CN101393016A - Three-dimensional shape measuring apparatus - Google Patents
Three-dimensional shape measuring apparatus Download PDFInfo
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- CN101393016A CN101393016A CNA2008102118799A CN200810211879A CN101393016A CN 101393016 A CN101393016 A CN 101393016A CN A2008102118799 A CNA2008102118799 A CN A2008102118799A CN 200810211879 A CN200810211879 A CN 200810211879A CN 101393016 A CN101393016 A CN 101393016A
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- optical path
- path length
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
- G01B11/25—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures by projecting a pattern, e.g. one or more lines, moiré fringes on the object
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B9/00—Measuring instruments characterised by the use of optical techniques
- G01B9/02—Interferometers
- G01B9/02055—Reduction or prevention of errors; Testing; Calibration
- G01B9/0207—Error reduction by correction of the measurement signal based on independently determined error sources, e.g. using a reference interferometer
- G01B9/02071—Error reduction by correction of the measurement signal based on independently determined error sources, e.g. using a reference interferometer by measuring path difference independently from interferometer
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B9/00—Measuring instruments characterised by the use of optical techniques
- G01B9/08—Optical projection comparators
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B2290/00—Aspects of interferometers not specifically covered by any group under G01B9/02
- G01B2290/60—Reference interferometer, i.e. additional interferometer not interacting with object
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- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Computer Vision & Pattern Recognition (AREA)
- Length Measuring Devices By Optical Means (AREA)
- Instruments For Measurement Of Length By Optical Means (AREA)
Abstract
The invention relates to a 3D shape measuring device, which is a technology capable of reducing measurement time for 3D measurement. A lightpath forming part receives a wideband light from a wideband light source, and branch of the light is incident to a reference lightpath and a measuring lightpath, the reflective light from a reference mirror and the reflective light from a measured object is mixed and output to a shooting mechanism. On the other hand, the measuring lightpath changes by a lightpath length variable mechanism. The shooting mechanism generates a time sequence of aliasing corresponding to the change of the lightpath length and shoots the output from the lightpath forming part, thereby obtaining interference fringe data including interference fringe. A lightpath length detecting mechanism removes the frequency component produced by aliasing from the interference fringe data obtained from the shooting mechanism, so a special lightpath length of an eigenvalue displaying the interference fringe is obtained.
Description
Technical field
The present invention relates to interference that a kind of use has the broad band light (for example, white light) of a plurality of frequency spectrums (spectrum) (below, describe with wavelength) and come the shape of measured object is carried out the 3 d shape measuring apparatus of measurement in space.Particularly relate to a kind of technology that in 3 d shape measuring apparatus, shortens the time of obtaining the optical path length that produces interference fringe, described 3 d shape measuring apparatus is to be incident to the reference path that far-end has reference mirror in a part that makes broad band light, make another part of broad band light be incident to the measurement light path that far-end has measured object, be used to each back light of self-reference mirror (catoptron) and measured object and produce in the interference part (interferometer) of interference, according to any the optical path length that makes reference path or the measure light path interference fringe that the obtains optical path length when producing that changes, measure the shape of measured object.
Background technology
Usually, utilized following phenomenon in the form measuring instrument of described use interference, that is: when reference path and measurement light path both sides' optical path length became equal, interference fringe can demonstrate high-high brightness.That is to say, any the optical path length that makes reference path or measure light path change (below, suppose to make the optical path length of reference path to fix, and the optical path length of measuring light path is changed, thereby describe), the optical path length (variable quantity of optical path length: hereinafter referred to as " specific optical path length ") that the interference fringe that produces this moment is demonstrated the position of high-high brightness is measured (patent documentation 1) as the displacement of the measured object on the change direction of optical path length.
In patent documentation 1, the interference light that makes optical path length change and be obtained according to variation along with the time, partial wave becomes B composition (blue band component), G composition (green band component) and R composition (red band component), detect the variation of the phase place of the interference fringe that changes with respect to optical path length respectively, and the optical path length when consistent is regarded as the specific optical path length that interference fringe demonstrates the position of high-high brightness with three's phase place.Carry out shape measure according to the specific optical path length of being assert again.
Patent documentation 1: Jap.P. is special is willing to 2006-371632 number
Usually, form measuring instrument will be implemented to measure to the measured object of a greater number, so the expectation Measuring Time can shorten slightly.When shortening Measuring Time, as the object element that improves, have optical path length variable time (perhaps speed), camera shooting time and take number of times etc., but shooting time be subjected to camera capturing element the restriction of intrinsic minimum exposure time.
Therefore, the viewpoint from Measuring Time below is investigated prior art.Under the situation of patent documentation 1, it is the phase place of specifying interference fringe according to the data of interference light, thereby obtain specific optical path length, and be the numerical data that converts the expression interference light from the simulated data of interference light at this moment, and the data of time zone (optical path length zone) are carried out FFT (Fast Fourier Transformation, fast fourier transform) handles, on frequency field, be separated into each band component, and on time zone, obtain the interference fringe of each band component once more, obtain the consistent point of its phase place.At this moment, in order to reproduce interference fringe by the numerical data of being obtained, usually must be according to sampling thheorem etc., the sequential (timing) of obtaining of repetition that can obtain the data of 3 points (point) in per 1 cycle of the interference fringe of wanting to reproduce at least converts numerical data to.
Usually, using the measured interference fringe of interferometric method in the form measuring instrument is by its numerical data, schematically show shown in Fig. 7 (A), to change with respect to the brightness of the optical path length that changes, its spectrum distribution such as Fig. 7 (B) represent on the coordinate of the frequency that is shown in to amplitude.As everyone knows, the envelope width Delta t of the interference fringe of Fig. 7 this moment (A) (for example, half value is wide: the brightness value of crest becomes the width of 1/2 o'clock transverse axis) exist correlativity with the bandwidth Δ F (for example, half value is wide: the amplitude of crest becomes the width of 1/2 o'clock transverse axis) of the frequency of Fig. 7 (B).Therefore, according to envelope width Delta t, can obtain that bandwidth Δ F narrows down shown in Fig. 7 (B), thereby there is the condition in the space (space) of Δ Fc in the frequency band in the bottom.That is to say, can obtain following condition, that is: shown in 2 chain lines of Fig. 7 (B), bandwidth Δ F can not become the broadband of frequency near 0 (flip-flop).
Say from sampling thheorem, as long as sample frequency Fs is the frequency that fully is higher than highest frequency component contained in the interference fringe, just can shown in Fig. 7 (B), reproduce the original frequency content that interference fringe had, but, can produce aliasing (aliasing) along with the reduction of this sample frequency Fs.That is to say, shown in Fig. 7 (C), the frequency content of turning back (dotted portion) that original required frequency content (solid line part) and aliasing cause is along with the decline (identical with the situation of frequency division) of the frequency of reproduction, and closer to each other shown in Fig. 7 (D), shown in Fig. 7 (E), become the just state of great change then.
Therefore, the present inventor is conceived to ensuing situation.That is to say, shown in Fig. 7 (B), because there is the space of Δ Fc in the frequency bandwidth characteristics of interference fringe self, so, just can shown in Fig. 7 (E), become required frequency content and state that the frequency content of turning back is separated on frequency by selecting sample frequency Fs.Therefore, shown in Fig. 7 (F), utilize wave filter to remove the frequency content of turning back, and sample frequency is further reduced, the reduction of frequency axis and frequency is correspondingly extended, thereby can reproduce.
Like this, even the frequency lower than the frequency that satisfies sampling thheorem also can obtain the required frequency content of interference fringe.That is to say, be conceived to reduction with sample frequency Fs and correspondingly reduce data and obtain number of times, thereby realize the shortening of Measuring Time.
This shows that above-mentioned existing form measuring instrument obviously still has inconvenience and defective, and demands urgently further being improved in structure and use.In order to solve the problem of above-mentioned existence, relevant manufacturer there's no one who doesn't or isn't seeks solution painstakingly, but do not see always that for a long time suitable design finished by development, and common product does not have appropriate structure to address the above problem, this obviously is the problem that the anxious desire of relevant dealer solves.Therefore how to found a kind of novel 3 d shape measuring apparatus, real one of the current important research and development problem that belongs to, also becoming the current industry utmost point needs improved target.
Because the defective that above-mentioned existing form measuring instrument exists, the inventor is based on being engaged in this type of product design manufacturing abundant for many years practical experience and professional knowledge, and the utilization of cooperation scientific principle, actively studied innovation, in the hope of founding a kind of novel 3 d shape measuring apparatus, can improve general existing form measuring instrument, make it have more practicality.Through constantly research, design, and, create the present invention who has practical value finally through after studying sample and improvement repeatedly.
Summary of the invention
The objective of the invention is to, overcome the defective that existing 3 d shape measuring apparatus exists, and a kind of novel 3 d shape measuring apparatus is provided, technical matters to be solved is to make it can shorten Measuring Time, is very suitable for practicality.
The invention provides a kind of 3 d shape measuring apparatus, it possesses: broadband light source, and output has the broad band light of a plurality of frequency spectrums; Light path formation portion, make described broad band light branch incide reference path and dispose the measurement light path of measured object, and make and export after closing ripple from the reflected light of described reference mirror with from each reflected light of the irradiation position of the range of exposures of irradiated described measured object with reference mirror; The optical path length changeable mechanism changes any optical path length of described reference path or described measurement light path; Photographic unit, with respect to the variation of the described optical path length that causes by described optical path length changeable mechanism, at the sampling time sequence of regulation to taking from the output of described light path formation portion, thereby obtain the interference fringe data that contain interference fringe; And optical path length testing agency, according to described interference fringe data from described photographic unit output, and the specific optical path length when obtaining the eigenwert that demonstrates described interference fringe, this 3 d shape measuring apparatus is measured the shape of described measured object according to the described specific optical path length of being obtained
The sampling time sequence of the described regulation when described photographic unit is taken, it is the sequential that produces aliasing in the interference fringe contained in the output of described light path composition, this sampling time sequence is made as at frequency field and is separable into the real frequency composition wanted and the sequential of the frequency content that produces because of described aliasing, and then
Described optical path length testing agency possesses: interference fringe data selection portion, to convert the data of frequency field by the interference fringe data that described photographic unit obtains at the sampling time sequence of described regulation to, and except the useless composition that described aliasing is produced, and the new interference fringe data of selecting described real frequency composition to produce; And the optical path length calculating part, according to described new interference fringe data, obtain the described specific optical path length of the eigenwert that demonstrates described interference fringe.
Aforesaid 3 d shape measuring apparatus, wherein said interference fringe data selection portion will be carried out fourier transform based on the sample data number of described sampling time sequence according to this from the number of interference fringes of described photographic unit output, thereby carry out the data-switching of described frequency field, and except the useless composition that on this frequency field, described aliasing is produced, select the new interference fringe data of this frequency field with this, described optical path length test section becomes sample data number based on sampling thheorem with the described sampled data number conversion of the new interference fringe data of this frequency field, then the new interference fringe data of this frequency field are carried out contrary fourier transform, converting the new interference fringe data of time zone to, and obtain the described specific optical path length of the eigenwert that demonstrates described interference fringe according to the new interference fringe data of this time zone.
Aforesaid 3 d shape measuring apparatus, wherein so-called with respect to the described optical path length that causes by described optical path length changeable mechanism variation and produce the sequential of described aliasing, be meant that when the approximate centre wavelength with described broad band light is made as λ the variation of this optical path length that is caused by this optical path length changeable mechanism surpasses the interval of λ/6.
Aforesaid 3 d shape measuring apparatus, wherein said photographic unit was taken with the intrinsic minimum exposure time, and when the speed that described optical path length is changed described optical path length changeable mechanism was made as v, the time interval that the variation of described optical path length is surpassed λ/(6v) took as described sequential.
Aforesaid 3 d shape measuring apparatus, wherein said optical path length testing agency has the wavelength selection portion, extract at least two wavelength components from the selected described new interference fringe data of described interference fringe data selection portion, described optical path length calculating part roughly becomes zero described optical path length according to the phase differential of at least two wavelength components of described extraction and obtains as described specific optical path length.
By technique scheme, 3 d shape measuring apparatus of the present invention has following advantage and beneficial effect at least:
For achieving the above object, must investigate envelope width Delta t, the bandwidth Δ F of interference fringe and the relation between the highest frequency Fh thereof, and usually the cycle of interference fringe be cycle λ about 1/2 of centre wavelength of the light source of broadband light source, described broadband light source becomes the source that produces interference originally.The envelope width Delta t of the interference fringe of this moment depends on the bandwidth Δ F of this broadband light source as mentioned above.Usually because satisfy Δ F＜＜[1/ (λ/2)]＜Fh, so can have space Δ Fc (=Fh-Δ F) fully in the frequency band as Fig. 7 (B) bottom that is shown in.
According to the present invention, it constitutes, obtain (sampling) interference fringe data in the sequential that produces aliasing, to be removed because of the unwanted frequency composition that this aliasing produces and measure displacement, therefore, with the mode that produces aliasing prolong data obtain sequential during, that is to say, reduce data and obtain number of times, can reduce the corresponding optical processing time, thereby can shorten Measuring Time.That is, as main Measuring Time, if with [optical path length variable time+data are obtained number of times * (time shutter
+Obtain the processing time)] represent, then can correspondingly shorten Measuring Time with the minimizing that data are obtained number of times.
In sum, a kind of 3 d shape measuring apparatus of the present invention is a kind ofly to shorten Measuring Time and carry out the technology of three-dimensional measurement.Light path formation portion receives the broad band light from broadband light source, makes its branch incide reference path and measures light path, and export to photographic unit after the reflected light of self-reference mirror closes ripple with reflected light from measured object in the future.On the other hand, the optical path length changeable mechanism changes the optical path length of measuring light path.Photographic unit is with respect to the variation of this optical path length and produce the sequential of aliasing, to taking from the output of light path formation portion, thereby obtains the interference fringe data that contain interference fringe.Optical path length testing agency will be removed because of the frequency content that aliasing produced from the interference fringe data that photographic unit obtained, and obtain the specific optical path length of the eigenwert that demonstrates interference fringe.The present invention has above-mentioned plurality of advantages and practical value, no matter it all has bigger improvement on product structure or function, obvious improvement is arranged technically, and produced handy and practical effect, and more existing 3 d shape measuring apparatus has the outstanding effect of enhancement, thereby being suitable for practicality more, really is a new and innovative, progressive, practical new design.
Above-mentioned explanation only is the general introduction of technical solution of the present invention, for can clearer understanding technological means of the present invention, and can be implemented according to the content of instructions, and for above-mentioned and other purposes, feature and advantage of the present invention can be become apparent, below especially exemplified by preferred embodiment, and conjunction with figs., be described in detail as follows.
Description of drawings
Fig. 1 is the figure that the function of expression the 1st embodiment constitutes.
Fig. 2 is the figure in order to the explanation interference fringe.
Fig. 3 is the figure that expression has changed the 2nd embodiment after the optical path length testing agency of Fig. 1.
Fig. 4 (A), Fig. 4 (B), Fig. 4 (C), Fig. 4 (D), Fig. 4 (E) are the figure in order to the action of the interference fringe data selection portion of key diagram 3.
Fig. 5 is the figure in order to the action of the optical path length determination means of key diagram 3, represents the interference fringe of each frequency content.
Fig. 6 is the figure in order to the action of the optical path length determination means of key diagram 3, represents the phase propetry of each frequency content.
Fig. 7 (A), Fig. 7 (B), Fig. 7 (C), Fig. 7 (D), Fig. 7 (E), Fig. 7 (F) are the figure that has removed the influence of aliasing and obtain the action of interference fringe in the 1st embodiment in order to illustrate.And Fig. 7 (A), Fig. 7 (B), Fig. 7 (C), Fig. 7 (D), Fig. 7 (E), Fig. 7 (F) are the figure that background of the present invention is described in order in " background technology " hurdle.
1: light source 2: collimation lens
3: spectroscope 4: object lens
5: spectroscope 6: reference mirror
7: measured object 8: piezoelectric part
9: imaging len 10: camera
13: storer 14: optical path length testing agency
14a, 14e: interference fringe data selection portion 14c: optical path length calculating part
14d: wavelength selection portion 14,14f: optical path length calculating part
The 14f1:B phase calculation 14f2:G of portion phase calculation portion
The 14f1m:R phase calculation 14f4 of portion: optical path length determination means
15: displacement arithmetical organ 16: the optical path length control gear
18: user interface 20,20a: signal processing mechanism
Embodiment
Reach technological means and the effect that predetermined goal of the invention is taked for further setting forth the present invention, below in conjunction with accompanying drawing and preferred embodiment, to its embodiment of 3 d shape measuring apparatus, structure, feature and the effect thereof that foundation the present invention proposes, describe in detail as after.
Relevant aforementioned and other technology contents, characteristics and effect of the present invention can be known to present in the following detailed description that cooperates with reference to graphic preferred embodiment.By the explanation of embodiment, when can being to reach technological means that predetermined purpose takes and effect to get one more deeply and concrete understanding to the present invention, yet appended graphic only provide with reference to the usefulness of explanation, be not to be used for the present invention is limited.
Use accompanying drawing that embodiments of the present invention are described.Fig. 1 is the figure that the function of expression the 1st embodiment constitutes.Fig. 2 is the figure in order to the explanation interference fringe.Fig. 3 is the figure that expression has changed the 2nd embodiment after the optical path length testing agency of Fig. 1.Fig. 4 (A), Fig. 4 (B), Fig. 4 (C), Fig. 4 (D), Fig. 4 (E) are the figure in order to the action of the interference fringe data selection portion of key diagram 3.Fig. 5, Fig. 6 are that Fig. 5 represents the interference fringe of each frequency content in order to the figure of the action of the optical path length changeable mechanism of key diagram 3, and Fig. 6 represents its phase propetry.Fig. 7 (A), Fig. 7 (B), Fig. 7 (C), Fig. 7 (D), Fig. 7 (E), Fig. 7 (F) are the figure that has removed the influence of aliasing and obtain the action of interference fringe in the embodiment of Fig. 1 in order to illustrate.In addition, Fig. 7 (A), Fig. 7 (B), Fig. 7 (C), Fig. 7 (D), Fig. 7 (E), Fig. 7 (F) are the figure that background of the present invention is described in order in " background technology " hurdle.
1. the integral body of the 1st embodiment constitutes
As mentioned above, the formation of the 1st embodiment is: from the sequential more late than the sequential that satisfies sampling thheorem, just from taking each data of gained by camera 10 as photographic unit in the sequential that produces aliasing, the useless composition that removal produces because of aliasing, satisfying the equal data of the interference fringe that sequential obtained of sampling thheorem and extract with original, then, the optical path length (also can be the variable quantity of the optical path length when making optical path length change till producing interference fringe) that the intensity peak of the interference fringe of this extraction is produced is obtained as specific optical path length (displacement).
In the following description, when the optical path length of measuring light path is changed, the optical path length (variable quantity of the optical path length when making optical path length change till producing interference fringe) that will produce interference fringe sometimes is called " specific optical path length ", and it represents the displacement of the shape of this measured object.
Among Fig. 1, in order to cause interference, light source 1 uses has the white light source that spreads all over the lower light of wide band a plurality of wavelength components and outgoing coherence (coherency).Collimation lens (collimatorlens) 2 will be sent to spectroscope (beamsplitter) 3 behind white light (broad band light) optically focused from light source 1.Spectroscope 3 is sent to object lens 4 after white direction of light is changed.Object lens 4 are sent to spectroscope 5 (light path formation portion) after making white light become directional light.The white light that spectroscope 5 will receive from object lens 4 is to both direction branch, one of them is sent to measured object 7 (will from spectroscope 5 to the light path of measured object 7 as measuring light path) as measuring light, another then is sent to reference mirror 6 (will from spectroscope 5 to the light path of reference mirror 6 as the reference light path) as reference light.In this example, fix between spectroscope 5 and the reference mirror 6, that is to say that the optical path length of reference path is made as certain regular length.
Also can replace spectroscope 5 and constitute with half-mirror (half mirror).
Measure constituting of light path, that utilizes that white light shines measured object 7 simultaneously lip-deeply wants the required range of exposures measured.
Measured object 7 is installed in as on the piezoelectric part of optical path length changeable mechanism (piezo) 8.Piezoelectric part 8 is made of piezoelectric element, under indication from optical path length control gear 16, make measured object 7 with respect to XY plane (with the face of the paper quadrature of Fig. 1) and to Z-direction (above-below direction of the paper of Fig. 1) displacement continuously (moving), thereby come the optical path length of measuring light path is carried out variable control with fixing speed.
In addition, here, as the variable method that optical path length is changed of the present invention, be continuous variable, and it is fixing that variable velocity is become, thereby describe, compare but obtain sequential, also can be tiny stepped and change with the data of following camera etc.
Piezoelectric part 8 is under the control of optical path length control gear 16, mechanism's (optical path length changeable mechanism) that the optical path length of measuring light path is changed with respect to the fixed position of spectroscope 5.In addition, here be the optical path length of reference path is fixed and the optical path length of measuring light path to be changed describe, but in order to generate interference fringe, also can be following formation: piezoelectric part 8 is installed on the reference mirror 6, the measurement light path is fixed, and make the optical path length of reference path variable.
Reflect respectively and the white light that comes (below, be sometimes referred to as " back light ") closes ripple (synthesizing) by spectroscope 5 from reference mirror 6 and measured object 7, carry out optically focused by object lens 4 again.Back light is input to camera 10 by spectroscope 3 and after becoming directional light under the effect of imaging len 9.
At this moment, under indication from optical path length control gear 16, the distance (time interval when perhaps changing) that the optical path length of measuring light path is changed according to piezoelectric part 8,10 pairs of back lights of camera are taken, take interference fringe that back light produces (in fact with this, described shooting is just taken back light, but has wherein comprised the Light Interference Streaks of returning that occurs when representing photographed data subsequently, so be expressed as " shooting interference fringe ").Taken interference fringe is stored in the storer 13.At this moment, as mentioned above, the formation of measuring light path is to utilize white light to shine the required whole range of exposures of measured object 7 simultaneously, so photograph with from each irradiation position of range of exposures, promptly with the corresponding interference fringe of back light from the position of wanting to measure (below, be called " measuring position ").
In addition, the distortion as the optical system of Fig. 1 also can be constructed as follows described optical system,, disposes object lens respectively measuring on light path and the reference path, to replace the position of object lens 4 on Fig. 1, so the present invention is not limited to the optical system of Fig. 1 that is.But, below illustrate according to Fig. 1.
The shooting sequential of camera 10 and the storage sequential of storer 13 be among the present invention data obtain sequential, all be to export synchronously by optical path length control gear 16.That is to say that the variable indication that optical path length control gear 16 sends optical path length with the speed of regulation to piezoelectric part 8 on the other hand, generates the clock signal of specific time interval and sends to camera 10 and storer 13, preface is obtained data at this moment.That is, camera 10 and storer 13 are taken into and store the photographed data (becoming the brightness data of the brightness of expression back light) of back light in the sequential of this clock signal.
Generally speaking, the broadband Light Interference Streaks has half repetition period of the central wavelength lambda of broad band light.At the waveform that obtains this λ/2 cycles and when reproducing, in order to prevent the generation of aliasing, in this cycle, require three data usually, so must obtain data in the sequential of the repetition more Zao than λ/(2 * 3).
Among the present invention, because be to obtain data, so the storage sequential of the photography sequential of camera 10 and storer 13 is the repetition periods (below, be sometimes referred to as " sampling time sequence Fs ") than λ/6 late (length) in the sequential that produces aliasing.Particularly, the speed that optical path length is variable is made as v if optical path length control gear 16 is driven piezoelectric part 8, then the control signal in the time interval that optical path length control gear 16 will be more late than λ/6v sends to camera 10 and storer 13, obtains data in the sequential of this control signal.Optical path length control gear 16 is carrying out stepper drive to piezoelectric part 8 but not during analog-driven, is generating the clock signal in the time interval more Zao than λ/6v, thus the variable indication of piezoelectric part 8 being sent optical path length.
As a result, storer 13 has been stored photographed data with the time interval of this clock signal as address (address).The direct of travel of these sequential (being address direction) expression optical path length direction (Z-direction).At this moment, with this photographed data and measuring position (Xm, Yp) corresponding and storing.(Xm, information Yp) is the position with the pixel of the corresponding XY direction in position of the capturing element of camera 10 in the measuring position.The data of being stored have been represented among Fig. 2, an example of the interference fringe that the processing by the signal processing mechanism 20 that next will illustrate obtains according in the storer 13.
As shown in Figure 1, optical path length testing agency 14 is made of interference fringe data selection portion 14a, optical path length calculating part 14c.Interference fringe data selection portion 14a receives the photographed data from storer 13, for example receives this measuring position (Xm, data Yp), and convert the data of frequency field by FFT (fourier transform) to.Like this, shown in Fig. 7 (E), owing to there are each data of the frequency content (dotted portion of Fig. 7 (E)) that produces because of aliasing and the frequency content of original interference fringe, so use wave filter to separate, the frequency content that aliasing produces is removed, thereby separated and take out the composition (Fig. 7 (E) solid line part) of interference fringe.
Then, shown in Fig. 7 (F), interference fringe data selection portion 14a makes frequency axis be reduced into original frequency axis, that is to say, the frequency axis that engineer's scale is reduced into the frequency field when the sampling time sequence that does not produce aliasing in accordance with sampling thheorem is sampled (is sampled in order to use the frequency lower than original sample frequency, and utilize so-called frequency axis to be represented by the form of frequency division, institute is so that the frequency axis reduction), convert the data of time zone once more to, that is, send to optical path length calculating part 14c (Fig. 2 is the data of the interference fringe of this moment) as the interference fringe data.
In addition, in the waveform of the interference fringe of Fig. 2,, be the situation that optical path length and the optical path length of measuring light path of above-mentioned reference path becomes identical as the crest location of the substantial middle of the interference fringe of the eigenwert of interference fringe.And the wavelength of white Light Interference Streaks is by as the synthetic made of each wavelength of the key element of broad band light, this wavelength be these frequency bands substantial middle wavelength X 1/2.And, the white Light Interference Streaks of Fig. 2 is to the expansion of optical path length direction, and just the width Delta t of the envelope of interference fringe is the degree (relevant (coherence) length) that depends on the coherence of white light, in other words, the width Delta F that depends on the frequency content of frequency field.Coherence's low more (coherent length is long more), be that Δ F is big more, width Delta t can become narrow more (with reference to Fig. 7 (A), Fig. 7 (B)) then.If the highest frequency of the frequency content of interference fringe is made as Fh, then the width Delta F of frequency content satisfy Δ F＜＜[1/ (λ/2)]＜Fh, and, if make width Delta F reduce (make coherence improve (coherent length is shortened)), then the amplitude of interference fringe can become almost fixed and crest can disappear, therefore, so that the width Delta t of interference fringe becomes the mode of the degree of the peak value that can hold interference fringe, decide width Delta F.For example, below schematically illustrate, if so that width Delta F is lower than the bandwidth that the mode of highest frequency Fh/2 decides light source 1, then shown in Fig. 7 (E), right half part in the band region after the sampling is divided into the real frequency composition of interference fringe, and left-half is divided into the frequency content (frequency content of turning back) that produces because of aliasing, and can be by Fh/2 being made as the real frequency composition that only extracts interference fringe by the Hi-pass filter (high pass filter) of (cut) frequency.That is obtain useless composition promptly have been turned back frequency number composition except the composition.
Real frequency composition except the frequency content (composition of turning back) that 14 pairs of optical path length testing agencies will produce because of aliasing carries out converting to after contrary FFT handles the new interference fringe of time zone, and obtain the crest location of described new interference fringe, thereby determine the optical path length (specific optical path length) of this position.So-called " crest location " (perhaps " position of crest "), the brightness (amplitude) that is meant white Light Interference Streaks become maximum (below, be called " crest ") transverse axis on the position, among Fig. 2, transverse axis is the optical path length direction (above-below direction of the paper of Z-direction: Fig. 1) of above-mentioned measurement light path, and is the time-axis direction of optical path length when variable (time-axis direction when utilizing camera 10 to take with specific time interval).
On the other hand, store photographed data in the storer 13 into and be storage sequential (sampling time sequence) in being stored in storer 13 and stored (Fig. 2 links up described photographed data and the figure of performance continuously), so optical path length testing agency 14 receives the data that disperse relevant with interference fringe from interference fringe data selection portion 14a.Like this, because data disperse, so though the crest location of the maximal point of amplitude and envelope and inconsistent sometimes, owing to have characteristic along cunning, thereby also can obtain the crest location of envelope by interpolative operation according to the maximal point of the amplitude of front and back.For example, as the method for obtaining the crest of interference fringe according to discrete photographed data, following technology is arranged: optical path length is changed interimly, and, carry out ensuing processing according to the captured discrete photographed data of optical path length of the regulation of corresponding each described variation.Utilize digital high-pass filter from the data of the interference fringe that photographed data obtained with except the flip-flop.The data that will become alternating component give square and carry out rectification.The wave digital lowpass filter that utilization makes the repetition composition lower than the repetition composition after the rectification give passing through carries out integration, calculates the envelop data of interference fringe.That is, carry out common envelope detection.At this moment, according to the requirement of the fineness of crest location, between the repetition composition after the rectification, for example carry out interpolation, and the repetition composition after the interpolation is carried out integration and obtains envelop data with square characteristic.Obtain the position of the crest of envelop data for this reason.In addition, as putting down in writing in the Japanese patent laid-open 9-318329 communique, signal processing mechanism 20 also can utilize discrete processes to obtain crest location, and no matter the cycle of the sequential (time interval) of photographed data and interference fringe how.
2. the 2nd embodiment
According to Fig. 3, Fig. 4 (A), Fig. 4 (B), Fig. 4 (C), Fig. 4 (D), Fig. 4 (E) and Fig. 5 describe (wherein, Fig. 4 (A), Fig. 4 (B), Fig. 4 (C), Fig. 4 (D), Fig. 4 (E) be in order to the explanation operating principle figure).The 1st embodiment of Fig. 1 is a crest location of obtaining interference fringe according to amplitude, relative therewith, the 2nd embodiment is with a plurality of frequency contents, for example the corresponding to optical path length of phase place of the wavelength of the phase place of the wavelength of red composition and green composition is obtained as specific optical path length.In the 2nd embodiment signal processing mechanism 20 of Fig. 1 is replaced to the signal processing mechanism 20a of Fig. 3, and then make the camera 10 of Fig. 5 become color camera.Therefore, among Fig. 1, light source 1 is the light source of composition that contains the wavelength band of at least two ripples in spreading all over wide band a plurality of wavelength components,, for example uses the light source that contains red, green wavelength band of all kinds here.Also the light of red, green wavelength of all kinds can be synthesized and is used.The formation of other beyond the signal processing mechanism 20a, action, sequential etc. are identical with Fig. 1.Below, 20a describes to signal processing mechanism.
Among Fig. 3, interference fringe data selection portion 14e is substantially the same with the interference fringe data selection portion 14a of Fig. 1, but because described interference fringe data selection portion 14e also is one of main composition of the present invention, so use Fig. 4 (A), Fig. 4 (B), Fig. 4 (C), Fig. 4 (D), Fig. 4 (E) to illustrate.Interference fringe data selection portion 14e causes as mentioned above that at camera 10 or storer 13 sampling time sequence (than the sequential during λ/6 length) of aliasing obtains data, so will convert the frequency field data to by FFT from the time zone data of storer 13, and filtering is because of the useless composition of described aliasing generation, to obtain the frequency content of interference fringe, and send to wavelength selection portion 14d, utilize wavelength selection portion 14d, make frequency axis be reduced into interference fringe on originally the time shaft.
Interference fringe data selection portion 14e utilizes wave filter, the data (data of representing with light gray among Fig. 4 (D)) of selecting and keeping the right half part in the data of the Fig. 4 (D) that obtains by FFT are with as required data, and the useless composition that will be in the previous frequency band is removed.Make the frequency axis elongation (right half part shown in the gray area of Fig. 4 (E)) of Fig. 4 (D) then and reduce, and send to wavelength selection portion 14d.
Here, use Fig. 4 to carry out the explanation of overall principle.Fig. 4 (A) is the interference fringe of red, green each wavelength components, is in an example that satisfies under the situation that the sampling time sequence T0 of sampling thheorem (than the Zao sequential of described λ/6v) measures.Fig. 4 (B) is the data that convert the frequency field of Fig. 4 (A) to.And, at this moment, select the data of left-half and be used by wave filter.As shown in the present, for example,, then can replace Fig. 4 (A) and the data of the time zone of acquisition Fig. 4 (C) if obtain (sampling) data at half place of the sampling time sequence T0 that satisfies sampling thheorem and in the sequential that produces aliasing.As the data of frequency field, replace the data of Fig. 4 (B) and about when obtaining to compare with the distribution of Fig. 4 (B) frequency content as Fig. 4 (D) be shown in distribution the data of changing have taken place.That is, the useless composition on the right side of Fig. 4 (B) appears at the frequency location in the left side of Fig. 4 (D) because of aliasing, and the composition of the original interference fringe in the left side of Fig. 4 (B) then appears at the frequency location on the right side of Fig. 4 (D).And the frequency axis of Fig. 4 (D) is compared with the frequency axis of Fig. 4 (B), and fastening in the pass of sample frequency becomes half.Therefore, the composition waveform in the left side of Fig. 4 (B) is identical with the composition waveform on the right side of Fig. 4 (D), as long as so utilize wave filter, and shown in Fig. 4 (E), change engineer's scale, just the data of the frequency content of the left-half of Fig. 4 that can obtain to go for originally (B) with its separation.
Below sequential relationship is specifically described.For example, if utilize camera 10 based on the x of the sampling time sequence T0 of sampling thheorem doubly the sample data reached of the sequential of (being 2 times among described Fig. 4 (c)) count m, convert the interference fringe data of time zone to the frequency field data by the FTT processing, if and will be made as n based on the sample data number of the sampling time sequence T0 of sampling thheorem the time, m=n/x then, and correspondingly the scale on the frequency number axis does to dwindle processing.That is, represent with the form of frequency division as mentioned above.Therefore, interference fringe data selection portion 14e is at the engineer's scale of the frequency axis that changes Fig. 4 (D), and shown in Fig. 4 (E) with based on the frequency axis (identical) of sampling thheorem when handling in the same manner with Fig. 4 (B), handled sample data number is made as m in the time of will carrying out the FFT processing, in addition, only logarithm Δ n=n-m=n (x-1)/x utilization value is that 0 data are replenished (0 fills (padding)) and handled.That is, the sample data number is tailed off and the frequency field of blank n-m utilizes 0 data to fill.In addition, theoretically,, be read as x and doubly handle and the scale on this frequency axis changed because the frequency axis engineer's scale only dwindled n/x, thereby also can not change the sample data number.And, even the sample data number that is produced by described FFT is also identical in described embodiment 1 with the relation of frequency axis.
Among Fig. 3, wavelength selection portion 14d receives the data of the frequency field that comes from interference fringe data selection portion 14e transmission, and frequency is divided into for example blue (B) composition, green (G) composition, this three class of redness (R) composition by wave filter, more described each composition is sent to optical path length calculating part 14f.In optical path length calculating part 14f, receiving each composition and carrying out in the interference fringe data of time zone of contrary fourier transform gained, the B phase calculation 14f1 of portion, the G phase calculation 14f2 of portion, the R phase calculation 14f1m of portion obtain the phase change (for example, obtaining phase place by quadrature demodulation) of the composition that is met respectively.Fig. 5 represents described each phase change (longitudinal axis) of the variation (transverse axis) with respect to optical path length.And as shown in Figure 6, optical path length determination means 14f4 is the specific optical path length on this measuring position with the optical path length decision of the phase place unanimity of described three kinds of compositions.At this moment, because data disperse, so under the situation that is difficult to the consistent optical path length of putting of designated phase, use methods such as aforesaid interpolation.
In described formation, signal processing mechanism 20,20a and optical path length control gear 16 can by central processing unit (Central processing unit, CPU) and storer constitute.
As mentioned above, measure owing to obtaining data, so can reduce the number of times that data are obtained in the sequential that produces aliasing.Therefore, as main Measuring Time,, then can correspondingly shorten Measuring Time with the minimizing that data are obtained number of times if represent with [optical path length variable time+data are obtained number of times * (time shutter+obtain the processing time)].
The above, it only is preferred embodiment of the present invention, be not that the present invention is done any pro forma restriction, though the present invention discloses as above with preferred embodiment, yet be not in order to limit the present invention, any those skilled in the art, in not breaking away from the technical solution of the present invention scope, when the technology contents that can utilize above-mentioned announcement is made a little change or is modified to the equivalent embodiment of equivalent variations, in every case be the content that does not break away from technical solution of the present invention, according to technical spirit of the present invention to any simple modification that above embodiment did, equivalent variations and modification all still belong in the scope of technical solution of the present invention.
Claims (5)
1, a kind of 3 d shape measuring apparatus, it possesses: broadband light source (1), output has the broad band light of a plurality of frequency spectrums; Light path formation portion (5), make described broad band light branch and incide reference path and dispose the measurement light path of measured object, and make and export after closing ripple from the reflected light of described reference mirror with from each reflected light of the irradiation position of the range of exposures of irradiated described measured object with reference mirror; Optical path length changeable mechanism (8) changes any optical path length of described reference path or described measurement light path; Photographic unit (10), with respect to the variation of the described optical path length that causes by described optical path length changeable mechanism, at the sampling time sequence of regulation to taking from the output of described light path formation portion, thereby obtain the interference fringe data that contain interference fringe; And optical path length testing agency (14), according to described interference fringe data from described photographic unit output, and the specific optical path length when obtaining the eigenwert that demonstrates described interference fringe, this 3 d shape measuring apparatus is measured the shape of described measured object according to the described specific optical path length of being obtained, and this 3 d shape measuring apparatus is characterised in that:
The sampling time sequence of the described regulation when described photographic unit is taken, it is the sequential that interference fringe contained in the output to described light path composition produces aliasing, this sampling time sequence is made as at frequency field and is separable into the real frequency composition wanted and the sequential of the frequency content that produces because of described aliasing, and then
Described optical path length testing agency possesses: interference fringe data selection portion (14a), to convert the data of frequency field by the interference fringe data that described photographic unit obtains at the sampling time sequence of described regulation to, and except the useless composition that described aliasing is produced, and the new interference fringe data of selecting described real frequency composition to produce; And optical path length calculating part (14c), according to described new interference fringe data, obtain the described specific optical path length of the eigenwert that demonstrates described interference fringe.
2,3 d shape measuring apparatus according to claim 1 is characterized in that:
Described interference fringe data selection portion will be carried out fourier transform based on the sample data number of described sampling time sequence according to this from the number of interference fringes of described photographic unit output, thereby carry out the data-switching of described frequency field, and except the useless composition that on this frequency field, described aliasing is produced, select the new interference fringe data of this frequency field with this
Described optical path length test section becomes sample data number based on sampling thheorem with the described sampled data number conversion of the new interference fringe data of this frequency field, then the new interference fringe data of this frequency field are carried out contrary fourier transform, with the envelop data of the new interference fringe that converts time zone to, and obtain the described specific optical path length of the eigenwert that demonstrates described interference fringe according to the new interference fringe data of this time zone.
3,3 d shape measuring apparatus according to claim 1 and 2 is characterized in that:
So-called with respect to the described optical path length that causes by described optical path length changeable mechanism variation and produce the sequential of described aliasing, be meant that when the approximate centre wavelength with described broad band light is made as λ the variation of this optical path length that is caused by this optical path length changeable mechanism surpasses the interval of λ/6.
4,3 d shape measuring apparatus according to claim 1 and 2 is characterized in that:
Described photographic unit was taken with the intrinsic minimum exposure time, and when the speed that described optical path length is changed described optical path length changeable mechanism was made as v, the time interval that the variation of described optical path length is surpassed λ/(6v) took as described sequential.
5,3 d shape measuring apparatus according to claim 1 and 2 is characterized in that:
Described optical path length testing agency has wavelength selection portion (14d), extracts at least two wavelength components from the selected described new interference fringe data of described interference fringe data selection portion,
Described optical path length calculating part is according to the new interference fringe data of the described time zone of at least two wavelength components of described extraction, their phase differential roughly become zero described optical path length and obtains as described specific optical path length.
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| Application Number | Priority Date | Filing Date | Title |
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| JP2007242193A JP4388113B2 (en) | 2007-09-19 | 2007-09-19 | 3D shape measuring device |
| JP2007242193 | 2007-09-19 |
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| CNA2008102118799A Pending CN101393016A (en) | 2007-09-19 | 2008-09-18 | Three-dimensional shape measuring apparatus |
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| JP (1) | JP4388113B2 (en) |
| KR (1) | KR101011925B1 (en) |
| CN (1) | CN101393016A (en) |
| TW (1) | TWI379067B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103033131A (en) * | 2012-12-10 | 2013-04-10 | 中国科学院苏州纳米技术与纳米仿生研究所 | Measuring device and measuring method of semiconductor micro-mesa array |
| CN105899909A (en) * | 2014-01-10 | 2016-08-24 | Ntn株式会社 | Height detection device, coating device, and height detection method |
| CN107796326A (en) * | 2016-09-06 | 2018-03-13 | 日本株式会社日立高新技术科学 | The three-dimensional shape measuring method of sweep type white interference microscope is used |
| CN110125802A (en) * | 2019-04-17 | 2019-08-16 | 郑州磨料磨具磨削研究所有限公司 | A kind of online test method and system of the small abrasion loss of extra hard material grinding wheel |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2412849B1 (en) | 2009-03-25 | 2016-03-23 | SUMCO Corporation | Silicon wafer and method for manufacturing same |
| JP2012078269A (en) * | 2010-10-05 | 2012-04-19 | Naoyuki Furuyama | Ranging method and laser ranging device |
| JP2016070918A (en) * | 2014-10-01 | 2016-05-09 | 本田技研工業株式会社 | Manufacturing method of molding, shape measurement method and shape measurement device |
| JP2023002228A (en) * | 2021-06-22 | 2023-01-10 | 昭和電工株式会社 | Information processing device and magnetic sensor system |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3220955B2 (en) * | 1996-05-31 | 2001-10-22 | 株式会社東京精密 | Non-contact surface shape measuring method and device |
| JP4197339B2 (en) | 2006-01-16 | 2008-12-17 | アンリツ株式会社 | 3D shape measuring device |
| JP3870275B2 (en) | 2006-07-24 | 2007-01-17 | 国立大学法人 和歌山大学 | Phase analysis method of projection grating using aliasing |
-
2007
- 2007-09-19 JP JP2007242193A patent/JP4388113B2/en not_active Expired - Fee Related
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2008
- 2008-09-16 KR KR1020080090749A patent/KR101011925B1/en not_active IP Right Cessation
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103033131A (en) * | 2012-12-10 | 2013-04-10 | 中国科学院苏州纳米技术与纳米仿生研究所 | Measuring device and measuring method of semiconductor micro-mesa array |
| CN103033131B (en) * | 2012-12-10 | 2015-08-05 | 中国科学院苏州纳米技术与纳米仿生研究所 | The measurement mechanism of semiconductor microactuator plane array and method |
| CN105899909A (en) * | 2014-01-10 | 2016-08-24 | Ntn株式会社 | Height detection device, coating device, and height detection method |
| CN105899909B (en) * | 2014-01-10 | 2019-10-18 | Ntn株式会社 | Height detecting device, apparatus for coating and height detection method |
| CN107796326A (en) * | 2016-09-06 | 2018-03-13 | 日本株式会社日立高新技术科学 | The three-dimensional shape measuring method of sweep type white interference microscope is used |
| CN107796326B (en) * | 2016-09-06 | 2021-03-12 | 日本株式会社日立高新技术科学 | Three-dimensional shape measuring method using scanning white interference microscope |
| CN110125802A (en) * | 2019-04-17 | 2019-08-16 | 郑州磨料磨具磨削研究所有限公司 | A kind of online test method and system of the small abrasion loss of extra hard material grinding wheel |
| CN110125802B (en) * | 2019-04-17 | 2020-12-01 | 郑州磨料磨具磨削研究所有限公司 | Online detection method and system for tiny abrasion loss of superhard material grinding wheel |
Also Published As
| Publication number | Publication date |
|---|---|
| KR101011925B1 (en) | 2011-02-01 |
| JP2009074837A (en) | 2009-04-09 |
| KR20090030222A (en) | 2009-03-24 |
| TWI379067B (en) | 2012-12-11 |
| JP4388113B2 (en) | 2009-12-24 |
| TW200914791A (en) | 2009-04-01 |
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