CN101819066B - Three-dimensional interference imaging spectrum method - Google Patents

Abstract

The invention discloses a novel three-dimensional interference imaging spectrum method. In the method, by adopting a double-slit interference device, a slit is placed in front of an object as a main wave source, and a double-slit is taken as a sub-wave source; interference beam is collected by a cylindrical mirror; and a two-dimensional CCD detector for receiving the beam is placed on an image plane of the cylindrical mirror. The method organically combines an interference imaging spectrum technology with an optical three-dimensional measuring technology together, thus three-dimensional space information and spectrum information of the object can be measured simultaneously, and the information can be directly processed and combined into a three-dimensional color photo of the object.

Description

Three-dimensional interference imaging spectrum method

Technical field

The invention belongs to three-dimensional interference imaging spectral technology field, relate in particular to a kind of three dimensions steric information of object and method of one dimension spectral information obtained simultaneously.

Background technology

Imaging spectral technology refers to and obtains a series of spectrograms with two-dimensional space coordinate, utilizes characteristic spectrum to reach the technology of recognition objective, its essence is the spatial image that both obtains target, its corresponding curve of spectrum of getting back.

Along with science and technology development, obtain the more information amount: promptly from obtaining two-dimensional space information to obtaining three-dimensional spatial information; Extend to multispectral segment limit from single visual light imaging; From only obtaining spatial discrimination information to both obtaining spatial information, obtain spectral information again, be a kind of trend.

Up to the present; Reported various interference imaging spectral technology all is how to improve to make progress aspect the key technical indexes such as luminous flux, spectral resolution, visual field, but the interference imaging spectral technology of quovis modo still can only obtain two-dimensional space information and one dimension spectral information; And various 3 d shape measuring techniques also only are to improve constantly measuring speed and measuring accuracy, but still can only Measuring Object the volume coordinate of surface each point, can not obtain the spectral information of object.Particularly in the three-dimensional measurement technology; Along with the innovation of industrial expansion with technology; In industries such as animation making, Mould Machining; Require to obtain the color three dimension data of color rendering, and have in the main method aspect the color three dimension digitizing technique at present: the coloud coding method promptly arrives body surface through the projection colored light, and color three dimension information is analyzed and calculated to color image shot; Utilization laser plane active scan Measuring Object surface color three-dimensional data is carried out data splicing through manual operation again.These methods are owing to need repeatedly to take again with data fusion, and therefore from all carrying out the aligning and the coupling of identical point data in essence, calculated amount is difficult to guarantee than precision big and that aim at.

Summary of the invention

The invention provides and a kind ofly can obtain the three dimensions steric information of object and the three-dimensional interference imaging spectrum method of one dimension spectral information simultaneously.

The technical solution adopted for the present invention to solve the technical problems is:

1. a two-slit interference device is set, places a slit before the testee;

2. the testee reflected light produces interference behind double slit, uses a cylindrical mirror that interfering beam is collected horizontal direction (along two-dimensional CCD detector delegation and be parallel to paper);

3. place on the image plane of cylindrical mirror with the two-dimensional CCD detector and receive interferogram;

4. being positioned on the slit distributes along the interference strength of the different visual field points of slit (perpendicular to paper) direction is received by the different rows of detector; Thereby obtain one dimension spectrum and object one-dimensional space information along slit direction; Push away again when sweeping object, can obtain the spatial information of object plane through slit;

5. carry out Fourier transform and calculate the rgb value of each spectral coverage of wavelength, obtain the monochromatic light spectrogram and the secondary color photo of testee;

6. testee one segment distance being left in a translation in the double slit, as radiation source, obtain the length value of testee through the changing value of measuring the position phase with the laser diode of wavelength-tunable system, promptly is depth information.

The advantage that the present invention has is:

1) this measuring method can obtain the spatial depth information of one dimension determinand more; With existing three-dimensional measurement compared with techniques, can obtain the spectral information of object more.

2) because can be through interferogram being carried out the multispectral information of every bit on the Fourier transform acquisition determinand; Promptly obtained a series of monochromatic spectrogram of determinand; Therefore be easy to directly these photos synthesized the three-dimensional colour photo of object, avoided the splicing and the alignment issues of data in the existing color three dimension measuring technique.

3) be measured as contactlessly, the line sweep mode makes suitable occasion more extensive, has also improved efficiency of measurement largely.

4) adopt the variation of the laser diode Measurement Phase of wavelength-tunable, the shortcoming that the phase place uncertainty that the fringe projection method of having avoided being adopted in the common three-dimensional geometry measurement amount is brought is brought.

Description of drawings

Below in conjunction with accompanying drawing the present invention is elaborated:

Fig. 1 is interference imaging principle figure;

Fig. 2 is vertical depth information measuring principle figure.

Reference numeral:

Slit, S before the S-measured object ₁First slit of-two-slit interference device,

S ₂Second slit of-two-slit interference device,

S ₂'-position move before the two-slit interference device second slit slit location,

S ₃Second slit of the two-slit interference device after move-position,

The CL-cylindrical mirror;

-cylindrical mirror focal plane; The laser diode that L-can modulate.

Embodiment

The measuring method of two-dimensional space information and one dimension spectral information

Utilize the two-slit interference device to form a kind of inteference imaging spectrometer of spatial modulation type.As shown in Figure 1: double slit S ₁, S ₂Perpendicular to paper, placed a slit S before the object, be positioned at slit S ₁, S ₂Axis of symmetry on.S ₁, S ₂Can regard as by two sub-wave sources on the light wave of S emission.As long as S ₁, S ₂The line direction parallel with the X axle, the always parallel linear fringe with Z axle (inwards) of interferogram then perpendicular to paper.If device is arranged in air, then the expression formula of optical path difference is:

${\mathrm{\Δ}}_{\mathrm{SP}}=l\frac{x}{d}---\left(1\right)$

The two-dimensional CCD detector places on the image plane of cylindrical mirror CL and receives interferogram; Cylindrical mirror CL collects horizontal direction (delegation is parallel to paper along detector) with interfering beam; Like this; Being positioned at interference strength perpendicular to the different visual field points of paper direction on the slit distributes and is received by the different rows of detector; These interference strengths distribute can obtain the spectral distribution of impact point through Fourier transform, thereby acquisition one dimension spectrum and one dimension are along the spatial information of Z-direction.

Sweep object when the slit when pushing away, can obtain the spatial information that another dimension is an X-direction.Slit S also limits the influence of the size of object under test (light source) to the interferogram degree of modulation here.Because cylindrical mirror does not have focal power in paper, therefore do not influence the conclusion of optical path difference.The interferogram that collects carries out Fourier transform and subsequent processes by the interferogram process software of special establishment to it behind image pick-up card, obtain the monochromatic light spectrogram and the secondary color photo of target to be measured.

Spatial resolution on the slit height direction is decided by the height of slit and the line number of CCD; Spatial resolution on the slit width is decided by the width of slit itself.For example; The width of slit is 0.1 millimeter; Height is 10 millimeter, and then the spatial resolution of X-direction is exactly the width of slit, and the spatial resolution of Z axle is then relevant with the vertical picture dot number of the height of slit and CCD; If the CCD camera that adopts is 1024 * 1024, then the spatial resolution of Z-direction is: 0.16 '.Spectral resolution is decided by optical path difference, if distance is 10mm between double slit, double slit is apart from 350 millimeters in CCD camera, if the picture dot of CCD is of a size of 10u, then spectral resolution is about 32cm ^-1

The measuring method of optical axis direction deep space information

If S is arrived S ₁Light path write as [SS ₁], S is to S ₂Light path write as [SS ₂], then the first phase potential difference of two sub-light sources is:

K wherein ₀Be wave number.S is positioned at the plane of X=0 generally speaking, the optical path difference expression formula of the optical path difference this moment that therefore

is arranged and order from the S point to P this moment for

not about parameter along the Y direction variation.

As shown in Figure 2, for the depth information that obtains target the spatial information of Y direction (promptly along), with slit S ₂Along Y direction translation distance H, rename as slit S ₃, and with the LASER Light Source L illumination slit S that expands after restrainting.The initial phase difference of this moment will no longer equal zero.

In the coordinate system of Fig. 2, the coordinate of each point is respectively: S (0 ,-(a+d)), S ₁(1/2 ,-d); S ₃(1/2 ,-(d-H)), P (x, 0); Utilize distance between two points formula and series expansion formula to obtain

$\left[{\mathrm{SS}}_3\right]-\left[{\mathrm{SS}}_1\right]=H-\frac{1}{2}(\frac{1}{a}-\frac{1}{a+H})---\left(2\right)$

If a＞＞H, then following formula can be reduced to:

$\left[{\mathrm{SS}}_3\right]-\left[{\mathrm{SS}}_1\right]=H-\frac{H}{2a^2}---\left(3\right)$

Continue to derive and can draw:

$\left[S_{3}P\right]-\left[S_{1}P\right]=l\frac{x}{d}-H---\left(4\right)$

Therefore total optical path difference does

${\mathrm{\Δ}}_{\mathrm{SP}}=l\frac{x}{d}-\frac{H}{2a^2}---\left(5\right)$

This moment, target was included in the expression formula of optical path difference along the spatial information of Y axle.Promptly along Y direction, different points has different a values on the target, thereby has different optical path difference and phase differential.

The laser interference figure that obtain this moment can be expressed as:

I(x)＝A ₁(1+cosφ)

Wherein, A ₁Be the interferogram amplitude, φ is the phase differential between the two-beam.The laser diode that the present invention adopts wavelength to modulate is tried to achieve phase place as radiation source.Its cardinal principle is the injection current that changes laser diode through linearity, obtains the distinct transmit wavelength, just can obtain length value to be measured through the changing value of measuring the position phase.

Suppose that optical path difference is p (not use optical path difference conventional sign Δ here, to avoid distinguish mutually with following Δ λ), the initial transmissions wavelength of laser diode is λ, and then phase value is 2 π p/ λ; If this moment, Wavelength of Laser became λ+Δ λ by λ; Then the phase change of this moment is:

further abbreviation the change amount owing to the injection current of Δ λ and laser tube is directly proportional for

, so the variable quantity of phase place also is directly proportional with the change amount of laser tube injection current.Because λ and Δ λ are known, and the change amount of phase place can be measured, and so just can obtain the value of optical path difference.Can know that by formula (5) L, x, H, d all are known quantities, therefore just can obtain object depth information a to be measured.The measurement that this method is adjusted the distance can be as accurate as 1 μ m.

Claims (2)

1. a three-dimensional interference imaging spectrum method is characterized in that, obtains the three dimensions steric information and the one dimension spectral information of object simultaneously, may further comprise the steps:

-a two-slit interference device is set, place a slit before the testee;

-testee reflected light produces interference behind double slit, use a cylindrical mirror that interfering beam is collected along the horizontal direction of detector delegation;

-with the two-dimensional CCD detector place cylindrical mirror as receiving interferogram on the plane;

The interference strength of the different visual field points of-slit upper edge slit direction distributes and is received by the different rows of detector, thereby acquisition one dimension spectrum and object push away and sweep testee along the one-dimensional space information of slit direction, can obtain the spatial information of object plane;

-carry out Fourier transform and calculate the rgb value of each spectral coverage of wavelength, obtain the monochromatic light spectrogram and the secondary color photo of testee;

-testee one segment distance is left in a translation in the double slit, be used to produce non-vanishing initial phase difference;

-with the LASER Light Source of wavelength-tunable as radiation source, obtain the length value of testee through the changing value of measuring the position phase along optical axis direction.

2. the method for claim 1 is characterized in that, the LASER Light Source of said wavelength-tunable is the laser diode light source of wavelength-tunable system.

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