CN103759673B - De-packaging method time phase based on double frequency three GTG sinusoidal grating fringe projection - Google Patents

Abstract

This proposes a kind of de-packaging method time phase based on double frequency three GTG sinusoidal grating fringe projection.The inventive method utilizes computer to generate two groups of totally five double-frequency ideal sinusoidal grating fringes, then three GTG space pulse modulation technologies are adopted to generate the three GTG sinusoidal grating stripeds corresponding with ideal sinusoidal striped, when projector keeps defocusing by five three GTG sinusoidal grating fringe projections to object under test surface, solve two groups that five width Contour fringes comprise and be wrapped phase diagram, utilize the relation between these wrapped phases and Contour fringes wavelength, solve and be wrapped the fringe order that phase place is corresponding, it is achieved wrapped phase go parcel.The inventive method improves certainty of measurement and measuring speed.

Description

De-packaging method time phase based on double frequency three GTG sinusoidal grating fringe projection

Technical field

The invention belongs to field of optical measuring technologies, be specifically related to a kind of de-packaging method time phase based on double frequency three GTG sinusoidal grating fringe projection.

Background technology

In order to realize the three-dimensional measurement of high-speed, high precision, first have to ensure high-quality sine stripe projection.In method traditional at present, major part still adopts the way directly projecting sinusoidal grating, and the sine streak of this direct projection is easily subject to the impact of projector nonlinear effect, and becomes non-sinusoidal grating fringe, can largely effect on the precision of final measurement.In order to reduce the nonlinear impact of projector, Zhang Song et al. proposes a kind of measurement Error Compensation method overcoming nonlinear effect in " Genericnonsinusoidalphaseerrorcorrectionforthree-dimensi onalshapemeasurementusingadigitalvideoprojector " literary composition, although the method can reduce nonlinear impact, but can not accomplish to get rid of completely.Because the non-linear of projector is continually changing, not unalterable, non-linear possibility obtains good rectification at the beginning in measurement, but As time goes on, owing to it is continually changing, the effect of rectification can be more and more undesirable.

Secondly, in order to realize measuring at a high speed, will reducing projected light grid image, more few raster image is more conducive to recovering the three-dimensional appearance of object within the shorter time as far as possible.But at present conventional method, generally minimum need to use 6 amplitude grating stripeds and solve the absolute phase without parcel, it is achieved the reconstruction of a width 3-D view, relatively expend time in, measuring speed is relatively low.

Summary of the invention

Present invention aim at providing a kind of de-packaging method time phase based on double frequency three GTG sinusoidal grating fringe projection, to improve certainty of measurement and measuring speed.

In order to solve above-mentioned technical problem, the present invention provides a kind of de-packaging method time phase based on double frequency three GTG sinusoidal grating fringe projection, comprises the following steps:

Step one, utilizing computer to generate five width ideal sinusoidal stripeds, wherein the wavelength of three width ideal sinusoidal stripeds is λ₁, phase contrastThe wavelength of other two width ideal sinusoidal stripeds is λ₂, phase contrast

The five width ideal sinusoidal stripeds that step one is generated by step 2, use grating encoding method convert five three GTG sinusoidal grating stripeds to, use projector when defocusing by five three GTG sinusoidal grating fringe projections to object under test surface, it is thus achieved that comprise five width ideal sinusoidal grating fringe measurement figure of object under test surface information；

Step 3, use camera acquisition five width ideal sinusoidal grating fringe measure figure, it is thus achieved that the light intensity of every width ideal sinusoidal grating fringe, and using the phase solution equations shown in formula (1) to go out three amplitude wave length is λ₁Ideal sinusoidal grating fringe in comprise be wrapped phase₁, using the phase solution equations shown in formula (2) to go out two amplitude wave length is λ₂Ideal sinusoidal grating fringe in comprise be wrapped phase₂,

${\mathrm{\φ}}_1(x,y)={\tan }^{-1}\left(\sqrt{3}\right(I_1(x,y)-I_3(x,y))/(2I_2(x,y)-I_1(x,y)-I_3(x,y)\left)\right)---\left(1\right)$

φ₂(x, y)=tan^-1((I₄(x,y)-A)/(I₅(x,y)-A))(2)

In formula (1) and (2), I₁、I₂And I₃Be wavelength successively it is λ₁The light intensity of three width ideal sinusoidal grating fringes, I₄And I₅Be two amplitude wave length successively it is λ₂The light intensity of ideal sinusoidal grating fringe；(x, y) for the pixel coordinate of video camera；A is background light intensity；

Step 4, use formula (3) are asked for and are wrapped phase diagram φ₁Middle pixel (x, the fringe order k corresponding to y)₁Be wrapped phase diagram φ₂Middle pixel (x, the fringe order k corresponding to y)₂,

Round((p₁φ₂(x,y)-p₂φ₁(x, y))/2 π)=k₂(x,y)p₁-k₁(x,y)p₂(3)

In formula (3), parameter p₁=LCM (λ₁,λ₂)/λ₁, parameter p₂=LCM (λ₁,λ₂)/λ₂, LCM represents and seeks λ₁With λ₂Least common multiple, Round () represents round numbers；

Step 5, use formula (4) calculate and are wrapped phase₁Remove the phase place Φ after parcel₁Be wrapped phase₂Remove the phase place Φ after parcel₂,

$\left\{\begin{array}{c}{\mathrm{\Φ}}_1(x,y)={\mathrm{\φ}}_1(x,y)+2{\mathrm{\πk}}_1(x,y)\\ {\mathrm{\Φ}}_2(x,y)={\mathrm{\φ}}_2(x,y)+2{\mathrm{\πk}}_2(x,y)\end{array}\right.---\left(4\right).$

The present invention is compared with prior art, it has the great advantage that, the present invention utilizes three GTG space pulse modulation technologies to generate high-quality sinusoidal grating striped, it is ensured that certainty of measurement, only five amplitude grating stripeds need to be used just to solve Carrier-smoothed code problem simultaneously, improve measuring speed.

Accompanying drawing explanation

Fig. 1 be the present invention based on double frequency three GTG sinusoidal grating fringe projection time phase de-packaging method schematic flow sheet.

Fig. 2 is five the three GTG sinusoidal grating stripeds using the inventive method to obtain when testing, and wherein Fig. 2 (a) is wavelength X₁Three GTG sinusoidal grating stripeds of=48 pixels, Fig. 2 (b) is wavelength X₁Three GTG sinusoidal grating stripeds of=28 pixels.

Five width ideal sinusoidal grating fringe measurement figure of shooting when Fig. 3 is use the inventive method to test, wherein Fig. 3 (a) is the first width wavelength X₁The ideal sinusoidal grating fringe of=48 pixels measures figure, Fig. 3 (b) the second width wavelength X₁The ideal sinusoidal grating fringe of=48 pixels measures figure, and Fig. 3 (c) is the 3rd width wavelength X₁The ideal sinusoidal grating fringe of=48 pixels measures figure, and Fig. 3 (d) is the first width wavelength X₁The ideal sinusoidal grating fringe of=28 pixels measures figure, and Fig. 3 (e) is the second width wavelength X₁The ideal sinusoidal grating fringe of=28 pixels measures figure.

Two width solved in step 3 when Fig. 4 is use the inventive method to test are wrapped phase diagram, and wherein, Fig. 4 (a) is for being wrapped phase diagram φ₁, Fig. 4 (b) is for being wrapped phase diagram φ₂。

Fig. 5 is the phase diagram after using two width that the inventive method finally obtains when testing to remove parcel, and wherein, Fig. 5 (a) is wrapped phase diagram φ₁Remove the phase diagram Φ after parcel₁, 5 (b) is wrapped phase diagram φ₂Remove the phase diagram Φ after parcel₂。

Detailed description of the invention

As it is shown in figure 1, the present invention is based on de-packaging method time phase of double frequency three GTG sinusoidal grating fringe projection, comprise the following steps:

Step one, generation double frequency ideal sinusoidal striped:

Utilizing computer to generate five width ideal sinusoidal stripeds, wherein three width ideal sinusoidal striped wavelength are λ₁, phase contrast beOther two width ideal sinusoidal striped wavelength are λ₂, phase contrast be

Described three amplitude wave length are λ₁The light distribution of ideal sinusoidal striped meet formula (1), (2) and (3) successively:

I₁ ^p(x^p,y^p)=A^p(x^p,y^p)+B^p(x^p,y^p)cos(2πx^p/λ₁-2π/3)(1)

I₂ ^p(x^p,y^p)=A^p(x^p,y^p)+B^p(x^p,y^p)cos(2πx^p/λ₁)(2)

I₃ ^p(x^p,y^p)=A^p(x^p,y^p)+B^p(x^p,y^p)cos(2πx^p/λ₁+2π/3)(3)

Described two amplitude wave length are λ₂The light distribution of ideal sinusoidal striped meet formula (4) and (5) successively:

I₄ ^p(x^p,y^p)=A^p(x^p,y^p)+B^p(x^p,y^p)sin(2πx^p/λ₂)(4)

I₅ ^p(x^p,y^p)=A^p(x^p,y^p)+B^p(x^p,y^p)cos(2πx^p/λ₂)(5)

In above-mentioned formula, A^pFor DC component, B^pFor amplitude, and A^p(x^p,y^p)=B^p(x^p,y^p)=127.5, (x^p,y^p) for projector pixel coordinate.

Step 2, three conversion of GTG sinusoidal grating striped and projections:

The five width ideal sinusoidal stripeds that step one is generated by grating encoding method are used to convert five three GTG sinusoidal grating stripeds to, use projector when defocusing by five three GTG sinusoidal grating fringe projections to object under test surface, it is thus achieved that comprise five width ideal sinusoidal grating fringe measurement figure of object under test surface information；

Above-mentioned grating encoding method and projector project when defocusing the method for three GTG sinusoidal grating stripeds may refer to application number be 201210275349.7, name be called the Chinese invention patent application of " based on the sinusoidal grating building method of three GTG spatial pulse lengths modulation in three dimensional optical measuring ".

Preferred version as this step, it is possible to first projection wavelength is λ₁Three three GTG sinusoidal grating stripeds, rear projection wavelength is λ₂Two three GTG sinusoidal grating stripeds.

Step 3, it is wrapped asking for of phase place:

Measuring figure with camera acquisition five width ideal sinusoidal grating fringe, it is thus achieved that the light intensity of every width ideal sinusoidal grating fringe, using the phase solution equations shown in formula (6) to go out three amplitude wave length is λ₁Ideal sinusoidal grating fringe in comprise be wrapped phase₁, using the phase solution equations shown in formula (7) to go out two amplitude wave length is λ₂Ideal sinusoidal grating fringe in comprise be wrapped phase₂,

${\mathrm{\φ}}_1(x,y)={\tan }^{-1}\left(\sqrt{3}\right(I_1(x,y)-I_3(x,y))/(2I_2(x,y)-I_1(x,y)-I_3(x,y)\left)\right)---\left(6\right)$

φ₂(x, y)=tan^-1((I₄(x,y)-A)/(I₅(x,y)-A))(7)

In formula (6) and (7), I₁、I₂And I₃Be wavelength successively it is λ₁The light intensity of three width ideal sinusoidal grating fringes, I₄And I₅Be two amplitude wave length successively it is λ₂The light intensity of ideal sinusoidal grating fringe；(x, y) for the pixel coordinate of video camera；A is background light intensity；

Obtain the derivation principle of formula (6) and (7):

The light distribution of five width ideal sinusoidal grating fringes of camera acquisition can use formula (8) to (12) to represent according to this:

I₁(x, y)=A (x, y)+B (x, y) cos (φ₁(x,y)-2π/3)(8)

I₂(x, y)=A (x, y)+B (x, y) cos (φ₁(x,y))(9)

I₃(x, y)=A (x, y)+B (x, y) cos (φ₁(x,y)+2π/3)(10)

I₄(x, y)=A (x, y)+B (x, y) sin (φ₂(x,y))(11)

I₅(x, y)=A (x, y)+B (x, y) cos (φ₂(x,y))(12)

Wherein, I₁, I₂And I₃Be wavelength successively it is λ₁The light intensity of three width ideal sinusoidal grating fringes, I₄And I₅Be two amplitude wave length successively it is λ₂The light intensity of ideal sinusoidal grating fringe, (x, y) for the pixel coordinate of video camera, (x, y) for background light intensity, (x, y) for phase-modulation degree, φ for B for A₁Be wavelength it is λ₁Three width ideal sinusoidal grating fringes comprise be wrapped phase place, φ₂Be two amplitude wave length it is λ₂Ideal sinusoidal grating fringe comprise be wrapped phase place,

Simultaneous formula (8), (9) and (10), can obtain φ₁With A (x, y), as shown in formula (13) and (14),

${\mathrm{\φ}}_1(x,y)={\tan }^{-1}\left(\sqrt{3}\right(I_1(x,y)-I_3(x,y))/(2I_2(x,y)-I_1(x,y)-I_3(x,y)\left)\right)---\left(13\right)$

A (x, y)=(I₁(x,y)+I₂(x,y)+I₃(x,y))/3(14)

Simultaneous formula (11) and (12), it is possible to obtain phase₂, as shown in formula (15),

φ₂(x, y)=tan^-1((I₄(x,y)-A(x,y))/(I₅(x,y)-A(x,y)))(15)

Step 4, Carrier-smoothed code:

Use formula (16) to ask for and be wrapped phase diagram φ₁Middle pixel (x, the fringe order k corresponding to y)₁Be wrapped phase diagram φ₂Middle pixel (x, the fringe order k corresponding to y)₂,

Round((p₁φ₂(x,y)-p₂φ₁(x, y))/2 π)=k₂(x,y)p₁-k₁(x,y)p₂(16)

In formula (16), parameter p₁=LCM (λ₁,λ₂)/λ₁, parameter p₂=LCM (λ₁,λ₂)/λ₂, LCM represents and seeks λ₁With λ₂Least common multiple, Round () represents round numbers；

In formula (16), due to λ₁With λ₂It has been determined that and be all integer, so parameter p₁With p₂Also it is determined and is all integer.After the left side of above formula rounds, due to p on the right of above formula₁With p₂It has been determined that k₁With k₂It is all integer, when object under test is positioned at projector pixel lateral extent [0, LCM (λ₁,λ₂)] among view field time, k₁With k₂Can be now uniquely determined.

Step 5, ask for phase place:

Use formula (17) to calculate and be wrapped phase₁Remove the phase place Φ after parcel₁Be wrapped phase₂Remove the phase place Φ after parcel₂,

$\left\{\begin{array}{c}{\mathrm{\Φ}}_1(x,y)={\mathrm{\φ}}_1(x,y)+2{\mathrm{\πk}}_1(x,y)\\ {\mathrm{\Φ}}_2(x,y)={\mathrm{\φ}}_2(x,y)+2{\mathrm{\πk}}_2(x,y)\end{array}\right.---\left(17\right).$

Effect of the present invention can be further illustrated by following experiment:

The measurement system of test the method for the invention includes projection arrangement (TIDLPLightCrafterDMD), high-speed camera (AOSX-PRI) and a computer processed for data, it is per second that fringe projection and Fringe Acquisition speed are 1250 frames.Object under test is static plaster statue and the scraps of paper waved.The lateral resolution 608 of projector, is positioned over object under test and is projected among the region that the interval pixel of instrument pixels across scope [0,336] can illuminate.

Using method of the present invention to be operated, generating three amplitude wave length in step 2 is λ₁Three GTG sinusoidal grating stripeds of=48 pixels, wherein a width is such as shown in Fig. 2 (a), generates two width wavelength X in step 2₂Three GTG sinusoidal grating stripeds of=28 pixels, wherein a width is such as shown in Fig. 2 (b).Then, comprising the ideal sinusoidal grating fringe measurement figure of object under test surface information in step 3 with five width of video camera shooting, measure figure as shown in Figure 3, wherein Fig. 3 (a) is the first width wavelength X₁The ideal sinusoidal grating fringe of=48 pixels measures figure, Fig. 3 (b) the second width wavelength X₁The ideal sinusoidal grating fringe of=48 pixels measures figure, and Fig. 3 (c) is the 3rd width wavelength X₁The ideal sinusoidal grating fringe of=48 pixels measures figure, and Fig. 3 (d) is the first width wavelength X₁The ideal sinusoidal grating fringe of=28 pixels measures figure, and Fig. 3 (e) is the second width wavelength X₁The ideal sinusoidal grating fringe of=28 pixels measures figure.

Then, utilizing the phase processing algorithm described in step 3, what solve is wrapped phase diagram as shown in Figure 4, and wherein, Fig. 4 (a) is for being wrapped phase diagram φ₁, Fig. 4 (b) is for being wrapped phase diagram φ₂。

Finally use method described in step 4 and step 5, solve and be wrapped phase diagram φ₁Remove the phase diagram Φ after parcel₁, as shown in Fig. 5 (a)；Solve and be wrapped phase diagram φ₂Remove the phase diagram Φ after parcel₂, as shown in Fig. 5 (b).

Claims (3)

1. based on de-packaging method time phase of double frequency three GTG sinusoidal grating fringe projection, it is characterised in that comprise the following steps:

Step one, utilizing computer to generate five width ideal sinusoidal stripeds, wherein the wavelength of three width ideal sinusoidal stripeds is λ₁, phase contrastThe wavelength of other two width ideal sinusoidal stripeds is λ₂, phase contrast

The five width ideal sinusoidal stripeds that step one is generated by step 2, use grating encoding method convert five three GTG sinusoidal grating stripeds to, use projector when defocusing by five three GTG sinusoidal grating fringe projections to object under test surface, it is thus achieved that comprise five width ideal sinusoidal grating fringe measurement figure of object under test surface information；

Step 3, use camera acquisition five width ideal sinusoidal grating fringe measure figure, it is thus achieved that the light intensity of every width ideal sinusoidal grating fringe, and using the phase solution equations shown in formula (1) to go out three amplitude wave length is λ₁Ideal sinusoidal grating fringe in comprise be wrapped phase₁, using the phase solution equations shown in formula (2) to go out two amplitude wave length is λ₂Ideal sinusoidal grating fringe in comprise be wrapped phase₂,

${\mathrm{\φ}}_1(x,y)={\tan }^{-1}\left(\sqrt{3}\right(I_1\left(x,y\right)-I_3\left(x,y\right))/(2I_2\left(x,y\right)-I_1\left(x,y\right)-I_3\left(x,y\right)\left)\right)---\left(1\right)$

φ₂(x, y)=tan^-1((I₄(x,y)-A)/(I₅(x,y)-A))(2)

In formula (1) and (2), I₁、I₂And I₃Be wavelength successively it is λ₁The light intensity of three width ideal sinusoidal grating fringes, I₄And I₅Be two amplitude wave length successively it is λ₂The light intensity of ideal sinusoidal grating fringe；(x, y) for the pixel coordinate of video camera；A is background light intensity；

Step 4, use formula (3) are asked for and are wrapped phase diagram φ₁Middle pixel (x, the fringe order k corresponding to y)₁Be wrapped phase diagram φ₂Middle pixel (x, the fringe order k corresponding to y)₂,

Round((p₁φ₂(x,y)-p₂φ₁(x, y))/2 π)=k₂(x,y)p₁-k₁(x,y)p₂(3)

In formula (3), parameter p₁=LCM (λ₁,λ₂)/λ₁, parameter p₂=LCM (λ₁,λ₂)/λ₂, LCM represents and seeks λ₁With λ₂Least common multiple, Round () represents round numbers；

Step 5, use formula (4) calculate and are wrapped phase₁Remove the phase place Φ after parcel₁Be wrapped phase₂Remove the phase place Φ after parcel₂,

$\left\{\begin{array}{c}{\mathrm{\Φ}}_1(x,y)={\mathrm{\φ}}_1(x,y)+2{\mathrm{\πk}}_1(x,y)\\ {\mathrm{\Φ}}_2(x,y)={\mathrm{\φ}}_1(x,y)+2{\mathrm{\πk}}_2(x,y)\end{array}\right.---\left(4\right).$

2. de-packaging method time phase based on double frequency three GTG sinusoidal grating fringe projection as claimed in claim 1, it is characterised in that in step one,

Described three amplitude wave length are λ₁The light distribution of ideal sinusoidal striped meet formula (5), (6) and (7) successively:

I₁ ^p(x^p,y^p)=A^p(x^p,y^p)+B^p(x^p,y^p)cos(2πx^p/λ₁-2π/3)(5)

I₂ ^p(x^p,y^p)=A^p(x^p,y^p)+B^p(x^p,y^p)cos(2πx^p/λ₁)(6)

I₃ ^p(x^p,y^p)=A^p(x^p,y^p)+B^p(x^p,y^p)cos(2πx^p/λ₁+2π/3)(7)

Described two amplitude wave length are λ₂The light distribution of ideal sinusoidal striped meet formula (8) and (9) successively:

I₄ ^p(x^p,y^p)=A^p(x^p,y^p)+B^p(x^p,y^p)sin(2πx^p/λ₂)(8)

I₅ ^p(x^p,y^p)=A^p(x^p,y^p)+B^p(x^p,y^p)cos(2πx^p/λ₂)(9)

In formula (5) to (9), A^pFor DC component, B^pFor amplitude, and A^p(x^p,y^p)=B^p(x^p,y^p), (x^p,y^p) for projector pixel coordinate.

3. de-packaging method time phase based on double frequency three GTG sinusoidal grating fringe projection as claimed in claim 1, it is characterised in that in described step 2, first projection wavelength is λ₁Three three GTG sinusoidal grating stripeds, rear projection wavelength is λ₂Two three GTG sinusoidal grating stripeds.