CN112666624B

CN112666624B - Quantum absolute gravimeter

Info

Publication number: CN112666624B
Application number: CN202011601431.5A
Authority: CN
Inventors: 罗顺烨; 郭彬; 邬黎明; 程冰; 吴彬; 周顺
Original assignee: Hangzhou Weijia Quantum Technology Co ltd
Current assignee: Hangzhou Weijia Quantum Technology Co ltd
Priority date: 2020-12-29
Filing date: 2020-12-29
Publication date: 2022-06-07
Anticipated expiration: 2040-12-29
Also published as: CN112666624A

Abstract

The invention discloses a quantum absolute gravimeter, which comprises a control system, a laser system and a probe system which are connected with each other through electric wires and/or optical fibers; the light path switch is arranged on a light emitting path of the laser system and comprises a power supply, a control component and an execution component, wherein the power supply, the control component and the execution component are connected with each other, the execution component is arranged on one side of the light emitting path of the laser system, the execution component comprises a light blocking component and a stepping motor which is connected with the light blocking component and used for driving the light blocking component to rotate so as to open or close the light path, the stepping motor comprises a rotor and at least a first winding and a second winding which are arranged along a certain circumferential direction outside the rotor, the control component is respectively connected with the first winding and the second winding, and the stepping motor is driven to rotate by controlling the current direction and the current size in the first winding and the second winding so as to enable the light blocking component to block or avoid light. The gravity meter can realize quick opening or disconnection of the laser band.

Description

Quantum absolute gravimeter

Technical Field

The invention relates to a gravity measurement device, in particular to a quantum absolute gravimeter capable of realizing quick turn-on and turn-off of a light path switch.

Background

The light path switch is generally applied to the on-off control of laser beams, and the beams can be completely turned off by rotating the blocking piece to a specified position, so that the controllable switching of the beams in the light path is achieved. With the miniaturization of the optical path, the mechanical shutter generally needs to have the characteristics of small volume, small noise, fast response, fast and accurate turn-off and the like.

The light path switch is generally mainly composed of three parts, namely a light blocking sheet, a stepping motor and a driving circuit. The light blocking sheet is used for blocking light, and is fixed on the rotor of the stepping motor, so that when the rotor of the stepping motor rotates, the light blocking sheet is driven to rotate together, and the opening and closing of the light path are realized. The process is controlled by a driving circuit, and the control of the stepping motor is realized by adjusting the magnitude and the direction of the current flowing through the stepping motor.

The current common stepping motor driving circuit is a subdivision step driving method, and is widely applied to various scenes and can basically meet the use requirements at present. The driving circuit of the stepping motor adopts pulse control signals to control the rotating angle and speed, and the forward and reverse rotation of the stepping motor is realized through direction control signals, so that the opening and closing of a light path are realized. When a subdivision step driving method is adopted to drive the stepping motor to rotate forwards or backwards, only the stepping speed can be controlled by changing the pulse frequency, and when a slower pulse frequency is given to the stepping motor, the baffle can stably rotate for a certain angle without the step loss conditions such as jitter or overshoot, but the requirement of quick turn-off cannot be met in time. After the pulse frequency is increased, the barrier sheet has a certain speed when reaching the light blocking position, so that the barrier sheet finally shakes back and forth near the light blocking position to influence the light blocking effect. Although this jitter can be adjusted by adjusting the fine dial switch, for example, increasing the fine fraction to reduce the jitter, this solution increases the turn-off time of the optical path, and is not suitable for application scenarios requiring fast switching.

In addition, in a miniaturized optical path requiring a fast optical switch, the diameter of a stepping motor is generally required to be not more than 15mm, the length of the stepping motor is required to be not more than 20mm, and meanwhile, a light spot with the maximum 10mm is required to be switched off. The rotational inertia of the rotor of the stepping motor with the common volume is less than 10gm ^2, and the rotational inertia of the light blocking sheet is greater than the rotational inertia of the rotor of the stepping motor, so that when the rotational inertia of the light blocking sheet is too large, the conventional subdivision step driving method can cause shaking caused by the fact that the light blocking sheet continuously moves forwards due to inertia after reaching a specified position. For example: after a common 20-step motor (one step is 18 degrees, the torque is about 1mNm), which meets the volume requirement, after the light blocking sheet is installed, the step time of one step is about 4ms, and the time from two steps to 36 degrees is about 6ms, but because the inertia can swing back and forth around the angle, the final stop time is about 100ms, the maximum angle of the initial overshoot can reach more than 18 degrees, the overshoot can affect the light blocking effect, generally, in order to achieve quick response of a mechanical shutter, the shape of the designed light blocking sheet is slightly larger than the size of a light spot, once the overshoot exceeds about 2-3 degrees, the light blocking sheet can not be turned off, so the traditional subdivision driving step can not be applied to a miniaturized light path needing a quick optical switch.

The quantum absolute gravimeter is one of main application scenes of a miniaturized light path switch, and the existing novel high-precision absolute gravimeter generally utilizes microscopic atoms as a test mass body and realizes precise gravity acceleration measurement based on a cold atom substance wave interference method. Cold atoms are used as a unique group of quantum substances, the atomic substance wave interference similar to the optical wave interference can be realized by utilizing the cold atoms, the beam splitting, the deflection and the beam combination of an atomic wave packet are realized through laser pulses, so that the atomic interference fringes are realized, and the falling path of microscopic atoms can be changed by the gravity acceleration, so that the phase of the interference fringes is changed. And extracting the phase of the atomic interference fringes to obtain the information of the gravity acceleration. In the instrument, the rapid opening and closing of the optical path is crucial in the processes of capturing, cooling, interfering and detecting atoms, and directly influences the final measurement precision.

Therefore, how to realize quick turn-off and avoid the jitter near the stop position is one of the main difficulties in the research field of the current optical path switch.

Disclosure of Invention

Based on the above technical problems, an object of the present invention is to provide a quantum absolute gravimeter, which can rapidly turn on or off a laser band, and can effectively improve the accuracy of a gravity measurement result.

In order to achieve the above object, the present invention provides a quantum absolute gravimeter including a control system, a laser system and a probe system connected to each other by electric wires and/or optical fibers; the control system comprises a main controller, a control assembly and a plurality of light path switches, wherein the main controller and the control assembly are mutually connected; the light path switch is arranged on a light ray outgoing path of the laser system and comprises a power supply, a control component and an execution component which are connected with each other,

the executing assembly is arranged on one side of a light-emitting optical path of the laser system and comprises a light blocking part and a stepping motor which is connected with the light blocking part and is used for driving the light blocking part to rotate so as to turn on or turn off the optical path;

the stepping motor comprises a rotor and a stator, wherein the rotor is provided with at least four magnetic poles distributed along the rotation circumferential direction of the rotor, the polarities of the adjacent magnetic poles are different, the stator at least comprises a first winding and a second winding, and when a magnetic yoke of the first winding is opposite to one magnetic pole of the rotor, a gap between the magnetic yoke of the second winding and the two adjacent magnetic poles of the rotor is opposite; when the first winding drives the rotor to rotate, the rotor is driven to accelerate and then decelerate by adjusting the current direction, and meanwhile, the second winding applies equidirectional magnetic force to the rotor;

the light blocking part is provided with a fixed end and a movable end, the fixed end is connected with the output end of the stepping motor, and the movable end extends outwards along a certain radial direction of the stepping motor to form a light blocking part;

the control assembly is respectively connected with the first winding and the second winding, and the stepping motor is driven to rotate by controlling the current direction and the current magnitude in the first winding and the second winding, so that the light blocking part is driven to rotate to enable the light blocking part to block or avoid light rays.

Preferably, when the first winding magnetic yoke is aligned with a certain magnetic pole of the rotor, the second winding magnetic yoke is aligned with the middle part of the gap between two adjacent magnetic poles of the rotor, so that, on one hand, when the stepping motor starts, one winding aligned with the middle part of the gap between two adjacent magnetic poles of the rotor can be used for guiding the rotor to start and rotate, and the stepping motor is prevented from being out of step at the starting moment; on the other hand, when the stepping motor drives the light blocking part to rotate, synchronous acceleration or synchronous deceleration of the rotor can be more easily realized by adjusting the current directions in the first winding and the second winding.

Preferably, the rotation stroke of the stepping motor is not less than the diameter of the laser system light spot.

Preferably, the stepping motor is a 20-step motor having a single step of 18 °, and the first winding and the second winding of the stepping motor are preferably arranged perpendicular to each other.

Preferably, when the spot diameter is 1-5mm, the stroke of the stepping motor is preferably one step of rotation, and when the spot diameter is 5-10mm, the stroke of the stepping motor is preferably two steps of rotation.

Preferably, the light blocking part is a sector structure extending gradually from the fixed end to both sides of the movable end, the light blocking part is disposed inside an arc-shaped edge of the sector structure, and in some cases, the arc-shaped outer edge of the sector structure may be further adjusted to be a straight edge perpendicular to the radial direction of the rotor.

Preferably, the fixed end and the movable end of the light blocking component are connected through a connecting component, and the light blocking part is a plate-shaped structure which is formed at the movable end of the light blocking component, perpendicular to the extending direction of the light path and can completely block light when needed; preferably, the fixed end, the connecting part and the movable end are fixedly connected or integrally formed. Further preferably, the connection structure between the light blocking part and the output end of the stepping motor is as follows: a connecting groove is formed at the fixed end of the light blocking part and is in interference fit with the output end of the stepping motor; further preferably, the fixed end of the light blocking component can be fixed on the output shaft of the stepping motor through a screw, and still further preferably, the connecting structure can also be that a plurality of tooth sockets extending longitudinally are formed on the inner wall of the connecting groove, and the tooth sockets are engaged with the output end of the stepping motor, so that the relative displacement between the light blocking component and the output end of the stepping motor can be effectively avoided in the rotating process.

Preferably, the optical path switch further comprises a support member for fixing and supporting the stepping motor. Preferably, the supporting component comprises a supporting seat and a sleeve, the stepping motor is fixed in the sleeve, and the sleeve is fixed on the supporting seat. Preferably, one end of the support seat close to the light blocking part is provided with a first limiting part and a second limiting part, the first limiting part and the second limiting part are respectively arranged at two sides of the light blocking part, wherein the limited range between the first limiting part and the second limiting part does not limit the rotation range of the movable end of the light blocking part, the first limiting part and the second limiting part are used for preventing the stepping motor from step-out overshoot, when the light blocking part rotates to the end close to the first limiting part, the light blocking part is far away from and completely avoids light, and the light path switch is opened; when the light blocking part rotates to a position close to one end of the second limiting part, the light blocking part completely blocks light, and the light path switch is closed.

Preferably, the probe system comprises a measuring part and a support frame, the measuring part comprises an ultra-vacuum unit for capturing atoms and providing free falling space for the atoms, and the periphery of the ultra-vacuum unit is provided with a light path structure which is connected with the laser system and guides to generate a plurality of laser bands and a magnetic field unit which is matched with the light path structure to generate a three-dimensional magnetic-optical trap for cooling and capturing the atoms; the light path switch is arranged between the laser system and the light path structure, and when gravity measurement is carried out, the control system carries out instantaneous realization or elimination of the laser band by controlling the opening or closing of the light path switch.

Preferably, the control system comprises a main controller and a control assembly connected with the main controller, the control assembly is provided with a control module and a driving module connected with the control module, the control module preferably comprises an STM32 series single chip microcomputer, and the driving module preferably comprises a DRV8812 integrated chip.

Compared with the prior art, the invention has the beneficial effects that:

the invention can realize quick starting or breaking of the laser band and effectively improve the accuracy of the gravity measurement result; the driving of the first half-way two-phase acceleration and the second half-way two-phase deceleration of the stepping motor is realized by controlling the current magnitude and the direction of the stator winding of the stepping motor, the action speed of the optical path switch is effectively improved, and the rapid switching requirement of a miniaturized optical path (especially precision instruments such as a quantum absolute gravimeter and the like) can be met; in addition, the single coil is adopted for maintaining the position, the power consumption is small (compared with the traditional two-phase maintenance, the power consumption is reduced by half), meanwhile, the electronic reversing times are reduced during the light blocking action, and the light blocking time is shortened.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the application and, together with the description, serve to explain the application and are not intended to limit the application.

Fig. 1 is a schematic perspective view of an optical switch actuator according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a side view of an optical switch actuator assembly according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of a light blocking structure of the optical path switch actuator according to an embodiment of the present invention;

FIG. 4 is a flow chart of a stepper motor driving method in an embodiment of the present invention;

FIG. 5 is a schematic diagram of the electrical connections of the stepper motor driver circuit in an embodiment of the present invention;

FIG. 6 is a circuit connection structure diagram of a stepping motor driving circuit in the embodiment of the invention;

FIG. 7 is a diagram of the internal logic of the driver module in an embodiment of the present invention;

FIG. 8 is a schematic diagram of a method for controlling attenuation in an H-bridge circuit according to an embodiment of the present invention;

FIG. 9(a) is a schematic diagram illustrating the positional relationship between the stator winding and the rotor when the stepping motor is in the start position according to the embodiment of the present invention;

fig. 9(b) is a schematic diagram of the position relationship between the stator winding and the rotor at a certain moment during the forward acceleration of the stepping motor in the embodiment of the present invention;

fig. 9(c) is a schematic diagram of the position relationship between the stator winding and the rotor at a certain moment during the forward deceleration process of the stepping motor in the embodiment of the present invention;

FIG. 9(d) is a schematic diagram illustrating the positional relationship between the stator winding and the rotor when the stepping motor is in the holding position according to the embodiment of the present invention;

fig. 10 is a control timing chart of the stepping motor in the embodiment of the present invention.

Wherein, 1, a supporting seat; 2. a sleeve; 3. an output end of the stepping motor; 4. a light-blocking member;

11. a first limit member; 12. a second limiting component;

41. a fixed end; 42. a movable end.

Detailed Description

The invention is further described with reference to the following figures and examples.

It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or to implicitly indicate the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, unless otherwise specified, "a plurality" means two or more unless explicitly defined otherwise.

In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

Specific terms in the present embodiment are explained below: in general, in the optical path switch, when the light blocking component is located at a position at one side of the light blocking path, the position of the corresponding stepping motor is set as the start position of the stepping motor, and when the light blocking component is located at one side of the light blocking path, the position of the corresponding motor is set as the holding position of the stepping motor.

The present embodiment provides an optical switch, which includes a power supply, a control component and an execution component, the power supply, the control component and the execution component are connected with each other, specifically,

the executing component is arranged at one side of the optical path, as shown in fig. 1 and fig. 2, and includes a light blocking component 4 and a stepping motor connected with the light blocking component for driving the light blocking component to rotate so as to turn on or off the optical path,

the light blocking part 4 is provided with a fixed end 41 and a movable end 42, the fixed end 41 is connected with the output end 3 of the stepping motor, and the movable end 42 extends outwards along a certain radial direction of the stepping motor to form a light blocking part;

the control assembly is respectively connected with the first winding and the second winding, and the stepping motor is driven to rotate by controlling the current direction and the current magnitude in the first winding and the second winding, so that the light blocking part 4 is driven to rotate to enable the light blocking part to block or avoid the light beam 5 (see fig. 3: light blocking state).

Preferably, when the first winding magnetic yoke is opposite to one magnetic pole of the rotor, the second winding magnetic yoke is opposite to the middle of the gap between two adjacent magnetic poles of the rotor. Therefore, on one hand, when the stepping motor starts, one winding which is opposite to the middle part of the gap between two adjacent magnetic poles of the rotor can be used for guiding the rotor to start and rotate, so that the stepping motor is prevented from being out of step at the starting moment; on the other hand, when the stepping motor drives the light blocking member 4 to rotate, synchronous acceleration or synchronous deceleration of the rotor is more easily achieved by adjusting the directions of currents in the first winding and the second winding.

As a preferred embodiment, the single step of the stepper motor is 18 °.

In a preferred embodiment, the light blocking member 4 is a sector structure extending gradually from the fixed end 41 to both sides of the movable end 42, and the light blocking portion is disposed inside an arc-shaped edge of the sector structure, and in some cases, the arc-shaped outer edge of the sector structure may be adjusted to be a straight edge perpendicular to the radial direction of the rotor.

As a preferred embodiment, the fixed end 41 and the movable end 42 of the light blocking member 4 are connected by a connecting component, and the light blocking portion is a plate-shaped structure that is formed at the movable end 42 of the light blocking member 4, is perpendicular to the extending direction of the light path, and can completely block light when necessary; preferably, the fixed end 41, the connecting member and the movable end 42 are fixedly connected or integrally formed. Further preferably, the connection structure between the light blocking part 4 and the output end of the stepping motor is as follows: the fixed end 41 of the light-blocking part 4 is formed with a connecting groove which is in interference fit with the output end of the stepping motor; further preferably, the connecting structure may further include a plurality of longitudinally extending tooth grooves formed in an inner wall of the connecting groove, and the tooth grooves are engaged with the output end of the stepping motor, so that the light blocking member 4 is effectively prevented from being displaced relative to the output end of the stepping motor during the rotation.

As a preferred embodiment, the optical path switch further comprises a support component for fixing and supporting the stepping motor.

As a preferred embodiment, the supporting assembly includes a supporting seat 1 and a sleeve 2, the stepping motor is fixed in the sleeve 2, and the sleeve 2 is fixed on the supporting seat 1.

As a preferred embodiment, a first limiting member 11 and a second limiting member 12 are disposed at one end of the supporting seat 1 close to the light blocking member 4, and the first limiting member 11 and the second limiting member 12 are disposed at two sides of the light blocking member 4, respectively, wherein a limited range between the first limiting member 11 and the second limiting member 12 does not limit a rotation range of the movable end 42 of the light blocking member 4, and both are present to prevent the stepping motor from stepping out and overshooting, when the light blocking member 4 rotates to an end close to the first limiting member 11, the light blocking portion is far away from and completely avoids light, and the light path switch is opened; when the light blocking member 4 rotates to a position close to one end of the second limiting member 12, the light blocking portion completely blocks light, and the light path switch is closed.

As a preferred implementation mode, the control assembly comprises a control module and a driving module connected with the control module, the control module preferably comprises an STM32 series single chip microcomputer, the specific model can be STM32F 103 and the like, and the driving module preferably comprises a DRV8812 integrated chip.

The embodiment further provides a light source device comprising the above light path switch, and the light source device further comprises a light emitting component, the light path switch is arranged on a light emitting path of the light emitting component, and the light blocking component 4 of the light path switch can be controlled to rotate so as to block or avoid the light emitting path, so that the light source device is turned on or turned off.

The embodiment also provides a quantum absolute gravimeter comprising the optical path switch, which comprises a control system, a laser system and a probe system which are connected with each other through an electric wire and/or an optical fiber; the control system comprises a main controller, a control assembly and a plurality of light path switches, wherein the main controller and the control assembly are mutually connected; wherein, the light path switch sets up on laser system's light outgoing path, and it includes power, control module and executive component, power, control module and executive component interconnect specifically:

the executing component is arranged at one side of the light-emitting path of the laser system, the executing component comprises a light-blocking component 4 and a stepping motor which is connected with the light-blocking component and is used for driving the light-blocking component to rotate so as to open or close the light path,

the light blocking part 4 is provided with a fixed end 41 and a movable end 42, the fixed end 41 is connected with the output end of the stepping motor, and the movable end 42 extends outwards along a certain radial direction of the stepping motor to form a light blocking part;

the control assembly is respectively connected with the first winding and the second winding, and the stepping motor is driven to rotate by controlling the current direction and the current magnitude in the first winding and the second winding, so that the light blocking part 4 is driven to rotate to enable the light blocking part to block or avoid light rays.

In a preferred embodiment, when the first winding is aligned with a magnetic pole yoke of the rotor, the second winding yoke is aligned with the middle of a gap between two adjacent magnetic poles of the rotor. Therefore, on one hand, when the stepping motor starts, one winding which is opposite to the middle part of the gap between two adjacent magnetic poles of the rotor can be used for guiding the rotor to start and rotate, so that the stepping motor is prevented from being out of step at the starting moment; on the other hand, when the stepping motor drives the light blocking member 4 to rotate, synchronous acceleration or synchronous deceleration of the rotor can be realized by adjusting the current directions in the a-phase winding and the B-phase winding.

In a preferred embodiment, the rotation stroke of the stepping motor is not less than the diameter of the laser system light spot.

In a preferred embodiment, the step motor is a 20-step motor, the step of which is 18 °, and preferably, the first winding and the second winding of the step motor are arranged perpendicular to each other.

As a preferred embodiment, when the spot diameter is 1-5mm, the stroke of the stepping motor is preferably rotated by one step, and when the spot diameter is 5-10mm, the stroke of the stepping motor is preferably rotated by two steps.

As a preferred embodiment, the fixed end 41 and the movable end 42 of the light blocking member 4 are connected by a connecting component, and the light blocking portion is a plate-shaped structure that is formed at the movable end 42 of the light blocking member 4, is perpendicular to the extending direction of the light path, and can completely block light when necessary; preferably, the fixed end 41, the connecting member and the movable end 42 are fixedly connected or integrally formed. Further preferably, the connection structure between the light blocking part 4 and the output end of the stepping motor is as follows: the fixed end 41 of the light-blocking part 4 is formed with a connecting groove which is in interference fit with the output end of the stepping motor; further preferably, the fixing end 41 of the light blocking member 4 may be further fixed to the output shaft 3 of the step motor by a screw, and still further preferably, the connecting structure may further include a plurality of longitudinally extending tooth sockets formed on an inner wall of the connecting slot, and the tooth sockets are engaged with the output end of the step motor, so that the light blocking member 4 and the output end of the step motor are effectively prevented from being displaced relative to each other during the rotation process.

As a preferred embodiment, the optical path switch further comprises a support member for fixing and supporting the stepping motor. Preferably, the supporting component comprises a supporting seat 1 and a sleeve 2, the stepping motor is fixed in the sleeve 2, and the sleeve 2 is fixed on the supporting seat 1. Preferably, a first limiting part 11 and a second limiting part 12 are arranged at one end of the support base 1 close to the light blocking part 4, the first limiting part 11 and the second limiting part 12 are respectively arranged at two sides of the light blocking part 4, wherein a limited range between the first limiting part 11 and the second limiting part 12 does not limit a rotation range of the movable end 42 of the light blocking part 4, the first limiting part and the second limiting part exist for preventing the stepping motor from step-out overshoot, when the light blocking part 4 rotates to the end close to the first limiting part 11, the light blocking part is far away from and completely avoids light, and the light path switch is opened; when the light blocking member 4 rotates to a position close to one end of the second limiting member 12, the light blocking portion completely blocks light, and the light path switch is closed.

As a preferred embodiment, the probe system comprises a measuring part and a support frame, wherein the measuring part comprises an ultra-vacuum unit for capturing atoms and providing free falling space for the atoms, and the periphery of the ultra-vacuum unit is provided with an optical path structure which is connected with the laser system and guides to generate a plurality of laser bands and a magnetic field unit which is matched with the optical path structure to generate a three-dimensional magnetic optical trap for cooling and capturing the atoms; the light path switch is arranged between the laser system and the light path structure, and when gravity measurement is carried out, the control system carries out instantaneous realization or elimination of the laser band by controlling the opening or closing of the light path switch.

As a preferred implementation mode, the control system comprises a main controller and a control assembly connected with the main controller, the control assembly is provided with a control module and a driving module connected with the control module, the control module preferably comprises an STM32F single chip microcomputer, the specific model can be STM32F 103 and the like, and the driving module preferably is a DRV8812 integrated chip.

The present embodiment further provides a driving method of a stepping motor applicable to the above optical path switch, as shown in fig. 4, including the following steps:

presetting the rotation stroke of a stepping motor according to an application scene;

when a forward rotation command is received, the first winding and the second winding apply equidirectional magnetic force to the rotor by controlling the current magnitude and direction in the first winding and the second winding, so that the rotor of the stepping motor rotates in the forward direction: starting from the initial position, firstly accelerating in two phases to the middle position of the rotation stroke, and then driving the rotor to decelerate in two phases to the holding position to stop;

holding the single coil in a holding position;

when a reverse rotation command is received, the first winding and the second winding apply equidirectional magnetic force to the rotor by controlling the magnitude and the direction of the current in the first winding and the second winding, so that the rotor of the stepping motor rotates reversely: the rotor is driven to accelerate to the middle position of the rotation stroke in a two-phase mode from the holding position, and then the rotor is driven to decelerate to the starting position in the two-phase mode to stop.

As a preferred embodiment, the specific method for driving the stepping motor to hold the single coil in the holding position includes: when the stepping motor is positioned at the holding position, the magnetic pole direction of one winding opposite to the rotor magnetic pole is adjusted to be opposite to the rotor magnetic pole, other windings are powered off, and the stepping motor is limited at the holding position through the attraction between the energized winding and the magnetic pole opposite to the energized winding. Therefore, the holding position is maintained by adopting the single coil, the power consumption is low (the power consumption is reduced by at least half compared with the power consumption of the traditional two-phase maintenance), and meanwhile, the electronic reversing times during the light blocking action are reduced, and the light blocking time is shortened.

As a preferred embodiment, the specific method for driving the two-phase acceleration of the stepping motor is as follows: the magnitude and direction of the stepping motor winding current are adjusted to make the magnetic poles of each winding opposite to the magnetic poles of the rotor closest to the winding and positioned on the upstream side of the stepping motor in the rotating direction, so that the rotor is positively rotated by the magnetic field attraction force.

As a preferred embodiment, the specific method for driving the two-phase deceleration of the stepping motor is as follows: the current magnitude and direction of the stepping motor winding are adjusted to make the magnetic poles of each winding be the same as the magnetic poles of the rotor which is closest to the winding and is positioned on the upstream side of the stepping motor in the rotating direction, so that the rotor is applied with reverse acceleration through the magnetic field repulsive force.

As a preferred embodiment, at the starting time of the two-phase acceleration of the stepping motor, the current of the winding opposite to a certain magnetic pole of the rotor is cut off and maintained for a time T, so that the starting process is smoother, wherein the maintaining time duration of the time T is not more than 1/3 of the two-phase acceleration time duration T1, and ideally, the time T should be a minimum value, namely, the smaller the time T is, the better the starting process is.

As a preferred embodiment, the method further includes obtaining an optimal acceleration time T1 and an optimal deceleration time T2 according to the rotation stroke.

As a preferred embodiment, the method for obtaining the optimal acceleration time T1 and the optimal deceleration time T2 according to the rotation stroke includes: driving the stepping motor to accelerate to the middle position of the rotation stroke in the whole course at the initial position, and collecting the time T1 required by driving the stepping motor to accelerate; when the stepping motor rotates to the middle position, the stepping motor is driven to decelerate to stop in the whole process, the time required by the deceleration of the stepping motor is collected, the process is repeated, the deceleration time is finely adjusted until the output end of the stepping motor just stops when rotating to the holding position, and the time T2 required by the deceleration of the stepping motor is obtained.

The present embodiment also provides a driving system of a stepping motor, including: the control component is connected with the driving module, and the driving module is connected with the stepping motor;

the control module is used for sending a forward rotation command or a reverse rotation command;

the driving module responds to a forward rotation command and drives the stepping motor to execute the following actions: the first winding and the second winding apply equidirectional magnetic force to the rotor by controlling the current magnitude and direction in the first winding and the second winding, so that the rotor of the stepping motor rotates positively: starting from the initial position, firstly accelerating in two phases to the middle position of the rotation stroke, and then driving the rotor to decelerate in two phases to the holding position to stop; holding the single coil in a holding position; responding to a reverse rotation command, and controlling the magnitude and the direction of current in the first winding and the second winding to enable the first winding and the second winding to apply equidirectional magnetic force to the rotor so as to enable the rotor of the stepping motor to rotate reversely: the rotor is driven to accelerate to the middle position of the rotation stroke in a two-phase mode from the holding position, and then the rotor is driven to decelerate to the starting position in the two-phase mode to stop.

As a preferred embodiment, the stepping motor includes a rotor having at least four magnetic poles distributed along a circumferential direction of rotation thereof and adjacent magnetic poles having different polarities, and a stator including at least a first winding and a second winding, the second winding being opposed to a gap between two adjacent magnetic poles of the rotor when the first winding yoke is opposed to one magnetic pole of the rotor; when the first winding drives the rotor to rotate, the rotor is driven to accelerate and then decelerate by adjusting the current direction, and meanwhile, the second winding applies equidirectional magnetic force to the rotor. Preferably, when the first winding is aligned with a certain magnetic pole of the rotor, the second winding is aligned with the middle part of the gap between two adjacent magnetic poles of the rotor, so that, on one hand, when the stepping motor starts, one winding aligned with the middle part of the gap between two adjacent magnetic poles of the rotor can be used for guiding the rotor to start and rotate, and step loss of the stepping motor at the starting moment is avoided; on the other hand, when the stepping motor drives the light blocking part 4 to rotate, synchronous acceleration or synchronous deceleration of the rotor can be realized by adjusting the current directions in the first winding and the second winding.

The present embodiment also provides a computer-readable storage medium, in which a computer program is stored, and when the computer program is processed and executed, the stepping motor driving method described above is implemented.

The stepping motor driving method, system, optical path switch, and the like described above will be described in detail based on the application to the quantum absolute gravimeter:

according to the driving method, the realization process is attached to the following circuit: control module and drive module specifically: as shown in fig. 5, the control component preferably includes a single chip microcomputer and the driving component includes an H-bridge module. The DC power supply supplies power to the singlechip and the H bridge circuit module, the output end of the control signal is connected with the input end of the singlechip, the output end of the singlechip is connected with the H bridge circuit module, the output end of the H bridge circuit module is connected with the positive end of a winding coil of the stepping motor, and the negative end of the winding coil is connected with the sampling resistor and finally grounded.

The singlechip is mainly used for receiving an external trigger signal, and after receiving the trigger signal, the singlechip controls the opening and closing of the H bridge module according to a preset program, so that the optimal motion process of the stepping motor is realized.

The H-bridge module is mainly used for controlling the magnitude and direction of the current of a winding coil of the stepping motor, wherein the single phase comprises 8 field effect transistors, and the adjustment of the current direction is realized by controlling the on and off of different field effect transistors. The current is adjusted by a chopping modulation method, the sampled current value is compared with a set value, the current is turned off when the sampled current value exceeds the set value, and the current is turned on when the sampled current value is lower than the set value.

Fig. 9(a) is a schematic diagram of a positional relationship between a stator winding and a rotor, which is suitable for a start bit or a hold bit (a single-coil hold bit) of a stepping motor, and it should be noted that if stepping by other steps is required, the timing sequence needs to be modified accordingly, but the roles of the control signals are consistent. Referring to fig. 5 and 6, the control signals of the stepping motor mainly include TTL control signals, DECAY signals, winding coil current ENABLE control signals ENABLE x, winding coil current direction control signals PHASE x, and winding coil current magnitude control signals xI0 and xI 1. Wherein x represents phase A or phase B. When the single-chip microcomputer U1 receives the TTL control signal (in this embodiment, the signal comes from the main controller of the quantum absolute gravimeter), it controls U2 according to the timing sequence shown in fig. 10, so as to complete the rotation of the stepping motor.

The form and function of each control signal will be described in detail below:

the TTL control signal described in this embodiment is a square wave signal and is used to control the forward and reverse rotation of the stepping motor, and when the signal jumps from a high level to a low level, the single chip controls the H-bridge module to drive the stepping motor to complete forward rotation through a series of timings, and when the low level jumps to the high level, the single chip completes reverse rotation of the stepping motor.

The delay signal described in this embodiment is a square wave signal, and is used to control the current attenuation mode of the H-bridge module, and includes both fast attenuation and slow attenuation. When the stepper motor is rotating, the current through the two phases changes rapidly, where it is desirable to change the current as fast as possible, so DECAY is set high, which is a fast DECAY mode. When the stepping motor is in a static state, the fast attenuation causes the current to generate huge ripples, so that the baffle of the stepping motor shakes back and forth near the maintaining position, and the DECAY signal is set to be low when the baffle is in a static maintaining state, and the slow attenuation mode is adopted.

The winding coil current ENABLE control signal ENABLE x described in this embodiment is a square wave signal. The control signal is used for controlling the on and off of the winding coil current. Because the mode of single coil maintenance is selected when the rotor is at the holding position, if the current direction of the winding coil is directly reversed when the stepping motor starts to move, the stepping motor is possibly in an out-of-control state, namely the stepping motor can rotate in the forward direction and the reverse direction, and step loss is easy to occur, the current direction in the corresponding winding coil can be adjusted through the ENABLE x so as to guide the stepping motor to rotate in the correct direction.

Referring to fig. 10, the timing chart shows phase B as an example of the holding phase, and when stationary, the first winding is energized, so that phase B is enabled, phase a is disabled, and the rotor position is maintained to be opposite to phase B. When the stepping motor moves forwards, the B phase is enabled, the A phase is disabled, the stepping motor slowly moves for a small angle according to the designated direction, the B phase is enabled again, the two winding coils apply force simultaneously to accelerate, the speed is reduced after the rotation angle is over half, and finally the B phase is enabled to be maintained after the designated position is reached, and the A phase is disabled. Therefore, phase B plays a role in maintaining and accelerating and decelerating, and phase A only plays a role in accelerating and decelerating. Of course, the A phase may be used as the maintenance phase.

The winding coil current direction control signal PHASE x described in this embodiment is a square wave signal. The control signal is used for controlling the direction of the current of the winding coil, thereby controlling the acceleration and deceleration of the stepping motor. Taking phase B as the holding phase for example, when in the rest position, phase B is enabled and gives forward current. The phase A is not enabled, so the forward and reverse directions of the phase A current do not influence the stress of the stepping motor. When the stepping motor starts to rotate forwards, the phase A supplies reverse current, the phase A enables, the stepping motor starts to rotate forwards, and after the stepping motor rotates for a small angle, the phase B supplies reverse current to accelerate the rotor of the stepping motor together with the phase A. When the stepping motor rotates to reach the position 1 in one step, the phase A can decelerate the rotor without changing the phase A current, the phase B current direction needs to be changed to decelerate the stepping motor, and finally the stepping two steps reach the position 2.

The winding coil current magnitude control signals xI0 and xI1 described in this embodiment are square wave signals. When the logic level of xI0 is 1 and the logic level of xI1 is 0, the current is output at 38% of full current, when the logic level of xI0 is 0 and the logic level of xI1 is 1, the current is output at 71% of full current, when the logic level of xI0 is 0 and the logic level of xI1 is 0, the current is output at 100% of full current, when the stepping motor is at rest, 38% of current is selected for maintenance, when the stepping motor is rotating at acceleration, 71% of current is supplied, and when the rotation frequency of the stepping motor is not high, 100% of current can be selected. The turn-off time, while faster, reduces the stepper motor life and increases the amount of heat generated by the stepper motor.

The circuit for implementing the driving method of the stepping motor provided by the embodiment mainly comprises a direct-current power supply, a control signal, a single chip microcomputer and an H bridge circuit module, and the circuit principle is shown in fig. 5 and 6. U1 is the singlechip, and the specific model is STM32F030F4P 6. The power supply terminal is connected to U1-5 and U1-16 and is connected to ground by a decoupling capacitor C10; a resistor R9 pulls die U1-1 down to ground. A reset circuit consisting of a resistor R11, a capacitor C11 and a switch S1 is connected to U1-4; the control signal BPHASE is connected to U1-6; control signal APHASE is connected to U1-9; control signal BENBL is connected to U1-7; the control signal AENBL is connected to U1-8; the control signal DECAY is connected to U1-10; the control signal BI1 is connected to U1-11; the control signal BI0 is connected to U1-12; control signal AI1 is connected to U1-13; control signal AI0 is connected to U1-18;

u2 is an H bridge integrated module, which uses an integrated chip DRV8812, the internal logic of which is shown in fig. 7, and fig. 8 shows the attenuation control method, in fig. 8, firstly shows the flow direction of the driving current, secondly shows the reverse fast attenuation process, and thirdly shows the slow attenuation process. The power supply end is connected to U2-4 and U2-11; the control signal BPHASE is connected to U2-23; control signal APHASE is connected to U2-20; control signal BENBL is connected to U2-22; the control signal AENBL is connected to U2-21; control signal DECAY is connected to U2-19; the control signal BI1 is connected to U2-27; the control signal BI0 is connected to U2-26; control signal AI1 is connected to U2-25; control signal AI0 is connected to U2-24; a capacitor C5 is connected between the U2-1 and the U2-2; u2-3 connects a resistor R1 and a capacitor R2 to the power supply terminal; the U2-15 reference voltage output terminal is connected to U2-12 and U2-13; u2-28 and U2-14 are connected directly to ground; u2-5 is connected to the positive terminal of the A phase winding coil; u2-7 is connected to the negative terminal of the A phase winding coil; u2-8 is connected to the positive terminal of the B phase winding coil; u2-10 is connected to the negative terminal of the B phase winding coil; u2-6 connects a sampling resistor R3 to ground; u2-9 connects a sampling resistor R4 to ground, the full current is finally determined by the sampling resistor, the current is calculated by formula IA 3.3/(5R 3), IB 3.3/(5R 4);

the direct-current power supply adopted by the embodiment is a common linear stabilized power supply or a switching power supply, the power supply voltage is 9-30V, the rated voltage is 24V, the rated current in a maintaining state is about 0.1A, the peak current in rotation is about 0.5A, and the specific current is determined by the power supply voltage and the specific motor model.

Fig. 9(a) is a schematic diagram of the positional relationship between the rotor and the stator winding of the stepping motor at the start position. When the default current control signal is low, the current direction is positive and the phase polarity is N. After power-on, the TTL control level is default to high, and the mechanical shutter is in an open state (if it is low, it is in a closed position, and the sequence will be described below with the open state as an initial position). At the moment, the single chip microcomputer receives the TTL control signal and is in a high level state, and the stepping motor is controlled to be in a static maintaining state. The specific control sequence is as follows:

firstly, setting DECAY to be low, and keeping current in slow attenuation;

enabling A is set low, phase A has no current, and no force is generated on a rotor of the stepping motor;

thirdly, enabling B is set high, and current passes through the B phase;

PHASE A is set to be low by default, and the PHASE A has no current at the moment, so the positive and negative are not influenced;

PHASE B is set high, the polarity of B PHASE is S, and the PHASE is attracted with rotor N, so that the stepping motor is maintained at the position shown in figure 1;

and sixthly, setting AI1 BI1 to be high and AI0 BI0 to be low, wherein the current flowing through the stepping motor is 38% of the full current.

Fig. 9(b) is a schematic diagram of a positional relationship between a rotor and a stator winding of a stepping motor at a certain time in a forward rotation dual-phase acceleration process of the stepping motor, if the stepping motor in a stationary state needs to be turned off (default clockwise and reverse rotation of the stepping motor is changed to forward turn-off operation of the stepping motor), only the TTL control high level needs to be set low, and when the single chip detects that the TTL control signal is low, the single chip outputs the following control timing sequence to start accelerated rotation of the stepping motor, where the specific control timing sequence is:

firstly, setting DECAY high, and keeping current in fast attenuation;

secondly, enabling A is set high, and current passes through the A phase;

thirdly, enabling B is set to be low for time t and then is set to be high immediately;

fourthly, the PHASE A is set low, the polarity of the PHASE A is N, and the positive acceleration force is provided for the stepping motor;

PHASE B is set low, the polarity of the B PHASE is N, and positive acceleration force is given to the stepping motor;

and sixthly, setting the AI1 BI1 to be low and the AI0 BI0 to be high, wherein the current flowing through the stepping motor is 71 percent of the full current.

And step three, firstly setting the time t to be low, and then immediately setting the time t to be high. Because the polarity of the phase B is N and the polarity of the phase B is repellent to the polarity of the rotor, the stepping motor can rotate in the forward direction and can also rotate in the reverse direction. When the rotor rotates a small angle under the action of the phase A, the rotor is immediately raised, and the phase B gives positive acceleration force to the stepping motor due to polarity repulsion.

Fig. 9(c) is a schematic diagram of a position relationship between a rotor and a stator winding of a stepping motor at a certain time in a forward rotation two-phase deceleration process of the stepping motor, and it should be noted that, since a rotation process of the stepping motor is divided into an acceleration process and a deceleration process, a phase a and a phase B both give a forward acceleration force to the rotor in the acceleration process, and a reverse deceleration force needs to be given to the rotor in the deceleration process, in application, a phase a and a phase B polarity are determined according to a polarity of a magnetic pole of the rotor, and a current direction is finally determined, where a specific control timing sequence is:

firstly, setting DECAY high, and keeping current in fast attenuation;

secondly, enabling A is set high, and current passes through the A phase;

thirdly, enabling B is set high, and current passes through the B phase;

the PHASE A is still set low without changing the level logic, the polarity of the PHASE A is N, and the positive deceleration force is provided for the stepping motor;

PHASE B is set high, the polarity of the B PHASE is S, and positive deceleration force is given to the stepping motor;

The advantage of the single coil maintaining position is that besides reducing power consumption, the coil A does not need to change the direction of the passing current, namely, the first half-way (0-18 degrees) acceleration and the second half-way deceleration (18-36 degrees) can be realized, compared with the double coil maintaining position, the electronic commutation time is reduced by 3-5 times, and the turn-off time can be shortened by more than 1 ms.

Fig. 9(d) is a schematic diagram of a positional relationship between the rotor and the stator winding of the stepping motor when the stepping motor is in the holding position, and the specific control timing sequence is as follows:

firstly, setting DECAY to be low, and keeping current in slow attenuation;

enabling A is set to be low, and no current passes through phase A;

thirdly, enabling B is set high, and current passes through the B phase;

PHASE B is set low, the polarity of the B PHASE is N, and the force is maintained for the stepping motor;

sixthly, setting AI1 BI1 to be high and setting AI0 BI0 to be low, wherein the current flowing through the stepping motor is 38% of the full current.

In addition, the reverse acceleration and deceleration process is basically consistent with the forward direction, and the description is not repeated, and the whole control logic diagram for controlling the stepping motor from the on state, the off state and the on state is as follows: time T represents the entire switching-off or switching-on process, T₁Indicating an acceleration process during the shut-down, T₂Indicating a deceleration process during shutdown.

When light blocking operation is carried out aiming at small light spots (3mm), in the prior art, the turn-off time of a light path switch of a quantum absolute gravimeter is about 4.5ms, and the turn-off time is about 3ms by adopting the driving method and the circuit. Through tests, under the condition that other test conditions are consistent, the same light blocking sheet is adopted, the rotational inertia is about 12 (gram) square millimeter), the 20-step motor (single step of 18 degrees) is adopted, the diameter of the stepping motor is 8mm, the rotational inertia of the rotor is 2.75 (gram) square millimeter), and through the tests, the small light spot test is turned off and turned on only by one step of stepping of the stepping motor.

When light blocking operation is carried out on a large light spot (9mm), in the prior art, a light path switch of the quantum absolute gravimeter can only carry out single-step back and forth movement, so that the method cannot be applied to the scene. With the traditional subdivision step driving method, the turn-off time is about 6ms, but the turn-off process can cause the stepping motor to shake back and forth at the turn-off position due to the fact that a deceleration process is not introduced, and the final stop time is about 100ms-200 ms. Since the design size of the light blocking sheet is generally slightly larger than the size of the light spot, the light blocking sheet can not block light in the period of time and cannot be applied. Under the same condition, the driving method and the circuit are adopted, the stepping process of the whole stepping motor is about 5ms, the stepping speed is increased by 2.5ms, the stepping speed is reduced by 2.5ms, the stepping motor is stepped to the turn-off position, and the requirement of quick turn-off can be met without shaking basically. The other test conditions were identical, using the same gobos, with a moment of inertia of about 20 (grams per square millimeter), using a 20-step motor (single step 18 degrees), a stepper motor diameter of 8mm, and a rotor moment of inertia of 2.75 (grams per square millimeter). Through experiments, when the light blocking operation is carried out on the large light spot, two steps of stepping of a stepping motor are needed for testing turn-off and turn-on; therefore, the mechanical shutter designed based on the driving method enables the stepping motor (taking a stepping motor with a single step stepping angle of 18 degrees as an example) to perform double-phase acceleration in the first half of the movement and perform double-phase deceleration in the second half (stepping two steps to 36 degrees) by analyzing the internal structure of the motor, enables the single-step stepping time to be about 2.5ms and the stepping two steps to be about 5ms, basically keeps still, has good light blocking efficiency and small vibration, and meets the requirement of a rapid optical switch of a miniaturized optical path. And the single coil is used as a maintaining position, the power consumption is small when the single coil is maintained statically (at least half of the power consumption is reduced compared with that of double-phase maintenance), the electronic reversing times are few when the light blocking moves, and the light blocking time is shortened. The driving method is not only suitable for two-step stepping, but also can be used for single-step or multi-step stepping, and the more complex the stepping number and the time sequence, the greater the difficulty in parameter adjustment. In the case of a stepping motor with 18 ° single step, a single step drive procedure is generally applied to a 1-5mm spot, and a two step procedure is applied to a 5-10mm spot.

To sum up, for the control of the stepping motor of the optical switch, the present embodiment adopts a driving method for directly controlling the current of the winding coil, and adopts the single coil as the maintaining position, which reduces the power consumption of the motor by the first half compared with the double-coil maintaining. In addition, because the single coil is maintained in the position stepping two steps, only the phase B needs to be electronically commutated once in the motor deceleration process, and the phase A does not need to be commutated in the acceleration and deceleration process. The coils are all provided with inductance, each commutation needs a certain time, and the more the commutation times are, the longer the motor stepping time is. If the holding position of the double coils is adopted to start moving, the double-phase coils need to be electronically commutated for 5 times, the inductance of the coils of the commonly used small-size stepping motors is large, and the turn-off time can be increased by 1-2ms due to the fact that the coils are commutated for multiple times, and therefore the use requirement of the rapid optical switch cannot be met.

Further, it should be noted that:

in the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and not to be construed as limiting the present invention, and those skilled in the art can make changes, modifications, substitutions and alterations to the above embodiments without departing from the principle and spirit of the present invention, and any simple modification, equivalent change and modification made to the above embodiments according to the technical spirit of the present invention still fall within the technical scope of the present invention.

Claims

1. A quantum absolute gravimeter is characterized by comprising a control system, a laser system and a probe system which are connected with each other through electric wires and/or optical fibers; the control system comprises a main controller, a control assembly and a plurality of light path switches, wherein the main controller and the control assembly are mutually connected; the light path switch is arranged on a light ray outgoing path of the laser system and comprises a power supply, a control component and an execution component which are connected with each other,

the executing assembly is arranged on one side of a light-emitting optical path of the laser system and comprises a light blocking component (4) and a stepping motor which is connected with the light blocking component and is used for driving the light blocking component to rotate so as to turn on or turn off the optical path;

the stepping motor comprises a rotor and a stator, wherein the rotor is provided with at least four magnetic poles distributed along the rotation circumferential direction of the rotor, the polarities of the adjacent magnetic poles are different, the stator at least comprises a first winding and a second winding, and when a magnetic yoke of the first winding is opposite to one magnetic pole of the rotor, a gap between the magnetic yoke of the second winding and the two adjacent magnetic poles of the rotor is opposite; when the first winding drives the rotor to rotate, the rotor is driven to accelerate and decelerate by adjusting the current direction, and meanwhile, the second winding applies equidirectional magnetic force to the rotor, so that the driving of the first half-stroke two-phase acceleration and the second half-stroke two-phase deceleration of the stepping motor is realized;

the light blocking part (4) is provided with a fixed end (41) and a movable end (42), the fixed end (41) is connected with the output end (3) of the stepping motor, and the movable end (42) extends outwards along a certain radial direction of the stepping motor to form a light blocking part;

the control assembly is respectively connected with the first winding and the second winding, and the stepping motor is driven to rotate by controlling the current direction and the current magnitude in the first winding and the second winding, so that the light blocking part (4) is driven to rotate to enable the light blocking part to block or avoid light rays.

2. A quantum absolute gravimeter according to claim 1, wherein when the first winding is aligned with a pole yoke of the rotor, the second winding yoke is aligned with the middle of the gap between two adjacent poles of the rotor.

3. A quantum absolute gravimeter according to claim 1, wherein the rotational travel of the stepping motor is not less than the diameter of the laser system spot.

4. A quantum absolute gravimeter according to claim 1, wherein the single step of the stepper motor is 18 °.

5. A quantum absolute gravimeter according to claim 3, wherein when the spot diameter is 1-5mm, the stroke of the stepping motor is one step of rotation; when the diameter of the light spot is 5-10mm, the stroke of the stepping motor is two steps of rotation.

6. A quantum absolute gravimeter according to claim 1, characterized in that the light-blocking element (4) is a sector structure extending gradually from the fixed end (41) to both sides of the movable end (42), and the light-blocking portion is disposed inside the arc-shaped edge of the sector structure.

7. A Quantum absolute gravimeter according to claim 1, characterized in that the fixed end (41) and the movable end (42) of the light blocking member (4) are connected by a connecting member, and the light blocking portion is a plate-like structure perpendicular to the extending direction of the light path and capable of completely blocking light when necessary, formed at the movable end (42) of the light blocking member (4).

8. A quantum absolute gravimeter according to claim 1, characterized in that the light switch further comprises a support assembly for fixing and supporting the stepping motor, the support assembly comprises a support base (1) and a sleeve (2), the stepping motor is fixed in the sleeve (2), and the sleeve (2) is fixed on the support base (1).

9. The quantum absolute gravimeter according to claim 1, wherein the probe system comprises a measuring part and a supporting frame, the measuring part comprises an ultra-vacuum unit for capturing atoms and providing a free-fall space for the atoms, and the periphery of the ultra-vacuum unit is provided with an optical path structure coupled with the laser system and guiding to generate a plurality of laser bands and a magnetic field unit cooperating with the optical path structure to generate a three-dimensional magnetic-optical trap for cooling and capturing atoms; the light path switch is arranged between the laser system and the light path structure, and when gravity measurement is carried out, the control system carries out instantaneous realization or elimination of the laser band by controlling the opening or closing of the light path switch.

10. A quantum absolute gravimeter according to claim 1, wherein the control system comprises a main controller and a control module connected thereto, the control module has a control module and a driving module connected thereto, the control module comprises an STM32 series single chip microcomputer, and the driving module is a DRV8812 integrated chip.