CN115032706A - Absolute gravimeter based on Michelson laser - Google Patents

Absolute gravimeter based on Michelson laser Download PDF

Info

Publication number
CN115032706A
CN115032706A CN202210640381.4A CN202210640381A CN115032706A CN 115032706 A CN115032706 A CN 115032706A CN 202210640381 A CN202210640381 A CN 202210640381A CN 115032706 A CN115032706 A CN 115032706A
Authority
CN
China
Prior art keywords
laser
prism
measuring
mirror
falling body
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202210640381.4A
Other languages
Chinese (zh)
Inventor
陈景标
秦晓敏
史田田
陈德朗
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Zhejiang Faraday Laser Technology Co ltd
Peking University
Original Assignee
Zhejiang Faraday Laser Technology Co ltd
Peking University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Zhejiang Faraday Laser Technology Co ltd, Peking University filed Critical Zhejiang Faraday Laser Technology Co ltd
Priority to CN202210640381.4A priority Critical patent/CN115032706A/en
Publication of CN115032706A publication Critical patent/CN115032706A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V7/00—Measuring gravitational fields or waves; Gravimetric prospecting or detecting
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00—Measuring instruments characterised by the use of optical techniques
    • G01B9/02—Interferometers
    • G01B9/02001—Interferometers characterised by controlling or generating intrinsic radiation properties
    • G01B9/02002—Interferometers characterised by controlling or generating intrinsic radiation properties using two or more frequencies
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00—Measuring instruments characterised by the use of optical techniques
    • G01B9/02—Interferometers
    • G01B9/02015—Interferometers characterised by the beam path configuration

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geophysics (AREA)
  • Instruments For Measurement Of Length By Optical Means (AREA)

Abstract

The invention discloses an absolute gravimeter based on a Michelson laser, which is characterized by comprising a Michelson laser, a spectrum analyzer, a vacuum cavity, a vibration isolation system and a data processing unit, wherein the Michelson laser is connected with the data processing unit; the front cavity mirror, the laser gain medium, the spectroscope and the feedback output mirror of the Michelson laser are sequentially arranged along a horizontal optical axis; the falling body prism and the reference prism are arranged along the vertical optical axis; the spectroscope is positioned at the intersection point of the horizontal optical axis and the vertical optical axis; taking a light path oscillating along the horizontal direction as a reference light path, and taking corresponding laser as reference laser; an oscillation light path outside the reference light path is used as a measuring light path, and the corresponding laser is used as measuring laser; the spectrum analyzer is arranged behind the feedback output mirror and is used for measuring beat frequency signals of the reference laser and the measuring laser; and the data processing unit is used for performing secondary fitting according to the clock signals corresponding to the beat frequency signal measuring points and the falling track data of the falling body prism obtained through calculation to obtain a gravity acceleration value.

Description

Absolute gravimeter based on Michelson laser
Technical Field
The invention belongs to the field of gravity measurement, and particularly relates to an absolute gravimeter based on a Michelson laser.
Background
The absolute gravity measurement is a direct measurement of the acceleration g of the earth surface, and has wide application in the fields of earth science, resource exploration, auxiliary navigation, measurement science and the like. Since 1960, with the development of laser technology, laser interference absolute gravimeters were developed and used for absolute gravity measurement. The traditional laser interference absolute gravimeter adopts a Michelson interferometer structure, when a free-falling prism moves a half-wavelength distance, interference fringe signals change for a period, and a photoelectric detector is used for collecting the interference fringe signals and carrying out processing analysis. And acquiring time sequences with zero amplitude of all interference signals to obtain falling body track signals, and performing quadratic fitting on the falling body track signals to obtain the acceleration of the falling body relative to the reference prism, namely the gravity acceleration.
The traditional laser interference absolute gravimeter judges the falling distance of a falling body by observing interference fringes, and records a clock signal when the light and shade of the interference fringes change for a period, thereby obtaining the falling body track. In this case, the drop is recorded once per half wavelength of the free-fall laser, i.e., the resolution of the fall distance is one half wavelength of the laser, on the order of nanometers. If the distance resolution is improved, the measurement accuracy of the gravity acceleration can be further improved, and the method has important application value.
The michelson laser is firstly proposed in the patent of a michelson laser and an implementation method and a displacement measurement method thereof (application number: 202210393703.X), and is a novel laser in technology and principle realized by adopting a michelson interferometer light path. Compared with the traditional laser interferometer only having the nano-scale displacement measurement resolution, the displacement measurement system realized by the Michelson laser and the frequency spectrograph can realize the picometer-scale or even more than picometer-scale displacement measurement resolution, and has extremely high research value in the field of precision metrology.
Disclosure of Invention
In order to solve the above problems, the present invention provides an absolute gravity interferometer based on a michelson laser to improve the measurement accuracy of the gravitational acceleration.
Firstly, the structure and the displacement measurement method of the Michelson laser are introduced: michelson laser has used for reference at the structural Michelson interferometer of light path, adopts four high reflectivity laser cavity mirrors to constitute the closed chamber of laser, has a plurality of return circuits in the intracavity, satisfies the laser resonance condition after, can form the laser of a plurality of different frequencies. And a frequency spectrograph is arranged behind the output mirror, so that an interference signal of the output laser can be observed. The displacement variation of the measuring arm can be deduced by comparing the variation of the laser interference beat frequency signals of the measuring arm and the reference arm. The scheme overcomes the limitation of the traditional laser interferometer, namely the displacement measurement resolution ratio caused by observing interference fringes to calculate the displacement variation quantity does not exceed the nanometer magnitude, and the idea of converting the displacement measurement into the frequency measurement is adopted, so that the displacement measurement resolution ratio can be improved to the picometer magnitude and even exceeds the picometer magnitude.
By utilizing the displacement measurement scheme based on the Michelson laser, the Michelson interferometer and the signal processing part thereof in the traditional laser interference absolute gravimeter are replaced, and larger data volume can be measured when the falling body falls for the same displacement, so that the measurement precision of the gravity acceleration is improved.
Based on the above thought, the invention provides an absolute gravimeter based on a michelson laser, which adopts the following technical scheme:
an absolute gravimeter based on a Michelson laser is characterized by structurally comprising a front cavity mirror 1, a laser gain medium 2, a spectroscope 3, a falling body prism 4, a reference prism 5, a feedback output mirror 6, a spectrum analyzer 7, a vacuum cavity 8, a vibration isolation system 9 and a data processing unit; wherein the content of the first and second substances,
the falling body prism 4 is a pyramid prism fixed inside the free falling object, and the pyramid prism can ensure that incident light and reflected light are absolutely parallel and eliminate errors caused by disturbance in the horizontal direction in the gravity acceleration measurement;
the front cavity mirror 1, the laser gain medium 2, the spectroscope 3, the falling body prism 4, the reference prism 5 and the feedback output mirror 6 jointly form a Michelson laser;
the light output by the laser gain medium 2 oscillates back and forth in the cavity, and the laser output is realized after the condition that the gain is larger than the loss is achieved. The laser cavity forming the laser of the mode is composed of a front cavity mirror 1 and a feedback output mirror 6; the resonant cavity corresponding to the measuring light path laser is composed of a front cavity mirror 1, a falling body prism 4, a reference prism 5 and a feedback output mirror 6, the measuring laser vertically upwards transmits to the falling body prism 4 after reaching the spectroscope 3, vertically downwards enters the reference prism 5 after being reflected by the falling body prism 4, is further reflected back to the spectroscope 3 and is output from the feedback output mirror 6. A frequency spectrograph 7 is arranged behind the feedback output mirror 6 and can be used for measuring beat frequency signals of the reference laser and the measuring laser.
The data analysis process of the data processing unit is as follows: the cavity length variation dl of the laser resonant cavity and the laser frequency variation delta v have the following corresponding relation:
Figure BDA0003682030650000021
and L is the cavity length of the resonant cavity of the measuring arm, v is the measuring laser frequency, and the cavity length variation dl corresponding to the measuring light path can be deduced by utilizing the variation delta v of the beat frequency signal according to the relation. Therefore, in practical application, the falling height of the falling body prism 4 can be obtained by reading the beat frequency signal on the frequency spectrograph and further performing calculation processing on the frequency data. And recording the clock signal of each beat frequency signal test point by using an atomic clock with high time measurement precision to obtain falling body track data, and performing quadratic fitting on the data according to the kinematic relationship of Newton's second law to obtain a gravity acceleration value.
Further, an antireflection film is plated on the emergent end face of the laser gain medium 2; the front cavity mirror 1 is a total reflection mirror, the falling body prism 4, the reference prism 5 and the feedback output mirror 6 are high reflection mirrors, and the front cavity mirror, the falling body prism 4, the reference prism 5 and the feedback output mirror 6 jointly form a closed laser resonant cavity, wherein the feedback output mirror 6 is used for outputting laser.
Further, in order to satisfy the abbe principle and reduce the influence of horizontal micro-vibration, the falling body prism 4 and the reference prism 5 should be placed on a vertical line. Meanwhile, the front cavity mirror 1 and the feedback output mirror 6 should be placed on a horizontal line.
Further, the splitting ratio of the beam splitter 3 is 1: 1.
further, the falling body prism 4 can be reset through a transmission device after freely falling down, and repeated measurement is realized.
Further, the vacuum chamber 8 maintains the vacuum environment in the chamber where the falling body and the falling body prism 4 are located through an ion pump, eliminates the interference of air, and ensures that the measured falling body motion acceleration is the gravity acceleration.
Further, the vibration isolation system 9 is used to reduce interference of external vibrations to the reference prism 5, keeping the reference prism 5 stationary with respect to the inertial system.
Compared with the existing laser interference absolute gravimeter, the absolute gravimeter based on the Michelson laser has the advantages that:
when the traditional laser interference absolute gravimeter acquires the falling body track, data can be acquired only by taking the half wavelength of laser as a unit. The method has the advantages that when the falling distance of the falling body is the same, more groups of data can be measured, and the accuracy of the quadratic fit gravity acceleration value is improved.
Drawings
Fig. 1 is a schematic structural diagram of an absolute gravimeter based on a michelson laser.
Wherein, 1-anterior chamber mirror; 2-a laser gain medium; a 3-beam splitter; 4-a falling body prism; 5-a reference prism; 6-a feedback output mirror; 7-a spectrum analyzer; 8-vacuum cavity; 9-vibration isolation system.
Detailed Description
The following examples serve to illustrate the technical solution of the present invention without limiting it.
The absolute gravimeter based on the Michelson laser is structurally shown in the figure and comprises a front cavity mirror 1, a laser gain medium 2, a spectroscope 3, a falling body prism 4, a reference prism 5, a feedback output mirror 6, a spectrum analyzer 7, a vacuum cavity 8 and a vibration isolation system 9. Wherein the front cavity mirror 1 is a total reflection mirror; the laser gain medium 2 can be a helium neon laser tube, a semiconductor laser diode, a YAG crystal and the like, and the light emergent end is plated with an anti-reflection film; the front end face of the spectroscope 3 is plated with a semi-reflecting and semi-permeable film, and the rear surface of the spectroscope is plated with an anti-reflection film; the falling body prism 4 is a pyramid prism fixed inside the free falling object; the falling body prism 4, the reference prism 5 and the feedback output mirror 6 are all high-reflection mirrors; the front cavity mirror 1, the laser gain medium 2, the spectroscope 3, the falling body prism 4, the reference prism 5 and the feedback output mirror 6 jointly form a Michelson laser.
When the laser gain medium works, light output by the laser gain medium 2 oscillates back and forth in the cavity, and laser output is achieved after the condition that the gain is larger than the loss is achieved. The laser cavity forming the laser of the mode is composed of a front cavity mirror 1 and a feedback output mirror 6; the resonant cavity corresponding to the measuring light path laser is composed of a front cavity mirror 1, a falling body prism 4, a reference prism 5 and an output feedback mirror 6, the measuring laser vertically upwards transmits to the falling body prism 4 after reaching the spectroscope 3, vertically downwards enters the reference prism 5 after being reflected by the falling body prism 4, is further reflected back to the spectroscope 3 and is output from the feedback output mirror 6. A frequency spectrograph 7 is arranged behind the feedback output mirror 6 and can be used for measuring beat frequency signals of the reference laser and the measuring laser. The cavity length variation dl of the laser resonant cavity and the laser frequency variation delta v have the following corresponding relation:
Figure BDA0003682030650000041
wherein L is a measuring armThe cavity length of the resonant cavity, ν is the measuring laser frequency, and the cavity length variation corresponding to the measuring optical path can be deduced by using the variation of the beat frequency signal according to the above relation, so that the falling height of the falling body prism 4 can be obtained. And recording the clock signal of each beat frequency signal test point by using an atomic clock with high time measurement precision to obtain falling body track data, and performing quadratic fitting on the data according to the kinematic relation of Newton's second law to obtain a gravity acceleration value.
Further, the falling body prism 4 can be reset through a transmission device after freely falling down, and repeated measurement is realized.
Further, in order to satisfy the abbe principle and reduce the influence of horizontal micro-vibration, the falling body prism 4 and the reference prism 5 should be placed on a vertical line. Meanwhile, the front cavity mirror 1 and the feedback output mirror 6 are placed on a horizontal line.
Further, the vacuum chamber 8 maintains a vacuum environment in the chamber through an ion pump, and ensures that the measured falling body motion acceleration is gravity acceleration.
Further, the vibration isolation system 9 is used to reduce interference of external vibrations to the reference prism 5, keeping the reference prism 5 stationary with respect to the inertial system.
The above examples are only intended to illustrate the technical solution of the present invention and not to limit it. Modifications and equivalents may be made to the disclosed embodiments by those skilled in the art without departing from the spirit and scope of the present invention as defined by the appended claims. Therefore, the invention should not be limited by the disclosure of the embodiments, but should be defined by the appended claims.

Claims (7)

1. The absolute gravimeter based on the Michelson laser is characterized by comprising a Michelson laser, a spectrum analyzer (7), a vacuum cavity (8), a vibration isolation system (9) and a data processing unit; wherein, the first and the second end of the pipe are connected with each other,
the Michelson laser comprises a front cavity mirror (1), a laser gain medium (2), a spectroscope (3), a falling body prism (4), a reference prism (5) and a feedback output mirror (6); the front cavity mirror (1), the laser gain medium (2), the spectroscope (3) and the feedback output mirror (6) are sequentially arranged along a horizontal optical axis; the falling body prism (4) and the reference prism (5) are arranged along a vertical optical axis; the spectroscope (3) is positioned at the intersection point of the horizontal optical axis and the vertical optical axis and is used for dividing the light output by the laser gain medium (2) into two paths which are transmitted along the horizontal optical axis and the vertical optical axis, so that the light output by the laser gain medium (2) is oscillated in a laser closed cavity formed by the front cavity mirror (1), the falling body prism (4), the reference prism (5) and the feedback output mirror (6) to form a plurality of lasers with different frequencies; taking a light path oscillating along the horizontal direction as a reference light path, and taking corresponding laser as reference laser; an oscillation light path outside the reference light path is used as a measuring light path, and the corresponding laser is used as measuring laser;
the falling body prism (4) is arranged in the vacuum cavity (8); the reference prism (5) is arranged in the vibration isolation system (9);
the spectrum analyzer (7) is arranged behind the feedback output mirror (6) and is used for measuring beat frequency signals of the reference laser and the measuring laser;
a data processing unit for processing data based on
Figure FDA0003682030640000011
Obtaining the falling height dl of the falling body prism (4), wherein L is the resonant cavity length dl corresponding to the measuring optical path, delta v is the frequency variation of the beat frequency signal, and v is the frequency of the measuring laser; and performing secondary fitting on the clock signals corresponding to the beat frequency signal measuring points and the falling trajectory data of the falling body prism (4) obtained through calculation to obtain a gravity acceleration value.
2. Absolute gravimeter according to claim 1, characterized in that the drop prism (4) is a corner cube prism fixed inside a free-falling object used for measuring absolute gravity.
3. Absolute gravimeter according to claim 1 or 2, characterized in that a transmission is provided in the vacuum chamber (8) for resetting the drop prism (4) after free fall.
4. The absolute gravimeter according to claim 1, characterized in that the oscillation optical path formed by the front cavity mirror (1), the falling body prism (4), the reference prism (5) and the feedback output mirror (6) is used as the measuring optical path.
5. The absolute gravimeter according to claim 1, characterized in that the exit face of the laser gain medium (2) is coated with an antireflection coating; the front cavity mirror (1) is a total reflection mirror, and the falling body prism (4), the reference prism (5) and the feedback output mirror (6) are high reflection mirrors.
6. Absolute gravimeter according to claim 1, characterized in that the splitting ratio of the splitter mirror (3) is 1: 1.
7. the absolute gravimeter according to claim 1 or 6, characterized in that the front surface of the spectroscope (3) is coated with a semi-reflecting and semi-permeable film and the rear surface is coated with an anti-reflection film.
CN202210640381.4A 2022-06-07 2022-06-07 Absolute gravimeter based on Michelson laser Pending CN115032706A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202210640381.4A CN115032706A (en) 2022-06-07 2022-06-07 Absolute gravimeter based on Michelson laser

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202210640381.4A CN115032706A (en) 2022-06-07 2022-06-07 Absolute gravimeter based on Michelson laser

Publications (1)

Publication Number Publication Date
CN115032706A true CN115032706A (en) 2022-09-09

Family

ID=83123678

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202210640381.4A Pending CN115032706A (en) 2022-06-07 2022-06-07 Absolute gravimeter based on Michelson laser

Country Status (1)

Country Link
CN (1) CN115032706A (en)

Similar Documents

Publication Publication Date Title
US20230243998A1 (en) Absolute gravimeter and measurement method based on vacuum optical tweezers
CN109781088B (en) Miniaturized atomic interference gyroscope device and measuring method
US8543350B2 (en) Synthetic vibration isolation system for freefall gravimeter
US8867026B2 (en) Chip-scale optomechanical gravimeter
CN108169804B (en) Atomic interference gravity gradient measurement method and device based on pyramid-like structure
CN107764189A (en) A kind of femtosecond laser Models of Absolute Distance Measurement Based device and method of a wide range of repetition modulation
CN111610571B (en) System and method for monitoring and compensating dynamic errors of atomic interference gravimeter
CN104166015A (en) High-precision wide-range optical NEMS micro accelerometer based on monolithic integration
CN111044417A (en) Device for detecting particle size by using mechanical effect of light and testing method
KR101156358B1 (en) Absolute gravimeter using high resolution optical interferometer with parallel multiple pass configuration
CN102621590A (en) System and method for measuring gravity acceleration by utilizing optical fiber technology
US20130042680A1 (en) Apparatus for measuring gravitational force and methods of using the same
Arnautov et al. " Gabl", an absolute free-fall laser Gravimeter
Zhang et al. Ultrahigh-sensitivity Bragg atom gravimeter and its application in testing Lorentz violation
CN115032706A (en) Absolute gravimeter based on Michelson laser
CN108801436B (en) The high-rate laser vialog of phase demodulating is estimated based on speed
CN206583930U (en) A kind of optical fiber interference type detector device with collimater
CN113466929B (en) Three-component optical fiber type seismic accelerometer based on quantum weak value amplification
Vitushkin et al. Laser displacement interferometers with subnanometer resolution in absolute ballistic gravimeters
US20220163557A1 (en) Optomechnical inertial reference mirror for atom interferometer and associated methods
CN112764115A (en) Quantum absolute gravimeter and probe thereof
CN108801435B (en) Based on the compound high-rate laser vialog for estimating phase demodulating of speed, acceleration
CN214067411U (en) Quantum absolute gravimeter and vacuum cavity thereof
CN214750873U (en) Quantum absolute gravimeter
CN112764114B (en) Quantum absolute gravimeter and light path structure thereof

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination