CN2151436Y

CN2151436Y - Electronic scattering interferometer

Info

Publication number: CN2151436Y
Application number: CN 92239009
Authority: CN
Inventors: 宋菲君; 俞蕾; 于国明; 冀平
Original assignee: CHINA DAHENG Co
Current assignee: CHINA DAHENG Co
Priority date: 1992-11-02
Filing date: 1992-11-02
Publication date: 1993-12-29
Anticipated expiration: 2002-11-02

Abstract

The utility model relates to an electronic scattering interferometer, which has the functions of continuously and maximally adjusting the aperture angle of illuminating beams and continuously and widely compensating the light path of object light. The utility model can be adapted to measured objects which have different dimensions and are positioned in different distances. The utility model has the advantages of high utilization rate of light power, uniform illumination, full compensation for light path of the object light, high contrast of an interference pattern, convenient regulation, compact structure, and stable performance. The utility model is applicable for the measurement of the displacement field, deformation field and oscillating field of the object and for the non-destructive inspection of materials and components.

Description

Electronic scattering interferometer

This utility model belongs to interferometry instrument class, is applicable to the measurement of displacement field, deformation field and oscillator field, and the Non-Destructive Testing of material, member.

Electronic speckle interferometer (Electronic Speckle Pattern Interferome-try, be called for short ESPI) be the novel interferometry instrument that occurs in recent years in the world, this instrument utilizes the microcomputer digital image system to handle automatically, in real time the interferogram that is obtained by laser interferometer.Interferogram is by Charge Coupled Device (CCD) (CCD) record.The electronic speckle interferometer that present each company produces, the aperture angle regulative mode of the illuminating bundle (thing light) of irradiation testee has following two kinds: (one) immutable aperture angle; (2) transmitting objective lens of using different size instead realizes that classification changes aperture angle.The variation of the thing light light path that causes for the variation of indemnity distance, these product employing amount class methods change the light path of reference light: (one) uses different length instead in reference path single mode polarization preserving fiber compensates; (2) employing is many to prism in reference path, and the thing light optical path compensation system of once turning back, the spacing that changes prism compensate (referring to Fig. 1, wherein label 1 is the compensating prism of once turning back).Last method can only compensate in segmentation, and single mode polarization preserving fiber price is higher, generally also will readjust after changing optical fiber, make troubles, though back one method can Continuous Compensation, and being limited in scope of compensation, the part number is more, and processing cost take height.Along with the increase of prism logarithm, to regulate more and more difficultly, occupation space is also increasing.

This utility model electronic speckle interferometer designs in the shortcoming aspect the compensation two of the adjusting of illuminating bundle aperture angle and thing light light path in order to overcome the said goods, have continuously, regulate significantly the illuminating bundle aperture angle and continuously, the characteristics of indemnity light light path on a large scale, can be called that the illumination light aperture angle is adjustable continuously, the novel electron speckle interferometer of thing light light path Continuous Compensation.

The design proposal and the technical characterictic of this utility model are as follows:

Fig. 2 sees in this instrumental optics system.Semiconductor laser by He-Ne laser instrument or band collimation

The narrow laser beam of device radiation at first is divided into thing light and reference light through spectroscope 22 after injecting instrument by entrance window 20.Wherein thing light carries out the pre-expansion bundle through the inverted telescope of negative lens 2 and positive lens 3 formations, expand the bundle parts through the continuous adjusting of negative lens 4 and positive lens 5 formations then, form divergent beams, through the adjustable reflective mirror 7 of fixed counter-mirror 6 and orientation, exit window 8 illumination testees, form speckle field at the body surface place, be imaged on the test surface 21 of Charge Coupled Device (CCD) (CCD) 15 through continuous vari-focus object lens 10, light beam synthetic prisms 9 again, form the image planes speckle.Pass through polished surface Σ from the reference light of 22 reflections ₁Enter thing light optical

path compensation prism

19,19 and another thing light optical path compensation prism 18 between the back of repeatedly turning back penetrate this compensating prism group, and through reflective mirror 17 reflections, after the neutral dim light dish 16 of no-load voltage ratio is decayed continuously, by microcobjective 14, spatial filter 13 expands the bundle parts with the reference light that beam expanding lens 12 constitutes and forms reference beam parallel or that disperse, reflect into into light beam synthetic prisms 9 and thing light by reflective mirror 11 and to converge, irradiation Charge Coupled Device (CCD) (CCD), form speckle interference figure at 21 places, write down and convert to electric signal by CCD, send into the microcomputer digital image processing system and handle.

The continuous regulatory function of illumination light aperture angle of this instrument is made of pre-expansion bundle parts and the continuous expansion bundle parts of regulating.Pre-expansion bundle parts are that focal length is f ₂Two gummed negative lenses 2 and focal length be f ₃The inverted telescopes that constitute of two gummed positive lenss 3, the output collimated light beam expands the beam ratio ratio of input laser beam spot size (the outgoing laser beam spot size with)

η＝｜ (f ₃)/(f ₂) ｜（1）

Regulating expansion bundle parts continuously is f by focal length ₄Two gummed negative lenses 4 and focal length be f ₅Two gummed positive lenss 5 constitute.If the laser spot size behind the pre-expansion bundle is 2 ω (referring to Fig. 3), then through regulate continuously expand the bundle parts after, outgoing illuminating bundle aperture angle (radian, down with)

2u′=2ω｜ (f ₄+f ₅-l)/(f ₄f ₅) ｜

Wherein

Back principal plane H ' for part 4 ₄Preceding principal plane H with part 5 ₅Spacing, f ₄＜0, f ₅＞0.Obviously change Size just can change the size of aperture angle 2u '.When

＝ _max＝f ₄＋f ₅（3）

The time, 2u '=0, outgoing be collimated light beam; When

＝0 （4）

The time, 2u ' reaches maximum value

2u′＝（2u′） _max＝2ω｜ (f ₄+f ₅)/(f ₄f ₅) ｜（5）

That is the aperture angle 2u ' of illuminating bundle is 0 and 2u ' _MaxScope in by regulating continuously.

Fig. 4 is the structural representation of this functional module.Two

lens

2,3 of pre-expansion bundle parts are contained in the same lens barrel, constitute inverted telescope.Regulate the lens 4 of expansion bundle parts and 5 interval continuously Regulate in the steep-lead thread mode by handwheel 23.Guide pin 24 guarantees that

lens

2,3 and 4 move vertically, thereby steadily and continuously adjusts the aperture angle of irradiating light beam.

The thing light light path serial compensator of this instrument is made of 45 ° of right-angle reflecting prism of a pair of D II-180

class

18,19, referring to Fig. 5.The input end face Σ that a polishing is arranged in 19 upper end ₁, at end face Σ ₁, Σ ₂And Σ ₃On be coated with the anti-reflection media coating of optical maser wavelength height.

Spot size is that the laser beam vertical center of 2 ω is injected Σ ₁, after 19, by Σ ₃ Import 18, because 18 and 19 opposing parallel place, and their axis of symmetry is along the orthogonal directions of the light incident spacing δ that staggers, thereby laser is at Σ ₄, Σ ₅, Σ ₆, Σ ₇Total reflection takes place on the face, repeatedly turn back between 18,19, at last from 19 end face Σ ₂Penetrate.

The spacing t of two prisms and all can regulating continuously of staggering mutually apart from δ, thus the light path of laser in this a pair of prism is adjustable continuously.

Be located at and be total to k light beam between prism, then

k＝2［ (d)/(4δ) ］（6）

D is the prism width in the formula, and ［］ shows rounding operation.The minimal value of obvious 2 δ

2δ _min＝ (ε＋2ω)/2 （7）

Wherein ε is Σ ₁The width of face, 2 ω are the mean value of the spot size of laser beam in the prism.Thereby the maximum value of k

k _max＝2［ (d)/(ε＋2ω) ］（8）

Laser beam is from Σ ₁Face is injected these parts to the end from Σ ₂Face penetrates the total optical path of parts

L＝kt＋knd＋ 1/2 n（d－ε）（9）

Wherein n is the refractive index of prism.Work as k=2, t=t _MinThe time, the L minimalization

L＝L _max＝2t _max＋2nd＋ 1/2 n（d－ε）（10）

Work as k=k _Max, t=t _MaxThe time L get maximum value

L＝L _max＝k _maxt _max＋k _max nd＋ 1/2 n（d－ε）（11）

Thereby optical path compensation scope

ΔL＝L _max－L _min（12）

The structure of these parts by handwheel 33 rotating threaded shafts 34, drags prism 19 in the x direction by shown in Figure 6, and drives the index line that is positioned at 31 end faces, demonstrates the value of the relative spacing t between prism on transparent long chi 30.To 35, rotational lead screw 25 drives prism 18 along the y direction by handwheel 32 and conical gear, and drives index lines 27 by the string of a musical instrument 28 and deflecting roller 29, shows the value of prism along the magnitude of misalignment δ of y direction on transparent short chi 26.

The electronic speckle interferometer of making according to such scheme, the repertoire that not only possesses existing electronic speckle interferometer, and needn't change object lens, the aperture angle that can regulate illuminating bundle continuously in an enough big scope just is to be adapted to the testee of different size; Needn't adopt additional optical fiber, just can be on a large scale Continuous Compensation thing light light path, to adapt to the measurement that is positioned at the object of different object distances before the instrument.Adopt this design proposal, obtain illumination more uniformly making full use of the testee surface that can make different size under the prerequisite of laser power, and can make with reference to light path full remuneration thing light light path on a large scale, to obtain the interferogram of hard contrast at one.This convenient instrument regulation, compact conformation, stable performance, and also cost is lower.

Embodiment of the present utility model sees Fig. 2-6.Pre-expansion bundle and the continuous actual parameter that expands the bundle parts of regulating are: f ₂=-10mm, f ₃=50mm, f ₄=-10mm, f ₅=50mm.If the spot size of input beam is 1mm, then the spot size of laser beams of pre-expansion bundle parts output is 2 ω=5mm.Substitution (5) formula, highest luminance beam angle (2u ') _Max=0.4 radian is equivalent to 23 °.For an object distance be 1000mm object, the about 405mm of illumination light spot diameter.Compensating prism width d=100mm, ε=8mm, the dimension limit t at the interval of two prisms _Min=3mm, t _mAx=100mm.Substitution (8) formula, k _Max=16; Substitution (10)～(12) formula obtains L _Min=377mm, L _Max=4085mm, (Δ L) _Max=3708mm.Highest luminance light beam hole pitch-angle (2u ') _MaxWith maximum optical path compensation scope (Δ L) _MaxCan satisfy most request for utilizations.

Description of drawings:

Fig. 1 is many to prism thing light optical path compensation system

1 compensating prism of once turning back

Fig. 2 optical system is always schemed

2 pre-expansion bundle parts negative lenses

3 pre-expansion bundle parts positive lenss

4 regulate expansion bundle parts negative lens continuously

5 regulate expansion bundle parts positive lens continuously

6 fixed counter-mirrors

The adjustable reflective mirror in 7 orientation

8 output windows

9 light beam synthetic prisms

10 continuous vari-focus object lens

11 reflective mirrors

12 beam expanding lenss

13 spatial filters

14 microcobjectives

15 Charge Coupled Device (CCD) (CCD)

The neutral dim light dish of 16 continuous no-load voltage ratios

17 reflective mirrors

18 thing light optical path compensation prisms

19 thing light optical path compensation prisms

20 input windows

21 Charge Coupled Device (CCD) test surfaces

22 spectroscopes

Σ ₀The testee surface

Σ ₁The compensating prism input end face

Fig. 3 pre-expansion bundle and continuous the adjusting are expanded bundle parts optical system diagram

H ' ₄ Lens 4 back principal planes

H ₅Principal plane before the lens 5

Fig. 4 pre-expansion bundle and continuous the adjusting are expanded bundle modular construction figure

23 handwheels

24 guide pins

Fig. 5 thing light light path Continuous Compensation parts optical system diagram

Σ ₂, Σ ₃Transmissive end face

Σ ₄, Σ ₅, Σ ₆, Σ ₇Total reflection surface

Fig. 6 thing light light path Continuous Compensation modular construction figure

25 leading screws

26 transparent short chis

27 index lines

28 strings of a musical instrument

29 deflecting rollers

30 transparent long chis

31 index lines

32 handwheels

33 handwheels

Claims

1, the novel electron speckle interferometer that has laser instrument, illumination light (thing light) system, reference light system, Charge Coupled Device (CCD) (CCD) and image processing system, it is characterized in that laser instrument is a kind of semiconductor laser that can give off narrow laser beam, be provided with the entrance window (20) and the spectroscope (22) that can produce thing light and reference light in the place ahead of this laser instrument, on the thing light light path after the beam split, be provided with pre-expansion bundle parts and the expansion bundle parts that can regulate divergent beams continuously, on the reference light light path after the beam split, be provided with a polished surface ∑ ₁And prism (18) and (19) Continuous Compensation parts.

2, according to the described novel electron speckle interferometer of claim 1, it is characterized in that:

A. pre-expansion bundle parts are inverted telescopic systems;

B. the continuous expansion bundle parts of regulating are made up of two different two positive and negative lens that glue together of focal length, and the spacing of regulating them just can obtain different illuminating bundle aperture angles;

C., the thread systems of the big helical pitch of one cover is set, regulates threadably, lens 2,3,4 are steadily moved vertically, to reach the aperture angle that adjusts irradiating light beam.

3, according to the described novel electron speckle interferometer of claim 1, the Continuous Compensation parts that it is characterized in that thing light light path are to be made of the thing light optical path compensation prism 18,19 in 45 ° of right angle reflections of a pair of D II-180 class that staggers mutually perpendicular to optical axis direction, and reference light is by polished surface Σ ₁Enter and penetrate this compensating prism group between compensating prism 18 and 19 after repeatedly turning back, this is regulated by two cover physical constructions the spacing of compensating prism and the distance that staggers, and indication is arranged:

A. Jian Ge adjusting is realized by precision lead screw, mother lead screw and steel wire spherical guide that a pitch is 1mm, and has index line indication numerical value at interval;

B. Cuo Wei adjusting is realized by pitch precision lead screw that is 0.5mm and dovetail guide, and has the numerical value of index line indication dislocation.