CN1808209A - Detection method for collimating mirror in synchrotron radiation - Google Patents

Abstract

The invention relates to a method for detecting the attitude of synchronizing irradiation curve collimating mirror, which comprises: generating a laser beam of same divergency with the synchronizing irradiation with lens and pinhole; measuring laser beam depth of parallelism output from the curve collimating mirror to adjust the position of the collimating mirror, pitching angle and mirror curvature to optimum. The invention also relates to a shearing interferometer which can judge the beam depth of parallelism according to fringe pattern, each interference fringe pattern corresponding to an attitude for identifying whole effect of X ray reflected from each points of the collimating mirror surface. The invention has the advantages of having high accuracy.

Description

The detection method of collimating mirror in synchrotron radiation

Technical field

The present invention relates to the detection method in optical devices technologies field, particularly a kind of collimating mirror in synchrotron radiation.

Background technology

Fig. 1 is the standard design light path of synchrotron radiation hard X ray light beam line, and wherein collimating mirror, monochromator and focus lamp are three main optical elements.Collimating mirror is between light source and monochromator, and its effect is that the synchrotron radiation light that will disperse is converged to directional light as much as possible, flows to monochromator then.High more from the depth of parallelism of the light beam of collimating mirror input, the monochromaticity of monochromator output beam is just good more.Therefore, the attitude correctness of collimating mirror is directly connected to the quality of light beam line output beam.In the synchrotron radiation light beam line Installation and Debugging, the detection of collimating mirror attitude is a ring of difficulty maximum during light beam line is adjusted.

Because X ray is invisible, during the collimating mirror on-line debugging, has often spent groping of long duration, can't determine the optimum posture of collimating mirror.For fear of the blindness of light modulation, before the on-line debugging, do offline inspection and debugging earlier.The collimating mirror method of adjustment that adopts both at home and abroad all is a local measurement at present, can not provide a certain attitude of collimating mirror and the whole relation of the output beam depth of parallelism, the measurement point difference of particularly choosing, and measurement result has than mistake.

Therefore, need a kind of method to determine the relation of the collimating mirror attitude and the output beam depth of parallelism, in view of the above collimating mirror is adjusted to optimum posture.Wherein, judge that the problem of press-bending mirror optimum posture also just is converted into the judgement of wavefront curvature radius on the press-bending direction, when radius-of-curvature reached infinity, the press-bending mirror had been adjusted to optimum posture, and the depth of parallelism of output beam is the highest.Simultaneously, by simple adjustment, can also be used to judging the press-bending homogeneity of collimating mirror to experimental provision.

Utilize lens that laser beam is focused on and disperse, can produce the laser beam identical with the synchrotron radiation light divergence.During this laser beam process press-bending collimating mirror, can adjust the radius-of-curvature of wavefront in the meridian ellipse by bending, and constant in sagittal surface inner light beam divergence, as Fig. 2.

When being tending towards infinitely-great after the meridian radius r is bent the mirror adjustment before the laser wave, wavefront is a vertical face of cylinder.

Simulate expensive collimating mirror with the post lens in experiment, its effect is of equal value fully, so the result who obtains when detecting is reliable.

In sum, the debugging of collimating mirror in synchrotron radiation can be reduced to detecting: the laser beam identical with synchrotron radiation divergence behind the post lens, the debugging and the detection of its wavefront in the vertical direction curvature.

At present, the method for utilizing interferogram to measure wavefront has two kinds:

1, reference wave interference technique.

The reference wave interference technique is to interfere with a reference wave and unknown corrugated, judges the shape on unknown corrugated by interference fringe.The general plane wave of using is as the reference ripple, and Fig. 3 is the interferogram of spherical wave.The reference wave interference technique is not suitable for measuring the larger radius of curvature wavefront.For example to the wavefront of radius-of-curvature r=10m, in the 5mm scope of in the vertical direction only to see that a complete light and shade replaces striped.Therefore, this method not only wavefront accuracy of detection to larger radius of curvature is not high, but also will introduce reference wave.

2, parallel flat shear interference method (lateral shear).

The ultimate principle of shear interference (list of references: " shearing interferometer and application thereof ", Xu Deyan, China Machine Press) be: tested wavefront is divided into (shearing) two parts by specific beam splitter, stagger mutually in horizontal (perpendicular to direction of wave travel), and interfere in the overlapping region, evaluation is verified the defective of wavefront itself according to interference fringe.

This method obtains required interference fringe by the distance (shearing displacement) that two wavefront that change after shearing stagger mutually in limited range.Its advantage is:

A. can make the spacing of striped and degree of tilt make corresponding change by simple adjusting gear;

B. do not need a reference wave;

C. antijamming capability is strong, to test environment require low;

D. facility is simple, conveniently builds, and is with low cost.

The shortcoming of this method: except (as spherical wave, cylindrical wave and plane wave etc.) before the simple wave were directly measured, before complex wave, lateral shear interferograms generally can not directly be judged tested wavefront shape, and the processing more complicated of lateral shear interferograms.

Though the shear interference striped match before the complex wave is a difficult point, before simple wave, does not have the difficulty of shear interference striped match.

The shear interference principle of parallel flat shear interference method:

Represent the wavefront equation with W, Δ W represents to shear the optical path difference of back two wavefront in same point; P is that the level of interference fringe is inferior, and λ is a wavelength.

Shearing is along the y direction of principal axis, and when shearing displacement s was smaller, optical path difference can be similar to and be written as (list of references: " shearing interferometer and application thereof ", Xu Deyan, China Machine Press):

$\mathrm{\ΔW}=\frac{\∂W}{\∂y}\·s=\mathrm{P\λ}---1$

If following formula is deformed into,

$\frac{\∂w}{\∂y}=\frac{P}{s}\mathrm{\λ}---2$

As can be known, the meaning of shear interference fringe density is: the interference fringe density on shear direction is directly proportional with the wavefront variation rate.

Wherein, the relation of width of fringe, shearing displacement and wavefront curvature radius is as follows:

If width of fringe is b, wavefront curvature radius to be measured is r, has

$b=\frac{\mathrm{r\λ}}{s}---3$

Expression formula and the Young two-slit interference striped of the width b of the interference fringe that draws thus are in full accord.This explanation should be a series of vertical bar lines perpendicular to shear direction for uniform curved shear interference striped.

According to 3 formulas, the little corresponding fringe density of wavefront curvature radius is big as can be known; And the big corresponding fringe density of wavefront curvature radius is little.

In collimating mirror press-bending process, the laser beam corrugated of collimated mirror reflection is flattened by protruding, and radius-of-curvature is changed from small to big, and until becoming infinity, the corrugated becomes recessed by flat then, and radius-of-curvature again from large to small.When with the monitoring of shear interference striped, be accompanied by said process, the shear interference fringe density until becoming zero, changes from small to big again from large to small then.Can judge the size of wavefront curvature radius thus by the density of striped.

There is limitation in the parallel flat shearing interferometer: for wavefront meridian radius detects, require the height of light beam in meridian ellipse behind shear interference, obtain several light and shade stripeds to complete cycle (establishing n to striped) at least.Because the light beam height H is that the overlapping region adds shearing displacement, promptly

$H=n\·b+s\⇒H=n\·\frac{\mathrm{r\λ}}{s}+s----4$

When $s=\sqrt{\mathrm{nr\λ}}$ The time, H has minimum value, promptly $H=2\sqrt{\mathrm{nr\λ}}.$ If n=5 for the wavefront of radius-of-curvature r=50m, requires the light beam height to be at least $H=2\×\sqrt{5\×50\×0.6328\×{10}^{-6}}=25.2\mathrm{mm},$ The overlapping region is $n\·b=s=\sqrt{\mathrm{nr\λ}}=12.6\mathrm{mm}.$ This explanation can only be seen two pairs of light and shade stripeds in this 5mm observation scope.Therefore the parallel flat shearing interferometer is not suitable for detecting vertically highly narrower synchrotron radiation light beam.

Reach a conclusion thus, the parallel flat shearing interferometer is not suitable for detecting the small-bore wavefront of larger radius of curvature.

More than two kinds of methods, all utilize fringe density interpretation wavefront curvature radius, measure the small-bore wavefront of larger radius of curvature and utilize the method for fringe density not to be suitable for.

Summary of the invention

The objective of the invention is to utilize the advantage of shear interference method, but avoid its shortcoming, a kind of detection method of collimating mirror in synchrotron radiation is provided, the spatial frequency composition principle is applied to lateral shearing interference, utilize interference fringe direction interpretation wavefront curvature radius.

A further object of the present invention provides a kind of biprism shearing interferometer, and it cooperates with associated components, and the detection method of collimating mirror in synchrotron radiation of the present invention is implemented.

Method of the present invention is applicable to measures the big vertically little light beam of bore of wavefront curvature radius, in offline inspection and debugging, position, luffing angle and the curvature mirror of collimating mirror in the standard design light path of synchrotron radiation hard X ray light beam line all can be adjusted to the optimum position.

For achieving the above object, technical solution of the present invention provides a kind of detection method of collimating mirror in synchrotron radiation, use the biprism shearing interferometer to carry out, it is to utilize lens and pin hole to produce a laser beam identical with synchrotron radiation divergence, by measuring the depth of parallelism, position, luffing angle and the curvature mirror of collimating mirror all can be adjusted to optimum condition through press-bending collimating mirror outgoing laser beam.

Described detection method, it comprises step:

A. calibration system: adjust the position and all directions inclination angle of biprism shearing interferometer, make the standard flat ripple on screen, obtain vertical interference fringe;

B. take lateral shear interferograms: pin hole is positioned over press-bending collimating mirror focal position, then the press-bending collimating mirror is moved forward and backward along optical axis, can change the curvature of light wave face in the vertical direction with this, light beam can obtain the interference fringe of slope variation by the biprism shearing interferometer, and this judges the foundation of radius-of-curvature just;

C. according to the interpretation method of interference fringe direction:

(1) clap in will detecting the interference image of picture carry out noise reduction and image enhancement processing;

(2) utilize the Radon conversion to judge the method for piece image cathetus position and angle, write image processing program;

(3) after treatment image is carried out the Radon conversion, promptly different angles are carried out integration, to obtain the maximum R of different angles correspondence _θValue gets R _θ～θ curve is then at R _θ～θ curve has carried out interpolation and match respectively, finally obtains the R ' of smoother _θ～θ curve map;

(4) program is returned at R ' _θIn～θ the curve map, just can judge on this basis the collimation of light beam:

The foundation of differentiating the wavefront curvature radius is the interference fringe vergence direction;

D. according to the interpretation method of interference fringe bending: the inhomogeneity foundation of bending is judged in the bending of interference fringe just, and the straight more press-bending homogeneity of striped is good more; The big interference fringe of the little corresponding slope of radius-of-curvature, the little interference fringe of the big corresponding slope of radius-of-curvature does not have certain bending if striped is not straight, just judges the press-bending homogeneity of press-bending collimating mirror integral body according to the variation of slope.

Described detection method, the biprism shear interference system of its described biprism shearing interferometer combination is by laser beam, draw together bundle convex lens, pin hole, press-bending collimating mirror, biprism shearing interferometer and display screen or film is formed; Wherein, laser beam, draw together bundle convex lens, pin hole, press-bending collimating mirror and biprism shearing interferometer and come on the light path in proper order, biprism support that shearing interferometer is joined is provided with the device of adjusting position and all directions inclination angle, display screen or film are positioned at biprism shearing interferometer side, on interferometer reflection light bright dipping light path.

Described detection method, the foundation of its described differentiation wavefront curvature radius is the interference fringe vergence direction, the slope of plane wave interference fringe is infinitely great.

The employed biprism shearing interferometer of described detection method, be on the basis of parallel flat shearing interferometer, to transform, be about to two flat boards and change two right-angle prisms into, the bottom surface of its two right-angle prisms is relative, leave the angle of wedge that microvoid gas gap forms between two bottom surfaces, both sides tighten up with fixture, and to obtain biprism shear interference wedge, this wedge is an air wedge.

Described biprism shearing interferometer by adjusting the air angle of wedge of biprism shearing interferometer, is selected the density of interference fringe, to make things convenient for the interpretation of striped.

Described biprism shearing interferometer, its prism shearing displacement s and thickness h about the variation relation of the overall inclination angle i ' of combined prism are: s/h=f (i '), f (i ') can know to obtain different shearing displacements thus, the wedge thickness and the prism inclination angle that need.

Described biprism shearing interferometer, total reflection during less than 40 °, does not take place at overall inclination angle i ' in it, promptly light beam can enter air wedge, can obtain shearing wave before.

Described biprism shearing interferometer, it improves the method for detection sensitivity and precision:

Increase air wedge thickness, it is right to have improved $\mathrm{\φ}=\arctan \frac{f_y}{f_x}$ Resolution sensitivity;

Suitably increase the air angle of wedge, under the situation that does not influence resolution and sharpness, such striped has obvious and sharp-pointed maximal value curve by the Radon conversion, and the interpretation meeting is more accurate.

The present invention proposes to utilize the method for small angle of wedge shearing interferometer measurement synchronization radiation press-bending collimating mirror attitude.Utilize lens and pin hole to produce a laser beam identical,, position, luffing angle and the curvature mirror of collimating mirror all can be adjusted to best method by measuring the depth of parallelism through press-bending collimating mirror outgoing laser beam with synchrotron radiation divergence.This shearing interferometer is simple in structure, can judge the depth of parallelism of light beam according to stripe, and each width of cloth interference fringe pattern is corresponding with a kind of attitude of collimating mirror, thereby this method can be determined the whole structure of each point reflection X ray of collimating mirror surface.Big and the little characteristics of output beam bore according to the collimating mirror radius-of-curvature, spatial frequency composition principle in the utilization Fourier optics, utilize small angle of wedge shear interference striped, to vertical bore is the 5mm light beam, the overall process of can the continuous monitoring collimating mirror bending, observe the reflection corrugated and flatten (parallel beam), become recessed (converging beam) change procedure again by protruding (divergent beams).The method that the present invention proposes is applicable to measures the big vertically little light beam of bore of wavefront curvature radius, precision height not only, and have practical value.

Description of drawings

Fig. 1 is the standard design light path of synchrotron radiation hard X ray light beam line;

Fig. 2 for laser beam through the light path of press-bending collimating mirror and the three-dimensional view of wavefront thereafter; Wherein: (a) wavefront generation mechanism synoptic diagram for this reason; (b) stereographic map of wavefront for this reason;

Fig. 3 is the interferogram of spherical wave and plane wave;

Fig. 4 is the side view and the vertical view of wedge shearing interferometer wedge;

Fig. 5 is the interference fringe picture of the inclination that obtains in theory;

Fig. 6 is (a) two dull and stereotyped shear interference light paths and (b) biprism shear interference light path synoptic diagram;

Fig. 7 is two right-angle prism shear interference wedges: (a) interfere the wedge structural representation, (b) the device design diagram;

Fig. 8 is a biprism shear interference system light path synoptic diagram;

The vertical striped hot spot that Fig. 9 obtains by the prism shearing interferometer for the plane wave light beam;

Figure 10 for the post lens respectively at interference fringe picture that diverse location obtains: (a) in one times of focal length, (b) near focus, (c) one times out-of-focus, (d) one times of out-of-focus farther place;

Figure 11 carries out filtering and figure image intensifying to original image for (a), (b) to after treatment image, and the integrated value that on the special angle direction, obtains and the R ' of angle _θ～θ graph of relation;

Figure 12 is the synoptic diagram of prism inclination angle i ' to prism shearing displacement s and thickness h influence;

Figure 13 when getting s=2.5mm and s=0.5mm, the graph of relation between prism inclination angle i ' and the required wedge thickness h;

Figure 14 is the graph of relation between first prism emergence angle θ and the prism inclination angle i '.

Embodiment

According to Fourier optics, the composite formula of spatial frequency is

$\frac{1}{f}=\frac{1}{\sqrt{f_x^2+{\mathrm{<figure-callout\; id="2"\; label="f\; y"\; filenames="A20051001121600161.png,A20051001121600201.png"\; state="\{\{state\}\}">f</figure-callout>}}_y^{}}},\mathrm{\&phi;}=\tan \frac{f_y}{f_x}----5$

In the following formula, f _xBe the component of horizontal direction, f _yBe the component of vertical direction, f is a frequency synthesis, and φ is the sensing of frequency synthesis f and the angle of x axle.

F here _yMove towards the interference fringe frequency for what obtain in the parallel flat shearing interferometer perpendicular to shear direction, level, it is corresponding with the shear interference fringe density.In order to introduce f _x, need to transform the parallel flat shearing interferometer as the wedge shearing interferometer.

Because the normal angle of wedge front surface and rear surface equates with the air angle of wedge, cause reflection corrugated, wedge rear surface to tilt in sagitta of arc direction, make rear surface reflection ray (among Fig. 4 shown in the dotted line) and front surface reflection light, incident ray not in same perpendicular, so produce the vertically interference fringe of trend.As shown in Figure 4.

The angle of wedge of wedge shearing interferometer is a among Fig. 4, and deflection 2a before the shearing wave of reflection causes producing frequency and is $f_x=\frac{2a}{\mathrm{\&lambda;}}$ Striped.So, synthetic shear interference striped trend tilts, with the frequency synthesis directed in orthogonal, as shown in Figure 5.

In practice, f _xExcessive (the promptly corresponding vertical fringe density that brings by the angle of wedge), striped is too close, not only can make troubles to interpretation, and stripe direction also will reduce with the sensitivity of wavefront curvature change in radius; f _xToo small, striped also can become very wide on the horizontal direction, also is unfavorable for interpretation.Can select a suitable f by adjusting the air angle of wedge _x

In actual observation, in horizontal 2cm scope, obtain 8 interference fringe ratios and be easier to observation, the air angle of wedge is approximately 26 as calculated " about.Such precision inconvenience processing utilizes the air layer between two glass plates, by adjusting the angle of wedge of air layer, can obtain the very little angle of wedge of angle easily, shown in Fig. 6-a.There is the problem that sharpness is relatively poor in two dull and stereotyped shear interferences, reason is the sharpness that the reflected light of the rear surface of the front surface of first block of glass plate and second block of glass plate can reduce striped, can separate the disadvantageous reflected light of interferogram with the method for Fig. 6-b, be about to two flat boards and change two right-angle prisms 7 into, the bottom surface of two right-angle prisms 7 is relative, leave the angle of wedge that microvoid gas gap constitutes between two bottom surfaces, both sides tighten up with fixture, the biprism shear interference wedge that finally obtains, fixture comprises the adhesive tape 9 of two adhesive tapes 8 and a specific thicknesses, two adhesive tapes 8 adhere to the both sides up and down of two right-angle prisms 7 respectively, adhesive tape 9 adheres to a side of air wedge, as shown in Figure 7, be the perspective view of biprism shear interference wedge, what play the effect of shear interference device in fact here is air wedge.

The shear interference light path of the biprism shearing interferometer that constitutes by the biprism wedge, as shown in Figure 8.Fig. 8 has also provided the structural representation of biprism shear interference system, its by laser beam 1, make light beam by some angles of divergence draw together bundle convex lens 2, pin hole 3, post lens 4, biprism shearing interferometer 5 and display screen or film 6 is formed.Wherein, laser beam 1, draw together bundle convex lens 2, pin hole 3, post lens 4 and biprism shearing interferometer 5 orders and come on the light path, support that biprism shearing interferometer 5 is joined is provided with the device of adjusting position and all directions inclination angle, display screen or film 6 are positioned at biprism shearing interferometer 5 sides, on interferometer 5 reflected light bright dipping light paths.

For dull and stereotyped shear interference, the relational expression of slab-thickness h and shearing displacement s is as follows:

$s/h=2\cos i\left\{\tan \right[\arcsin \left(\frac{\sin i}{n}\right)\left]\right\}---6$

Then be expressed as for air wedge:

s/h＝2cosi{tan[arcsin(n?sin?i} 7

Prism inclination angle i ' to the influence of above-mentioned relation as shown in figure 12, with respect to the incident angle i ' of horizontal light beam in the dull and stereotyped shear interference, incident angle becomes i after by first prism, the change by incident angle behind first prism can be obtained by following formula:

sin(45°-i′)＝nsin(45°-i) 8

Can draw the variation relation of s/h by above two formula, put above two formulas in order relational expression that cancellation i in back obtains about the overall inclination angle i ' of combined prism:

s/h＝f(i′)，f(i′) 9

Can know to obtain different shearing displacement s the wedge thickness and the prism inclination angle that need thus.

When getting s=2.5mm and s=0.5mm, the relation between prism inclination angle i ' and the required wedge thickness h is provided by the relation curve of Figure 13.

When comparatively moderate 15 ° of i ' selection, requiring air wedge thickness is about 1.5mm and 0.3mm, as seen, in the detection when being difficult to obtain bigger air wedge thickness, be that air wedge is very thin, but the angle of wedge again must be very little simultaneously, at this moment fine setting is very important and necessary to thickness.This is the main factor that influence detects observation effect.

Must be noted that in the detection, when avoiding light beam to inject prism, the situation of total reflection occurs to the air wedge first surface.

Among Figure 12: sin θ=nsini combination

Formula then has:

Figure 14 is exactly the relation curve between first prism emergence angle θ and the prism inclination angle i ', can be first prism generation total reflection, depend on the emergence angle θ shown in Figure 12, the scope of the prism inclination angle i ' of total reflection does not as can be seen from Figure 14 take place in first prism, at prism inclination angle i ' during less than 40 °, total reflection does not take place, and promptly light beam can enter air wedge, can obtain shearing wave before.

The detection method of collimating mirror in synchrotron radiation of the present invention comprises the following steps:

1. calibration system: adjust the position and all directions inclination angle of biprism shearing interferometer 5, make the standard flat ripple on screen, obtain vertical interference fringe.

LASER Light Source added to obtain plane wave after parallel light tube is as beam-expanding system, this plane wave light beam is by behind the biprism shearing interferometer 5, detection is also adjusted biprism shearing interferometer 5 on this basis to the striped degree of tilt, is met to detect the vertical striped hot spot that requires, as shown in Figure 9.Interference fringe among Fig. 9 is to obtain by position and all directions inclination angle of adjusting biprism shearing interferometer 5, and judges that by the image processing method that hereinafter will introduce this striped slope is for infinitely great.The size and Orientation that the angle of wedge can be described so adjusted to satisfy detect required.

2. shooting lateral shear interferograms: pin hole is positioned over post lens focus position, then the post lens are moved forward and backward along optical axis, can change the curvature of light wave face in the vertical direction with this, the interference fringe that light beam can obtain changing by biprism shearing interferometer 5, this judges the foundation of radius-of-curvature just.

3. according to the interpretation method of interference fringe direction:

For a width of cloth gray scale bar graph, if calculating is in the projection of assigned direction epigraph matrix, the just line integral of image array on projecting direction.In the result who returns, the maximum value correspondence of integrated value R the bright straight line in the image.This thinking is similar to the method for utilizing the Radon conversion to judge piece image cathetus position and angle.

Shown in Figure 10, for the post lens respectively at interference fringe picture that diverse location obtains: (a) in one times of focal length, (b) near focus, (c) one times out-of-focus, (d) one times of out-of-focus farther place.

Utilize preceding method, writing image processing program analyzes 10-b figure, can obtain as shown in figure 11 coupled columns lens after near the striped of taking the focus carries out Flame Image Process, the image and the curve that return of program again, wherein, (a) original image is carried out filtering and figure image intensifying, (b) to after treatment image, the integrated value that on the special angle direction, obtains and the R ' of angle _θ～θ graph of relation

Clap in the detection picture and the interference fringe of theory shown in Figure 5 be very different: shape of stripes is not so straight, even thickness; " noise " in the image is very serious or the like.So must look like to carry out noise reduction (utilizing medium filtering) and figure image intensifying (strengthen picture contrast, make striped sharp outline) to original interferogram.Figure 11-a is exactly the image that the treated front and back of original graph obtain.

After treatment image is carried out the Radon conversion, promptly different angles are carried out integration, can obtain the maximum R of different angles correspondence _θValue is shown in Figure 11-b.Original R in this width of cloth image _θ～θ curve undulatory property big (not expression in the drawings), its reason can't be removed its influence by Flame Image Process fully from " noise " of original image.Then at R _θ～θ curve has carried out interpolation and match respectively, finally obtains the R ' of smoother _θ～θ curve map.Here R ' _θBe one ten rank polynomial expression, can reflect R _θChanging Pattern, can well carry out smooth treatment again to curve.

Through above processing, program is returned at R ' _θAmong～θ the figure, maximum R ' _θValue is corresponding to 1.76 °.As seen, the corresponding state of 10-b figure still is not vertical curvature infinity.Just can judge the collimation of light beam on this basis.

According to above analysis as can be known, the wedge lateral shear interferograms is different with the parallel flat lateral shear interferograms, and the foundation that it differentiates the wavefront curvature radius is not a fringe density, but the striped vergence direction.

The interference fringe picture that obtains can always straight lines, and the inhomogeneity foundation of bending is judged in the bending of striped just.

Through above analysis as can be known, striped pitch angle $\mathrm{\&phi;}=\arctan \frac{f_y}{f_x}$ It is big more that more little correspondence radius-of-curvature r, otherwise then r is more little.The straight more explanation press-bending of striped homogeneity is good more.Can select fringe density by adjusting the air angle of wedge, the convenient observation.

Biprism shearing interferometer of the present invention, it improves the method for detection sensitivity and precision:

Increase air wedge thickness.

By formula As can be known: under the constant prerequisite of wavefront curvature radius r, the increase of s can make width of fringe b reduce, i.e. f _yIncrease, then this equates improved right $\mathrm{\&phi;}=\arctan \frac{f_y}{f_x}$ Resolution sensitivity.

Suitably increase the air angle of wedge.

The air angle of wedge suitably increase can make f _xBecome big, promptly striped becomes finer and closely woven, and under the situation that does not influence resolution and sharpness, such striped has obvious and sharp-pointed maximal value curve by the Radon conversion, and so the interpretation meeting is more accurate.

The detection method that proposes among the present invention can be determined collimating mirror surface each point in conjunction with Computer Processing The whole structure of reflection X ray namely can by the inclined degree of judging angle of wedge Shearing interference fringes Judge the depth of parallelism by the small-bore light beam of post lens, namely be equivalent to export through the press-bending collimating mirror The collimation of light beam is adjusted to the collimating mirror attitude best method thus. The method has solved together Step radiant light larger radius of curvature wavefront and the little detection difficult problem of bringing of output beam bore. This method Be fit to the little wavefront of the big observation scope of radius of curvature and detect, the method precision height has practical value.

Claims (9)

1. the detection method of a collimating mirror in synchrotron radiation, use the biprism shearing interferometer to carry out, it is characterized in that: be to utilize lens and pin hole to produce a laser beam identical with synchrotron radiation divergence, by measuring the depth of parallelism, position, luffing angle and the curvature mirror of collimating mirror all can be adjusted to optimum condition through press-bending collimating mirror outgoing laser beam.

2. detection method as claimed in claim 1 is characterized in that: comprise step:

A. calibration system: adjust the position and all directions inclination angle of biprism shearing interferometer, make the standard flat ripple on screen, obtain vertical interference fringe;

B. take lateral shear interferograms: pin hole is positioned over press-bending collimating mirror focal position, then the press-bending collimating mirror is moved forward and backward along optical axis, can change the curvature of light wave face in the vertical direction with this, light beam can obtain the interference fringe of slope variation by the biprism shearing interferometer, and this judges the foundation of radius-of-curvature just;

C. according to the interpretation method of interference fringe direction:

(1) clap in will detecting the interference image of picture carry out noise reduction and image enhancement processing;

(2) utilize the Radon conversion to judge the method for striped position and angle in the piece image, write image processing program;

(3) after treatment image is carried out the Radon conversion, promptly different angles are carried out integration, to obtain the maximum R of different angles correspondence _θValue gets R _θ～θ curve is then at R _θ～θ curve has carried out interpolation and match respectively, finally obtains the R ' of smoother _θ～θ curve map;

(4) program is returned at R ' _θIn～θ the curve map, just can judge on this basis the collimation of light beam:

The foundation of differentiating the wavefront curvature radius is the interference fringe vergence direction;

D. according to the interpretation method of interference fringe bending: the inhomogeneity foundation of bending is judged in the bending of interference fringe just, and the straight more press-bending homogeneity of striped is good more; The big interference fringe of the little corresponding slope of radius-of-curvature, the little interference fringe of the big corresponding slope of radius-of-curvature does not have certain bending if striped is not straight, just judges the press-bending homogeneity of press-bending collimating mirror integral body according to the variation of slope.

3. detection method as claimed in claim 1, it is characterized in that: the biprism shear interference system of described biprism shearing interferometer combination, by laser beam, draw together bundle convex lens, pin hole, press-bending collimating mirror, biprism shearing interferometer and display screen or film is formed; Wherein, laser beam, draw together bundle convex lens, pin hole, press-bending collimating mirror and biprism shearing interferometer and come on the light path in proper order, biprism support that shearing interferometer is joined is provided with the device of adjusting position and all directions inclination angle, display screen or film are positioned at biprism shearing interferometer side, on interferometer reflection light bright dipping light path.

4. detection method as claimed in claim 2 is characterized in that: the foundation of described differentiation wavefront curvature radius is the interference fringe vergence direction, and the inclination angle of the interference fringe of plane wave is zero.

5. as claim 1 or the employed biprism shearing interferometer of 3 described detection methods, be on the basis of parallel flat shearing interferometer, to transform, be about to two flat boards and change two right-angle prisms into, it is characterized in that: the bottom surface of two right-angle prisms is relative, leave the angle of wedge that microvoid gas gap constitutes between two bottom surfaces, both sides tighten up with fixture, and to obtain biprism shear interference wedge, this wedge is an air wedge.

6. biprism shearing interferometer as claimed in claim 5 is characterized in that: by adjusting the air angle of wedge of biprism shearing interferometer, select the fringe density of being convenient to observe.

7. biprism shearing interferometer as claimed in claim 5, it is characterized in that: prism shearing displacement s and thickness h about the variation relation of the overall inclination angle i ' of combined prism are: s/h=f (i '), f (i '), can know to obtain different shearing displacements the wedge thickness and the prism inclination angle that need thus.

8. biprism shearing interferometer as claimed in claim 5 is characterized in that: during less than 40 °, total reflection does not take place at overall inclination angle i ', promptly light beam can enter air wedge, can obtain shearing wave before.

9. biprism shearing interferometer as claimed in claim 5 is characterized in that: the method that improves detection sensitivity and precision:

Increase air wedge thickness, it is right to have improved $\mathrm{\&phi;}=\arctan \frac{f_y}{f_x}$ Resolution sensitivity;

Suitably increase the air angle of wedge, under the situation that does not influence resolution and sharpness, such striped has obvious and sharp-pointed maximal value curve by the Radon conversion, and the interpretation meeting is more accurate.

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