CN111721741B - Spectral line measurement air chamber structure without buffer gas - Google Patents
Spectral line measurement air chamber structure without buffer gas Download PDFInfo
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- CN111721741B CN111721741B CN202010621166.0A CN202010621166A CN111721741B CN 111721741 B CN111721741 B CN 111721741B CN 202010621166 A CN202010621166 A CN 202010621166A CN 111721741 B CN111721741 B CN 111721741B
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- air chamber
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/39—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using tunable lasers
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/01—Arrangements or apparatus for facilitating the optical investigation
- G01N21/03—Cuvette constructions
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/01—Arrangements or apparatus for facilitating the optical investigation
- G01N21/03—Cuvette constructions
- G01N21/0303—Optical path conditioning in cuvettes, e.g. windows; adapted optical elements or systems; path modifying or adjustment
Abstract
The invention discloses a spectral line measurement air chamber structure without buffer gas, which comprises: the device comprises an air chamber window, an air chamber shell, a vacuum maintaining valve, an atomic reflux net, a resistance wire system, heat preservation cotton, a temperature display device and a heating power supply, wherein the air chamber shell is tubular, and the air chamber window is coaxially and symmetrically arranged at two ends of the air chamber shell and is connected with the air chamber shell through a flange; the atom reflux net is a metal net, is arranged in the middle of the air chamber shell and covers 50-60% of the length of the inner wall of the air chamber shell; the vacuum maintaining valve is communicated with the air chamber shell through a connecting pipe; the resistance wire system is respectively connected with the temperature display device and the heating power supply. The invention provides a high-precision spectral line measuring structure, particularly provides a spectral line with high signal-to-noise ratio for a narrow-linewidth spectrum, and can lock a laser to the central frequency of atomic transition with narrow linewidth.
Description
Technical Field
The invention relates to the technical field of atomic absorption measurement, in particular to an alkali metal vapor chamber structure which is free of buffer gas, self-reflows atoms and provides a spectral line with a high signal-to-noise ratio, namely a spectral line measurement gas chamber structure free of buffer gas.
Background
The basic principle of an optical atomic clock is to extract spectral information from an atomic system and then obtain a stable optical frequency. The laser is locked on a narrow-linewidth spectral line to obtain a stable atomic spectral line with high signal-to-noise ratio, and the method has important significance for cooling and controlling quantum gas, stability of an optical atomic clock time frequency scale system and the like.
However, for narrow line-width atomic lines, where the line absorption is low, the effective line signal is often buried in probe light intensity noise and other electronic noise. And collision between buffer gas and atoms in the gas chamber brings great collision broadening, so that the signal-to-noise ratio of spectral line signals is further reduced. At present, commercially, the frequency stability of each optical waveband can be obtained by establishing an optical frequency reference system through an ultrastable cavity system, but the feedback and calibration of the long-term stability of the atomic system are still needed. However, optical reference systems with different wave bands need to be respectively coated with films to establish a system, the capital requirement is high, and an additional high-precision temperature control and vacuum system is needed to isolate environmental noise.
The atomic gas chamber has a simple structure, and directly obtains the frequency stability from atoms. And the atomic gas cell is used as a core component of the atomic absorption measurement device, and is required to provide a spectral line signal with a high signal-to-noise ratio.
Therefore, designing an atomic gas cell which has a simple structure and can provide a spectral line signal with a high signal-to-noise ratio has become a technical problem which is urgently needed.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a spectral line measuring gas chamber structure without buffer gas, which has low leakage rate and stable working state and can continuously and stably work.
The specific technical scheme for realizing the purpose of the invention is as follows:
a line measurement plenum structure without a buffer gas, the plenum structure comprising: the device comprises an air chamber window, an air chamber shell, a vacuum maintaining valve, an atomic reflux net, a resistance wire system, heat preservation cotton, a temperature display device and a heating power supply, wherein the air chamber shell is tubular, and the air chamber window is coaxially and symmetrically arranged at two ends of the air chamber shell and is connected with the air chamber shell through a flange;
the atomic reflux net is a metal net, is arranged in the middle of the air chamber shell, covers 50-60% of the length of the inner wall of the air chamber shell and covers 360 degrees of the cylindrical area of the inner wall of the air chamber shell;
the vacuum maintaining valve is communicated with the air chamber shell through a connecting pipe, and the connecting pipe is fixed on the air chamber shell outside the corresponding atom reflux net area;
the resistance wire system includes:
a plurality of layers of high-temperature cement which are arranged on the outer wall of the air chamber shell and correspond to the atom reflux net area;
thermocouples evenly arranged between the two layers of high-temperature cement;
resistance wire wound on the outer layer of the thermocouple;
a high temperature cement layer laid on the resistance wire;
the thermocouple of the resistance wire system is connected with the temperature display device, and the resistance wire is connected with the heating power supply;
the heat preservation cotton is coated outside the high-temperature cement layer laid on the resistance wire of the resistance wire system.
The length of the air chamber shell is 0.5m-2m; the light passing diameter of the gas chamber window is at most 13mm.
The high-temperature cement can resist the temperature of 1400 ℃, and the volume resistivity is at least 10 8 Omega-cm, coefficient of thermal expansion of at most 1X 10 -5 The thickness of each layer of the cement is 1-3mm.
The invention overcomes the defects of the traditional air chamber and has the following advantages:
1) The long air cell structure, 0.5m to 2m long, longer air cell size can accommodate longer size radicals, and under the condition of same atomic number density of the radicals, the optical density of the radicals is increased. For narrow line width atomic spectral lines, the high optical thickness can increase the spectral line signal amplitude, directly increase the signal-to-noise ratio and system stability.
2) The inner diameter of the pipe wall of the narrow-pipe type air chamber is 10-13mm, an atom reflux net is heated and combined in the middle section to form an atom inner circulation system, and the addition of buffer gas is avoided on the premise that an air chamber window is not evaporated. The addition of no buffer gas enables collision broadening of atomic spectral lines to be obviously reduced, and the signal-to-noise ratio of the atomic spectral lines is further improved.
3) The vacuum valve maintains the vacuum environment in the air chamber for a long time.
4) The internal temperature of the atomic gas chamber can be controlled according to the absorption condition, and the adjustment range of the spectral line is enlarged. This allows the chamber to be filled with a variety of atoms separately and to establish their appropriate operating points separately, which can provide a source of stability for different atomic systems.
5) The simple and straight laser channel is suitable for various spectral measurement methods, and measurement schemes such as absorption spectrum, saturated absorption spectrum, modulation transfer spectrum and the like can be applied to the gas chamber.
Drawings
FIG. 1 is a schematic structural view of the present invention;
fig. 2 is a schematic structural diagram of an embodiment of the present invention.
Detailed Description
The invention is described in detail below with reference to the drawings and examples.
Referring to fig. 1, the present invention includes: the device comprises an air chamber window 1, an air chamber shell 2, a vacuum maintaining valve 3, an atom reflux net 4, a resistance wire system 5, heat insulation cotton 6, a temperature display device 7 and a heating power supply 8, wherein the air chamber shell 2 is tubular, and the air chamber window 1 is coaxially and symmetrically arranged at two ends of the air chamber shell 2 and is connected with the air chamber shell 2 through flanges;
the atom reflux net 4 is a metal net, is arranged in the middle of the inner wall of the air chamber shell 2, covers 50-60% of the length of the inner wall of the air chamber shell 2, and covers 360 degrees of a cylindrical area of the inner wall of the air chamber shell 2;
the vacuum maintaining valve 3 is communicated with the air chamber shell 2 through a connecting pipe, and the connecting pipe is fixed on the air chamber shell 2 outside the corresponding atom reflux net 4 area.
a plurality of layers of high-temperature cement which are arranged on the outer wall of the air chamber shell 2 and correspond to the atomic reflux net 4 area;
a resistance wire 52 wound on the outer layer of the thermocouple 51 and made of high-temperature cement;
a high temperature cement layer laid on resistance wire 52;
a thermocouple 51 of the resistance wire system 5 is connected with the temperature display device 7, and a resistance wire 52 is connected with the heating power supply 8;
the heat insulation cotton 6 is coated outside the high-temperature cement layer of the resistance wire system 5 laid on the resistance wire 52.
The length of the air chamber shell 2 is 0.5m-2m; the light-passing size of the gas chamber window 1 is at most 13mm.
The high-temperature cement can resist the temperature of more than 1400 ℃ and has the volume resistivity of more than 10 8 Omega-cm, coefficient of thermal expansion lower than 1 x 10 -5 1mm to 3mm per layer thickness.
The total length of the air chamber shell 2 can be adjusted, actual cases are 1.2m, 0.5m and the like, and the air chamber shell is oriented to different application scenes. The middle part of the inner wall of the air chamber shell 2 is provided with an atom reflux net 4, and the atom reflux net 4 accounts for 50-60% of the total length of the air chamber shell 2. After the atomic metal sample is placed in the central area of the atomic reflux net 4, the background protective gas is pumped out and heated, so that the atomic metal sample is distributed on the atomic reflux net structure.
The outer surface of the air chamber shell 2 is coated with a first layer of high-temperature cement, a thermocouple 51 is arranged outside the high-temperature cement, and the thermocouple 51 provides a temperature measuring end for the temperature display device 7. The thermocouple 51 is wrapped with a second layer of high temperature cement. And a resistance wire 52 is wound outside the second layer of high-temperature cement, and the resistance wire 52 is connected to the heating power supply 8. And a third layer of high-temperature cement is coated outside resistance wire 52. And the outer side of the third layer of high-temperature cement is provided with heat-insulating cotton 6. The heat insulation cotton 6 concentrates heat, reduces the power requirement of the heating power supply 8 and simultaneously protects the working safety of peripheral instruments and personnel.
The middle part of the outer wall of an air chamber shell 2 is matched with the range of an atomic reflux net 4, and a heating resistance wire system 5 is arranged, wherein the heating resistance wire system 5 comprises resistance wires wound at intervals clockwise and anticlockwise and high-temperature cement wrapping the resistance wires. The high-temperature cement prevents the resistance wire from contacting with the metal wall of the air chamber shell 2 and simultaneously fastens the resistance wire structure, so that the mechanical strength of the system is increased.
The method is particularly suitable for measurement of narrow-linewidth atomic spectral lines, and the Doppler broadening is reduced by using a saturated absorption spectrum technology while the probe light enhances the absorption.
Examples
Referring to FIG. 2, the present embodiment is shown 6 Li atomic spectral line measurement is taken as an example.
One side of the air chamber shell 2 is welded with a pipeline which is connected with a vacuum maintaining valve 3.
The coaxial opposed air chamber window 1, the light passing size of the air chamber window 1 is matched with the inner diameter of the air chamber shell 2, and the diameter of the inner wall of the air chamber shell 2 is 13mm. The chamber window 1 is fastened and sealed to the chamber housing 2 by means of a CF flange construction.
The total length of the air chamber shell 2 is 1.2m, an atom reflux net 4 is arranged in the middle of the inner wall of the air chamber shell 2, and the atom reflux net 4 accounts for 50% of the total length of the air chamber shell 2.
The atom reflux net 4 is a stainless steel metal net with 1300 meshes.
The surface of the air chamber shell 2 is coated with a first layer of high-temperature cement, a thermocouple 51 is arranged outside the high-temperature cement, and the thermocouple 51 provides a temperature measuring end for the temperature display device 7. The thermocouple 51 is wrapped with a second layer of high temperature cement. And a resistance wire 52 is wound outside the second layer of high-temperature cement, and the resistance wire 52 is connected to the heating power supply 8. And a third layer of high-temperature cement is wrapped outside the resistance wire 52, and heat-preservation cotton 6 is arranged outside the third layer of high-temperature cement.
Under the protection of inert gas, the mixture is 6 After the Li atomic metal sample is placed in the central area of the atomic reflux net 4, inert gas is pumped out and then heated, so that the Li atomic metal sample is distributed on the atomic reflux net 4.
The heating power supply 8 supplies current to the resistance wire 52, the gas chamber of the embodiment is heated to 280-400 ℃, and radicals are formed inside the gas chamber.
Laser 1', corresponding to a laser wavelength of 323nm. Laser output by the laser 1' is divided into two beams after passing through the optical glass 2' and the polarization beam splitter prism 3', one beam has weak power and enters the air chamber through the air chamber window 1 to interact with atomic groups in the air chamber; a beam of strong light enters the inside of the air chamber through two full-reflecting sheets 4' and through another air chamber window 1 which is symmetrically arranged, and interacts with atomic groups inside the air chamber. The strong light and the weak light are oppositely irradiated, and the weak light forms a saturated absorption spectrum. After passing through the air chamber, the weak light enters the photoelectric detector 5 'after passing through the other polarization beam splitter prism 3'. By frequency scanning the laser 1', obtained at the photodetector 5 6 Saturated absorption line signal of Li atoms.
The structure of the strong light and weak light pair can form a transparent peak near the absorption spectrum of weak light and the frequency corresponding to the atomic energy level, namely the saturated absorption spectrum. The laser is modulated and fed back through the saturated absorption spectral line obtained by the photoelectric detector 5', so that the laser can be locked on the peak of the saturated absorption spectral line. The transfer of the stability of the atomic spectral line to the laser is realized.
In the examples, the absorption saturation line is at 323nm, the absorption peak depth is 80% to 90%, and the absorption saturation peak width is 3MHz. After the laser locks to the saturation absorption peak, the laser linewidth narrows to 50 to 100kHz.
The stability transfer transfers the natural frequency signal of the atom to the laser, thereby realizing the frequency stability of the laser.
In summary, the atomic gas chamber structure provided by the invention realizes the gas chamber design without buffer gas filling by utilizing the vacuum environment maintained for a long time, the small clear aperture, the increased length of the gas chamber and the combination of the atomic reflux net. Therefore, the absorption intensity of spectral line signals is improved, the collision broadening of atomic spectral lines is reduced, and the signal-to-noise ratio atomic spectral line is finally improved.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention, and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (1)
1. A line measurement plenum structure without buffer gas, the plenum structure comprising: the air chamber comprises an air chamber window (1), an air chamber shell (2), a vacuum maintaining valve (3), an atom reflux net (4), a resistance wire system (5), heat preservation cotton (6), a temperature display device (7) and a heating power supply (8), wherein the air chamber shell (2) is tubular, and the air chamber window (1) is coaxially and symmetrically arranged at two ends of the air chamber shell (2) and is connected with the air chamber shell (2) through a flange;
the atom reflux net (4) is a metal net, is arranged in the middle of the inner wall of the air chamber shell (2), covers 50-60% of the length of the inner wall of the air chamber shell (2), and covers 360 degrees of a cylindrical area of the inner wall of the air chamber shell (2);
the vacuum maintaining valve (3) is communicated with the air chamber shell (2) through a connecting pipe, and the connecting pipe is fixed on the air chamber shell (2) outside the corresponding atom reflux net (4) area;
the resistance wire system (5) comprises:
a plurality of layers of high-temperature cement which is arranged on the outer wall of the air chamber shell (2) and corresponds to the atomic reflux net (4) area;
thermocouples (51) uniformly arranged between the two layers of high-temperature cement;
a resistance wire (52) wound on the outer layer high-temperature cement of the thermocouple (51);
a high temperature cement layer laid on the resistance wire (52);
a thermocouple (51) of the resistance wire system (5) is connected with the temperature display device (7), and the resistance wire (52) is connected with the heating power supply (8);
the heat insulation cotton (6) is coated outside a high-temperature cement layer of the resistance wire system (5) laid on the resistance wire (52);
the length of the air chamber shell (2) is 0.5m-2m; the light passing diameter of the air chamber window (1) is at most 13mm;
the high-temperature cement can resist the temperature of 1400 ℃ and has the volume resistivity of at least 10 8 Omega cm, coefficient of thermal expansion of at most 1X 10 -5 The thickness of each layer of the cement is 1-3mm.
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| CN202010621166.0A CN111721741B (en) | 2020-07-01 | 2020-07-01 | Spectral line measurement air chamber structure without buffer gas |
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| CN202010621166.0A CN111721741B (en) | 2020-07-01 | 2020-07-01 | Spectral line measurement air chamber structure without buffer gas |
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| CN111721741B true CN111721741B (en) | 2023-02-03 |
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| JP3631410B2 (en) * | 2000-03-28 | 2005-03-23 | アンリツ株式会社 | Gas cell type atomic oscillator |
| CN103017524B (en) * | 2012-12-10 | 2014-08-06 | 哈尔滨商业大学 | Environment-friendly automatic-temperature-control quartz tube furnace device for pyrolysis of high polymer |
| CN106017783A (en) * | 2016-07-18 | 2016-10-12 | 北京航空航天大学 | Method of measuring pressures of two gases in alkali metal gas chamber simultaneously |
| CN108562550B (en) * | 2018-04-04 | 2020-09-29 | 中国计量科学研究院 | Frequency-stabilized optical cavity ring-down spectrometer for absolute measurement of carbon isotope content in atmosphere |
| CN109696417A (en) * | 2019-02-01 | 2019-04-30 | 清华大学 | A kind of measuring system of the line parameters based on gas absorption spectra |
| CN110319854B (en) * | 2019-05-17 | 2021-01-26 | 北京航空航天大学 | Alkali metal air chamber structure convenient to preparation anti relaxation coating |
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