The full tensor gradiometry method and gravity gradiometer to be suspended based on luminous power
Technical field
The present invention relates to test device more particularly to a kind of full tensor gradiometry methods to be suspended based on luminous power
And gravity gradiometer.
Background technique
Gravitational field is the geophysics basic field for reflecting interior material structure and its transition, gravity gradient characterization
It is the change rate of acceleration of gravity in a certain direction in unit distance, unit s-2(conventional unit E, 1E=10-9s-2), it
Gravity anomaly caused by earth interior variable density is reflected, there is force of gravity to measure more higher leveled resolution ratio, and more applicable
In motion platform.Based on these advantages, gradiometry all has in fields such as geodesic survey, resource exploration, gravity navigations
Extremely important application.
Gravity gradient is gravitational acceleration vectorOn cartesian coordinate system x, tri- directions y, z
Derivative, these derivatives constitute gravity gradient tensor matrix, as shown in formula (1):
Gravity gradient tensor matrix T is symmetrical matrix, meets Txy=Tyx,Tyz=Tzy,Tzx=Txz, and three along axis gravity
Gradient meets Txx+Tyy+Tzz=0, therefore gravity gradient only has 5 isolated components.Full tensor gravity gradiometer is to survey simultaneously
The instrument of all 5 independent gravity gradient tensors is measured, research is deep to be paid attention to by domestic and international scientific research personnel.
Currently, the full tensor gravity gradiometer of international mature is rotating accelerometer gravity gradiometer, basic principle
As shown in Fig. 1,4 accelerometers are symmetrically distributed on disk, the sensitive direction of accelerometer along disk tangential direction,
It rotates disk with certain angular speed, acquires the output signal of accelerometer a1-a4, make signal and the acceleration of acceleration a1
The signal of degree meter a2 is added, and the signal of accelerometer a3 is added with the signal of accelerometer a4, then the two is subtracted each other, to obtain
Obtain 3 signals containing gravity gradient information.12 accelerometers are installed using three orthogonal turntables, make turntable with
Identical angular speed rotation, using same signal acquisition method, can obtain 9 signals containing gravity gradient element, lead to
5 independent gravity gradient tensors can be calculated by crossing mathematical method.
Rotating accelerometer gravity gradiometer can be carried out the full Tensor measuring of gravity gradient, but it needs measurement accuracy pole
High accelerometer exists simultaneously accelerometer installation direction error, between accelerometer nonlinearity erron, accelerometer
Scale factor is inconsistent and each sensitive axes not strict orthogonal and the error etc. that generates.
Summary of the invention
For overcome the deficiencies in the prior art, the present invention provides a kind of full tensor gravity gradients to be suspended based on luminous power
Measurement method and gravity gradiometer.
A kind of full tensor gradiometry method to be suspended based on luminous power, it is quick using three microballoon luminous powers three axis of suspension
Sense unit is respectively placed in 3 points of solid space, not collinearly, measures respectively at 3 points by microballoon luminous power three axis sensing units of suspension
Then the acceleration of gravity at place obtains gravity gradient whole tensor using differential principle.
The method, using three structures, three axis sensing units of identical microballoon luminous power suspension, space coordinate is respectively
(0, d, 0) on (d, 0,0), Y-axis, (0,0, d) on Z axis in X-axis;It is surveyed by microballoon luminous power three axis sensing units of suspension
Obtain the acceleration of gravity (g at (d, 0,0)1x,g1y,g1z), measure the acceleration of gravity (g at (0, d, 0)2x,g2y,g2z), it surveys
Obtain the acceleration of gravity (g at (0,0, d)3x,g3y,g3z),
The gravity gradient that respective direction is acquired using differential principle, its calculation formula is:
Wherein, TxxFor gxChange rate along the x-axis direction, TyyFor gyChange rate along the y-axis direction, TzzFor gzAlong the z-axis direction
Change rate;TxyFor gyChange rate along the x-axis direction, TyxFor gxChange rate along the y-axis direction, TxzFor gzChange along the x-axis direction
Rate, TzxFor gxChange rate along the x-axis direction, TyzFor gzChange rate along the y-axis direction, TzyFor gyVariation along the z-axis direction
Rate.
The microballoon luminous power three axis sensing units of suspension are detected including sensitive microballoon suspending module, sensitive microballoon displacement
Module, wherein sensitive microballoon suspending module realizes the suspension of sensitive microballoon using luminous power effect, sensitive microballoon is displaced detecting module
It realizes that the three-shaft displacement of sensitive microballoon detects using intensity balancing detection principle, the rigidity of luminous power floating unit is recycled to resolve
Three axis acceleration of gravity out.
A kind of full tensor gravity gradiometer to be suspended based on luminous power using the method, including three structures are identical
Microballoon luminous power suspend three axis sensing units, space coordinate is respectively (d, 0,0) in X-axis, (0, d, 0) in Y-axis, on Z axis
(0,0, d);
Wherein it is placed in the microballoon luminous power three axis sensing units of suspension of (0,0, d) on Z axis, including suspension light beam
Laser, acousto-optic modulator, the first beam splitter, the first condenser lens, light power meter, dichroscope, the first reflecting mirror, second
Condenser lens, detection light beam laser, the second reflecting mirror, sensitive microballoon, the first band pass filter, the second beam splitter, the first D
Type mirror, third reflecting mirror, Z axis balanced detector;
The suspension laser that suspension light beam laser issues horizontally to the right is divided into after acousto-optic modulator by the first beam splitter
Suspension light beam horizontally to the right and power reference beam straight up, wherein power reference beam passes through the first condenser lens
Laggard optical power meter, it is rear to modulate acousto-optic modulator by power measurements, keep suspension light beam power to stablize, suspension light
Beam transmits after dichroscope and the first reflecting mirror straight up respectively, using after the second condenser lens with sensitive microballoon
Interaction makes sensitive microballoon suspend;
Detection light beam laser issues respectively to be detected light straight down and detects light straight up, wherein visiting straight down
It surveys light beam and is total to road transmission with suspension light beam after dichroscope reflects;
Dichroscope is selected according to the wavelength of suspension light beam and detection light beam, and suspension light beam can be made to be transmitted through, make to detect
Light beam is reflected into be transmitted horizontally to the right;
Detection light straight up becomes transmitting horizontally to the right after the second reflecting mirror, behind sensitive microballoon region
It is transmitted through the first band pass filter, then becomes after the second beam splitter Z axis detection light beam horizontally to the right and straight up
X-axis detects optical path, and wherein Z axis detection light beam passes through respectively enters Z axis after the reflection of the first D type mirror and third reflecting mirror and balance
Two sensing points of detector obtain sensitive microballoon in the displacement of Z-direction by photoelectric conversion and signal differential, then bring Z into
The rigidity of axis direction can acquire corresponding acceleration of gravity.
Beneficial effects of the present invention:
The present invention using be placed in 3 points of solid space three microballoon luminous powers suspend three axis sensing units measure at 3 points
Acceleration of gravity three axis components, then obtain the full tensor of gravity gradient using differential principle.Due to microballoon luminous power suspension three
Axis sensing unit can reach 10-14N/ μm of magnitude rigidity, acceleration of gravity measurement sensitivity pass through difference up to 100 μm/g
Divide the high-sensitivity measurement that gravity gradient may be implemented, simultaneously because three axis sensing units of single microballoon luminous power suspension can be real
The three-axis measurement of existing acceleration of gravity, can effectively reduce the integrated difficulty of full tensor gravity gradiometer.
Detailed description of the invention
Fig. 1 is the rotating accelerometer gravity gradiometer schematic illustration of the prior art;
Fig. 2 is stress analysis schematic diagram of the sensitive microballoon in Gaussian beam;(a) production principle of scattering force, it is (b) terraced
Spend the production principle of power;
Fig. 3 is sensitive microballoon gradient force production principle schematic diagram in Gaussian beam;(a) optical gradient forces are assembled and generates original
Reason (b) dissipates optical gradient forces production principle;
Fig. 4 is the structural schematic diagram of three axis sensing units of microballoon luminous power suspension in the present invention;
Wherein, suspension light beam laser 1, acousto-optic modulator 2, the first beam splitter 3, the first condenser lens 4, light power meter
5, dichroscope 6, the first reflecting mirror 7, the second condenser lens 8, detection light beam laser 9, the second reflecting mirror 10, sensitive microballoon
11, the first band pass filter 12, the second beam splitter 13, the first D type mirror 14, third reflecting mirror 15, tertiary focusing lens 16,
Four condenser lenses 17, Z axis balanced detector 18, the 2nd D type mirror 19, the 4th reflecting mirror 20, the 5th condenser lens the 21, the 6th are poly-
Focus lens 22, X-axis balanced detector 23, the second band pass filter 24, the 3rd D type mirror 25, the 5th reflecting mirror the 26, the 7th focus
Lens 27, the 8th condenser lens 28, Y-axis balanced detector 29, suspension light beam 100, modulated suspension light beam 101, power ginseng
Light beam 102 is examined, light beam 103 is detected straight down, detects light beam 104, Z axis detection light beam 105, X-axis detection light straight up
Beam 106, Z axis D type mirror the reflected beams 107, Z axis balanced reference light beam 108, X-axis D type mirror the reflected beams 109, X-axis balanced reference
Light beam 110, Y-axis detect light beam 111, Y-axis D type mirror the reflected beams 112, Y-axis balanced reference light beam 113;
Fig. 5 is the full tensor gravity gradiometer schematic illustration of the invention to be suspended based on luminous power;
Wherein, three axis sensing unit A1 of X-direction microballoon luminous power suspension, Y direction microballoon luminous power three axis of suspension are sensitive single
First A2, three axis sensing unit A3 of Z-direction microballoon luminous power suspension.
Specific embodiment
To keep the principle of the present invention, purposes, technical schemes and advantages more clear, below with reference to specific embodiment party
Formula and referring to attached drawing, invention is further described in detail.
Light beam is the photon stream that the existing quality of a group has momentum again, when illumination is mapped to body surface and object interaction
When, the momentum change of photon generates the effect of power to irradiated object, can be divided into two parts:Reflect the scattering force and folding generated
Penetrate the gradient force of generation.
As shown in Fig. 2 (a), Gaussian beam, which is irradiated on microballoon, to be reflected, incident beamBecome after bead reflects
The reflected beamsIt is poor to produce momentum, this momentum is passed to microballoon by photon.Microballoon just receives a scattering forceAssuming that bead is located at the center of Gaussian beam, in the other side by an an equal amount of powerThe conjunction of the two power
Power along light transmission direction, i.e., because the scattering force that is subject in Gaussian beam of reflection microballoon is always along the transmission direction of light
's.
As shown in Fig. 2 (b), using the above method, the principle that refraction generates gradient force can analyze, unlike, gradient
The direction of power and the transmission direction of light are unrelated.Assuming that the light intensity in left side is greater than the light intensity on right side, then the gradient that left side particle is subject to
PowerIt will be greater than the gradient force that right side particle is subject toThat is the direction of resultant force will be skewed towards on the left of particle.
In order to preferably explain gradient force resultant direction, following two situation is introduced as a comparison, as shown in figure 3, from figure
In can obtain, for converging light, the direction of the gradient force that bead is subject to along light transmission direction, for diverging light
Speech, the direction for the gradient force that bead is subject to and the transmission direction of light are opposite.It is obtained in conjunction with two kinds of situations above, gradient force
Direction always points at the big place of light intensity in light beam.
It, will be micro- based on above-mentioned analysis it is found that the interaction of Gaussian beam and microballoon, can form an optical trap
Grain stablizes the potential well center that is strapped in, that is, realizes the suspension of microballoon.
Based on luminous power levitation effect, the invention proposes a kind of full tensor gradiometry sides to be suspended based on luminous power
Method is respectively placed at 3 points of solid space using three microballoon luminous powers three axis sensing units of suspension, and not conllinear (i.e. 3 points do not exist
On straight line), the acceleration of gravity at 3 points is measured respectively by microballoon luminous power three axis sensing units of suspension, is then utilized
Differential principle obtains gravity gradient whole tensor.
The microballoon luminous power three axis sensing units of suspension are detected including sensitive microballoon suspending module, sensitive microballoon displacement
Module, wherein sensitive microballoon suspending module realizes the suspension of sensitive microballoon using luminous power effect, sensitive microballoon is displaced detecting module
It realizes that the three-shaft displacement of sensitive microballoon detects using intensity balancing detection principle, the rigidity of luminous power floating unit is recycled to resolve
Three axis acceleration of gravity out.
Microballoon luminous power three axis sensing units of suspension, structure are as shown in Figure 4.Entire sensing unit includes suspension beam laser
Device 1, acousto-optic modulator 2, the first beam splitter 3, the first condenser lens 4, light power meter 5, dichroscope 6, the first reflecting mirror 7,
Two condenser lenses 8, detection light beam laser 9, the second reflecting mirror 10, sensitive microballoon 11,12, second points of the first band pass filter
Beam device 13, the first D type mirror 14, third reflecting mirror 15, tertiary focusing lens 16, the 4th condenser lens 17, Z axis balanced detector
18, the 2nd D type mirror 19, the 4th reflecting mirror 20, the 5th condenser lens 21, the 6th condenser lens 22, X-axis balanced detector 23,
Two band pass filters 24, the 3rd D type mirror 25, the 5th reflecting mirror 26, the 7th condenser lens 27, the 8th condenser lens 28, Y-axis are flat
Weigh detector 29.
Suspension light beam laser 1 issues suspension light beam 100 (its typical wavelengths value is 1064nm) horizontally to the right and passes through sound
Power for modulated suspension light beam 101 horizontally to the right and straight up is divided to join by the first beam splitter 3 after optical modulator 2
Examine light beam 102, wherein power reference beam 102 pass through the laggard optical power meter 5 of the first condenser lens 4, after pass through power test
As a result acousto-optic modulator 2 is modulated, modulated 101 power stability of suspension light beam is kept.Suspension light beam 101 respectively by two to
It transmits after Look mirror 6 and the first reflecting mirror 7, interacts using after the second condenser lens 8 with sensitive microballoon 11 straight up,
Make its suspension, rear reach is blocked at the second band pass filter 24.
Detection light beam laser 9 issues respectively detects light beam 103 and straight up detection (its allusion quotation of light beam 104 straight down
Type wavelength be 532nm), wherein straight down detection light beam 103 by dichroscope 6 reflection after with modulated suspension light beam
101 road transmission altogether, reach at the second band pass filter 24 behind sensitive microballoon region, transmit through the second band pass filter 24
After become Y-axis detection light beam 111, part of light by the 3rd D type mirror 25 reflect after become 112 water of Y-axis D type mirror the reflected beams
It is flat to transmit to the left, it is converged at a sensing point of Y spindle balance detector 29 by the 7th condenser lens 27, Y-axis detects light beam
111 another part light is become after being reflected by the 5th reflecting mirror 26, and Y-axis balanced reference light beam 113 is horizontal to be transmitted to the left, by the
Eight condenser lenses 28 converge at another sensing point of Y spindle balance detector 29.
In test process, the acceleration of gravity of the Y direction suffered by the sensitive microballoon 11 increases, and bead is to Y-axis positive direction
It is mobile, it will lead to the increase of 112 light intensity of Y-axis D type mirror the reflected beams, the light intensity of Y-axis balanced reference light beam 113 reduces, subsequent process
Y-axis balanced detector 29 carries out photoelectric conversion and signal differential, can obtain sensitive microballoon 11 in the displacement of Y direction, then band
The rigidity for entering Y direction can acquire the acceleration of gravity of Y direction at sensitive microballoon 11.
Dichroscope 6 is selected according to the wavelength of suspension light beam and detection light beam, can make modulated suspension light beam 101 thoroughly
It penetrates and passes through, make to detect light beam 103 straight down to be reflected into and transmit horizontally to the right.
Second band pass filter 24 is selected according to the wavelength of suspension light and detection light, it transmits Y-axis detection light beam 111
Pass through, stops suspension light, influence of the isolation suspension light for microballoon displacement detection.
Detection light 104 straight up becomes transmitting horizontally to the right after the second reflecting mirror 10, by sensitive microballoon area
It is transmitted through the first band pass filter 12 behind domain, then becomes Z axis detection light beam 105 horizontally to the right after the second beam splitter 13
X-axis straight up detects light beam 106, and wherein Z axis detection 105 part light of light beam is become Z after the reflection of the first D type mirror 14
Axis D type mirror the reflected beams 107 are transmitted straight down, converge at one of Z axis balanced detector 18 by tertiary focusing lens 16
At sensing point, another part light of Z axis detection light beam 105 becomes Z axis balanced reference light beam after being reflected by third reflecting mirror 15
108 transmit straight down, converge at another sensing point of Z axis balanced detector 18 by the 4th condenser lens 17.
In test process, the acceleration of gravity of the Z-direction suffered by the sensitive microballoon 11 increases, and bead is to Z axis positive direction
It is mobile, it will lead to the reduction of 107 light intensity of Z axis D type mirror the reflected beams, the light intensity of Z axis balanced reference light beam 108 increases, subsequent process
Z axis balanced detector 18 carries out photoelectric conversion and signal differential, can obtain sensitive microballoon 11 in the displacement of Z-direction, then band
The rigidity for entering Z-direction can acquire the acceleration of gravity of Z-direction at sensitive microballoon 11.
X-axis detection 106 part light of light beam straight up is become X-axis D type mirror reflected light after the reflection of the 2nd D type mirror 19
Beam 109 transmits horizontally to the right, converges at a sensing point of X-axis balanced detector 23 by the 5th condenser lens 21, X-axis
Another part light for detecting light beam 106 is become X-axis balanced reference light beam 110 after the reflection of the 4th reflecting mirror 20 and is passed horizontally to the right
It is defeated, it is converged at another sensing point of X-axis balanced detector 23 by the 6th condenser lens 22.
In test process, the acceleration of gravity of the X-direction suffered by the sensitive microballoon 11 increases, and bead is to X-axis positive direction
It is mobile, it will lead to the reduction of 109 light intensity of X-axis D type mirror the reflected beams, the light intensity of X-axis balanced reference light beam 110 increases, subsequent process
X-axis balanced detector 23 carries out photoelectric conversion and signal differential, can obtain sensitive microballoon 11 in the displacement of X-direction, then band
The rigidity for entering X-direction can acquire the acceleration of gravity of X-direction at sensitive microballoon 11.
First band pass filter 12 is selected according to the wavelength of suspension light and detection light, it makes Z axis detection light beam 105 and X-axis
Detection light beam 106 is transmitted through, and stops suspension light, influence of the isolation suspension light for microballoon displacement detection.
As shown in figure 5, the present invention is based on luminous power suspend full tensor gravity gradiometer include space coordinate be (d, 0,0)
X-direction microballoon luminous power suspend three axis sensing unit A1, space coordinate be (0, d, 0) Y axis direction microballoon luminous power suspend three
Axis sensing unit A2, space coordinate are the three axis sensing unit A3 of Z-direction microballoon luminous power suspension of (0,0, d).
Wherein three axis sensing unit A1 of X-direction microballoon luminous power suspension can measure the acceleration of gravity (g at (d, 0,0)1x,
g1y,g1z), corresponding Y direction microballoon luminous power three axis sensing unit A2 of suspension and Z-direction microballoon luminous power three axis of suspension are sensitive
Unit A3 can measure the acceleration of gravity (g of corresponding test point2x,g2y,g2z) and (g3x,g3y,g3z), utilize differential principle
The gravity gradient for acquiring respective direction, its calculation formula is:
Using formula (2), it is poor that three microballoon luminous powers, the three axis sensing units of suspension placed according to one fixed spacing of space carry out
Divide and calculates the full tensor test for realizing gravity gradient.