CN205718873U - A kind of double frequency phase shift tripleplane measuring instrument - Google Patents

Abstract

This utility model provides a kind of grating pair, is made up of the sinusoidal grating of high and low frequency fringe period, and its fringe period meetsWherein, T₁For low frequency fringes cycle, T₂For the high frequency fringes cycle,Represent and take downwardsMaximum integer, T₂It is C₁Integral multiple.This utility model also provides for a kind of double frequency phase shift tripleplane measuring instrument applying described grating pair.The grating that this utility model provides to and double frequency phase shift tripleplane measuring instrument can expand tolerance, the problem solving erroneous judgement striped numbering.

Description

A kind of double frequency phase shift tripleplane measuring instrument

Technical field

This utility model relates to optical three-dimensional measurement field, particularly relates to a kind of cycle and meets specific Contour fringes The grating of cycle combination to and apply the double frequency phase shift tripleplane measuring instrument of described grating pair.

Background technology

At present, optical three-dimensional measurement instrument based on grating loss mainly by optical projection system, image-taking system and Information processing system forms: optical projection system is by white light source, condenser lens group, projecting lens, sinusoidal grating mould Plate and phase-shifter composition, be used for producing sinusoidal grating and being incident upon body surface；Image-taking system master Will be made up of high resolution CCD video camera, platform for video camera and pick-up lens, the grating obtaining body surface becomes Information processing system is passed to after shape image；Information processing system is mainly computer and relevant process software, uses Rebuild and information output in object dimensional.

The solution technique for packing that double frequency phase shift tripleplane measuring instrument uses mainly has double frequency heterodyne method and look-up table, Phase error is required strict by double frequency heterodyne method, comprises division item and expand error in algorithm, it is impossible to keep phase The wrapped phase precision that shifting technology is obtained, in application time error tolerance less than look-up table.Look-up table utilizes The relation in phase contrast and cycle makes " phase contrast " → " cycle numbering " mapping table, directly tries to achieve this position by tabling look-up Put (pixel) cycle numbering, after adding wrapped phase value, obtain true phase.But, judging that the cycle compiles Number time, mapping table the distribution spacing being respectively worth forms tolerance, and owing to being randomly distributed, usual tolerance is the most too Little so that judgement cycle numbering is extremely difficult causes decision error.Only in the feelings that system signal noise ratio is the highest Could be suitable under condition, actually used be very restricted.

Utility model content

The purpose of this utility model is, solves that look-up table tolerance is little in prior art, is easily caused and is determining The technical problem gone wrong during striped numbering.

The purpose of this utility model realizes by the following technical solutions:

A kind of grating pair, is made up of the sinusoidal grating of high and low frequency fringe period, and its fringe period meetsWherein, T₁For low frequency fringes cycle, T₂For the high frequency fringes cycle,Represent Take downwardsMaximum integer, T₂It is C₁Integral multiple, C₁For setting range to low-frequency cycle T₁Multiple.

A kind of double frequency phase shift tripleplane measuring instrument, including computer, CCD camera, optical projection system, and Testee platform, described optical projection system includes a grating pair, described optical projection system by described grating to point Not successively it is projected on testee, described CCD camera collection striped after described testee is modulated, And be transferred to described computer and carry out phase analysis, described grating is to by the sinusoidal light of high and low frequency fringe period Grid form, and its fringe period meetsWherein, T₁For low frequency fringes cycle, T₂For high frequency Fringe period,Represent and take downwardsMaximum integer, T₂It is C₁Integral multiple, C₁For set amount Journey is to low-frequency cycle T₁Multiple.

Compared to prior art, the grating of this utility model design to and apply the double frequency phase shift of this grating pair Tripleplane's measuring instrument can expand tolerance, the problem solving erroneous judgement striped numbering.

Described above is only the general introduction of technical solutions of the utility model, in order to it is new to better understand this practicality The technological means of type, and can being practiced according to the content of description, and in order to allow of the present utility model on State and can become apparent with other objects, features and advantages, below especially exemplified by preferred embodiment, and coordinate attached Figure, describes in detail as follows.

Accompanying drawing explanation

Fig. 1 is the light path signal of the double frequency phase shift tripleplane measuring instrument that this utility model first embodiment provides Figure.

Fig. 2 is the structural representation of the double frequency phase shift tripleplane measuring instrument that this utility model first embodiment provides Figure.

Fig. 3 is the measuring method flow chart of double frequency phase shift tripleplane measuring instrument.

Fig. 4 is to repeat two schematic diagrams that striped is numbered respectively caused by phase truncation.

Fig. 5 is the schematic diagram of the look-up table utilizing MATLAB software to set up.

Fig. 6 is the schematic diagram of triangle telemetry.

Detailed description of the invention

For the ease of understanding this utility model, below with reference to relevant drawings, this utility model is carried out more comprehensively Description.Accompanying drawing gives better embodiment of the present utility model.But, this utility model can be with Many different forms realize, however it is not limited to embodiments described herein.On the contrary, provide these The purpose of embodiment be make disclosure of the present utility model is understood more thorough comprehensively.

Unless otherwise defined, all of technology used herein and scientific terminology with belong to of the present utility model The implication that those skilled in the art are generally understood that is identical.Institute in description of the present utility model herein The term used is intended merely to describe the purpose of specific embodiment, it is not intended that in limiting this utility model. Term as used herein " and/or " include the arbitrary and all of of one or more relevant Listed Items Combination.

Seeing also Fig. 1, Fig. 1 is that the double frequency phase shift tripleplane that this utility model first embodiment provides surveys The light path schematic diagram of amount instrument 20.Fig. 2 is the double frequency phase shift tripleplane that this utility model first embodiment provides The structural representation of measuring instrument 20.

Grating to 10 by the sinusoidal grating 101 of a high fringe period and the sinusoidal light in a low frequency fringes cycle Grid 102 form, and its fringe period meetsWherein, T₁For low frequency fringes cycle, T₂For The high frequency fringes cycle,Represent and take downwardsMaximum integer, T₂It is C₁Integral multiple,It is Remainder, C₁For setting range to low-frequency cycle T₁Multiple.

When using this grating to 10 projection, high frequency fringes has the higher precision that unpacks, but frequency is the most unsuitable The highest, otherwise it is easily subject to noise jamming and produces error.In the present embodiment, T can be chosen₂=22 conducts Optimum precision striped.In order to suppress influence of noise, the value of A is usually no more than 5, and therefore A is set to 4, Wherein C₁For range S to low-frequency cycle T₁Multiple, (S=LCM (T₁,T₂) it is T₁,T₂Least common multiple), C₁Take T as far as possible₂Approximate number in mediant, be used for making tolerance and range obtain higher value simultaneously.According to above Data and formula it follows that low-frequency cycle T₁=99.So can complete a high and low frequency bar The stricture of vagina cycle is respectively the sinusoidal grating pair of 99 and 22.

Grating meets specific period relation to 10, and the striped producing its projection can when carrying out three-dimensional measurement Expand system margins.

Double frequency phase shift tripleplane measuring instrument 20 includes: computer 30 (built-in related software), CCD camera 40, Optical projection system 50, and testee platform 60.

Wherein, computer 30 is for being responsible for phase analysis and the three-dimensional reconstruction of testee, and controls phase-shifter Mobile.CCD camera 40 is used for gathering information.Testee platform 60 is used as the platform of projected fringe.

Optical projection system 50 at least includes: white light source 51, grating to 10, phase-shifter 52, and condenser lens group 53.

Wherein, white light source 51 is used for producing white light.Grating is used for producing striped to 10, and phase-shifter 52 is used for making Grating produces four-step phase-shifting to 10, and condenser lens group 53 is for spreading the light that white light source 51 sends.

The double frequency phase shift tripleplane measuring instrument 20 that the present embodiment the provides light to meeting special stripe period-luminosity relation Grid are to projecting, it is possible to expand tolerance, it is simple to number for striped, under conditions of hardware signal to noise ratio is low also Can normally measure.

Refer to the measuring method flow chart that Fig. 3, Fig. 3 are double frequency phase shift tripleplane measuring instruments 20.

Step 1, produces two groups of four-step phase-shifting projected fringes by phase-shifter 52 and grating to 10, and is projected in The surface of testee.

Specifically, phase-shifter 52 can be automatically controlled output voltage width by computer 30 by D/A interface board Degree, circuit design is closed control circuit, use motor produce displacement, have the highest voltage-regulation coefficient and Less phase displacement error.Before experiment, use coherent phase detection scaling method that phase-shifter 52 is demarcated, In experiment when to phase shift driver voltage output 110v, phase-shifter 52 just produces the phase shift of 90 °.

Step 2, uses CCD camera 40 shooting, collecting to effect preferably phase shift streak photograph.

Step 3, utilizes the phase shift information of MATLAB software analysis striped, is solved by four-step phase-shifting and obtains Wrapped phase φ₁,φ₂。

Step 4, utilizesTwo wrapped phases can be normalized and obtain Wherein (x y) is wrapped phase value to φ.

Repeat two stripeds caused by phase truncation are numbered (such as Fig. 4 institute by step 5 respectively Show).

Step 6, utilizes MATLAB to set up one and meets " the intrinsic phase contrast between two groups of wrapped phases Correspond to the numbering combination of intrinsic fringe period " the fringe period numbering combination table of this relation is (such as Fig. 5 institute Show).

In a previous step, utilize

Two wrapped phases can be normalized and obtainCamera coordinates for sinusoidal cycles definition System has:

Wherein h₁(x, y) location of pixels that expression low frequency fringes records, h₂(x, y) expression high frequency fringes records Location of pixels；T₁Represent the cycle of low frequency fringes, T₂Represent the cycle of high frequency fringes；(x y) represents low frequency to n Fringe period is numbered, and (x y) represents high frequency fringes cycle numbering to m；Represent the normalization phase value of low frequency fringes,Represent the normalization phase value of high frequency fringes.

From the definition of camera coordinates, camera coordinates value be one with striped numbering, wrapped phase value and The function that fringe period is relevant.

For unpacking same location of pixels in scene, camera coordinates only with this location of pixels (x, y) relevant, And it is unrelated, therefore with the cycle numbering of projection striped and phase value

h₁(x, y)=h₂(x,y) (3)

Simultaneous (2--1) (2--2) (3) can obtain

Transposition can obtain

Definition normalization phase difference function:

Definition height striped numbering difference function:

δ (n, m)=nT₁-mT₂(7)

Intrinsic phase contrast between visible two wrapped phasesCorrespond to intrinsic fringe period numbering Combination δ (n, m).

Step 7, calculating phase difference function:

Step 8, table look-up obtain correspondence striped numbering (n, m), then utilize numbering recover absolute phase.

Note maximum range h_maxX ()=S meets S=c_iT_i, expression S is T_iIntegral multiple, i=1,2 in this amount In journey, exhaustive all ni, m_jCombination value condition, set up ni, m_jCombination and a_ijCorresponding look-up table, Tried to achieve by formula (6) when unpackingThen n is obtained by tabling look-up_i,m_jValue, obtain phase Machine coordinate figure, completes to unpack.

After having unpacked, Fig. 6 can be referred to by the actual height of common triangle telemetry reduction object, Fig. 6 is the schematic diagram of triangle telemetry.

${\mathrm{PP}}^{\′}=\frac{l({\mathrm{\θ}}_A-{\mathrm{\θ}}_B)}{({\mathrm{\θ}}_A-{\mathrm{\θ}}_B)+2\mathrm{\π}d/\mathrm{\λ}}$

Wherein λ is to change the length corresponding to the cycle for grating intercept, i.e. phase place.

Above formula is the height phase place corresponding relation formula of classical optical grating projection, meet video camera, projector and On the premise of the corresponding relation of plane of reference three, solve phase by projecting to the raster image of reference plane X Place value θ_B.When measuring, owing to reference plane X place testee 200, light beam can be adjusted because of body surface System makes raster image deform, and can solve phase theta by the raster image of deformation_A, finally will deformation Grating and original grating subtract each other, and draw body surface phase difference θ_A-θ_BBring above formula into and just can obtain this thing The height of point, completes the conversion from phase place to object height.

To sum up, the double frequency phase shift tripleplane measuring instrument 20 that the present embodiment provides closes meeting the special stripe cycle The grating of system is to projecting, it is possible to expand tolerance, it is simple to number for striped, at the bar that hardware signal to noise ratio is low Also can normally measure under part.

Embodiment described above only have expressed several embodiments of the present utility model, its describe more concrete and In detail, but therefore can not be interpreted as the restriction to this utility model the scope of the claims.It should be pointed out that, For the person of ordinary skill of the art, without departing from the concept of the premise utility, it is also possible to Making some deformation and improvement, these broadly fall into protection domain of the present utility model.Therefore, this utility model The protection domain of patent should be as the criterion with claims.

Claims (2)

1. a grating pair, it is characterised in that: described grating forms by the sinusoidal grating of high and low frequency fringe period, Its fringe period meetsWherein, T₁For low frequency fringes cycle, T₂For the high frequency fringes cycle,Represent and take downwardsMaximum integer, T₂It is C₁Integral multiple, C₁For setting range to the low-frequency cycle T₁Multiple.

2. a double frequency phase shift tripleplane measuring instrument, including computer, CCD camera, optical projection system, and quilt Surveying object platform, described optical projection system includes a grating pair, described optical projection system by described grating to respectively Successively it is projected on testee, described CCD camera collection striped after described testee is modulated, and It is transferred to described computer and carries out phase analysis, it is characterised in that: described grating is to by high and low frequency striped week The sinusoidal grating composition of phase, its fringe period meetsWherein, T₁For the low frequency fringes cycle, T₂For the high frequency fringes cycle,Represent and take downwardsMaximum integer, T₂It is C₁Integral multiple, C¹ For setting range to low-frequency cycle T₁Multiple.