KR101677585B1 - 3-D Shape Mesuring Apparatus Using Multi Frequency light Source For High Speed Foucs Position Movement - Google Patents

3-D Shape Mesuring Apparatus Using Multi Frequency light Source For High Speed Foucs Position Movement Download PDF

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Publication number
KR101677585B1
KR101677585B1 KR1020150073494A KR20150073494A KR101677585B1 KR 101677585 B1 KR101677585 B1 KR 101677585B1 KR 1020150073494 A KR1020150073494 A KR 1020150073494A KR 20150073494 A KR20150073494 A KR 20150073494A KR 101677585 B1 KR101677585 B1 KR 101677585B1
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South Korea
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light source
wavelength
measurement object
light
image
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KR1020150073494A
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Korean (ko)
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박윤창
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선문대학교 산학협력단
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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
    • 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
    • G01B11/254—Projection of a pattern, viewing through a pattern, e.g. moiré
    • 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
    • G01B11/30—Measuring arrangements characterised by the use of optical techniques for measuring roughness or irregularity of surfaces

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

The present invention relates to a 3D shape measuring apparatus using a multi-wavelength light source for high-speed focus position movement. The 3D shape measuring apparatus comprises: a light source unit including a first light source having a first wavelength and a second light source having a second wavelength; a projection grid installed in front of the light source part, and having a periodic component projected onto an object to be measured through a reception of light provided from the light sources; an image acquisition unit acquiring a pattern image of the projection grid projected onto the object; a projection lens positioned between the image acquisition unit and the object to be measured; and a control unit having the image acquisition unit acquire the pattern image while changing central wavelengths of the light sources by controlling the light source unit to change an image formation position of the object to be measured, and acquiring 3D information of the object to be measured by calculating an amplitude and an amplitude size of the pattern the projection grid acquired by the image acquisition unit. According to the present invention, transferring an object to be measured or examination apparatus is not necessary for adjustment of a focus and high-speed movement of a position of the focus is facilitated. Accordingly, an examination speed may be notably increased.

Description

BACKGROUND OF THE INVENTION Field of the Invention [0001] The present invention relates to a three-dimensional shape measuring apparatus using a multi-wavelength light source for high-

The present invention relates to a three-dimensional shape measuring apparatus for measuring the shape of an object using a white light impinging system, and more particularly, to a three-dimensional shape measuring apparatus for measuring a shape of an object using a multi- So that the height of the object can be calculated quickly and accurately.

BACKGROUND ART [0002] Techniques for measuring a shape in a fine region using a white light interferometer have been widely spread and are currently used in many fields. The white live interferometer is well described in Korean Patent Registration No. 10-598572. In the white light interferometer, there is a process of applying a transparent thin film layer on the surface of an opaque metal layer in a semiconductor and LCD (Liquid Crystal Display) manufacturing process. At this time, information about the thickness of the transparent thin film layer and its surface shape is measured Several methods have been proposed.

White-light scanning interferometry (WSI) has been proposed as a method for measuring the surface shape of such a transparent thin film layer. The white-light scanning interferometry (WSI) ), It is now possible to measure a measurement surface having a rough surface or a high-stage difference with high resolution.

The basic measurement principle of the white light scanning interference method utilizes the short coherence length property of white light. It uses the principle that an interference signal occurs only when the reference light and measurement light separated by a beam splitter, which is a light splitter, undergo almost the same optical path difference.

Therefore, when the interference signal at each measurement point in the measurement region is observed while moving the measurement object in the direction of the optical axis by a minute distance of several nanometers with a conveyance means such as a PZT actuator, A short interfering signal is generated.

When the position of generation of the interference signal is calculated at all measurement points in the measurement region, information on the three-dimensional shape of the measurement surface is obtained, and the surface shape of the thin film layer is measured from the obtained three-dimensional information.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a view showing a surface shape measuring apparatus using a white light scanning interference method. FIG. As shown in the figure, a conventional surface shape measuring apparatus includes a light source 110, a light dividing unit 150, an interference module 120, an image pickup unit 140, a transfer unit 130 and a control unit 160 .

The light source 110 emits white light. The light source 110 emits monochromatic light, for example, white light, and uses a tungsten-halogen lamp of about 70 W or so. Here, the light emitted from the light source 110 is output through an optical fiber (not shown) not shown in the outgoing direction.

The light emitted from the optical fiber spreads around the pinhole of the fixing member 171. The light passing through the pinhole is transmitted through the convex lens 172 disposed between the fixing member 171 and the light splitting unit 150, and is aligned with a constant width.

The light transmitted through the convex lens 172 is incident on the light splitting section 150. Here, the light incident on the light splitting unit 150, for example, a beam splitter, is reflected at about 45 degrees with respect to the incident direction, and is directed to the measurement object 100.

The light reflected by the light splitting unit 150 and directed toward the measurement object 100 is incident on the interference module 120. The light incident on the interference module 120 is divided into the direction of the reference mirror provided in the interference module 120 and the direction of the measurement object 100 and is output. The interference light is formed by the reflected light reflected from the reference mirror and the measurement object 100, respectively, and is output to the light splitting unit 150.

The image sensing unit 140 senses interference light emitted from the interference module 120 and passed through the light splitting unit 150 and the convex lens 174 and applies the sensed interference light to the control unit 160.

The control unit 160 controls the transfer unit 130 according to the white light scanning interferometry to adjust the separation distance between the transfer unit 130 and the object to be measured 100. The control unit 160 measures the surface shape of the measurement object 100 based on the data captured by the imaging unit 140 in correspondence to the separation distance between the transfer unit 130 and the measurement object 100. [

However, since the white light interferometer has an interference interval of about 2-4 um and a period of the interference fringe is about 0.3 um, in order to measure the three-dimensional shape in which the height is present, It is necessary to acquire the interference fringes over a long period of time, thereby increasing the time required for the measurement.

Such a measurement method is effective in a stable environment in which there is little difference in height of a measurement object and is stable in a vibration-free environment. However, it is difficult to obtain appropriate measurement results in circumstances where there is mechanical vibration with a large difference in height of the measurement object.

2, a three-dimensional shape measuring apparatus according to Korean Patent No. 10-1333299 includes an image sensor 260, an image board 261 A projection grating 220, a beam splitter 230, a projection grating controller 221, a pinhole 241, an objective lens 240, a position sensor 242, and a projection lens 243 constituting a pattern projection portion. A control unit 340, a motor 252 for driving the measurement object 250, a motor driver 253, and a position sensor 242. In the case of the conventional three-dimensional measuring apparatus shown in FIG. 2, in order to acquire the amplitude and amplitude magnitude of the pattern, focus adjustment is implemented through the focus, and then, a focus grating pattern corresponding to one frame of the projection grating is obtained. And the height information of the object to be measured is calculated by driving through the projection grating driver.

However, in the case of the above-mentioned prior art, it is necessary to determine the amplitude values of the grid transfer axis, determine the height values using the amplitude values of the respective amplitude values, and this method has an advantage of high measurement accuracy , There is a problem in that the measurement speed is very slow because a large number of scans must be implemented for one point of the measurement object.

As a technique for solving the problem of the three-dimensional shape measuring apparatus according to Korean Patent No. 10-1333299, Korean Patent Registration No. 1423829 discloses a technique of transferring a measurement object at an inclination angle (x axis and z axis) (Focussing effect) can be obtained at the same time, and a technique for improving the measurement speed can be obtained because the projection grating driving and the measurement object transfer can be acquired at a time without separately implementing them .

Korean Patent No. 10-1333299 has an advantage of simultaneously acquiring a phase effect and an amplitude magnitude by moving an object to be measured in an oblique direction, but since it is required to move to a position where a real image of the grating is clearly imaged, The point that the relative distance between the three-dimensional shape measuring devices must be changed is the same as in the prior art.

In this case, when the measurement object moves, it takes time to move without changing the vibration or the posture, and when the measurement device moves, the high speed transfer is difficult and the transfer time is considerably long, .

Korean Patent No. 10-1333299 (Apparatus and method for measuring three-dimensional shape using projection grating amplitude) Korean Patent No. 10-1423829 (Apparatus and method for measuring three-dimensional shape using projection grating amplitude)

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the related art, and an object of the present invention is to provide a method and apparatus for enabling a high-speed focus position shift without physical movement of a measurement object or a measurement device, will be.

According to an aspect of the present invention, there is provided a light source unit including a first light source having a first wavelength and a second light source having a second wavelength, a light source unit disposed in front of the light source unit, An image acquiring unit that acquires a pattern image of a projection grating projected on the measurement object, a projection lens positioned between the image acquiring unit and the measurement object, and a light source unit The center wavelength of the light source is changed to change the image forming position of the measurement object to obtain the pattern image in the image acquisition unit, and the amplitude and amplitude magnitude of the projection grating pattern acquired in the image acquisition unit are calculated And a control unit for acquiring three-dimensional information of an object using the multi-wavelength light source A three-dimensional shape measuring device is provided.

Here, when the projection lens is a lens having a chromatic aberration, the principle is used that the imaging position of the projection grid pattern is changed in accordance with the central wavelength of the light source. When the projection lens is a chromatic aberration lens, The same principle can be applied by interposing a transparent plate between objects.

The transparent plate is a transparent material having a refractive index n = 1, and a glass material may be used.

The center wavelength of the light source may be changed by adjusting the intensity of the first light source and the second light source, or adjusting the ON time or the duty ratio of the first light source and the second light source, respectively.

According to another aspect of the present invention, there is provided a method of adjusting a center wavelength of a light source irradiated by a light source unit including a first light source of a first wavelength and a second light source of a second wavelength, Dimensional image of the measurement object by acquiring the pattern image reflected by the measurement object for each wavelength band of the light source and calculating amplitude and amplitude magnitudes of the acquired projection grid pattern by using the pattern projection light, Dimensional shape measuring method using a multi-wavelength light source for high-speed focal position movement.

According to the present invention as described above, it is not necessary to transfer a measurement object or an inspection apparatus for focus adjustment, and a high-speed focal position can be moved, thereby enabling an inspection speed to be remarkably increased.

1 is a schematic configuration diagram of a conventional three-dimensional measuring apparatus.
FIG. 2 is a schematic diagram of a three-dimensional measurement apparatus using a projection grating amplitude magnitude according to Korean Patent No. 10-1333299.
3 is a schematic block diagram of a three-dimensional shape measuring apparatus according to an embodiment of the present invention.
4 is a schematic block diagram of a three-dimensional shape measuring apparatus according to another embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a schematic block diagram of a three-dimensional shape measuring apparatus according to an embodiment of the present invention.

3, a three-dimensional shape measuring apparatus according to an embodiment of the present invention includes a light source 10, a projection grating 20, a light splitter 40, an image acquiring unit 50, a projection lens 60, And a control unit 70.

Unlike the prior art, the light source of the present invention has first and second light sources for outputting lights of different wavelength bands, and the first and second light sources And the center wavelength of the light output from the light source unit 10 is changed by controlling the output of the two light sources.

The projection grating 20 is disposed in front of the light source 10 so that the light emitted from the light source 10 passes through the projection grating 20 and is changed into grating light having a constant periodic component. The projection grating 20 is controlled in its projection position by using the phase-shift driving system 30. Although the physical projection grating 20 has been described in the present embodiment, it is needless to say that the projection grating 20 may be implemented in software.

The grating pattern light is incident on the light splitter 40, and is reflected to about 45 degrees with respect to the incident direction, and is directed to the measurement object 100. [

The grating pattern light reflected by the light splitter 40 and directed to the side of the object 100 is irradiated onto the object of measurement 100 through the projection lens 60.

The image acquiring unit 50 acquires a pattern image projected on the measurement object, and includes an image sensor that acquires a pattern of a grid projected on the measurement object 100, an image board that transmits an image acquired by the image sensor to the controller, And an objective lens disposed between the image sensor and the measurement object 100.

The control unit 70 controls the light source unit 10 to change the central wavelength of the light source so as to obtain the pattern image at the image acquisition unit while changing the imaging position of the measurement object 100, And obtains three-dimensional information of the measurement object 100 by calculating amplitude and amplitude magnitudes of the acquired projection grid pattern. The control unit 70 controls the light source unit 10 and the image obtaining unit 50 and the calculation function of measuring the shape of the measurement object at the same time. However, in addition to the control unit 70, It is obvious that it is possible to provide the light emitting diode.

The main feature of the present invention is that the light source unit 10 is composed of a light source having two different wavelengths, and the center wavelength of the light source can be changed by controlling each light source, When the light is irradiated while varying the central wavelength, the imaging position of the light, that is, the focal position, can be varied, and the image obtaining unit 50 obtains the pattern image at each focal position.

After obtaining the pattern image at each focal position, the controller 70 extracts the magnitude of the amplitude of the pixels corresponding to each point of the measurement object, and then determines the largest amplitude as the height of the corresponding point do. It is an object of the present invention to compare the amplitude magnitudes of pixels at various focal positions to obtain the highest sharpness value and to calculate the height of the corresponding point, as described in Korean Patent No. 10-1333299 and Korean Patent No. 10-1423829 It is the same.

However, according to the present invention, since the focal position can be moved at a high speed through the center wavelength shift of the light source without using a physical transferring means like the above-mentioned prior art documents for changing the focal position, the examination speed is much shorter The vibration is not generated and the inspection accuracy is improved.

Here, various methods can be applied to the method of changing the central wavelength of the light source.

As an example of such a method, there are a method of adjusting the light intensity of two light sources having different wavelengths, a method of adjusting the ON time of two light sources having different wavelengths (for example, when the image sensor exposure time is 1 second, ON, the second light source is ON for 0.6 seconds), and a method of adjusting the duty ratios of the two light sources having different wavelengths.

4 is a schematic block diagram of a three-dimensional shape measuring apparatus according to another embodiment of the present invention.

The embodiment of FIG. 3 is a technique that can be applied well when the projection lens 60 is a lens having chromatic aberration. That is, in the case of a lens having a chromatic aberration, the focal length varies depending on the wavelength band of the light, so that the characteristic is used.

On the other hand, when the projection lens 60 is a chromatic aberration correcting lens, it is difficult to apply the embodiment of Fig. 3 because such characteristics are not displayed well by chromatic aberration correction.

4, a transparent plate 80 is interposed between the projection lens 60 and the object to be measured 100.

As the transparent plate 80, a transparent material having a refractive index n of not 1 may be used, and glass may be used typically. When a transparent material having a refractive index n of 1 is used, the focal length of the transparent plate 80 varies according to the wavelength band of the light passing through the transparent plate 80. Therefore, It becomes possible to measure.

10: light source 20: projection grating
30: phase transfer driving system 40: optical splitter
50: image acquisition unit 60: projection lens
70: control unit 80: transparent plate
100: object to be measured

Claims (12)

A light source unit including a first light source of a first wavelength and a second light source of a second wavelength;
A projection grating installed at a front side of the light source unit and having a periodic component that receives light of the light source and is projected onto a measurement object;
An image acquiring unit acquiring a pattern image of a projection grating projected on the measurement object;
A projection lens positioned between the image acquisition unit and the measurement object; And
The image acquiring unit acquires the pattern image while changing the center wavelength of the light source by controlling the light source unit to change the image forming position of the measurement object and adjusts the amplitude and amplitude magnitude of the projection grating pattern acquired by the image acquiring unit And a control unit for calculating three-dimensional information of the object to be measured by using the multi-wavelength light source. The method according to claim 1,
Wherein when the projection lens is a lens having a chromatic aberration, an image forming position of the projection grating pattern is changed in accordance with a change in a central wavelength of the light source. The method according to claim 1,
Wherein a transparent plate is interposed between the projection lens and the measurement object when the projection lens is a chromaticity correction lens, wherein the transparent plate is interposed between the projection lens and the measurement object. The method of claim 3,
Wherein the transparent plate is made of a transparent material having a refractive index n = 1, and the transparent plate is a transparent material having a refractive index n = 1. 5. The method of claim 4,
Wherein the transparent plate is made of a glass material having a refractive index n = 1. The method according to claim 1,
Wherein the center wavelength of the light source is changed by adjusting the intensity of the first light source and the intensity of the second light source, respectively. The method according to claim 1,
Wherein the changing of the center wavelength of the light source is performed by adjusting ON time or duty ratio of the first light source and the second light source, respectively. In a three-dimensional shape measuring method,
The measurement object is irradiated through a projection lens of a lattice pattern while changing the central wavelength of the light source irradiated from the light source section including the first light source of the first wavelength and the second light source of the second wavelength, Dimensional information of the object to be measured is obtained by acquiring a pattern image reflected by the object to be measured and calculating amplitude and amplitude magnitudes of the projection grating pattern to be obtained. Dimensional shape measurement method. 9. The method of claim 8,
Wherein when the projection lens is a chromaticity correction lens, a grating pattern light is irradiated onto the measurement object through a transparent plate positioned between the projection lens and the measurement object. Shape measuring method. 10. The method of claim 9,
Wherein the transparent plate is a transparent material having a refractive index n = 1, and the transparent plate is a transparent material having a refractive index n = 1. 9. The method of claim 8,
Wherein the center wavelength of the light source is changed by adjusting the intensities of the first light source and the second light source, respectively. 9. The method of claim 8,
Wherein the changing of the center wavelength of the light source is performed by adjusting ON time or duty ratio of the first light source and the second light source, respectively.


KR1020150073494A 2015-05-27 2015-05-27 3-D Shape Mesuring Apparatus Using Multi Frequency light Source For High Speed Foucs Position Movement KR101677585B1 (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20040055014A (en) * 2002-12-20 2004-06-26 한국과학기술원 3D shape measuring instrument using multi-channel phase shifting moire technique
JP2013205295A (en) * 2012-03-29 2013-10-07 Noa:Kk Image processing device
KR101333299B1 (en) 2011-09-09 2013-11-27 주식회사 인스펙토 3D Shape Mesurement Mehod and Device by using Amplitude of Projection Grating
KR20140032665A (en) * 2012-09-07 2014-03-17 주식회사 인스펙토 3d shape mesurement mehod and device by using amplitude of projection grating
JP2015505039A (en) * 2011-12-12 2015-02-16 ザイゴ コーポレーションＺｙｇｏ Ｃｏｒｐｏｒａｔｉｏｎ Non-contact surface shape evaluation using modulated light

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20040055014A (en) * 2002-12-20 2004-06-26 한국과학기술원 3D shape measuring instrument using multi-channel phase shifting moire technique
KR101333299B1 (en) 2011-09-09 2013-11-27 주식회사 인스펙토 3D Shape Mesurement Mehod and Device by using Amplitude of Projection Grating
JP2015505039A (en) * 2011-12-12 2015-02-16 ザイゴ コーポレーションＺｙｇｏ Ｃｏｒｐｏｒａｔｉｏｎ Non-contact surface shape evaluation using modulated light
JP2013205295A (en) * 2012-03-29 2013-10-07 Noa:Kk Image processing device
KR20140032665A (en) * 2012-09-07 2014-03-17 주식회사 인스펙토 3d shape mesurement mehod and device by using amplitude of projection grating
KR101423829B1 (en) 2012-09-07 2014-07-25 주식회사 인스펙토 3D Shape Mesurement Mehod and Device by using Amplitude of Projection Grating

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