CN107664648B - A kind of X-ray differential phase contrast microscopic system and its two-dimensional imaging method - Google Patents

A kind of X-ray differential phase contrast microscopic system and its two-dimensional imaging method Download PDF

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CN107664648B
CN107664648B CN201610617865.1A CN201610617865A CN107664648B CN 107664648 B CN107664648 B CN 107664648B CN 201610617865 A CN201610617865 A CN 201610617865A CN 107664648 B CN107664648 B CN 107664648B
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grating
image
ray
angle signal
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CN107664648A (en
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朱佩平
张凯
袁清习
黄万霞
朱中柱
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Jinan Hanjiang Photoelectric Technology Co ltd
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Institute of High Energy Physics of CAS
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Abstract

The invention discloses a kind of X-ray differential phase contrast microscopic system and its two-dimensional imaging method, the X-ray differential phase contrast microscopic system includes: the light source for generating X-ray；And condenser, central stop, beam-splitting optical grating, pin hole, sample stage, object lens, annular analysis grating and the imaging detector set gradually along x-ray spread direction.The beneficial effects of the present invention are: the X-ray differential phase contrast microscopic system, only increases beam-splitting optical grating and annular analysis grating in traditional X-ray microscope, can be achieved with phase contrast quantitative imaging, have the advantages that structure is simple, easy to spread.In addition, X-ray source, condenser, beam-splitting optical grating can be integrated into an X-ray ring-shaped gate source element, then entire X-ray differential phase contrast microscopic system length can further shorten, the manufacturing cost of X-ray microscope system can be not only reduced, but also the utilization efficiency of light also can be further improved.

Description

A kind of X-ray differential phase contrast microscopic system and its two-dimensional imaging method
Technical field
The present invention relates to nano-resolution X-ray microscope technical field of imaging more particularly to X-ray differential phase contrast are aobvious Micromirror systems and its two-dimensional imaging method.
Background technique
Substance can represent the effect of X-ray with refractive index, and n=1- δ+i β, wherein δ is refractive index real part attenuation rate, β It is Absorption Terms.The physical significance of δ is to produce by the X-ray of unit length substance relative to the X-ray Jing Guo unit length vacuum Raw corrugated is mobile；The physical significance of β is the decreased amplitude generated by the X-ray of unit length substance.According to the object of δ and β Meaning is managed, X-ray can be obtained after a sample, complex amplitude can be expressed asWherein
For the variable quantity by the opposite X-ray phase for passing through equal length vacuum of the X-ray phase of sample, abbreviation phase It moves, l is the path that X-ray passes through sample；Because the integrated value outside sample is zero, the bound of integral be can extend to It is infinite；
To absorb, μ is linear absorption coefficient.Since more than big three magnitudes of δ ratio β of hard X ray wave band light element, institute It is possible to generate the light intensity signal more much bigger than Change of absorption with phase change.Dutch scientist Ze Nike (Zernik) is phase Contrast imaging it is the first.Early in nineteen thirty-five, he just proposes the microscopical theory and method of phase contrast in visible light wave range, He has won the Nobel Prize in physics of nineteen fifty-three thus.People are successfully by Ze Nike phase contrast microscope side at present Method is generalized to the X-ray microscope using zone plate as object lens, succeeds in developing the X-ray phase that phase contrast is obtained using phase shift ring Position contrast microscope, as shown in Figure 1, the microscope according to x-ray spread direction successively include X-ray source 10, condenser 1, Central stop 2, pin hole 3, sample stage 4, object lens 5, phase shift ring 6 and imaging detector 7.However, the phase contrast of Ze Nike invention There are clearly disadvantageous for imaging: its application range is confined to absorb negligible weak phase samples.When absorbing cannot ignore, It cannot distinguish between Intensity response caused by absorbing the Intensity response generated and phase shift；When sample is not weak phase object, special sample When the phase shift of product is more than π/4, the relationship of phase shift and Intensity response no longer meets linear relationship, and Intensity response will be with phase cycling Generate oscillation.These deficiencies are that quantitative study sample rate structure brings difficulty.
Summary of the invention
An object of the present invention provides one kind and is capable of the high sensitivity of quantitative study sample rate structure in conventional suction The X-ray differential phase contrast microscopic system of X-ray microscope.
The second object of the present invention provides a kind of X-ray differential phase contrast microscope system for the high sensitivity The two-dimensional imaging method of system.
According to an aspect of the present invention, a kind of X-ray differential phase contrast microscopic system is disclosed, may include: For generating the light source of X-ray；And condenser, central stop, beam-splitting optical grating, the needle set gradually along x-ray spread direction Hole, sample stage, object lens, annular analysis grating and imaging detector；Wherein, the light source for generating X-ray is homogeneous X-ray light Source；The condenser is ellipsoid capillary, tapered capillaries, zone plate or other X-ray optics members with focusing function Part, for generating the focus on light beam of illumination sample；The central stop is located at condenser export center position, comes from for stopping The straight-through light of X-ray source forms the hollow cone light beam of illumination sample；The beam-splitting optical grating is the absorption for being micron dimension the period Grating, after the central stop of condenser outlet, for dividing the hollow cone light beam from condenser and central stop Beam becomes the hollow cone light beam with space periodic structure；The pin hole after being located at beam-splitting optical grating, comes from X for stopping The straight-through light and stray light of ray source；The sample stage is located at object plane, for carrying sample, and can translate and rotate sample； The object lens are zone plate or other optical elements with X-ray lens imaging function, for having positioned at object plane The sample structure of nanometer scale is enlarged into the picture in image planes with micron dimension structure, and shines beam-splitting optical grating by hollow cone light beam Bright annular section is formed about circular grating picture and circular grating as light beam in object lens back focal plane；The annular analyzes grating Period is the absorption grating of micron or sub-micrometer scale, is located near object lens back focal plane, shape and size and the beam splitting Circular grating of the grating near object lens back focal plane is as identical, for the circular grating to the object lens back focal plane attachment as light beam It is filtered；The imaging detector is located at image planes, for shooting the two-dimentional intensified image of sample.
Optionally, the material of the beam-splitting optical grating and the annular analysis grating is gold or other heavy metals.
Optionally, in the case where the beam-splitting optical grating and the little annular analysis grating thickness, the thickness of beam-splitting optical grating Degree is the odd-multiple of π phase shift, the even-multiple with a thickness of π phase shift of annular analysis grating.
According to another aspect of the present invention, it discloses a kind of for the X-ray differential phase contrast microscopic system Two-dimensional imaging method includes the following steps:
S1 is opened and is adjusted light source: the X-ray beam alignment condenser for generating the light source；
S2, adjustment condenser, central stop and pin hole: the hollow cone beam alignment institute for generating condenser and central stop It states and carries sample position on sample stage, central stop and pin hole is made to stop straight-through light and stray light from the X-ray source；
S3 adjusts object lens: object lens being made to focus the imaging detector that the imaging beam to be formed alignment is located at image planes；
S4, feed-in beam-splitting optical grating: after the central stop of condenser outlet, feed-in beam-splitting optical grating shines hollow cone light beam The annular section of bright beam-splitting optical grating is formed about circular grating picture and circular grating as light beam in object lens back focal plane；
S5, feed-in and adjustment ring conformal analysis grating: make annular analysis grating alignment beam-splitting optical grating near object lens back focal plane The circular grating picture of formation, adjustment ring conformal analysis grating grizzly bar direction make annular analysis grating grizzly bar be parallel to beam-splitting optical grating grid Item；
Measuring angle signal response curve: S6 gradually moves beam-splitting optical grating along perpendicular to optical axis and grating grizzly bar direction, makes The circular grating of beam-splitting optical grating as opposed annular analysis grating occur shear displacemant, with imaging detector image planes measure brightness with The angle signal response curve of circular grating image displacement variation；
S7, be fitted angle signal response curve with cosine curve: angle signal response curve is similar to cosine curve, with remaining Chord curve is fitted the angle signal response curve measured, it is made to obtain the Analytical Expression of cosine curve；
S8 shoots sample two dimension intensified image: the circular grating picture of beam-splitting optical grating being separately fixed at the angle signal and is rung Paddy position, the upward slope position, peak position, descending position for answering curve, place sample on sample stage, shoot the paddy position intensified image of sample, go up a slope Intensified image, peak position intensified image, descending intensified image；
S9 extracts sample in the quantitative two-dimensional image of object space: putting from the paddy position intensified image of sample, upward slope intensified image, peak position Sample is extracted in big picture, descending intensified image in the absorption picture of object space, dioptric image and scattering picture；From any in four kinds of intensified images Sample is extracted in three kinds of intensified images in the absorption picture of object space, dioptric image and scattering picture.
In the step S6, it is contemplated that sample influences the refraction of depth of focus light pencil and scattering, that is, considers sample Influence of the angle signal of generation to imaging process, therefore sample angle signal function f (xo,yo,ψx) be expressed as
Wherein (xo,yo,zo) it is space coordinate at sample, M (xo,yo)、θx(xo,yo) andRespectively sample The sample absorb, required in refraction angle and scattering angular variance and the imaging of X-ray differential phase contrast microscope two-dimensional quantitative exists The absorption picture of object space, dioptric image and scattering picture, their expression formula are
Wherein (xo,yo,zo) it is space coordinate at object plane, μ is linear absorption coefficient, and δ is refractive index real part attenuation rate, ωx It is perpendicular to the linear scattering coefficient in grating grizzly bar direction.
What is measured in the step S6 is angle signal response curve, is with fitting cosine curve Analytical Expression
Or it is expressed as
Wherein η is object lens diffraction efficiency, B0For incident beam brightness, x at object planepPosition coordinates at grating are analyzed for annular,Angular displacement for circular grating image displacement with respect to object plane, doObject distance for sample with respect to object lens, p are annular analysis light The period of grid,For angle signal response curve average value, RmaxAnd RminRespectively angle signal response curve Maximum value and minimum value,For the visibility of angle signal response curve, n is modulation parameter, n=0,1, 2,3 respectively correspond paddy position response curve, upward slope response curve, peak position response curve and descending response curve.
In the step S8, the two-dimentional intensified image of imaging detector shooting is described with angle signal imaging equation, angle Image formation equation is the convolution of angle signal function and angle signal receptance function, expression formula are as follows:
Wherein (xo,yo) it is object plane coordinate, (xi,yi) it is image coordinates, η is object lens diffraction efficiency, B0It is incident at object plane Beam brightness, n=0,1,2,3 respectively corresponds paddy position amplification imaging equation, the amplification imaging equation that goes up a slope, peak position amplification imaging equation Amplify imaging equation with descending.
It is described that the circular grating picture of beam-splitting optical grating is fixed on angle signal response curve paddy in the step S8 Sample is placed in position on sample stage, and imaging detector takes the paddy position intensified image of sample, and expression formula is
It is described that the circular grating picture of beam-splitting optical grating is fixed on angle signal response curve upward slope in the step S8 Position, places sample, imaging detector takes the upward slope intensified image of sample, and expression formula is on sample stage
It is described that the circular grating picture of beam-splitting optical grating is fixed on angle signal response curve peak in the step S8 Position, places sample, imaging detector takes the peak position intensified image of sample, and expression formula is on sample stage
It is described that the circular grating picture of beam-splitting optical grating is fixed on angle signal response curve descending in the step S8 Position, places sample, imaging detector takes the descending intensified image of sample, and expression formula is on sample stage
Due to
BV(xi,yi)+BP(xi,yi)=BU(xi,yi)+BD(xi,yi)
So three width seem independent in paddy position intensified image, upward slope intensified image, peak position intensified image, descending intensified image, wherein Any width picture can be expressed with its excess-three width picture；It is above it is various in, (xi,yi) it is image coordinates, η is the diffraction of object lens Efficiency, B0For illuminate object plane light beam brightness,For the average value of angle signal response curve, RmaxAnd RminPoint Not Wei angle signal response curve maximum value and minimum value,For the visibility of angle signal response curve, doObject distance for sample with respect to object lens, p are annular analysis screen periods.
It is described to be put from paddy position intensified image, upward slope intensified image, peak position intensified image, the descending of sample in the step S9 The big extraction sample as in is as follows in the absorption picture of object space, dioptric image and scattering image space method:
Sample, which is extracted, in the formula that object space absorbs picture is
Sample, which is extracted, in the formula of object space dioptric image is
Under the conditions of scattering negligible, extracting sample in the simplified formula of object space dioptric image is
Sample, which is extracted, in the formula that object space scatters picture is
Under the conditions of reflecting negligible, the simplified formula for extracting sample in object space scattering picture is
It is above it is various in, (xo,yo) it is object plane coordinate, (xi,yi) it is image coordinates, doObject distance for sample with respect to object lens,
As an alternative embodiment, the X-ray source, condenser and beam-splitting optical grating can integrate as a week Phase is the element in the X-ray ring-shaped gate source of micron dimension, at this time in the exit in X-ray ring-shaped gate source, successively along optical axis Two annular light holes are placed, the light beam for issuing the ring-shaped gate source forms illumination sample after two annular light holes Hollow cone light beam, and be formed about ring-shaped gate source image and ring-shaped gate source image light beam in object lens back focal plane, the annular analysis light The shape and size of grid are identical as the ring-shaped gate source image.
X-ray differential phase contrast microscopic system disclosed by the invention only increases in traditional X-ray microscope and divides Beam grating and annular analysis grating, can be achieved with phase contrast quantitative imaging, have the advantages that structure is simple, easy to spread.Separately Outside, X-ray source, condenser, beam-splitting optical grating can be integrated into an X-ray ring-shaped gate source element, and gone out in ring-shaped gate source Opening's edge optical axis direction successively disposes two annular light holes, then entire X-ray differential phase contrast microscopic system length can be with Further shorten, can not only reduce the manufacturing cost of X-ray microscope system, but also the utilization efficiency of light also can be mentioned further Height has broad application prospects.
Detailed description of the invention
It should be appreciated that identical appended drawing reference indicates identical or corresponding component and feature in following all attached drawings.
Fig. 1 is the light path schematic diagram of X-ray phase contrast microscopic system in the prior art.
Fig. 2 is the schematic diagram according to the X-ray differential phase contrast microscopic system of one embodiment of the invention.
Fig. 3 is the two-dimensional imaging method according to the X-ray differential phase contrast microscopic system of one embodiment of the invention Flow diagram.
Fig. 4 is the refraction angle image formation according to the X-ray differential phase contrast microscopic system of the embodiment of the present invention Schematic diagram.
Fig. 5 is the angle of scattering image formation according to the X-ray differential phase contrast microscopic system of the embodiment of the present invention Schematic diagram.
Fig. 6 is four kinds of angle signal receptance function curve graphs of X-ray differential phase contrast microscopic system.
Fig. 7 is the X ray differential phase microscopic system based on ring-shaped gate source according to another embodiment of the present invention Schematic diagram.
Each appended drawing reference is simply described as follows in attached drawing:
1: condenser
2: central stop
3: pin hole
4: sample stage
5: object lens
6: phase shift ring
7: imaging detector
3 ': beam-splitting optical grating
6 ': annular analysis grating
10:X ray source
10 ': X-ray ring-shaped gate source
20: first annular light hole
30: the second annular light holes.
Specific embodiment
With reference to the accompanying drawing to the X-ray differential phase contrast microscopic system of embodiment disclosed by the invention and for being somebody's turn to do The two-dimensional imaging method of system is described in detail.
Fig. 2 is the schematic diagram according to the X-ray differential phase contrast microscopic system of one embodiment of the invention.Such as Fig. 2 Shown, X-ray differential phase contrast microscopic system 100 successively includes X-ray source 10 (in figure according to x-ray spread direction Be not drawn into), condenser 1, central stop 2, beam-splitting optical grating 3 ', pin hole 3, sample stage 4, object lens 5, annular analysis grating 6 ' and imaging Detector 7 is constituted.Property, the structure and function of each element are described below respectively:
X-ray source 10:X ray object lens usually have the diffraction optical element of lens imaging function, such as zone plate, So X-ray source 10 used in X-ray differential phase contrast microscopic system can be homogeneous X-ray light source, as electronics is hit Hit characteristic spectral line X-ray source, the laser plasma X-ray source, synchrotron radiation homogeneous X-ray light source of metallic target generation.
Condenser 1: can be ellipsoid capillary, tapered capillaries, zone plate or other X-rays with focusing function Optical element, effect is to provide focused subbeams for sample.
Central stop 2: being located at 1 export center part of condenser, too strong straight from the X-ray source for stopping Light passing illuminates sample and detector, and the focus on light beam for illuminating sample is made to become hollow cone light beam.
Beam-splitting optical grating 3 ': can be the absorption grating that the period is micron dimension, the central stop 2 exported positioned at condenser 1 Afterwards, it for being split to the hollow cone light beam from condenser 1 and central stop 2, becomes with space periodic structure Hollow cone light beam.
Pin hole 3: being located at beam-splitting optical grating 3 ' afterwards before sample stage, too strong leads directly to for stops from the X-ray source Light and stray light illumination sample and detector.
Sample stage 4: it between pin hole 3 and object lens 5, hangs down for carrying sample, translation and rotation sample, position Directly it is known as object plane in the plane of optical axis.
Object lens 5: can be the optical element with X-ray lens imaging function, such as zone plate, be a block period with half Diameter increases gradually smaller circular grating, has lens function, therefore referred to as X-ray lens to homogeneous X-ray；Its effect has Two, first effect is that object plane is located at there is the sample structure amplification of nanometer scale to image in image planes, and being formed has micron The picture of scale structure, second effect is after imaging in object lens 5 by the annular section of hollow cone beam lighting on beam-splitting optical grating Focal plane is formed about circular grating picture and circular grating as light beam.
Annular analysis grating 6 ': it can be the absorption grating for being micron dimension or sub-micrometer scale in the period, be located at object lens 5 Near back focal plane, shape and size are with beam-splitting optical grating 3 ' when no sample by the annular section of hollow cone beam lighting in object lens 5 Circular grating near back focal plane as identical, for the circular grating near 5 back focal plane of object lens as light beam is filtered.
Imaging detector 7: (such as X-ray CCD) is formed by two-dimensional array pixel arrangement, each pixel has independent spy Survey light intensity function, for measurement angle signal response curve, detection light intensity spatial position change, shoot sample intensified image, Its position is known as image planes perpendicular to the plane of optical axis.
Further, although beam-splitting optical grating 3 ' and annular analysis grating 6 ' be all absorption grating, grating thickness not In the case where big, have partial x-ray across gratings strips, make across X-ray generate phase shift, in order to avoid phase shift bring is negative Face effect, the odd-multiple with a thickness of π phase shift of beam-splitting optical grating 3 ', the even-multiple with a thickness of π phase shift of annular analysis grating 6 '.
In addition, the material of beam-splitting optical grating 3 ' and annular analysis grating 6 ' is gold or other heavy metals.
The X-ray differential phase contrast microscopic system of the embodiment of the present invention is traditional X-ray microscope and beam splitting Grating 3 ' and annular analysis grating 6 ' are combined into, and on the basis of the imaging process of traditional X-ray microscope system, are increased The physical content of two aspects: first, consider that sample influences the refraction of depth of focus light pencil and scattering, i.e., consideration sample generates Influence of the angle signal to imaging process；Second, consider the circular grating picture of angle signal regulation beam-splitting optical grating of sample in ring Shear displacemant on conformal analysis grating makes angle signal obtain Intensity response.
Fig. 3 is the two-dimensional imaging method according to the X-ray differential phase contrast microscopic system of one embodiment of the invention Flow diagram, as shown in figure 3, be used for the X-ray differential phase contrast microscopic system two-dimensional imaging method, including Following steps:
S1 is opened and is adjusted light source: the X-ray beam alignment condenser for generating the light source；
S2, adjustment condenser, central stop and pin hole: the hollow cone beam alignment institute for generating condenser and central stop It states and carries sample position on sample stage, central stop and pin hole is made to stop straight-through light and stray light from the X-ray source；
S3 adjusts object lens: object lens being made to focus the imaging detector that the imaging beam to be formed alignment is located at image planes；
S4, feed-in beam-splitting optical grating: after the central stop of condenser outlet, feed-in beam-splitting optical grating shines hollow cone light beam The annular section of bright beam-splitting optical grating is formed about circular grating picture and circular grating as light beam in object lens back focal plane；
S5, feed-in and adjustment ring conformal analysis grating: make annular analysis grating alignment beam-splitting optical grating near object lens back focal plane The circular grating picture of formation, adjustment ring conformal analysis grating grizzly bar direction make annular analysis grating grizzly bar be parallel to beam-splitting optical grating grid Item；
Measuring angle signal response curve: S6 gradually moves beam-splitting optical grating along perpendicular to optical axis and grating grizzly bar direction, makes The circular grating of beam-splitting optical grating as opposed annular analysis grating occur shear displacemant, with imaging detector image planes measure brightness with The angle signal response curve of circular grating image displacement variation；Wherein, the angle signal measured in each pixel of imaging detector Response curve is essentially identical, and when measurement angle signal response curve, the light intensity signal that detector obtains is stronger, and beam-splitting optical grating is mobile Step-length is more intensive, and the data SNR measured is higher；When the circular grating picture and annular analysis grating of beam-splitting optical grating are completely coincident When, circular grating is minimum as light beam percent of pass, and entire visual field becomes dark field, extreme lower position-paddy with angle signal response curve Position is corresponding；When the circular grating picture of beam-splitting optical grating and annular analysis grating are staggered a quarter period, circular grating picture light Beam half passes through, the other half is blocked, and entire visual field becomes half bright field, corresponding with the upward slope position of angle signal response curve； When the circular grating picture of beam-splitting optical grating and annular analysis grating be staggered the half period when, circular grating as light beam percent of pass most Height, entire visual field becomes bright field, corresponding with extreme higher position-peak position of angle signal response curve；When the annular of beam-splitting optical grating Grating image and annular analysis grating be staggered 3/4ths periods when, circular grating is blocked as light beam half, the other half passes through, whole A visual field becomes half bright field, and it is corresponding to respond the shifting descending position of curve with angle signal；
S7, be fitted angle signal response curve with cosine curve: angle signal response curve is similar to cosine curve, with remaining Chord curve is fitted the angle signal response curve measured, it is made to obtain the Analytical Expression of cosine curve；Wherein, it is fitted angle signal When response curve, the light intensity signal that detector obtains is stronger, and beam-splitting optical grating moving step length is more intensive, and the data SNR measured is got over The cosine curve of height, fitting is more accurate；
S8 shoots sample two dimension intensified image: the circular grating picture of beam-splitting optical grating being separately fixed at the angle signal and is rung Paddy position, the upward slope position, peak position, descending position for answering curve, place sample on sample stage, shoot the paddy position intensified image of sample, go up a slope Intensified image, peak position intensified image, descending intensified image；
S9 extracts sample in the quantitative two-dimensional image of object space: putting from the paddy position intensified image of sample, upward slope intensified image, peak position Sample is extracted in big picture, descending intensified image in the absorption picture of object space, dioptric image and scattering picture；Because of paddy position intensified image and peak position The sum of intensified image is equal to the sum of upward slope intensified image and descending intensified image, so being there are three types of intensified image only in above-mentioned four kinds of intensified images It is independent, can be extracted from any three kinds of intensified images in four kinds of intensified images sample the absorption picture of object space, dioptric image and Scatter picture.
In the step S6 of the two-dimensional imaging method of the X-ray differential phase contrast microscopic system, sample is considered The refraction of depth of focus light pencil and scattering are influenced, i.e. the influence in view of the angle signal of sample generation to imaging process, because This, needs to establish the mathematical model that sample acts on X-ray, finds out the mathematic(al) representation of sample angle signal function, specifically Method is as described below:
Define the rectangular coordinate system (x of sampleo,yo,zo), it is a little defined in sample, in two-dimensional imaging, sample A bit (x on the object plane of placeo,yo), a not instead of two-dimensional geometry point, one with (xo,yo) centered on object cell area Δ x The size of Δ y, Δ x and Δ y are determined by the numerical aperture and detector resolution of object lens.It illustrates herein, it is cited below Object point, meaning are object cell area.
Absorbing (including inelastic scattering) is the dissipation process that an X-ray energy is converted into thermal energy in the sample, sample In a bit (xo,yo) depth of focus light pencil is absorbed, cause depth of focus light pencil brightness decay.A bit (x in sampleo,yo) to by being somebody's turn to do The absorption of the depth of focus light pencil of point can be expressed as:
WhereinIndicate Dirac function (to avoid obscuring with refractive index real part attenuation rate δ, with top tape labelTable Show Dirac function),Deflection angle vector for the depth of focus light pencil being incident on sample,
Wherein μ (xo,yo,zo) be sample linear absorption coefficient.The physical significance of formula (1) is that absorption causes the thin light of depth of focus Beam energy loss leads to depth of focus light pencil brightness reduction, but does not change the depth of focus light pencil direction of propagation, is zero degree signal.Formula (1) it is also denoted as component form:
Wherein ψxAnd ψyRespectivelyAlong xoDirection and yoThe component in direction.
Fig. 4 is the refraction angle image formation according to the X-ray differential phase contrast microscopic system of the embodiment of the present invention Schematic diagram, the arrow in partial enlarged view describe the refractive direction of depth of focus light pencil.As shown in figure 4, poly- from beam-splitting optical grating Coke can be divided into multiple depth of focus light pencils in the hollow cone light beam of sample, in object plane, each depth of focus light pencil illuminates one Object point (xo,yo), object point (xo,yo) refraction is generated to by the depth of focus light pencil of the point, cause the annular near object lens back focal plane Grating image opposed annular analysis grating is subjected to displacement, and makes to analyze grating arrival image planes picture point (x by annulari,yi) number of photons hair It is raw to increase or reduce, (xo,yo) and (xi,yi) between be conjugate imaging relationship, it is mutually unique corresponding.
Refraction is the process of a conservation of energy, according to Fig. 4, a bit (x in sampleo,yo) can to the refraction of depth of focus light pencil To be expressed as
WhereinPhysical significance for refraction angle vector, formula (4) is that refraction changes the propagation side of depth of focus light pencil To, but depth of focus light pencil energy is not lost, do not lead to depth of focus light pencil brightness reduction.Formula (4) can also be written as component form,
Wherein θx(xo,yo) and θy(xo,yo) be respectivelyIn the x-direction with the component in the direction y.Enable δ (xo,yo,zo) Representative sample refractive index real part attenuation rate, thenIn (xo,yo) weight expression of rectangular coordinate system is
Fig. 5 is the angle of scattering image formation according to the X-ray differential phase contrast microscopic system of the embodiment of the present invention Schematic diagram, arrow depicts scattering depth of focus light pencil is caused to be extended to multiple sides from a direction of propagation in partial enlarged view To.As shown in figure 5, the hollow cone light beam for focusing on sample from beam-splitting optical grating, it is thin can be divided into multiple depths of focus in object plane Light beam, each depth of focus light pencil illuminate an object point (xo,yo), object point (xo,yo) generated to by the depth of focus light pencil of the point Scattering causes the striped of the circular grating picture near object lens back focal plane fuzzy, makes to analyze grating arrival image planes picture point by annular (xi,yi) number of photons occur increase or reduce, (xo,yo) and (xi,yi) between be conjugate imaging relationship, it is mutually unique right It answers.
Scattering (herein means refraction caused by little particle inside cell area) is the process of a conservation of energy, scattering and refraction The difference is that refraction is as a whole studied a cell area on sample object plane, i.e., one on sample object plane A cell area is scattered as one piece of prism then using this cell area as one block of ground glass, studies the uneven of its inside Particle, bubble, crystallite, impurity inside property, such as cell area etc..Therefore, for each cell area, the thin light of the depth of focus of outgoing Only one refractive direction of beam but has multiple scattering directions.In other words, scattering is the process of depth of focus light pencil dispersion.Cause There is certain thickness for sample, along the depth of focus light pencil direction of propagation inside cell area, each little particle distribution is random, front and back The refraction that two little particles generate is independent from each other, and the angle that little particle reflects deviation depth of focus light pencil incident direction every time is It is random, so angle of scattering is the normal state statistical distribution centered on incidence angle according to central-limit theorem, can with variance come Scattering angular distribution range is described.
It is small inside cell area as depth of focus light pencil is walked in the sample when depth of focus light pencil injects sample according to Fig. 5 The continuous generation of particle refraction event, scattering angular variance are gradually widened.Because using the angle signal of grating acquisition sample, It is necessary to scattering angle signal is decomposed.A bit (x of sampleo,yo) (x is scattered in depth of focus light pencilo,yo) rectangular co-ordinate The weight expression of system is
WhereinWithFor (xo,yo) at point sample integral thickness respectively in xoDirection and yoIs produced from direction Raw scattering angular variance.According to formula (7) and formula (8), although beam energy is not lost in scattering, scattering causes depth of focus light pencil Angle of flare increases.It enablesThe scattering angular variance of representative sample integral thickness, subscript κ can be x or y, then It is X-ray by Δ z a series of on pathoThe scattering angular variance of thin sliceThe sum of, so sample is whole thick The scattering angular variance of degree can be expressed as the integral of scattering angular variance, it may be assumed that
Wherein ωκ(xo,yo,zo) it is perpendicular to light beam along the linear scattering coefficient in the direction κ.
Comprehensively consider above-mentioned three kinds of effects, a bit (x in sampleo,yo) can be with to the effect of the depth of focus light pencil by the point With the angle signal function f (x of sampleo,yo,ψκ) expression are as follows:
Wherein subscript κ can be x or y.
According to formula (10), it is known that perpendicular to light beam along the direction κ, exit Xray carry sample three kinds of angles letter Number, zero degree signal: M (xo,yo), refraction angle signal: θκ(xo,yo), scattering angle signal:They can be indicated For line integral, this is just that computer tomography obtains sample three-dimensional structure using data for projection and established Fundamentals of Mathematics.
In the step S6 of the two-dimensional imaging method of the X-ray differential phase contrast microscopic system, it is contemplated that sample Angle signal regulation beam-splitting optical grating circular grating picture annular analysis grating on shear displacemant, make angle signal obtain light Strong response.Therefore, it is necessary to establish the angle signal receptance function of X-ray differential phase contrast microscopic system, specific method is such as It is lower described:
In traditional X-ray microscope, beam propagation process when no sample can be described as follows.From X-ray light The diffusion light beam in source is assembled by condenser and central stop stops, and forms the hollow cone light beam for focusing on sample, can be in object Face is divided into multiple depth of focus light pencils according to spatial coherence area, the hollow cone light beam of focusing, each depth of focus light pencil shines A bright object point position.It is coherent light inside depth of focus light pencil, and it is mutually incoherent between two adjacent depth of focus light pencils.By object Behind face, the relevant hollow cone light beam that each depth of focus light pencil becomes to spread one by one again is respectively spread by the focussing force of object lens Relevant hollow cone light beam becomes the relevant hollow cone light beam focused one by one again, and picture point one by one is formed in image planes.It is propagating In the process, it is relevant inside relevant hollow cone light beam, and is incoherent between two relevant hollow cone light beams.It is focusing When, each relevant hollow cone light beam all forms depth of focus light pencil, disconnected from each other on object plane and image planes, but before and after focusing, example Such as in condenser, central stop, object lens, object lens back focal plane position, these relevant hollow cone light beams are spatially mutual weights It closes.In traditional X-ray microscope imaging theory, only consider sample absorption and phase shift, do not consider sample refraction and Scattering, or even if sample has refraction and scattering, but there is no the response mechanism for refraction and scattering being changed into light intensity, it passes The X-ray microscope imaging theory of system thinks, after being put into sample, other than sample absorption causes beam brightness decline and phase shift, Without difference when beam propagation process and no sample.
It is inserted into one piece of beam-splitting optical grating after the condenser outlet of traditional X-ray microscope system, central stop, in object lens Back focal plane is nearby inserted into one block of annular analysis grating, the X-ray differential phase contrast being formed in one embodiment of the invention Microscope.The effect of beam-splitting optical grating is hollow cone light beam to be divided into the hollow cone light beam with space structure, and make beam splitting light Grid are formed about circular grating picture and circular grating as light beam in object lens back focal plane by the annular section of hollow cone beam lighting.Ring The shape and size and beam-splitting optical grating of conformal analysis grating shape near object lens back focal plane by the annular section of hollow cone beam lighting Circularize that grating image is identical, effect is to the circular grating near the object lens back focal plane as light beam is filtered.By This is it is found that in X-ray differential phase contrast microscope, and beam propagation process when no sample can be described as follows: Lai Ziju The hollow cone light beam of light microscopic and central stop forms the sky for focusing on sample with space structure by beam-splitting optical grating beam splitting The heart bores light beam.In object plane according to spatial coherence area, the hollow cone light beam of focusing is divided into multiple depth of focus light pencils, each Depth of focus light pencil illuminates an object point.It is coherent light inside depth of focus light pencil, and mutual not phase between two adjacent depth of focus light pencils It is dry.After object plane, each depth of focus light pencil becomes the relevant hollow cone light beam spread one by one again, makees by the focusing of object lens With again the relevant hollow cone light beam respectively spread becomes the relevant hollow cone light beam focused one by one, not only attached in object lens back focal plane Respective circular grating is closely formed as light beam, and forms picture point one by one in image planes.Although each relevant hollow cone light beam exists The circular grating that object lens back focal plane is formed about mutually coincides as light beam, but each independent propagation, mutually incoherent.
If placing sample on the microscopical object plane of X-ray differential phase contrast, a little to passing through the point in sample Depth of focus light pencil generates refraction and scattering process, so that the depth of focus light pencil is generated two kinds of angle signals of deflection and diverging, this two Kind angle signal will necessarily cause the circular grating picture of the depth of focus light pencil that position movement and item occurs on annular analysis grating Line is fuzzy, causes the number of photons for analyzing grating by annular to increase or reduce, the angle signal of any in sample will be in picture Intensity response is obtained in the picture point in face.Therefore, filter action of the annular analysis grating to the circular grating picture of beam-splitting optical grating is X Ray differential phase contrast microscope provides angle signal response image-forming mechanism.Because sample reflects the ring for causing beam-splitting optical grating Beam-splitting optical grating equivalence is artificially moved when the position movement of shape grating image and no sample, so in no sample, it can be taking human as movement Beam-splitting optical grating measures circular grating as the shear displacemant generation between annular analysis grating using one pixel of imaging detector Intensity response, to measure X-ray differential phase contrast microscope to the angle signal receptance function of any on object plane.As for sample Product scattering causes the circular grating picture generation striped of beam-splitting optical grating fuzzy, is considered as each local opposed annular point of circular grating picture Analysis grating does irregular shear displacemant, and resulting Intensity response can also be carried out with the angle signal receptance function measured It explains.Because the circular grating of each object point as be near object lens back focal plane be overlapped, it is possible to one piece of beam-splitting optical grating with One block of annular analysis grating can be changed into the angle signal of object point each on object plane the Intensity response of each picture point in image planes.Change speech It, the mechanism that the refraction angle signal and scattering angle signal of sample each point are converted to response light intensity is all the same, has unified angle Signal receptance function.Therefore, can be primary taking human as the mobile beam-splitting optical grating of stepping in no sample, utilize each picture of imaging detector Element can measure respective angle signal receptance function parallel simultaneously.
Since beam-splitting optical grating and annular analysis grating are only capable of generating Intensity response to vertical raster grizzly bar orientation angle signal, And the angle signal for being parallel to grating grizzly bar direction is not responded to, so need only consider the angle letter perpendicular to gratings strips direction Number function.According to the shear displacemant of the circular grating picture of beam-splitting optical grating and annular analysis grating, it is known that the angle signal measured is rung Answering curve is a rectilinear oscillation curve.It is all low-angle signal due to reflecting and scattering, so not being whole angle signal response In action, but angle signal response curve part is in action for curve.Therefore, not according to beam-splitting optical grating step-scan starting point Together, angle signal receptance function curve can be divided into four seed types:
(i) it is completely coincident with the circular grating picture of beam-splitting optical grating and annular analysis grating as zero point, as beam-splitting optical grating walks Into scanning, the circular grating of beam-splitting optical grating measures the song that brightness gradually rises as opposed annular analysis grating generation shear displacemant Line, referred to as paddy position response curve；
(ii) a quarter period is staggered as zero point using the circular grating picture of beam-splitting optical grating and annular analysis grating, with point Beam grating step-scan, the circular grating of beam-splitting optical grating is as opposed annular analysis grating generation shear displacemant, along shear displacemant Augment direction measures brightness gradually linearly increasing curve, along the direction that shear displacemant reduces, measures brightness gradually linear decline Curve, referred to as upward slope response curve；
(iii) the half period is staggered as zero point using the circular grating picture of beam-splitting optical grating and annular analysis grating, with As opposed annular analysis grating shear displacemant occurs for beam-splitting optical grating step-scan, the circular grating of beam-splitting optical grating, measure brightness by Walk the curve of decline, referred to as peak position response curve；
(iv) 3/4ths periods were staggered as zero point using the circular grating picture of beam-splitting optical grating and annular analysis grating, with dividing Beam grating step-scan, the circular grating of beam-splitting optical grating is as opposed annular analysis grating generation shear displacemant, along shear displacemant Augment direction measures brightness gradually linear decline curve, along the direction that shear displacemant reduces, measures brightness gradually linear rise Curve, referred to as descending response curve.
Fig. 6 is four kinds of angle signal receptance function curve graphs of X-ray differential phase contrast microscopic system.According to Fig. 6, It knows that angle signal response curve is similar to cosine curve, cosine curve can be used to be fitted approximate, make angle signal response curve can To carry out Analytical Expression with the cosine curve of fitting, have
Or it is expressed as
Wherein xpPosition coordinates at grating are analyzed for annular,It is opposite for the circular grating image displacement of beam-splitting optical grating The angular displacement of object plane, doObject distance for sample with respect to object lens, p are the period of annular analysis grating,For angle Signal response curve average value, RmaxAnd RminThe respectively maximum value and minimum value of angle signal response curve,For the visibility of angle signal response curve, n is modulation parameter, and n=0,1,2,3 corresponds respectively to Fig. 6 In (a) paddy position response curve, (b) upward slope response curve, (c) peak position response curve and (d) descending response curve.
According to the derivation process of angle signal receptance function, it is known that angle signal receptance function describes the angle of an object point Percent of pass of the imaging subnumber of signals-modulating object point when by annular analysis grating.
According to the constant theorem of brightness, in the perfect optical system of noenergy decaying, brightness is a conserved quantity.Although true The efficiency of transmission of real optical system can not reach 100%, but true optical system can be seen in the brightness of image planes Make the product of object plane brightness and an efficiency of transmission.In X-ray differential phase contrast microscopic system, from object plane to image planes, Other than sample absorption causes brightness to decline, diffraction efficiency and annular analysis of the main contributions for causing brightness to decline from object lens The percent of pass of grating, thus image planes brightness be considered as object plane brightness and object lens diffraction efficiency and annular analysis grating percent of pass Product.When no sample, if incident beam brightness is B at object plane0, the diffraction efficiency of object lens is η, then near object lens back focal plane Beam-splitting optical grating circular grating picture brightness be η B0.According to formula (12), when no sample, the percent of pass of annular analysis grating is exactly Angle signal receptance function, thus annular analysis grating after brightness or image planes brightness be
Formula (13) is exactly the angle signal receptance function for considering object lens diffraction efficiency.
In the step S8 of the two-dimensional imaging method of the X-ray differential phase contrast microscopic system, imaging detector The two-dimentional intensified image of shooting is described with angle signal imaging equation.Therefore, it is necessary to establish angle signal imaging equation, specific method It is as described below:
For sample amplification imaging, each pixel of detector is parallel and mutually indepedent to the imaging of object plane each point , therefore, as soon as imaging of the detector pixel to any in sample need only be discussed, it is aobvious that X-ray differential phase contrast can be established Micro mirror imaging equation.Because the mechanism that the refraction of sample each point and scattering are converted to light intensity is all the same, there is translation not on object plane Denaturation, it is possible to which the X-ray differential phase is derived according to the convolution of above-mentioned angle signal function and angle signal receptance function The microscopical angle signal imaging equation of contrast.It needs to illustrate herein, convolution algorithm is the refraction in angle signal function Angle, angle of scattering and angle signal receptance function convolution algorithm, convolution algorithm and space coordinate are unrelated；Suction in angle signal function Receipts are zero degree signals, are not involved in convolution algorithm.
After being put into sample, an object point (x on object planeo,yo) to the absorption of the depth of focus light pencil by the point can after object lens it is burnt Face nearby causes circular grating picture that brightness decline occurs, and refraction can cause circular grating picture that position occurs near object lens back focal plane Offset, it is fuzzy that scattering can cause circular grating picture that striped occurs near object lens back focal plane.After annular analysis grating filtering, Picture point (x in image planesi,yi) brightness be angle signal function and angle signal receptance function convolution.Due to beam-splitting optical grating and ring Conformal analysis grating is only capable of generating Intensity response to vertical raster grizzly bar orientation angle signal, and to being parallel to grating grizzly bar direction Angle signal does not respond to, so need only consider the angle signal function and angle signal receptance function perpendicular to gratings strips direction Convolution.Thus have
Wherein (xo,yo) it is object plane coordinate, (xi,yi) it is image coordinates, B (xi,yi,ψx) it is to pass through object point (xo,yo) coke Deep light pencil is in picture point (xi,yi) brightness.Formula (17) be X-ray differential phase contrast microscope establish angle signal at Image space journey.
In the step S8 of the two-dimensional imaging method of the X-ray differential phase contrast microscopic system, the handle point The circular grating picture of beam grating is fixed on the paddy position of angle signal response curve, and sample, imaging detector are placed on sample stage The paddy position intensified image of sample is taken, the method for specifically shooting two-dimentional intensified image in an experiment is as described below:
Before being put into sample, circular grating picture is fixed on the paddy position of angle signal response curve, even ψx=0, n=0, so After place sample, detector can take the paddy position intensified image of sample, and expression formula is
In the step S8 of the two-dimensional imaging method of the X-ray differential phase contrast microscopic system, the handle point The circular grating picture of beam grating is fixed on the upward slope position of angle signal response curve, the method for shooting sample upward slope position intensified image: Before being put into sample, circular grating picture is fixed on the upward slope position of angle signal response curve, even ψxThen=0, n=1 are placed Good sample, detector can take the upward slope intensified image of sample, and expression formula is
In the step S8 of the two-dimensional imaging method of the X-ray differential phase contrast microscopic system, the handle point The circular grating picture of beam grating is fixed on the peak position of angle signal response curve, the method for shooting sample peak position intensified image: is put into Before sample, circular grating picture is fixed on the peak position of angle signal response curve, even ψxThen=0, n=2 place sample Product, detector can take the peak position intensified image of sample, and expression formula is
In the step S8 of the two-dimensional imaging method of the X-ray differential phase contrast microscopic system, the handle point The circular grating picture of beam grating is fixed on the descending position of angle signal response curve, the method for shooting sample descending position intensified image: Before being put into sample, circular grating picture is fixed on the descending position of angle signal response curve, even ψxThen=0, n=3 are placed Good sample, detector can take the descending intensified image of sample, and expression formula is
It is described from sample in the step S9 of the two-dimensional imaging method of the X-ray differential phase contrast microscopic system The paddy position intensified image of product, peak position intensified image, extracts absorption picture, folding of the sample in object space in descending intensified image at upward slope intensified image Image and scattering image space method are as described below: extracting the formula that sample absorbs picture in object space are as follows:
Sample is extracted in the formula of object space dioptric image are as follows:
Under the conditions of scattering negligible, sample is extracted in the simplified formula of object space dioptric image are as follows:
Sample is extracted in the formula of object space scattering picture are as follows:
Under the conditions of reflecting negligible, sample is extracted in the simplified formula of object space scattering picture are as follows:
In addition, as an alternative embodiment, X-ray source 10, condenser 1, beam-splitting optical grating 3 ' can integrate for One element, i.e. period are the X-ray ring-shaped gate source of micron dimension, as shown in fig. 7, at this time in X-ray ring-shaped gate source exit Two annular light holes 20 and 30 are sequentially placed along optical axis direction, make the light beam from X-ray ring-shaped gate source by two annulars After light hole 20 and 30, hollow cone light beam illumination sample and with space periodic structure is formed, and attached in 5 back focal plane of object lens Close to form ring-shaped gate source image and ring-shaped gate source image light beam, the shape and size of annular analysis grating 6 ' are identical with ring-shaped gate source image. This X-ray differential phase contrast microscopic system 100 ' based on ring-shaped gate source makes entire X-ray differential phase contrast aobvious The length of micromirror systems can further shorten, and can not only reduce the manufacturing cost of X-ray microscope system, but also the benefit of light It also can be further improved, have broad application prospects with efficiency.
Since the above-mentioned X-ray differential phase contrast based on ring-shaped gate source, ring-shaped gate source image and annular analysis grating is micro- The two-dimensional imaging method of mirror system, with the aforementioned X based on beam-splitting optical grating, the circular grating picture of beam-splitting optical grating and annular analysis grating The two-dimensional imaging method of ray differential phase contrast microscopic system is similar, and details are not described herein again.
Above description is only the preferred embodiment of the application and the explanation to institute's application technology principle.Those skilled in the art Member is it should be appreciated that invention scope involved in the application, however it is not limited to technology made of the specific combination of above-mentioned technical characteristic Scheme, while should also cover in the case where not departing from the inventive concept, it is carried out by above-mentioned technical characteristic or its equivalent feature Any combination and the other technical solutions formed.Such as features described above has similar function with (but being not limited to) disclosed herein Can technical characteristic replaced mutually and the technical solution that is formed.

Claims (10)

1. a kind of X-ray differential phase contrast microscopic system, comprising: for generating the light source of X-ray；And it is passed along X-ray Broadcast condenser, central stop, beam-splitting optical grating, pin hole, sample stage, object lens, annular analysis grating and imaging that direction is set gradually Detector, in which:
The light source for generating X-ray is homogeneous X-ray light source；
The condenser is ellipsoid capillary, tapered capillaries, zone plate or other X-ray optics members with focusing function Part, for generating the focus on light beam of illumination sample；
The central stop is located at the condenser export center, for stopping the straight-through light from the X-ray source, is formed Illuminate the hollow cone light beam of sample；
The beam-splitting optical grating is the absorption grating for being micron dimension the period, after being located at the central stop, for from described The hollow cone light beam of condenser and the central stop is split, and becomes the hollow cone light with space periodic structure Beam；
After the pin hole is located at the beam-splitting optical grating, for stopping straight-through light and stray light from the X-ray source；
The sample stage is located at object plane, for carrying sample, and can translate and rotate sample；
The object lens are zone plate or other optical elements with X-ray lens imaging function, for the tool for being located at object plane Have the sample structure of nanometer scale, be enlarged into the picture in image planes with micron dimension structure, make to have micron dimension pixel at As detector can shoot the intensified image of sample, and make the beam-splitting optical grating by the annular section of hollow cone beam lighting after object lens Focal plane is formed about circular grating picture and circular grating as light beam；
The annular analysis grating is the absorption grating for being micron or sub-micrometer scale the period, and it is attached to be located at the object lens back focal plane Closely, the circular grating of shape and size and the beam-splitting optical grating near object lens back focal plane is as identical, for the object lens Circular grating near back focal plane is filtered as light beam；
The imaging detector is located at image planes, for shooting the two-dimentional intensified image of sample.
2. X-ray differential phase contrast microscopic system according to claim 1, the beam-splitting optical grating and the annular point The material for analysing grating is gold or other heavy metals.
3. X-ray differential phase contrast microscopic system according to claim 1, in the beam-splitting optical grating and the annular Analyze grating thickness it is little in the case where, the odd-multiple with a thickness of π phase shift of beam-splitting optical grating, annular analysis grating with a thickness of π The even-multiple of phase shift.
4. a kind of two-dimensional imaging side for the described in any item X-ray differential phase contrast microscopic systems of claim 1-3 Method includes the following steps:
S1 is opened and is adjusted light source: the X-ray beam alignment condenser for generating the light source；
S2, adjustment condenser, central stop and pin hole: sample described in the hollow cone beam alignment for generating condenser and central stop Sample position is carried in sample platform, and central stop and pin hole is made to stop straight-through light and stray light from the X-ray source；
S3 adjusts object lens: object lens being made to focus the imaging detector that the imaging beam to be formed alignment is located at image planes；
S4, feed-in beam-splitting optical grating: after the central stop of condenser outlet, feed-in beam-splitting optical grating makes hollow cone beam lighting point The annular section of beam grating is formed about circular grating picture and circular grating as light beam in object lens back focal plane；
S5, feed-in and adjustment ring conformal analysis grating: it is formed about annular analysis grating alignment beam-splitting optical grating in object lens back focal plane Circular grating picture, adjustment ring conformal analysis grating grizzly bar direction, make annular analysis grating grizzly bar be parallel to beam-splitting optical grating grizzly bar；
Measuring angle signal response curve: S6 gradually moves beam-splitting optical grating along perpendicular to optical axis and grating grizzly bar direction, makes beam splitting As opposed annular analysis grating shear displacemant occurs for the circular grating of grating, measures brightness with annular in image planes with imaging detector The angle signal response curve of grating image change in displacement；
S7, be fitted angle signal response curve with cosine curve: angle signal response curve is similar to cosine curve, with cosine song Line is fitted the angle signal response curve measured, it is made to obtain the Analytical Expression of cosine curve；
S8 shoots sample two dimension intensified image: the circular grating picture of beam-splitting optical grating being separately fixed at the angle signal and responds song Paddy position, the upward slope position, peak position, descending position of line, place sample on sample stage, the paddy position intensified image for shooting sample, amplification of going up a slope Picture, peak position intensified image, descending intensified image；
S9 extracts sample in the quantitative two-dimensional image of object space: from the paddy of sample position intensified image, upward slope intensified image, peak position intensified image, Sample is extracted in descending intensified image in the absorption picture of object space, dioptric image and scattering picture；From any three kinds in four kinds of intensified images Sample is extracted in intensified image in the absorption picture of object space, dioptric image and scattering picture.
5. the two-dimensional imaging method of X-ray differential phase contrast microscopic system according to claim 4, wherein in institute It states in step S6, it is contemplated that sample influences the refraction of depth of focus light pencil and scattering, i.e., in view of the angle that sample generates is believed Influence number to imaging process, therefore sample angle signal function f (xo,yo,ψx) be expressed as
Wherein M (xo,yo)、θx(xo,yo) andRespectively the absorption of sample, refraction angle and scattering angular variance and X are penetrated The sample required in the imaging of line differential phase contrast microscope two-dimensional quantitative is in the absorption picture of object space, dioptric image and scatters picture, Their expression formula is
Wherein (xo,yo,zo) it is space coordinate at object plane, μ is linear absorption coefficient, and δ is refractive index real part attenuation rate, ωxIt is vertical Directly in the linear scattering coefficient in grating grizzly bar direction.
6. the two-dimensional imaging method of X-ray differential phase contrast microscopic system according to claim 4, in the step What is measured in S6 is angle signal response curve, is with fitting cosine curve Analytical Expression
Or it is expressed as
Wherein η is object lens diffraction efficiency, B0For incident beam brightness, x at object planepPosition coordinates at grating are analyzed for annular,Angular displacement for circular grating image displacement with respect to object plane, doObject distance for sample with respect to object lens, p are annular analysis light The period of grid,For angle signal response curve average value, RmaxAnd RminRespectively angle signal response curve Maximum value and minimum value,For the visibility of angle signal response curve, n is modulation parameter, n=0,1, 2,3 respectively correspond paddy position response curve, upward slope response curve, peak position response curve and descending response curve.
7. the two-dimensional imaging method of X-ray differential phase contrast microscopic system according to claim 4, in the step In S8, the two-dimentional intensified image of imaging detector shooting is described with angle signal imaging equation, and angle signal imaging equation is angle The convolution of signal function and angle signal receptance function, expression formula are as follows:
Wherein (xo,yo) it is object plane coordinate, (xi,yi) it is image coordinates, η is object lens diffraction efficiency, B0For incident beam at object plane Brightness, n=0,1,2,3 respectively correspond paddy position amplification imaging equation, go up a slope amplification imaging equation, peak position amplification imaging equation and under Amplify imaging equation, f (x in slopeo,yo,ψx) it is angle signal function, η B0Rn(ψx) it is angle signal receptance function.
8. the two-dimensional imaging method of X-ray differential phase contrast microscopic system according to claim 4, wherein
It is described that the circular grating picture of beam-splitting optical grating is fixed on angle signal response curve paddy position in the step S8, Sample is placed on sample stage, imaging detector takes the paddy position intensified image of sample, and expression formula is
It is described that the circular grating picture of beam-splitting optical grating is fixed on angle signal response curve upward slope position in the step S8, Sample is placed on sample stage, imaging detector takes the upward slope intensified image of sample, and expression formula is
It is described that the circular grating picture of beam-splitting optical grating is fixed on angle signal response curve peak position in the step S8, Sample is placed on sample stage, imaging detector takes the peak position intensified image of sample, and expression formula is
It is described that the circular grating picture of beam-splitting optical grating is fixed on angle signal response curve descending position in the step S8, Sample is placed on sample stage, imaging detector takes the descending intensified image of sample, and expression formula is
Due to
BV(xi,yi)+BP(xi,yi)=BU(xi,yi)+BD(xi,yi)
So paddy position intensified image, upward slope intensified image, peak position intensified image, in descending intensified image three width seem it is independent, it is any Width picture can be expressed with its excess-three width picture；It is above it is various in, (xi,yi) it is image coordinates, η is the diffraction efficiency of object lens, B0For illuminate object plane light beam brightness,For the average value of angle signal response curve, RmaxAnd RminRespectively The maximum value and minimum value of angle signal response curve,For the visibility of angle signal response curve, doFor For sample with respect to the object distance of object lens, p is annular analysis screen periods.
9. the two-dimensional imaging method of X-ray differential phase contrast microscopic system according to claim 4, in the step It is described to extract sample in object from the paddy position intensified image of sample, upward slope intensified image, peak position intensified image, descending intensified image in S9 The absorption picture in space, dioptric image and scattering image space method are as follows:
Sample, which is extracted, in the formula that object space absorbs picture is
Sample, which is extracted, in the formula of object space dioptric image is
Under the conditions of scattering negligible, extracting sample in the simplified formula of object space dioptric image is
Sample, which is extracted, in the formula that object space scatters picture is
Under the conditions of reflecting negligible, the simplified formula for extracting sample in object space scattering picture is
It is above it is various in, (xo,yo) it is object plane coordinate, (xi,yi) it is image coordinates, doObject distance for sample with respect to object lens,For the visibility of angle signal response curve,It is average for angle signal response curve Value, RmaxAnd RminThe respectively maximum value and minimum value of angle signal response curve, p are the period of annular analysis grating, BVFor Paddy position intensified image, BUFor upward slope intensified image, BPFor peak position intensified image, BDFor descending intensified image, B0For the bright of illumination object plane light beam Degree.
10. X-ray differential phase contrast microscopic system according to claim 1, the X-ray source, condenser and Beam-splitting optical grating is integrated into the X-ray ring-shaped gate source element that a cycle is micron dimension, at this time in X-ray ring-shaped gate source Exit is sequentially placed two annular light holes along optical axis, and the light beam for issuing the ring-shaped gate source is by two annular light passings Kong Hou, forms the hollow cone light beam of illumination sample, and is formed about ring-shaped gate source image and ring-shaped gate source image light in object lens back focal plane The shape and size of beam, the annular analysis grating are identical as the ring-shaped gate source image.
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