomic gas;

[0132] Optionally, the laser coupling module 1 includes a first fiber jumper 1, a first fiber collimator 2, a first reflector 4-1, a second reflector 4-2, a dichroic mirror 5, a quarter wave plate 6 and a first focusing lens 7 which are sequentially arranged along the light beam transmission direction;

[0133] Optionally, the laser coupling module 2 includes a second optical fiber jumper 19, a second optical fiber collimator 20, a third reflector 22-1, a fourth reflector 22-2, a second focusing lens 23, a 1 / 2 wave plate 24 and a hollow core optical fiber 18;

[0134] The vacuum cavity 26 is also connected to the vacuum pipe 35; the hollow core optical fiber 18 is fixed to the inner wall of the vacuum pipe 35 by an optical fiber clamp;

[0135] Further, the glass window assembly includes a first glass window 8, a second glass window 9, a third glass window 10, a fourth glass window 11, a fifth glass window 27 and a sixth glass window 28;

[0136] Optionally, the cold radical preparation module includes an anti-Helmholtz coil assembly 13 and a lens barrel assembly;

[0137] Further, the lens barrel assembly includes a first lens barrel 14 - 1 , a second lens barrel 14 - 2 and a third lens barrel 14 - 3 ;

[0138] Further, the anti-Helmholtz coil assembly 13 includes an anti-Helmholtz coil 1 13 - 1 and an anti-Helmholtz coil 2 13 - 2 ;

[0139] The anti-Helmholtz coil 1 13-1 and the anti-Helmholtz coil 2 13-2 are coaxial with the fifth glass window and the sixth glass window respectively, and are connected to the two end surfaces of the vacuum chamber. Figure 2 As shown (a cross-sectional view of the cavity skeleton along the yoz plane), a quadrupole gradient magnetic field is generated after power is turned on, and the atoms produce a first-order Zeeman frequency shift in the quadrupole gradient magnetic field to provide a position-related frequency shift, which ultimately binds the atoms to the zero point of the magnetic field;

[0140] Furthermore, the fiber axis of the hollow-core optical fiber 18 coincides with the y-axis; one end of the hollow-core optical fiber 18 is located below the center of the cavity skeleton 26; the hollow-core optical fiber 18 has the characteristics of high bandwidth, low loss, large core diameter, etc., and can ensure long-distance uniform transmission of the laser mode.

[0141] Furthermore, the rubidium atomic source 25, the first glass window 8, the second glass window 9, the third glass window 10, the fourth glass window 11, the first lens barrel 14-1 and the second lens barrel 14-2 are respectively arranged in corresponding circumferential glass window grooves; wherein the second glass window 9 is arranged opposite to the first lens barrel 14-1, the third glass window 10 is arranged opposite to the second lens barrel 14-2; the rubidium atomic source 25 is arranged opposite to the fourth glass window 11;

[0142] The fifth glass window 27 and the sixth glass window 28 are respectively disposed in the first end surface glass window groove and the second end surface glass window groove.

[0143] It can be understood that the second glass window 9 and the third glass window 10 are used to transmit the third collimated laser 12 - 1 and the fourth collimated laser 12 - 2 ;

[0144] The fifth glass window 27 is used to transmit the fifth collimated laser 12-3;

[0145] It can be understood that the third collimated laser 12-1, the fourth collimated laser 12-2 and the fifth collimated laser 12-3 all include cooling light and pumping light; the cooling light is used to cool the room temperature atomic gas, and the pumping light re-pumps the atoms that are detuned and excited outside the closed transition back to the closed transition energy level, ensuring that the cycle of atomic cooling continues.

[0146] In one embodiment of the present invention, the third collimated laser 12-1 is incident perpendicularly to the second glass window 9 along the xo (-y) direction and is reflected by the first lens barrel 14-1 to obtain a first pair of circularly polarized cooling beams;

[0147] The fourth collimated laser 12-2 is incident perpendicularly to the third glass window 10 along the (-x)o(-y) direction, and is reflected by the second lens barrel 14-2 to obtain a second pair of circularly polarized cooling beams;

[0148] The fifth collimated laser 12-3 is incident from the fifth glass window 27 along the -z axis and reflected by the third lens barrel 14-3 to obtain a third pair of circularly polarized cooling beams three;

[0149] The first pair, the second pair and the third pair of circularly polarized cooling beams each include two circularly polarized laser beams, the two circularly polarized laser beams have opposite propagation directions, polarization states are orthogonal to each other, and the three pairs of circularly polarized cooling beams are perpendicular to each other;

[0150] The first, second and third pairs of circularly polarized cooling light beams and the anti-Helmholtz coil group 13 form a magneto-optical trap; the magneto-optical trap cools and traps the room temperature atomic gas in the cavity skeleton 26 to form a cold atomic cluster 15 at the center of the cavity skeleton 26.

[0151] Optionally, the gravity acceleration measurement module includes a bias magnetic field coil assembly, an atomic interference system and an atomic detection system;

[0152] The bias magnetic field coil assembly includes a bias magnetic field coil 1 16 - 1 and a bias magnetic field coil 2 16 - 2 ; the bias magnetic field coil 1 16 - 1 and the bias magnetic field coil 2 16 - 2 are arranged outside the vacuum pipe 35 and are coaxial with the vacuum pipe 35 ;

[0153] It can be understood that the bias magnetic field coil assembly is used to generate the splitting of the Zeeman energy level of the cold atoms in the optical fiber, for the preparation of the magnetically insensitive state of the atoms, and at the same time define the quantization axis;

[0154] Further, the atomic interference system includes Raman light coupled in the second optical fiber jumper 19 and the optical fiber internal cold atomic group 17;

[0155] The atom detection system includes detection light, pump light and a photodetector; the detection light and pump light are coupled in the second optical fiber jumper 19, and the photodetector is used to detect the absorption of the detection light by atoms.

[0156] In one embodiment of the present invention, the first collimated laser 3 passes through the laser coupling module 1, the vacuum chamber assembly, the cold atom group preparation module and the gravity acceleration measurement module to output the first guide light 29 coupled from top to bottom; the second collimated laser 21 passes through the laser coupling module 2 and the gravity acceleration measurement module to output the second guide light 30 coupled from bottom to top; Figure 3 As shown, the first guided light 29 and the second guided light 30 have opposite transmission directions, the same power, and their polarization states are both linear polarization and have the same polarization direction;

[0157] The second collimated laser includes a second guiding light, a third Raman pulse laser, a fourth Raman pulse laser, a resonance detection light and a pumping light;

[0158] The first collimated laser light includes a first guide light.

[0159] The first guided light 29 and the second guided light 30 form a movable optical lattice;

[0160] Atoms are loaded into the optical lattice at the position of the cold atomic group 15 , and the transmission speed v of the atoms entering the hollow-core optical fiber is further controlled by scanning the detuning amount of the first guiding light 29 and the second guiding light 30 .

[0161] Further, based on the second collimated laser 21, a third Raman pulse laser 33 and a fourth Raman pulse laser 34 are respectively coupled into the hollow core optical fiber 18 from bottom to top;

[0162] It can be understood that the third Raman pulse laser 33 and the fourth Raman pulse laser 34 are a pair of linearly polarized lasers with a frequency difference of 6.834 GHz, and the switching timing of the Raman light in the second collimated laser 21 is precisely controlled to obtain a Raman laser pulse sequence of "π / 2-π-π / 2", and the time interval between adjacent Raman pulse lasers is T, which is called the free evolution time;

[0163] The third Raman pulse laser 33 and the fourth Raman pulse laser 34 are output from the upper end face of the hollow core optical fiber 18, pass through the quarter wave plate 6 and are reflected by the dichroic mirror 5, and then pass through the quarter wave plate 6 again to form the first Raman pulse laser 31 and the second Raman pulse laser 32 which are reflected oppositely.

[0164] The third Raman pulse laser 33 and the second Raman pulse laser 32 form a counter-injection Raman light combination 1; the fourth Raman pulse laser 34 and the first Raman pulse laser 31 form a counter-injection Raman light combination 2; the counter-injection Raman light combination 1 or the counter-injection Raman light combination 2 is selected to act on the cold atomic group 17 in the hollow core optical fiber to realize the counter-injection Raman interference experiment; Figure 4 As shown;

[0165] It can be understood that the said opposite Raman light combination is a Doppler-sensitive opposite Raman light combination, wherein the propagation direction of the third Raman pulse laser 33 and the second Raman pulse laser 32 is opposite, and the frequency difference is 6.834 GHz;

[0166] The second counter-infrared Raman light combination is a Doppler-sensitive counter-infrared Raman light combination, wherein the fourth Raman pulse laser 34 and the first Raman pulse laser 31 have opposite propagation directions and a frequency difference of 6.834 GHz;

[0167] Another object of the present invention is to provide a method for using a hollow-core fiber-guided cold atom inertial measurement system, comprising:

[0168] Step 1, providing room temperature atomic gas to the vacuum chamber assembly through the rubidium atomic source 25;

[0169] The third collimated laser 12-1, the fourth collimated laser 12-2 and the fifth collimated laser 12-3 are respectively obtained and reflected by the lens barrel assembly to obtain the first pair, the second pair and the third pair of circularly polarized cooling beams respectively;

[0170] A cold atomic cluster 15 is obtained based on the first, second and third pairs of circularly polarized cooling beams and the anti-Helmholtz coil group 13;

[0171] Preferably, the specific steps of obtaining the cold atomic groups in step 1 include:

[0172] A rubidium atom source 25 is used to provide room temperature atomic gas to obtain a third collimated laser 12 - 1 , a fourth collimated laser 12 - 2 , and a fifth collimated laser 12 - 3 ;

[0173] The cooling lights in the third collimated laser 12-1, the fourth collimated laser 12-2 and the fifth collimated laser 12-3 are respectively passed through the first lens barrel 14-1, the second lens barrel 14-2 and the third lens barrel group 14-3 to obtain the first, second and third pairs of circularly polarized cooling light beams with opposite transmission directions and orthogonal to each other;

[0174] The first, second and third pairs of circularly polarized cooling beams decelerate the room temperature atomic gas;

[0175] The anti-Helmholtz coil group 13 is energized to generate a quadrupole gradient magnetic field, which forms a magneto-optical trap with the first, second and third pairs of circularly polarized cooling light beams, and the decelerated room temperature atomic gas is trapped at the center of the magneto-optical trap to obtain a cold atomic group 15 with a temperature of μK;

[0176] Step 2, obtaining the first guide light 29 and the second guide light 30 in the first collimated laser 3 and the second collimated laser 21;

[0177] The first guided light 29 and the second guided light 30 respectively pass through the laser coupling module 1 and the laser coupling module 2 and then couple into the hollow core optical fiber 18 through the corresponding glass windows to interfere and form an optical lattice;

[0178] Setting a transport speed; the cold atomic group 15 is loaded into the optical lattice and transmitted into the hollow-core optical fiber 18 at the transport speed to form a cold atomic group 17 in the optical fiber;

[0179] Preferably, the specific steps of transmitting into the hollow core optical fiber 18 at the transport speed in step 2 to form the cold atomic group 17 in the optical fiber include: simultaneously turning on the first guide light 29 in the first collimated laser 3 and the second guide light 30 in the second collimated laser 21, such as Figure 2 As shown;

[0180] The first guide light 29 is reflected by the first reflector 4-1 and the second reflector 4-2, and then transmitted to the first focusing lens 7 through the dichroic mirror 5 and the quarter wave plate 6 for focusing, and is coupled into the hollow core optical fiber 18 from top to bottom through the first glass window 8;

[0181] The second guide light 30 is reflected by the third reflector 22-1 and the fourth reflector 22-2, and then focused by the second focusing lens 23 and transmitted to the 1 / 2 wave plate 24, and coupled into the hollow core optical fiber 18 from bottom to top through the sixth glass window 28;

[0182] Obtaining an optical lattice formed by the first guided light and the second guided light in the hollow core optical fiber;

[0183] The cold atomic group 15 is bound in the optical lattice and is transmitted into the hollow core optical fiber 18 at the transmission speed to form the cold atomic group 17 in the optical fiber. Figure 3 shown.

[0184] Furthermore, the specific steps of adjusting the transport speed of the cold atomic groups include:

[0185] Gradually reduce and turn off the current of the third collimated laser 12 - 1 , the fourth collimated laser 12 - 2 , the fifth collimated laser 12 - 3 and the anti-Helmholtz coil assembly 13 ;

[0186] By scanning the AOM driving signal frequencies corresponding to the first guide light 29 and the second guide light 30, the frequency detuning amount Δf between the two guide light beams is controlled to adjust the transport speed of the cold atomic clusters after entering the optical lattice, and the cold atomic clusters are manipulated to perform accelerated, uniform, or decelerated transport.

[0187] Furthermore, the expression of the transport velocity is:

[0188] v=Δfλ L / 2

[0189] Where Δf is the frequency detuning of the two guiding laser beams, λ L is the wavelength of the guided light, and v is the transport velocity of the optical lattice.

[0190] Step 3, energizing the bias magnetic field coil assembly to generate a bias magnetic field and define a quantization axis;

[0191] The bias magnetic field splits the |F=1> energy level of the cold atomic group 17 in the hollow core optical fiber into |F=1,m F =0, ±1> three Zeeman sub-levels, atoms are evenly distributed on the three Zeeman sub-levels, F represents the angular momentum quantum number, which is the hyperfine energy level structure of the atom, m F represents the magnetic quantum number;

[0192] Turn on the pump light in the second collimated laser 21, and evenly distribute it in |F=1,m F =0,±1> All cold atoms on the three Zeeman sublevels are pumped to the magnetically insensitive state |F=1,m F =0>, eliminate the atomic interference phase shift caused by the ambient magnetic field, and then turn off the pump light to complete the atomic state preparation;

[0193] Step 4, turning off the first guide light 29 in the first collimated laser 3, and only using the second guide light 30 in the second collimated laser 21 to transversely bind the cold atomic group 17 in the optical fiber;

[0194] The cold atomic group 17 in the optical fiber is freely released along the optical fiber axis at an initial velocity v0;

[0195] The third Raman pulse laser 33 and the fourth Raman pulse light 34 in the second collimated laser 21 are turned on, and after being reflected by the third reflector 22-1 and the fourth reflector 22-2, they are focused to the lower end face of the hollow core optical fiber 18 by the second focusing lens 23, and coupled into the hollow core optical fiber 18 from bottom to top;

[0196] After being output from the upper end face of the hollow core optical fiber, it is collimated by the first focusing lens 7, transmitted to the dichroic mirror 5 through the 1 / 4 wave plate 6 for reflection, and then transmitted to the 1 / 4 wave plate 6 again to form the first Raman pulse laser 31 and the second Raman pulse laser 32 transmitted from top to bottom, as shown in FIG. Figure 4 As shown; based on the first Raman pulse laser 31, the second Raman pulse laser 32, the third Raman pulse laser 33 and the fourth Raman pulse light 34, the opposite Raman light combination one and the opposite Raman light combination two are determined;

[0197] Determine the Raman pulse sequence; apply the Raman light combination 1 and / or the Raman light combination 2 to the cold atomic group 17 in the optical fiber with a Raman pulse sequence of π / 2-π-π / 2, perform atomic splitting, reflection, and beam combining operations, and realize internal state interference of atoms in the two evolution paths;

[0198] The π / 2-π-π / 2 Raman pulse sequence includes a π / 2 Raman pulse laser, a π Raman pulse laser and a π / 2 Raman pulse laser;

[0199] Preferably, the specific steps of the atomic interference include:

[0200] At the initial moment, the atom is in the |F=1,p> state, where F represents the angular momentum quantum number, which is the hyperfine energy level structure of the atom, and p is the initial momentum of the atom.

[0201] After the π / 2 Raman pulse laser acts on the cold atomic group 17 in the optical fiber, the atomic matter wave is split, and the atoms are in the |F=1,p> state and The coherent superposition state of the state; where k eff is the effective wave vector of the incident Raman light combination 1 or the incident Raman light combination 2, is the reduced Planck constant.

[0202] After the free evolution time T, the π Raman pulse laser is used to act on the cold atomic group 17 in the optical fiber to achieve the internal energy level reversal and external momentum transfer of the atoms, that is, the atoms in the |F=1,p> state transition to state, and Then it transitions to the |F=1,p> state;

[0203] After a free evolution time T, the atoms in the two energy states gradually merge in space;

[0204] The third group of π / 2 Raman pulse laser acts on the cold atomic group 17 in the optical fiber, so that the |F=1,p> state and The atoms in the two internal states undergo another transition with a probability of half, and now half of the atoms in the two internal states come from two different evolutionary paths, ultimately achieving internal state interference of atoms.

[0205] Step 5, turn on the resonant detection light in the second collimated laser 21; the resonant detection light is output from the upper end face of the hollow-core optical fiber 18, reflected by the dichroic mirror 5, returns to the second fiber collimator 20 along the original optical path, and is output by the second fiber jumper 19, transmitted to the photodetector through the designated spatial optical path for power detection, and then the second guide light 30 in the second collimated laser 21 is turned off, and the resonant detection light is turned off.

[0206] The internal state of the cold atomic group 17 in the hollow-core optical fiber after beam combination is detected by resonant detection light, and the probability of the atom being in the |F=2> state is obtained;

[0207] The gravitational acceleration component g along the optical fiber axis is obtained based on the probability calculation of atoms in the |F=2> state.

[0208] Preferably, the expression for the probability of being in the |F=2> state is:

[0209]

[0210] Among them, k eff g 2 is the phase shift caused by the uniform gravitational acceleration component along the fiber axis, where k eff is the effective wave vector of the incident Raman light pulse combination, g is the gravitational acceleration component along the fiber axis, is the initial phase corresponding to the first group of π / 2 Raman pulse lasers, is the initial phase corresponding to the second group of π Raman pulse lasers, is the initial phase of the third group of π / 2 Raman pulse laser, P is the atomic transition probability, and T is the free evolution time.

[0211] After the present invention uses the optical lattice scheme to transport the cold atomic group 15 into the hollow core optical fiber, the uniform optical potential well constructed by the hollow core optical fiber can effectively limit the movement of the atomic group in the non-measurement direction. In addition to being sensitive to the component of gravitational acceleration in the axial direction of the optical fiber, it can also be sensitive to the component of the carrier inertial acceleration in the axial direction of the optical fiber.

[0212] The third object of the present invention is to provide an application of vector acceleration measurement, where the hollow-core fiber-guided cold atom inertial measurement system is used to construct a cold atom vector accelerometer to achieve inertial acceleration measurement.

[0213] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A hollow-core fiber-guided cold atom inertial measurement system, characterized in that: Vacuum chamber assembly, laser coupling module 1, laser coupling module 2, cold atom group preparation module and gravity acceleration measurement module; The vacuum chamber assembly comprises a chamber frame (26) and a glass window assembly; the chamber frame (26) is connected to the glass window assembly; The laser coupling module 1 and the laser coupling module 2 are respectively arranged at the outer ends of the vacuum chamber assembly; The cold radical preparation module comprises an anti-Helmholtz coil assembly (13) and a lens barrel assembly; the anti-Helmholtz coil assembly (13) and the lens barrel assembly are respectively connected to the cavity assembly (26); The vacuum chamber (26) is also connected to a vacuum pipe (35); The gravity acceleration measurement module comprises a bias magnetic field coil component, an atomic interference system and an atomic detection system; the bias magnetic field coil component (16) is coaxially arranged with the vacuum pipe (35).

2. The hollow-core fiber-guided cold atom inertial measurement system according to claim 1, characterized in that: The laser coupling module 1 comprises a dichroic mirror (5); The second laser coupling module comprises a second optical fiber jumper (19), a second optical fiber collimator (20) and a hollow core optical fiber (18) which are sequentially arranged along the light beam transmission direction; The hollow core optical fiber (18) is arranged inside the vacuum pipe (35).

3. The hollow-core fiber-guided cold atom inertial measurement system according to claim 1, characterized in that: The cavity frame (26) is a columnar frame having a plurality of support members (26-1); the cavity frame comprises a first end surface (26-2), a second end surface (26-3) and an outer peripheral surface; The plurality of support members (26-1) are arranged in a circumferential direction and respectively penetrate the outer peripheral surface; on a side of each support member away from the center of the cavity frame (26), corresponding peripheral glass window grooves are formed between two support members; A first end surface glass window groove and a second end surface glass window groove are formed on one side of each support member close to the center of the cavity frame (26), respectively penetrating the first end surface (26-2) and the second end surface (26-3).

4. The hollow-core fiber-guided cold atom inertial measurement system according to claim 3, characterized in that: The glass window assembly comprises a first glass window (8), a second glass window (9), a third glass window (10) and a fourth glass window (11); The lens barrel assembly comprises a first lens barrel (14-1) and a second lens barrel (14-2); The rubidium atomic source (25), the first glass window (8), the second glass window (9), the third glass window (10), the fourth glass window (11), the first lens barrel (14-1) and the second lens barrel (14-2) are respectively arranged in corresponding circumferential glass window grooves; The second glass window (9) and the third glass window (10) are used to transmit the third collimated laser (12-1) and the fourth collimated laser (12-2).

5. The hollow-core fiber-guided cold atom inertial measurement system according to claim 1, characterized in that: The glass window assembly further comprises a fifth glass window (27) and a sixth glass window (28); the fifth glass window (27) is used to transmit a fifth collimated laser (12-3); The fifth glass window (27) and the sixth glass window (28) are respectively arranged in the second end surface glass window groove and the first end surface glass window groove.

6. The hollow-core fiber-guided cold atom inertial measurement system according to claim 5, characterized in that: The anti-Helmholtz coil assembly (13) comprises an anti-Helmholtz coil 1 (13-1) and an anti-Helmholtz coil 2 (13-2); The anti-Helmholtz coil 1 (13-1) and the anti-Helmholtz coil 2 (13-2) are coaxial with the fifth glass window and the sixth glass window, and are connected to the two end surfaces of the vacuum cavity.

7. The hollow-core fiber-guided cold atom inertial measurement system according to claim 1, characterized in that: The bias magnetic field coil assembly comprises a bias magnetic field coil 1 (16-1) and a bias magnetic field coil 2 (16-2); the bias magnetic field coil 1 (16-1) and the bias magnetic field coil 2 (16-2) are arranged outside the vacuum pipe (35).

8. A method for using a hollow-core fiber-guided cold atom inertial measurement system according to any one of claims 1 to 7, characterized in that: Step 1, respectively obtaining a third collimated laser (12-1), a fourth collimated laser (12-2) and a fifth collimated laser (12-3), and reflecting them through a lens barrel assembly to obtain a first pair, a second pair and a third pair of circularly polarized cooling beams, respectively; Based on the circularly polarized cooling beam pairs one, two and three and the anti-Helmholtz coil group (13), a cold atomic group (15) is obtained; Step 2: Obtain a first collimated laser (3) and a second collimated laser (21), pass through a laser coupling module 1 and a laser coupling module 2 respectively, and then couple into a hollow core optical fiber (18) through corresponding glass windows to form an optical lattice; The transport speed is set; the cold atomic group (15) is placed in the optical lattice and is transmitted into the hollow-core optical fiber (18) at the transport speed to form a cold atomic group (17) in the optical fiber; Step 3, generating a bias magnetic field using a bias magnetic field coil assembly; In the bias magnetic field, the ground state energy level |F=1> of the cold atomic group (17) in the hollow core optical fiber is split into three Zeeman sub-energy levels, and the atoms are evenly distributed on the three Zeeman sub-energy levels, and F represents the angular momentum quantum number; The pumping light in the second collimated laser (21) is turned on to pump the cold atomic group (17) in the hollow core optical fiber to m F = 0, the atomic state preparation is completed, m F represents the magnetic quantum number; Step 4: using the second guide light (30) in the second collimated laser (21) to laterally bind the cold atomic group (17) in the optical fiber; and freely releasing the cold atomic group (17) in the optical fiber at an initial speed; Turning on the third Raman pulse laser (33) and the fourth Raman pulse light (34) in the second collimated laser (21), coupling them into the hollow core optical fiber (18), and then passing through the laser coupling module 1 to form the first Raman pulse laser (31) and the second Raman pulse laser (32); Determining a first counter-indicator Raman light combination and a second counter-indicator Raman light combination based on a first Raman pulse laser (31), a second Raman pulse laser (32), a third Raman pulse laser (33) and a fourth Raman pulse light (34); The first and / or second Raman light combinations act on the cold atomic group (17) in the optical fiber with a Raman pulse sequence of π / 2-π-π / 2 to perform atomic splitting, reflection and beam combining operations to achieve atomic internal state interference; Step 5, turning on the resonant detection light in the second collimated laser (21), outputting it through the hollow core optical fiber (18), reflecting it from the dichroic mirror (5), entering the second optical fiber collimator (20) along the original optical path, outputting it from the second optical fiber jumper (19), transmitting it through a designated spatial optical path to a photodetector for power detection, and then turning off the second guide light (30) in the second collimated laser 21, and turning off the resonant detection light; The internal state of the cold atomic group (17) in the hollow-core optical fiber after beam combination is detected by resonant detection light, and the atomic state is obtained. | F=2 ＞ The probability of the state; Atom-based | F=2 ＞ The gravitational acceleration component along the optical fiber axis is calculated from the probability of the state, the free evolution time, the effective wave vector of the incident Raman light and the initial phase of the three groups of incident Raman light pulses.

9. The method for using the hollow-core fiber-guided cold atom inertial measurement system according to claim 8, characterized in that: The first collimated laser (3) comprises a first guide light (29); The second collimated laser (21) comprises a second guide light (30), a third Raman pulse laser (33), a fourth Raman pulse laser (34), a resonance detection light and a pumping light; The third collimated laser (12-1), the fourth collimated laser (12-2), and the fifth collimated laser (12-3) all include cooling light and pumping light.

10. An application of a hollow-core fiber-guided cold atom inertial measurement system according to any one of claims 1 to 7, characterized in that: The hollow-core optical fiber guided cold atom inertial measurement system is used to construct a cold atom vector accelerometer to achieve inertial acceleration measurement.

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