CN1527027A - Differential defocused parallel global 3D detection method and detector - Google Patents
Differential defocused parallel global 3D detection method and detector Download PDFInfo
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- CN1527027A CN1527027A CNA031129366A CN03112936A CN1527027A CN 1527027 A CN1527027 A CN 1527027A CN A031129366 A CNA031129366 A CN A031129366A CN 03112936 A CN03112936 A CN 03112936A CN 1527027 A CN1527027 A CN 1527027A
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Abstract
The present invention features that differential defocused detection method is used in parallel global detection and differential light strength algorithm for the same flare is adopted. Two CCD detectors are used in the synchronous defocused differential detection and their output signal difference is used in judging the magnitude and sign of the object plane defocus amount. When the object under detection moves axially, the distances from each point on the object to the focus plane may be used in characterizing the contour height of the object. The present invention can suppress the effects of light source noise and drift effectively to raise the measurement precision and obtain high axial resolution in relatively large interval to balance the measurement resolution and the measurement speed.
Description
Technical field:
The present invention relates to a kind of optical 3-dimensional pattern detection technique, particularly light focus detection technology.
Background technology:
Along with the high speed development of modern science and technology, make that the characteristic dimension of part is more and more littler, precision is also more and more higher.Three-dimensional appearance to these parts detects fast and accurately, becomes the important topic of modern test method and instrument research.Confocal measurement method is owing to its high precision, high resolving power and be easy to realize that the digitized unique advantage of three-dimensional imaging is widely used.But traditional confocal measurement adopts the single-point aiming to add method for scanning mostly and realizes the two dimension aiming, and not only scanning mechanism is comparatively complicated, and the influence of vibration has limited the raising of measuring accuracy and speed.
A kind of non-scanning whole audience confocal technology based on micro-optical device has appearred in recent years.This method is by micro-optical device, and realization is cut apart light beam, becomes multidiameter delay from simple scan and surveys, and the difference to measured surface aims at detection synchronously, thereby realizes whole audience synchro measure.Adopt the pixel on the CCD face battle array to replace aperture to intercept the light intensity of confocal some picture.But this method is because the drift of light source can cause the light intensity fiducial error in the measuring process; When being applied in whole audience parallel measurement, the noise of light source can cause the light source benchmark difference of different sensing points again, causes the measurement plane error; In traditional confocal method, improve axial resolution, will reduce vertical sampling interval, but can cause slowing down of measuring speed like this.
Summary of the invention:
Technical matters to be solved by this invention is to avoid existing weak point in the above-mentioned prior art, and a kind of high precision, the parallel whole audience 3 D detection method of high-speed differential confocal are provided, and the pick-up unit of this method of realization is provided.In the hope of under big sampling interval, obtaining high axial resolution, effectively solve the contradiction between Measurement Resolution and the measuring speed, can effectively suppress the influence that source noise and drift produce simultaneously, improve measuring accuracy.
The technical scheme that technical solution problem of the present invention is adopted is:
The characteristics of the parallel whole audience 3 D detection method of differential confocal are: carry out differential confocal and survey in the parallel whole audience detects, and adopt with the moving algorithm of hot spot light intensity difference.
The technical scheme that technical solution problem of the present invention is adopted also is:
Implementing the pick-up unit of the inventive method is made up of optic probe, ccd image acquisition process and displacement mechanism.Described optic probe is pointolite, collimation lens, microlens array, pinhole array, a beam splitter, object lens and can axially movable measured object microscope carrier with central point with being on a optical axis, setting gradually from a side to opposite side; Wherein the reflecting surface of a beam splitter becomes miter angle with plane, object lens place.
The design feature of this device is that differential detection mechanism is set, described differential detection mechanism is provided with the b beam splitter on the reflected light b of described a beam splitter optical axis, on the reflected light c of the described b beam splitter optical axis and on its transmitted light b optical axis, reflected light ccd detector and transmitted light ccd detector are set respectively, the test surface of two groups of detectors is the out of focus setting on optical axis separately, and two test surface out of focus distance equates that the out of focus direction is opposite.
Measuring principle of the present invention is to utilize two ccd detectors to carry out synchronous out of focus differential detection, press the size of hot spot, the pixel of CCD sensitive area is divided into probe unit one by one, the corresponding hot spot of probe unit, this moment, each CCD probe unit was equivalent to pinhole detector.When object plane was positioned at the focal plane, the spot size on two detectors equated, light intensity is identical, and therefore the difference of two detector output signals is zero; When object plane departed from the focal plane, flare on two detectors and transmission spot size were no longer equal, and a detector spot diameter becomes big, and spot diameter diminishes on the detector, and the difference of two detector output signals is also different.Therefore according to the size of two detector output signal differences and positive and negative, just can judge the size of object plane defocusing amount and positive and negative.When testee scans when mobile vertically, because the height difference of each point on the object, the distance that corresponding each point arrives the focal plane is also different, and each point just can characterize the profile height of object on the object to the distance of focal plane.
When detector axis when departing from picture focal plane micro-displacement ± Δ Z, the detector light intensity signal is:
Fig. 2 shows normalization output of detector light intensity and defocusing amount relation curve.
As shown in Figure 2, when detector axial dipole field, its axial response family curve does not change, and has just introduced axial dipole field in response curve, and promptly it has produced certain phase shift with respect to the axial response characteristic of desirable confocal imaging.As seen detector axial dipole field is little to the influence of system axial resolution, and the differential confocal method has been utilized this characteristic exactly.The difference of getting the output of two detectors is signal output, and then signal is:
Differential thus curve of output can be found out bigger linearity range, and in the focus zero passage.The range of linearity of curve is relevant with parameter of optical system with sensitivity.
Compared with the prior art, the present invention uses the differential confocal probe method in the parallel whole audience detects, and adopt with the moving algorithm of hot spot light intensity difference, the noise of light source and drift act on the same hot spot point that two CCD detect simultaneously, so the output signal after differential can effectively suppress the influence of source noise and drift generation.Adopting the another one advantage of differential confocal probe method is to improve measuring speed greatly, and in traditional confocal method, improve axial resolution, will reduce vertical sampling interval, but can cause slowing down of measuring speed like this.The present invention utilizes the differential confocal probe method, because it has unique differential curve of output of S shape, there is good linearity range the centre, as long as vertical sampling interval is in the range of linearity, just can calculate actual height value, so just can obtain the resolution of little sampling interval according to the linear relationship of output signal and defocusing amount.The present invention can be widely used in semiconductor product manufacturing processing and detect and biomedical detection range.
The drawing explanation:
Fig. 1 is a structural representation of the present invention.
Fig. 2 is detector light intensity normalization output of the present invention and defocusing amount relation curve.
Embodiment:
The parallel whole audience 3 D detection method of differential confocal is in the present embodiment, uses the differential confocal probe method in the parallel whole audience detects, and adopts with the moving algorithm of hot spot light intensity difference.
Be specially:
A, two-dimensional points light source focus on the measured object surface after the beam splitting first time, the reflected light on measured object surface generates transmitted light and reflected light respectively after twice beam splitting;
B, simultaneously the out of focus that the carrying out of described transmitted light and catoptrical spot array distance equates, direction is opposite is surveyed, and obtained the gray-scale value that each hot spot is put corresponding probe unit, calculate the differential confocal signal output I of each probe unit
D
|x
i，y
j，I
D(i，j)|(i＝1，2，........n；j＝1，2，.......m)
In the formula, n and m are respectively the columns and the line number of pointolite array (being microlens array)
I
DBe the differential output signal of the probe unit of corresponding identical point light source
C, array of source form parallel section n time in vertical (Z-direction), and the spacing of establishing each section is Δ Z, sampled point (i, the sampling array of j) locating is:
[Z
1，I
D1(i，j)]，[Z
2，I
D2(i，j)]，.....，[Z
n，I
Dn(i，j)]
In the formula,, Z
nBe the longitudinal scanning height.
D, the output signal value of above n section is compared, found null value I
D(i j)=0, determines residing section layer k, and then this point highly is: Z
k=k Δ Z; If there was not null value, then according to the sampled point place profile position computed altitude value that drops on differential curve of output linearity range;
E, use Z
kSubstitute I
D(i, j), the three-dimensional value that obtains the face of measuring is:
|x
i，y
j，Z
k|(i＝1，2，.........n；j＝1，2，.......m)。
According to parameter of optical system, can calculate and the corresponding pick-up unit output signal variation of measured point defocusing amount, obtain the differential curve of output performance plot of S shape as shown in Figure 2.
Curve of output can find out that this curve has bigger linearity range thus, and in positive burnt location point zero passage.Have drop on (being that vertical sampling interval guarantees half less than the range of linearity) in the range of linearity at 2 as long as guarantee vertical sampled point, just can calculate the true altitude value according to the linear relationship of output signal and defocusing amount, so just can obtain resolution less than sampling interval, be implemented in big sampling interval and obtain higher axial resolution down, effectively solve the contradiction between Measurement Resolution and the measuring speed.The range of linearity of curve is relevant with parameter of optical system with sensitivity.
Referring to Fig. 1, in the present embodiment, the concrete pick-up unit of implementing above method is made up of optic probe, ccd image acquisition process and displacement mechanism, and optic probe is on a optical axis 1 together, sets gradually from a side to opposite side and be pointolite 2, collimation lens 3, microlens array 4, pinhole array 5, a beam splitter 6, object lens 7 and can axially movable measured object microscope carrier 8 with central point.Wherein the reflecting surface of a beam splitter 6 becomes miter angle with plane, object lens 7 place.
In the present embodiment, differential detection mechanism is set, this differential detection mechanism is provided with b beam splitter 9 on the reflected light b of described a beam splitter 6 optical axis 10, on the reflected light c of b beam splitter 9 optical axis 12 and on its transmitted light b optical axis 10, reflected light ccd detector 13 and transmitted light ccd detector 11 are set respectively, the test surface of two groups of detectors is the out of focus setting on optical axis separately, and two test surface out of focus distance equates that the out of focus direction is opposite.
This device adopts a microlens array to realize a two-dimensional points array of source.The single color point light source becomes directional light through behind the collimation lens, shines on the microlens array.Utilize microlens array that light beam is cut apart convergence, improved the efficiency of light energy utilization; Fix an array of orifices in the focal plane of microlens array, aperture is corresponding one by one with lens, and the aperture bore is close with corresponding lenticule focal spot size.Adopt aperture to stop passing through of parasitic light, improved signal to noise ratio (S/N ratio).The light beam of the pointolite that microlens array produces is by beam splitter, and to measured object 14 surfaces, reflected light is reflected to the b beam splitter through a beam splitter, makes reflected light be divided into two bundles, is imaged onto respectively on two black-white CCD test surfaces by object lens focusing.In the image capturing system with black-white CCD as the acquisition of signal element, survey through transmission spot array and flare array behind the b beam splitter, image pick-up card is gone into computing machine with the ccd image collection, is calculated by computer program.Displacement mechanism is made up of measured object microscope carrier 8 and displacement drive circuit, drives measured object 14 in vertical step-wise displacement.
The course of work is as follows:
1, measured object 14 is fixed on the measured object microscope carrier 8, opens light source switch, CCD power supply and computing machine, the operating measurement program;
2, control measured object microscope carrier 8 in vertical (Z-direction) step-wise displacement by the displacement drive circuit, per step is further, and two CCD respectively gather an images;
3, carry out data processing to gathering two width of cloth images, obtain the gray-scale value that each hot spot is put pairing CCD unit, calculate the differential confocal signal output I of this unit
D(i, j).The signal array that obtains every section is:
|x
i，y
j，I
D(i，j)|(i＝1，2，.........n；j＝1，2，.......m)
In the formula, n and m are respectively the columns and the line number of pointolite array (being microlens array)
4, array of source forms parallel section n time in vertically (Z-direction), and the spacing of establishing each section is Δ Z, this value by micro-displacement driver step distance determine.Sampled point (i, the sampling array of j) locating is:
[Z
1，I
D1(i，j)]，[Z
2，I
D2(i，j)]，.....，[Z
n，I
Dn(i，j)]
In the formula, I
DIt is the differential output signal of probe unit that two CCD go up corresponding identical point light source.
Z
nBe the longitudinal scanning height.
5, the output signal value to above n section compares processing, finds null value I
D(i j)=0, determines residing section layer k, and then this point highly is: Z
k=k Δ Z.If there was not null value, then can calculate height value according to the linearity range in the differential curve of output.
6, use Z
kSubstitute I
D(i, j), the three-dimensional value that obtains the face of measuring is:
|x
i，y
j，Z
k|(i＝1，2，.........n；j＝1，2，.......m)
7, with the computing machine Survey Software three-dimensional appearance that draws.
Claims (3)
1, the parallel whole audience 3 D detection method of differential confocal is characterized in that carrying out differential confocal and surveys, and adopts with the moving algorithm of hot spot light intensity difference in the parallel whole audience detects.
2, the parallel whole audience 3 D detection method of differential confocal according to claim 1 is characterized in that:
A, two-dimensional points light source focus on the measured object surface after the beam splitting first time, the reflected light on measured object surface generates transmitted light and reflected light respectively after twice beam splitting;
B, simultaneously described transmitted light and catoptrical spot array are carried out the out of focus that distance equates, direction is opposite and survey, and obtain the gray-scale value that each hot spot is put corresponding probe unit, calculate the differential confocal signal output I of each probe unit
D
|x
i，y
j，I
D(i，j)|(i＝1，2，.........n；j＝1，2，.......m)
In the formula, n and m are respectively the columns and the line number of pointolite array (being microlens array)
I
DBe the differential output signal of the probe unit of corresponding identical point light source
C, array of source form parallel section n time in vertical (Z-direction), and the spacing of establishing each section is Δ Z, sampled point (i, the sampling array of j) locating is:
[Z
1，I
D1(i，j)]，[Z
2，I
D2(i，j)]，.....，[Z
n，I
Dn(i，j)]
In the formula,, Z
nBe the longitudinal scanning height.
D, the output signal value of above n section is compared, found null value I
D(i j)=0, determines residing section layer k, and then this point highly is: Z
k=k Δ Z; If there was not null value, then according to the sampled point place profile position computed altitude value that drops on differential curve of output linearity range;
E, use Z
kSubstitute I
D(i, j), the three-dimensional value that obtains the face of measuring is:
|x
i，y
j，Z
k|(i＝1，2，.........n；j＝1，2，.......m)。
3, a kind of device of implementing the parallel whole audience 3 D detection method of the described differential confocal of claim 1, be made up of optic probe, ccd image acquisition process and displacement mechanism, described optic probe is gone up, is set gradually from a side to opposite side and be pointolite (2), collimation lens (3), microlens array (4), pinhole array (5), a beam splitter (6), object lens (7) and can axially movable measured object microscope carrier (8) with being in a optical axis (1) with central point; Wherein the reflecting surface of a beam splitter (6) becomes miter angle with object lens (7) plane, place; It is characterized in that being provided with differential detection mechanism, described differential detection mechanism is provided with b beam splitter (9) on the reflected light b of described a beam splitter (6) optical axis (10), on the reflected light c of described b beam splitter (9) optical axis (12) and on its transmitted light b optical axis (10), reflected light ccd detector (13) and transmitted light ccd detector (11) are set respectively, the test surface of two groups of detectors is the out of focus setting on optical axis separately, and two test surface out of focus distance equates that the out of focus direction is opposite.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101799273A (en) * | 2010-03-29 | 2010-08-11 | 华中科技大学 | Nanoscale size structure measuring method and device |
| CN105371757A (en) * | 2015-10-27 | 2016-03-02 | 西安交通大学 | Differential parallel optical chromatographic microscopic measuring device and method |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1026515A (en) * | 1996-07-12 | 1998-01-27 | Olympus Optical Co Ltd | Step-measuring apparatus |
| CN2600814Y (en) * | 2003-03-06 | 2004-01-21 | 合肥工业大学 | Differential out-of-focus parallel whole place three-D testing device |
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- 2003-03-06 CN CNB031129366A patent/CN1301397C/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101799273A (en) * | 2010-03-29 | 2010-08-11 | 华中科技大学 | Nanoscale size structure measuring method and device |
| CN101799273B (en) * | 2010-03-29 | 2011-08-24 | 华中科技大学 | Nanoscale size structure measuring method and device |
| CN105371757A (en) * | 2015-10-27 | 2016-03-02 | 西安交通大学 | Differential parallel optical chromatographic microscopic measuring device and method |
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| CN1301397C (en) | 2007-02-21 |
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