CN105466887A - Detection system of thin-walled closed glass chamber's optical parameters and method thereof - Google Patents

Abstract

The invention discloses a detection system of a thin-walled closed glass chamber's optical parameters. The system comprises a light source, lock-in amplifiers, an optical chopper, a photoelectric detector, a beamsplitter, lenses, a diaphragm and a computer. The light source generates laser which enters a main optical path; spot size is adjusted through the two lenses; through the diaphragm, light spot undergoes shaping and light intensity is controlled; the input beam passes through the beamsplitter to form a reference optical path and a measurement optical path; laser of the measurement optical path passes through the surface of the chamber to be reflected into the photoelectric detector, an output signal is modulated by one of the lock-in amplifiers, and the computer is connected; and laser of the reference optical path is directly detected by the photoelectric detector, an output signal is modulated by the other lock-in amplifier, and the computer is connected. The invention also brings forward a detection method corresponding to the system. According to the invention, the problem of nondestructive testing of optical parameters (physical wall thickness and refractive index) of the thin-walled closed glass chamber is solved. The invention provides a foundation for subsequent in-depth study on ultrahigh sensitive inertia and magnetic field measuring equipment.

Description

The detection system of thin-walled closed glass chamber optical parameter and method

Technical field

The invention belongs to spectral analysis and laser measuring technique field, the detection system of especially a kind of ultra-high sensitive inertia and responsive gauge outfit (the thin-walled closed glass chamber) optical parametric of magnetic field measuring device and method.

Background technology

Based on SERF effect atomic spin inertia and magnetic field measuring device, utilize the angular momentum characteristic of atom and the Larmor precession characteristic of atom, carry out inertia and magnetic-field measurement, measurement sensistivity is far above conventional apparatus.Ultra-high sensitive inertia and magnetic field measuring device, can serve chemical composition and structure analysis and biomolecular structure analysis, atomic spin gyroscope the field such as magnetometer.The thin-walled closed glass chamber of interior alkali metal containing and inert gas is the responsive gauge outfit of ultra-high sensitive magnetic field and inertial measuring unit, and the performance of chamber inherently determines the limit of instrumental sensitivity.Therefore, to the research of thin-walled closed glass chamber own optical parameter, be ultra-high sensitive inertia and the requisite part of magnetic field measuring device.

At present, for the detection of thin-walled closed glass chamber own optical parameter mainly through destructive test, chamber is broken into pieces, utilizes its thickness of vernier caliper measurement, additionally by the refractive index of chemical experiment detection chambers material; This method is simple, but can cause permanent damage to chamber, cannot restore.

Summary of the invention

Goal of the invention: for problems of the prior art, the invention provides a kind of detection system of thin-walled closed glass chamber optical parameter, realizes the Non-Destructive Testing to chamber, and provide a kind of method that can realize said system further.

Technical scheme: the present invention proposes a kind of detection system of thin-walled closed glass chamber optical parameter, comprise: for generation of the light source of input light, for the lock-in amplifier of modulating and demodulating signal, optical chopper and photodetector, for components and parts light splitting piece, lens, the diaphragm of optical path adjusting, and computing machine;

Light source produces laser and enters main optical path, through two lens adjustment spot sizes, then through diaphragm shaping hot spot, control light intensity; Input light forms reference path and optical path after light splitting piece, and the laser of optical path, through the surface of chamber, reflexes in photodetector, and its output signal, after lock-in amplifier modulation, connects computing machine; The laser of reference path is directly detected by photodetector, and its output signal, after the modulation of another lock-in amplifier, connects computing machine.

The present invention also proposes a kind of detection method of thin-walled closed glass chamber optical parameter, comprises the steps:

1) experiment laser instrument used is demarcated;

2) control temperature changing laser instrument regulates the frequency of laser, and by related experiment equipment record raw data, comprises the amplitude of measuring-signal and frequency, the amplitude of modulation signal and frequency;

3) carry out square-wave frequency modulation to measured signal, the frequency of optical chopper is set, such as formula (1); And utilize orthogonal two paths of signals to carry out demodulation measured signal, such as formula (3) and formula (4); According to the principle of Multi-channel crossed modulation, modulation signal is interacted by phase sensor with measured signal, such as formula (5) and formula (6); It exports after low-pass filter, and most of high-frequency signal is removed, such as formula (7) and formula (8); Two-way restituted signal through vector summer, output signal U _out, such as formula (9);

Sig(t)＝V _r·Sq(ωt)(1)

In formula, Sig (t) represents measured signal, V _rrepresent the amplitude of measured signal, Sq (ω t) represents square-wave frequency modulation function, and ω represents angular frequency;

Ref ₁(t)＝V _icos(ωt+θ)(3)

Ref ₂(t)＝V _isin(ωt+θ)(4)

In formula, Ref ₁t () represents modulation signal 1, Ref ₂t () represents modulation signal 2, it and modulation signal 1 have 90 ° of phase differential, V _irepresent the amplitude of modulation signal, θ represents the offset phase angle of modulation signal;

$R_{Sig\·{\mathrm{Ref}}_1}\left(\mathrm{\τ}\right)=\frac{1}{T}\underset{0}{\overset{T}{\∫}}\frac{4V_r}{\mathrm{\π}}\·\underset{n=1}{\overset{\mathrm{\∞}}{\Σ}}\frac{1}{2n-1}sin\[\left(2n-1\right)\mathrm{\ω}t\]\·V_i\·cos\[\mathrm{\ω}\left(t-\mathrm{\τ}\right)+\mathrm{\θ}\]dt---\left(5\right)$

$R_{Sig\·{\mathrm{Ref}}_2}\left(\mathrm{\τ}\right)=\frac{1}{T}\underset{0}{\overset{T}{\∫}}\frac{4V_r}{\mathrm{\π}}\·\underset{n=1}{\overset{\mathrm{\∞}}{\Σ}}\frac{1}{2n-1}sin\[\left(2n-1\right)\·\mathrm{\ω}t\]\·V_i\·sin\[\mathrm{\ω}\·\left(t-\mathrm{\τ}\right)+\mathrm{\θ}\]dt---\left(6\right)$

$R_{Sig\·{\mathrm{Ref}}_1}\left(\mathrm{\τ}\right)=\underset{T\→\mathrm{\∞}}{\lim }\frac{1}{T}\underset{0}{\overset{T}{\∫}}\frac{4V_r}{\mathrm{\π}}\·sin\left(\mathrm{\ω}t\right)\·V_i\·cos\[\mathrm{\ω}\left(t-\mathrm{\τ}\right)+\mathrm{\θ}\]dt\≈\frac{2\·V_i\·V_r}{\mathrm{\π}}sin\mathrm{\θ}---\left(7\right)$

$R_{Sig\·{\mathrm{Ref}}_2}\left(\mathrm{\τ}\right)=\underset{T\→\mathrm{\∞}}{\lim }\frac{1}{T}\underset{0}{\overset{T}{\∫}}\frac{4V_r}{\mathrm{\π}}\·sin\left(\mathrm{\ω}t\right)\·V_i\·sin\[\mathrm{\ω}\·\left(t-\mathrm{\τ}\right)+\mathrm{\θ}\]dt\≈\frac{2\·V_i\·V_r}{\mathrm{\π}}cos\mathrm{\θ}---\left(8\right)$

$U_{out}=\sqrt{{\left(\frac{2\·V_i\·V_r}{\mathrm{\π}}sin\mathrm{\θ}\right)}^2+{\left(\frac{2\·V_i\·V_r}{\mathrm{\π}}cos\mathrm{\θ}\right)}^2}=\frac{2\·V_i\·V_r}{\mathrm{\π}}---\left(9\right)$

In formula, represent that measured signal and modulation signal 1 carry out the result of modulating, represent that measured signal and modulation signal 2 carry out the result of modulating, T represents integral time, U _outrepresent the amplitude of measured signal;

4) refer step 3, obtains reflected light signal and incident optical signal, carries out related data matching, obtain thin-walled closed glass chamber optical parameter, i.e. wall thickness and refractive index, specifically such as formula shown in (10):

$\frac{I_R}{I_{in}}=1-\frac{I_t}{I_{in}}=1-\frac{{(1-R_0)}^2}{1-2R_0*cos(\frac{2\mathrm{\π}}{\mathrm{\λ}}*(\frac{2nd}{cos\mathrm{\β}}-2dtan\mathrm{\β}sin\mathrm{\α}\left)\right)+R_0^2}---\left(10\right)$

In formula, I _inrepresent the light intensity of incident laser, I _rrepresent the light intensity of reflects laser, I _trepresent the light intensity of transmission laser, R ₀represent the reflectivity measuring sample surfaces, λ represents the wavelength of laser instrument, and n represents the refractive index of testing sample, and d represents the physical thickness of testing sample, and α represents the incident angle of laser, and β represents the emergence angle of laser.

Beneficial effect: the detection method and the system that propose inertia and the responsive gauge outfit optical parametric of magnetic field measuring device detected based on Multi-channel crossed, the invention solves the problem of thin-walled closed glass chamber optical parameter (physics wall thickness, refractive index) Non-Destructive Testing, for ultra-high sensitive inertia and the follow-up further investigation of magnetic field measuring device provide the foundation.

Accompanying drawing explanation

Fig. 1 is the schematic diagram of detection method;

Reference numeral in figure is: modulation signal 1, phaselocked loop 2, crystal oscillator 3, phase-modulator 4, phase sensor 5, low-pass filter 6, X are to DC component 7, vector summer 8, output signal 9, Y-direction DC component 10, operational amplifier 11, square-wave modulator 12, bandpass filter 13, measuring-signal 14;

Fig. 2 is system architecture schematic diagram of the present invention;

Reference numeral in figure is: lock-in amplifier 15, measurement sample 16, photodetector 17, light splitting piece 18, lens 19, optical chopper 20, diaphragm 21, lens 22, laser instrument 23, computing machine 24;

Fig. 3 is the Distributed Feedback Laser calibration result figure of the embodiment of the present invention;

Fig. 4 is the experiment test raw readings figure of the embodiment of the present invention.

Embodiment

Composition graphs 1 and Fig. 2 describe the present invention.

Fig. 1 is the schematic diagram of detection method, first the running route of analysis to measure signal 14, measuring-signal 14 enters detection system, through bandwidth filter 13, remove power frequency component to the impact of measuring, modulated by square wave function 12 pairs of measuring-signals, interacted by phase sensor and modulation signal after operational amplifier 11; The running route of lower surface analysis reference signal, reference signal 1 is after phaselocked loop 2 and inner crystal oscillator 3, phase place and frequency information are by Obtaining Accurate, then a part of reference signal is directly interacted by phase sensor 5 and measuring-signal, and a part of reference signal is interacted by phase sensor 5 and measuring-signal after 90 ° of phase shifts occur phase-modulator 4 in addition; Two-way output signal 7 and 10, respectively through after Butterworth low-pass filter 6, is carried out vector computing through vector summer 8 and is just obtained, the output signal 9 of needs.

Fig. 2 is system architecture schematic diagram of the present invention, and laser is derived from light source 23, is regulated the size of hot spot by two lens 19 and 22, carries out shaping, control the intensity of light with diaphragm 21 to input light; Input light becomes two bundle laser by beam of laser after light splitting piece 18, wherein beam of laser is through the surface of chamber, reflex in the middle of photodetector 17, the output signal of photodetector is received lock-in amplifier 15 and is modulated, output signal enters computing machine 24, beam of laser directly detects with photodetector 17 in addition, outputs signal and is modulated by lock-in amplifier 15, finally enters computing machine 24.

Described main optical path connects reference path and optical path through light splitting piece; Reference signal light path incident laser is detected by photodetector, and lock-in amplifier modulates this output signal, finally connects computing machine; Measuring-signal light path incident laser reflexes to photodetector through chamber surfaces, and another lock-in amplifier modulates this output signal, finally connects computing machine.

Thin-walled glass chamber (simple substance Cs, 600torr is closed below with Cs simple substance ⁴he, 50torrN ₂, square air chamber, length of side 2.5cm) and be example.First, demarcate experiment Distributed Feedback Laser used, calibration result as shown in Figure 3.

Second step, by changing the control temperature of laser instrument, regulates the frequency of laser; Be the temperature of step-size change laser instrument with 1 DEG C, and by related experiment equipment record raw data, as shown in Figure 4.

3rd step, carries out square-wave frequency modulation to measured signal, and the frequency arranging optical chopper is 65Hz, shown in (1); And utilize orthogonal two paths of signals to carry out demodulation measured signal, such as formula (3) and formula (4); According to the principle of Multi-channel crossed modulation, modulation signal is interacted by phase sensor with measured signal, such as formula (5) and formula (6); It exports after low-pass filter, and most of high-frequency signal is removed, such as formula (7) and formula (8); Two-way restituted signal through vector summer, output signal U _out, such as formula (9).

Sig(t)＝V _r·Sq(ωt)(1)

In formula, Sig (t) represents measured signal, V _rrepresent the amplitude of measured signal, Sq (ω t) represents square-wave frequency modulation function, and ω represents angular frequency.According to fourier series, formula (1) is expanded into following expression:

$Sig\left(t\right)=\frac{4V_r}{\mathrm{\π}}\·\underset{n=1}{\overset{\mathrm{\∞}}{\Σ}}\left(\frac{1}{2n-1}\right)\·sin\[\left(2n-1\right)\mathrm{\ω}t\]---\left(2\right)$

Ref ₁(t)＝V _icos(ωt+θ)(3)

Ref ₂(t)＝V _isin(ωt+θ)(4)

In formula, Ref ₁t () represents modulation signal 1; Ref ₂t () represents modulation signal 2, it and modulation signal 1 have 90 ° of phase differential; V _irepresent the amplitude of modulation signal, θ represents the offset phase angle of modulation signal;

$R_{Sig\·{\mathrm{Ref}}_1}\left(\mathrm{\τ}\right)=\frac{1}{T}\underset{0}{\overset{T}{\∫}}\frac{4V_r}{\mathrm{\π}}\·\underset{n=1}{\overset{\mathrm{\∞}}{\Σ}}\frac{1}{2n-1}sin\[\left(2n-1\right)\mathrm{\ω}t\]\·V_i\·cos\[\mathrm{\ω}\left(t-\mathrm{\τ}\right)+\mathrm{\θ}\]dt---\left(5\right)$

$R_{Sig\·{\mathrm{Ref}}_2}\left(\mathrm{\τ}\right)=\frac{1}{T}\underset{0}{\overset{T}{\∫}}\frac{4V_r}{\mathrm{\π}}\·\underset{n=1}{\overset{\mathrm{\∞}}{\Σ}}\frac{1}{2n-1}sin\[\left(2n-1\right)\·\mathrm{\ω}t\]\·V_i\·sin\[\mathrm{\ω}\·\left(t-\mathrm{\τ}\right)+\mathrm{\θ}\]dt---\left(6\right)$

$R_{Sig\·{\mathrm{Ref}}_1}\left(\mathrm{\τ}\right)=\underset{T\→\mathrm{\∞}}{\lim }\frac{1}{T}\underset{0}{\overset{T}{\∫}}\frac{4V_r}{\mathrm{\π}}\·sin\left(\mathrm{\ω}t\right)\·V_i\·cos\[\mathrm{\ω}\left(t-\mathrm{\τ}\right)+\mathrm{\θ}\]dt\≈\frac{2\·V_i\·V_r}{\mathrm{\π}}sin\mathrm{\θ}---\left(7\right)$

$R_{Sig\·{\mathrm{Ref}}_2}\left(\mathrm{\τ}\right)=\underset{T\→\mathrm{\∞}}{\lim }\frac{1}{T}\underset{0}{\overset{T}{\∫}}\frac{4V_r}{\mathrm{\π}}\·sin\left(\mathrm{\ω}t\right)\·V_i\·sin\[\mathrm{\ω}\·\left(t-\mathrm{\τ}\right)+\mathrm{\θ}\]dt\≈\frac{2\·V_i\·V_r}{\mathrm{\π}}cos\mathrm{\θ}---\left(8\right)$

$U_{out}=\sqrt{{\left(\frac{2\·V_i\·V_r}{\mathrm{\π}}sin\mathrm{\θ}\right)}^2+{\left(\frac{2\·V_i\·V_r}{\mathrm{\π}}cos\mathrm{\θ}\right)}^2}=\frac{2\·V_i\·V_r}{\mathrm{\π}}---\left(9\right)$

In formula, represent that measured signal and modulation signal 1 carry out the result of modulating, represent that measured signal and modulation signal 2 carry out the result of modulating, T represents integral time, U _outrepresent the amplitude of measured signal.

4th step, refer step three, can Obtaining Accurate reflected light signal I _rwith incident optical signal I _in, carry out related data matching, just can obtain thin-walled closed glass chamber optical parameter (physics wall thickness, refractive index), shown in (10):

$\frac{I_R}{I_{in}}=1-\frac{I_t}{I_{in}}=1-\frac{{(1-R_0)}^2}{1-2R_0*cos(\frac{2\mathrm{\π}}{\mathrm{\λ}}*(\frac{2nd}{cos\mathrm{\β}}-2dtan\mathrm{\β}sin\mathrm{\α}\left)\right)+R_0^2}---\left(10\right)$

In formula, λ represents the wavelength of laser instrument; N represents the refractive index of testing sample; D represents the physical thickness of testing sample; α represents the incident angle of laser; β represents the emergence angle of laser; R ₀represent the reflectivity measuring sample surfaces; I _inrepresent the light intensity of incident laser; I _rrepresent the light intensity of reflects laser; I _trepresent the light intensity of transmission laser.

More than describe the preferred embodiment of the present invention in detail; but the present invention is not limited to the detail in above-mentioned embodiment, within the scope of technical conceive of the present invention; can carry out multiple equivalents to technical scheme of the present invention, these equivalents all belong to protection scope of the present invention.

It should be noted that in addition, each the concrete technical characteristic described in above-mentioned embodiment, in reconcilable situation, can be combined by any suitable mode.In order to avoid unnecessary repetition, the present invention illustrates no longer separately to various possible array mode.

Claims (2)

1. the detection system of a thin-walled closed glass chamber optical parameter, comprise: for generation of the light source of input light, for the lock-in amplifier of modulating and demodulating signal, optical chopper and photodetector, for components and parts light splitting piece, lens, the diaphragm of optical path adjusting, and computing machine;

Light source produces laser and enters main optical path, through two lens adjustment spot sizes, then through diaphragm shaping hot spot, control light intensity; Input light forms reference path and optical path after light splitting piece, and the laser of optical path, through the surface of chamber, reflexes in photodetector, and its output signal, after lock-in amplifier modulation, connects computing machine; The laser of reference path is directly detected by photodetector, and its output signal, after the modulation of another lock-in amplifier, connects computing machine.

2. a detection method for thin-walled closed glass chamber optical parameter, is characterized in that, comprise the steps:

1) experiment laser instrument used is demarcated;

2) control temperature changing laser instrument regulates the frequency of laser, and by related experiment equipment record raw data, comprises the amplitude of measuring-signal and frequency, the amplitude of reference signal and frequency;

3) carry out square-wave frequency modulation to measured signal, the frequency of optical chopper is set, such as formula (1); And utilize orthogonal two paths of signals to carry out demodulation measured signal, such as formula (3) and formula (4); According to the principle of Multi-channel crossed modulation, modulation signal is interacted by phase sensor with measured signal, such as formula (5) and formula (6); It exports after low-pass filter, and most of high-frequency signal is removed, such as formula (7) and formula (8); Two-way restituted signal through vector summer, output signal U _out, such as formula (9);

Sig(t)＝V _r·Sq(ωt)(1)

In formula, Sig (t) represents measured signal, V _rrepresent the amplitude of measured signal, Sq (ω t) represents square-wave frequency modulation function, and ω represents angular frequency;

Ref ₁(t)＝V _icos(ωt+θ)(3)

Ref ₂(t)＝V _isin(ωt+θ)(4)

In formula, Ref ₁t () represents modulation signal 1, Ref ₂t () represents modulation signal 2, it and modulation signal 1 have 90 ° of phase differential, V _irepresent the amplitude of modulation signal, θ represents the offset phase angle of modulation signal;

$R_{Sig\·{\mathrm{Ref}}_1}\left(\mathrm{\τ}\right)=\frac{1}{T}\underset{0}{\overset{T}{\∫}}\frac{4V_r}{\mathrm{\π}}\·\underset{n=1}{\overset{\mathrm{\∞}}{\Σ}}\frac{1}{2n-1}sin\[(2n-1)\mathrm{\ω}t\]\·V_i\·cos\[\mathrm{\ω}(t-\mathrm{\τ})+\mathrm{\θ}\]dt---\left(5\right)$

$R_{Sig\·{\mathrm{Ref}}_2}\left(\mathrm{\τ}\right)=\frac{1}{T}\underset{0}{\overset{T}{\∫}}\frac{4V_r}{\mathrm{\π}}\·\underset{n=1}{\overset{\mathrm{\∞}}{\Σ}}\frac{1}{2n-1}sin\[(2n-1)\·\mathrm{\ω}t\]\·V_i\·sin\[\mathrm{\ω}\·(t-\mathrm{\τ})+\mathrm{\θ}\]dt---\left(6\right)$

$R_{Sig\·{\mathrm{Ref}}_1}\left(\mathrm{\τ}\right)=\underset{T\→\mathrm{\∞}}{\lim }\frac{1}{T}\underset{0}{\overset{T}{\∫}}\frac{4V_r}{\mathrm{\π}}\·sin\left(\mathrm{\ω}t\right)\·V_i\·cos\[\mathrm{\ω}(t-\mathrm{\τ})+\mathrm{\θ}\]dt\≈\frac{2\·V_i\·V_r}{\mathrm{\π}}sin\mathrm{\θ}---\left(7\right)$

$R_{Sig\·{\mathrm{Ref}}_2}\left(\mathrm{\τ}\right)=\underset{T\→\mathrm{\∞}}{\lim }\frac{1}{T}\underset{0}{\overset{T}{\∫}}\frac{4V_r}{\mathrm{\π}}\·\sin \left(\mathrm{\ω}t\right)\·V_i\·\sin \[\mathrm{\ω}\·\left(t-\mathrm{\τ}\right)+\mathrm{\θ}\]dt\≈\frac{2\·V_i\·V_r}{\mathrm{\π}}\cos \mathrm{\θ}---\left(8\right)$

$U_{out}=\sqrt{{\left(\frac{2\·V_i\·V_r}{\mathrm{\π}}\sin \mathrm{\θ}\right)}^2+{\left(\frac{2\·V_i\·V_r}{\mathrm{\π}}\cos \mathrm{\θ}\right)}^2}=\frac{2\·V_i\·V_r}{\mathrm{\π}}---\left(9\right)$

In formula, represent that measured signal and modulation signal 1 carry out the result of modulating, represent that measured signal and modulation signal 2 carry out the result of modulating, T represents integral time, U _outrepresent the amplitude of measured signal;

4) refer step 3, obtains reflected light signal and incident optical signal, carries out related data matching, obtain thin-walled closed glass chamber optical parameter, i.e. wall thickness and refractive index, specifically such as formula shown in (10):

$\frac{I_R}{I_{in}}=1-\frac{I_t}{I_{in}}=1-\frac{{(1-R_0)}^2}{1-2R_0*cos(\frac{2\mathrm{\π}}{\mathrm{\λ}}*(\frac{2nd}{cos\mathrm{\β}}-2dtan\mathrm{\β}sin\mathrm{\α}\left)\right)+R_0^2}---\left(10\right)$

In formula, I _inrepresent the light intensity of incident laser, I _rrepresent the light intensity of reflects laser, I _trepresent the light intensity of transmission laser, R ₀represent the reflectivity measuring sample surfaces, λ represents the wavelength of laser instrument, and n represents the refractive index of testing sample, and d represents the physical thickness of testing sample, and α represents the incident angle of laser, and β represents the emergence angle of laser.