CN101033948A - Measurement system for three-dimensional deformation based on splitting optical fiber - Google Patents

本发明涉及了一种基于分束光纤的三维变形测量系统。它由一个提供光源的激光器、一个带CCD摄像机的图像接收系统和一个分光传光及相移系统组成，分光传光及相移系统是一个一分五型光纤分光传光及相移系统。通过光纤出口端的遮挡开关的选择，可以实现物体面内竖直方向、水平方向以及离面方向的变形测量。本发明结构合理紧凑，操作简便，适用于物体表面的准实时三维变形测量。

The invention relates to a three-dimensional deformation measurement system based on splitting optical fiber. It consists of a laser that provides a light source, an image receiving system with a CCD camera, and a light splitting and phase shifting system. Through the selection of the shielding switch at the outlet end of the optical fiber, the deformation measurement in the vertical direction, horizontal direction and out-of-plane direction of the object plane can be realized. The invention has a reasonable and compact structure and is easy to operate, and is suitable for quasi-real-time three-dimensional deformation measurement of object surfaces.

Measurement system for three-dimensional deformation based on splitting optical fiber

Technical field

The present invention relates to the optical 3-dimensional deformation measuring system, particularly a kind of measurement system for three-dimensional deformation based on splitting optical fiber.

Background technology

Along with industrial expansion, people to material stressed after, the research of performance parameters such as the distortion of generation, stress, strain requires also to improve constantly.Can only be applied to metal stresses scale that object point measures to speckle The Application of Technology that can Measuring Object face zone from the past.Utilize the speckle technology that there have been many methods hardware system and the deformation process scheduling algorithm processing aspect that object carries out the deformation measurement of bidimensional or three-dimensional.

In the present at home document record, the technology of electronic speckle pattern interferometry commercial measurement body surface three-dimensional anamorphotic system is: adopt three laser instruments to shine to provide radiation source, the reference substance that irradiation testee and its side are placed from three different directions.Promote to stick on three catoptrons above the reference substance with PZT phase-shifter, being used to provides the reference light of corresponding three beams thing light interference and introduces phase shift.Before ccd video camera, place the big shearing prism, make the information on body surface information and the reference substance all enter among the CCD, in conjunction with four step phase-shifting techniques, three laser instruments shine measured object successively respectively, and the speckle pattern of being gathered is carried out computing and separate obtaining three independently deformation fields.But this system is because the quantity of laser instrument is many, and structure is huge, and three level crossing directions on the reference substance are adjusted difficulty, and because the separating effect of big shearing prism may influence the speckle image quality, and this system can not carry out the measurement of one dimension or two dimension separately.

In patent US 6188483 B1, measure in the system of three-dimensional object surface distortion, utilize a laser instrument that light source is provided, utilize spectroscope and reflective mirror characteristic, carry out beam split, pass light.Two twin-beam electronics diffusing class interference system and a surface deformation detection system are attached in the system, rely on four bundle laser beam finished surface internal strains of outgoing to detect respectively, and utilize a branch of and inner another light beams in the four bundle laser to constitute the surface deformation detection system.With the electronic speckle figure that obtains before and after the distortion use directly cut algorithm mutually handle after, obtain the 3 D deformation data.This system can carry out the measurement of one dimension, two dimension or 3 D deformation separately.Shortcoming is to adopt discrete element to carry out beam split, pass light, and optical device is various, and optics positions is placed the accuracy requirement height, and system debug precision prescribed height is adjusted operating difficulties.

Summary of the invention

The objective of the invention is at the defective that exists in the prior art, a kind of improved measurement system for three-dimensional deformation based on splitting optical fiber is provided, simple in structure, easy to operate, and can guarantee measuring accuracy.

In order to achieve the above object, design of the present invention is:

The present invention is primarily aimed at hardware system and improves and innovate, adopt one fen five type optical fiber to carry out beam split, pass light, getting wherein, four bundle branch optical fibers constitute two opposite internal strains detections, by being scheduled to of optical fiber exit ports angle of divergence parameter, can directly be met the divergent beams of system requirements, need not beam expander spare.In order to improve the deformation measurement precision, still adopt four step phase shift algorithm, adopt traditional introducing phase shifting method, in above-mentioned two pairs of coherent light beams, select wherein a branch of branch optical fiber exit ports position to paste a PZT phase-shifter respectively respectively, promotion by the PZT phase-shifter drives the branch optical fiber fine motion, just can introduce phase shift in this light beam.The light beam of shared wherein a branch of introducing phase shift in conjunction with the 5th bundle branch optical fiber, obtains to satisfy the coherent light beam of system requirements.Therefore, entire system is owing to the employing of optical fiber, and structure is simplified greatly, debugging operations is convenient, because the use of blocking switch, this system can carry out the measurement of one dimension, two dimension or 3 D deformation separately, and make the software configuration of image post-processed simply, and guaranteed measuring accuracy.

According to above-mentioned inventive concept, the present invention adopts following technical proposals:

A kind of measurement system for three-dimensional deformation based on splitting optical fiber, pass light and Phase Shifting System is formed by the image receiving system of a laser instrument that light source is provided, a band ccd video camera and beam split, it is characterized in that described beam split passes light and Phase Shifting System is one fen five type optical fibre light splitting biography light and Phase Shifting System.

The structure that above-mentioned one minute five type optical fibre light splitting passes light and Phase Shifting System is: the main fiber that comes from described laser instrument connects one fen fiber coupler input port of five through a fiber adjusting mount, the output port of fiber coupler connects five bundle fiber optic taps to carry out beam split and pass light: a branch of branch optical fiber is connected the image receiving system of described band ccd video camera, the output port of four bundle branch beams is respectively placed one and is blocked switch, the output port of four bundle branch optical fibers is aimed at testee respectively, wherein two branch optical fibers are fixed by Phase Shifting System, respectively paste a PZT phase-shifter in the Phase Shifting System, expansion by the PZT phase-shifter is moved, the branch optical fiber that drives its stickup moves, and phase shift is introduced in the light beam.

The structure of above-mentioned Phase Shifting System is: branch optical fiber is fixed on the L type optical fiber fixed block, and L type optical fiber fixed block is pasted to become to be rigidly connected with the PZT phase-shifter, and then, the PZT phase-shifter is pasted to become to be rigidly connected with the fiber support frame.Branch optical fiber is not connected with the PZT phase-shifter with the fiber support frame.The PZT phase-shifter is moved forward by driven promotion L type optical fiber fixed block, moves axially along optical fiber thereby make L type optical fiber fixed block drive branch optical fiber, and phase shift is introduced in the branch optical fiber.

Above-mentioned no phase shift optical fiber fixed sturcture is: branch optical fiber directly is fixed on the fiber support frame.

The structure of the image receiving system of above-mentioned band ccd video camera is: from described laser emitting light beam through a microscope and fiber adjusting mount, pass light by branch optical fiber, by the spectroscope beam split, spectroscope places between ccd video camera and the CCD camera lens light beam after protecting the bundle collimating mirror, blocking switch.

Above-mentioned ccd video camera connects a computing machine.

The present invention compares with existing three-dimensional electronic speckle deformation detection system, has following conspicuous outstanding substantive distinguishing features and remarkable advantage: adopted one minute five type optical fibre light splitting in the system of the present invention, passed light; A shared light beams; Be met two of requirement of experiment by two PZT phase-shifters and restraint the laser branch beam that to introduce phase shift.By the beam split of optical fiber, three pairs of coherent light beams that the system that just can obtain is required.Optical device required for the present invention is few, and compactness rational in infrastructure is easy and simple to handle, is applicable to that the quasi real time 3 D deformation of body surface is measured.

Description of drawings

Fig. 1 is the system architecture synoptic diagram of one embodiment of the invention.

Fig. 2 is the structural representation that one minute five type optical fibre light splitting in Fig. 1 example passes light and Phase Shifting System.

Fig. 3 is the no phase shift branch beam fixed sturcture synoptic diagram in Fig. 2 example.

Fig. 4 is the phase shift branch beam fixed sturcture synoptic diagram in Fig. 2 example.

Fig. 5 is the adjustment schematic diagram of the harvester in Fig. 1 example.

Fig. 6 is that two pedal line coplanes are adjusted synoptic diagram.

Fig. 7 is the projection coplane principle schematic that vertical direction two branch beams are adjusted coplane.

Fig. 8 is vertical direction two branch optical fiber exit ports locus synoptic diagram.

Fig. 9 is that two horizontal line coplanes are adjusted synoptic diagram.

Figure 10 is the projection coplane principle schematic that horizontal direction two branch beams are adjusted coplane.

Figure 11 is vertical direction and horizontal direction four bundle branch optical fiber exit ports locus synoptic diagram.

Embodiment

System's adjustment process

The purpose of adjusting mainly contains 3 points:

1. horizontal direction two is restrainted branch beams about sample surface centre normal symmetry in the assurance face;

2. vertical direction two is restrainted branch beams about sample surface centre normal symmetry in the assurance face;

3. the size of obtaining four bundle branch beam space requirements is used for the demarcation of incident angle.

1. the adjustment of image collecting device

Like this, can finish the adjustment of harvester, make the consistance of irradiation area and pickup area, and make the collection direction be positioned at perpendicular (y-z).

2. the adjustment of vertical direction illumination beam

The coplane of the first step, two pedal line (being in the y-z face) is adjusted;

Adopt principle (two straight lines constitute a plane principle) adjustment as shown in Figure 6, purpose is: adjust two pedal line and make its coplane, and in the y-z face.

3. the adjustment of horizontal direction illumination beam

The first step, two horizontal coplanes (being in the x-z face) are adjusted;

Adopt principle (two straight lines constitute a plane principle) adjustment as shown in Figure 9, purpose is: adjust two horizontal lines and make its coplane, and in the x-z face.

4. from the adjustment of face direction reference beam

α = arctan ( L 1 C 1 ) - - - ( 1 )

θ = arctan ( L 1 C 1 ) - - - ( 2 )

Principle of work of the present invention

In the said system, the data acquisition operation steps is:

Speckle image before the distortion in three direction deformation detection systems is represented that with same form four width of cloth speckle images are expressed as respectively: I _Ba, I _Bb, I _Bc, I _Bd, that is:

I Ba = I 1 ( x , y ) + I 2 ( x , y ) + 2 I 1 ( x , y ) I 2 ( x , y ) cos [ φ R ( x , y ) - φ B ( x , y ) ] - - - ( 3 )

I Bb = I 1 ( x , y ) + I 2 ( x , y ) + 2 I 1 ( x , y ) I 2 ( x , y ) cos [ φ R ( x , y ) - φ B ( x , y ) - π 2 ] - - - ( 4 )

I Bc = I 1 ( x , y ) + I 2 ( x , y ) + 2 I 1 ( x , y ) I 2 ( x , y ) cos [ φ R ( x , y ) - φ B ( x , y ) - π ] - - - ( 5 )

I Bd = I 1 ( x , y ) + I 2 ( x , y ) + 2 I 1 ( x , y ) I 2 ( x , y ) cos [ φ R ( x , y ) - φ B ( x , y ) - 3 2 π ] - - - ( 6 )

Speckle image after the distortion in three direction deformation detection systems is represented with same form the width of cloth speckle image that gather the distortion back is designated as I _A, that is:

I A = I 1 ( x , y ) + I 2 ( x , y ) + 2 I 1 ( x , y ) I 2 ( x , y ) cos [ φ R ( x , y ) - φ B ( x , y ) + Δφ ( x , y ) ] - - - ( 7 )

In the formula, I ₁(x, y) and I ₂(x y) refers to the light intensity of thing light wave and reference light wave respectively; φ _B(x, y) and φ _R(x, y) refer to respectively thing light wave and reference light wave the position mutually; (x y) refers to be out of shape the phasic difference that causes to Δ φ.

Utilize " 4+1 " phase shift algorithm, formula (3), (4), (5), (6) are subtracted each other respectively with formula (7) respectively, then square, after being averaged, be expressed as respectively;＜I _FA ²,＜I _FB ²,＜I _FC ²,＜I _FD ², that is:

<I _FA ²>＝<[I _Ba(x，y)-I _A(x，y)] ²>

≈4I ₁(x，y)I ₂(x，y){1-cos[Δφ(x，y)]}

(8)

<I _FB ²>＝<[I _Bb(x，y)-I _A(x，y)] ²>

≈4I ₁(x，y)I ₂(x，y){1+sin[Δφ(x，y)]}

(9)

<I _FC ²>＝<[I _Bc(x，y)-I _A(x，y)] ²>

≈4I ₁(x，y)I ₂(x，y){1+cos[Δφ(x，y)]}

(10)

<I _FD ²>＝<[I _Bd(x，y)-I _YA(x，y)] ²>

≈4I ₁(x，y)I ₂(x，y){1-sin[Δφ(x，y)]}

(11)

With formula (8), (9), (10), (11) utilize trigonometric function operation handle the phase Δ φ that puts in place (x, y), that is:

Δφ(x，y)＝atan2(I _FB ²-I _FD ²，I _FC ²-I _FA ²)?(12)

According to vertical direction position in the face mutually and deformation relationship:

In the formula, α is illumination beam and body surface normal angle, and v is the distortion of vertical direction in the face, and λ is an optical maser wavelength.The position phase and the deformation relationship of horizontal direction in the face:

In the formula, θ is illumination beam and body surface normal angle, and u is the distortion of horizontal direction in the face, and λ is an optical maser wavelength.

And mutually and deformation relationship from the position of face direction:

In the formula, α is illumination beam and body surface normal angle, and v is the distortion of vertical direction in the face, and w for the quantification system of equations that obtains 3 D deformation from the face direction is: