KR102092276B1 - A method of generating three-dimensional shape information of an object to be measured - Google Patents

A method of generating three-dimensional shape information of an object to be measured Download PDF

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KR102092276B1
KR102092276B1 KR1020180114368A KR20180114368A KR102092276B1 KR 102092276 B1 KR102092276 B1 KR 102092276B1 KR 1020180114368 A KR1020180114368 A KR 1020180114368A KR 20180114368 A KR20180114368 A KR 20180114368A KR 102092276 B1 KR102092276 B1 KR 102092276B1
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light
hologram
image
measured
frequency component
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KR1020180114368A
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Korean (ko)
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김병목
김지훈
성맑음
이상진
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주식회사 내일해
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    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B30/00Optical systems or apparatus for producing three-dimensional [3D] effects, e.g. stereoscopic images
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B5/00Optical elements other than lenses
    • G02B5/32Holograms used as optical elements
    • GPHYSICS
    • G06COMPUTING; CALCULATING; COUNTING
    • G06TIMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T5/00Image enhancement or restoration
    • G06T5/001Image restoration

Abstract

The three-dimensional shape of the object to be measured from the image including the intensity information of the object hologram generated by the interference of the reference light reflected from the optical mirror and the object light affected by the object to be measured according to an embodiment of the present invention The method for generating information includes: identifying at least one frequency component included in the image; Extracting a real image component corresponding to a real image among the at least one frequency component; Generating a real image hologram including a correction light having a conjugate relationship with the reference light based on the real components and real information of the object to be measured; Generating an intermediate hologram from which the information of the reference light is removed from the actual hologram based on the corrected light; Generating curvature aberration correction information from the intermediate hologram; Generating a correction hologram in which errors due to curvature aberration are removed from the intermediate hologram based on the curvature aberration correction information; And generating the 3D shape information of the object to be measured from the correction hologram.

Description

A method of generating three-dimensional shape information of an object to be measured by removing noise included in the frequency component of the object to be measured

The present invention relates to a method of generating 3D shape information by removing noise included in a frequency component of an object to be measured. More specifically, the present invention extracts and measures frequency components from an image including intensity information of an object hologram generated by interference of a reference light reflected from an optical mirror and an object light reflected from an object to be measured or transmitted through an object to be measured. The present invention relates to a method of generating 3D shape information by removing noise included in a frequency component of a target object.

A digital holography microscope refers to a microscope that acquires the shape of an object using digital holography technology.

If a general microscope is a device that acquires the shape of an object by acquiring reflected light reflected from the object, a digital holography microscope acquires interference light and / or diffracted light generated by the object, and acquires the shape of the object therefrom to be.

A digital holography microscope uses a laser that generates light of a single wavelength as a light source, and uses a light splitter to divide the light generated by the laser into two lights. At this time, one light (hereinafter referred to as reference light) is directed to the image sensor, and the other light (hereinafter referred to as object light) is reflected from the target object and directed to the above-described image sensor so that interference between the reference light and the object light occurs. do.

The image sensor may record the interference fringe according to the interference phenomenon as a digital image, and restore the 3D shape of the object to be measured from the recorded interference fringe. At this time, the interference fringe recorded by the image sensor is usually referred to as a hologram.

Conventional optical holography microscopy records the interference pattern according to the interference phenomenon between the reference light and the object light as a special film. At this time, when the reference light is irradiated to the special film on which the interference fringe is recorded, the shape of the virtual object to be measured is restored where the object to be measured is located.

Compared with the conventional optical holography microscope, the digital holography microscope digitizes (or digitizes) the interference pattern of light through an image sensor, and restores the shape of the object to be measured through electronic calculation rather than an optical method. There is a difference.

On the other hand, the conventional digital holography microscope using a single wavelength laser light source has a problem that the minimum unit length of the measurement of the object is limited to the wavelength length of the laser. In order to compensate for this, another conventional digital holography microscope using a laser light source having two or more wavelengths has a problem in that it is impossible to obtain a three-dimensional shape of an object in real time, as well as a high manufacturing cost of the microscope.

In addition, the above-mentioned conventional digital holography microscopes generate a computer generated hologram (CGH) with a computer to restore the shape of the object to be measured, and display it on a spatial light modulator (SLM), and display the A 3D hologram image of the object was obtained by illuminating the reference light. However, this method not only requires the use of an expensive spatial light modulator (SLM), but also has a clear technical limitation by simply digitizing a special film in the above-described optical holography microscope.

In order to solve the problems of the conventional digital holography microscopes, for example, Republic of Korea Patent Publication No. 10-2016-0029606 (hereinafter referred to as "published prior art") proposes a digital holography microscope and a digital hologram image generation method. Hereinafter, the disclosed prior art will be briefly described.

1 is a block diagram showing in detail a two-wavelength digital holography microscope device according to the disclosed prior art.

Referring to FIG. 1, the disclosed prior art two-wavelength digital holography microscope device includes a mixed light source unit 100, a wavelength division unit 200, an interference pattern acquisition unit 300, an objective unit 400, and an image sensor unit 500. ), An image storage unit 600, a control unit 700, and an object shape restoration unit 800.

The mixed light source unit 100 includes a mixed light source emitting unit 110 and a light source unit lens 120. The mixed light source light emitting unit 110 emits mixed light having a wavelength band distributed in several non-uniform bands. The light source unit lens 120 optically adjusts the mixed light generated by the mixed light source emitting unit 110 and makes it incident on the wavelength division unit 200.

The wavelength division unit 200 includes a first light splitter 210, a first filter plate 220, a second filter plate 230, and a first reflector 240. The first light splitter 210 receives the mixed light incident from the mixed light source unit 100 and divides it into two lights. At this time, the first light splitter 210 serves to divide the incident mixed light in different directions. The first filter panel 220 receives one light among the lights divided by the first light splitter 210 to obtain a first light beam having a predetermined single wavelength. Here, the light input to the first filter plate 220 is filtered while passing through the first filter plate 220, and a first ray having a single wavelength determined according to the characteristics of the first filter plate 220 is obtained. The second filter plate 230 receives the other one of the light split by the first optical splitter 210 in the same manner as the first filter plate 220, and has a second wavelength different from that of the first filter Acquire rays. And the second ray is sent to the interference pattern acquisition unit 300. The first reflector 240 serves to receive the first light obtained from the first filter plate 220 and reflect it to the interference pattern acquisition unit 300.

The interference pattern acquisition unit 300 includes a second light splitter 310, a third light splitter 320, a second reflector 330, a third filter plate 340, and a third reflector 350. The second light splitter 310 receives the first light input from the wavelength division unit 200 and divides it into a first object light and a first reference light. At this time, the second light splitter 310 serves to divide the incident first light beams in different directions and proceed. The third light splitter 320 receives the second light beam in the same manner as the second light splitter 310 and divides it into a second object light and a second reference light. The second reflector 330 receives the first reference light and sends the reflected first light to the second light splitter 310. The third filter panel 340 may receive the first reference light divided by the second light splitter 310 and send it to the second reflector 330, and receive the reflected first reflection reference light and send it to the second light splitter. In addition, the third filter plate 340 prevents the second object light from reaching the second reflector 330 when the second object light reaches the second light splitter 310 and the light is split, so that the second reflector 330 does not reach the second reflector 330. . To this end, the third filter plate 340 is a filter plate having the same characteristics as the first filter plate 220 in transmitting light. The third reflector 350 receives the second reference light, and sends the reflected second reference light to the third light splitter 320, wherein the second reflector 330 and the third reflector 350 are the control unit 700 ) Can be configured to adjust the angle under control, so that an off-axis hologram can be implemented.

On the other hand, the first object light and the second object light obtained as described above are converted to each of the first reflection object light and the second reflection object light through the following process and sent to the image sensor unit 500. The second optical splitter 310 injects the first object light divided as described above into the object to be measured mounted on the objective unit 400, and further sends the second object divided by the third optical splitter 320. Light is incident on the object to be measured. In this case, the reflected light reflecting the first object light incident from the object to be measured is referred to as the first reflected object light. In addition, the reflected light reflecting the second object light incident from the object to be measured is referred to as the second reflected object light. The second light splitter 310 receives the first reflected object light and the second reflected object light reflected as described above and sends them to the third light splitter 320. The third light splitter 320 sends the first reflected object light and the second reflected object light input as described above to the image sensor unit 500 again.

In addition, the first reflection reference light and the second reflection reference light obtained as described above are sent to the image sensor unit 500 through the following process. Specifically, the second light splitter 310 receives the first reflection reference light reflected from the second reflector 330 and sends it to the third light splitter 320. As described above, the third light splitter 320 receives the first reflecting reference light sent from the second light splitter 310 and the second reflecting reference light reflected from the third reflector 350, and then re-images the image sensor unit 500. To send. Accordingly, after the first light reflection object light, the first reflection reference light, the second reflection object light, and the second reflection reference light are both sent in the same direction to the image sensor unit 500 in the third light splitter 320, and interfere with each other. Interference patterns are generated.

On the other hand, the second reflector 330 and the third reflector 350 are angled under the control of the control unit 700 to form an off-axis system that allows different wavelengths of light to form different interference patterns. Characterized in that it can be adjusted in multiple directions. That is, as the angles of the second reflector 330 and the third reflector 350 are different from each other, the first reflecting reference light reflected from the second reflector 330 and the second reference reflecting from the third reflector 350 When a distance occurs in the direction of the light, the first reflection reference light and the second reflection reference light are combined with the first reflection object light and the second reflection object light reaching the image sensor unit 500 to form an interference pattern, each wavelength Very differently disjointed interference patterns are formed.

The objective unit 400 includes an object holder 410 and an objective lens 420. The object holder 410 is fixed to the object to be measured to be measured, and the objective lens 420 optically adjusts the first object light and the second object light incident on the object to be measured.

The image sensor unit 500 projects the interference pattern obtained from the interference pattern acquisition unit 300 onto a digital image sensor, measures the projected interference pattern using the digital image sensor, and disperses the measurement value. Convert to Usually, the interference fringe is recorded as a hologram. As the digital image sensor, various image sensors such as a CCD may be used.

The image storage unit 600 stores the interference fringe information converted from the image sensor unit 500 into discrete signals in various storage media such as a memory or a disk device.

The control unit 700 implements the above-described off-axis system and adjusts the position and angle of the second reflector 330 and the third reflector 350 to obtain an interference pattern, such as the interference pattern acquisition unit 300 ) To control, and to control the objective unit 400, such as adjusting the objective lens 420 to adjust the first object light and the second object light incident on the object to be measured, the interference fringe is measured and the The image sensor unit 500 is controlled to allow information to be converted into a discrete signal, and the image storage unit 600 is controlled to store interference fringe information converted into a discrete signal.

The object shape restoration unit 800 includes a phase information acquisition unit 810, a thickness information acquisition unit 820, and a shape restoration unit 830. The phase information acquisition unit 810 acquires the phase information of the interference pattern for the first ray and the interference pattern for the second ray by using the interference pattern information, respectively, and the thickness information acquisition unit 820 Obtains the thickness information of the object to be measured using the phase information, and the shape restoration unit 830 restores the real-time three-dimensional shape of the object to be measured using the thickness information. At this time, the thickness information of the object to be measured includes difference information between the paths of the object light and the reference light. Due to the optical path difference between the object light and the reference light, the interference pattern is formed when the object light and the reference light overlap.

According to the disclosed prior art including the above, it is possible to improve measurement resolution and secure real-time image acquisition, but still has the following problems.

Since the conventionally disclosed prior art uses a mixed light source having a wavelength band distributed in several bands, the wavelength division unit 200 divides the first and second light sources having different wavelengths to obtain at least two single wavelengths. To do so, the first filter plate 220, the second filter plate 230, and the first reflector 240 should be used.

In addition, the interference pattern acquisition unit 300, a third light splitter 320 for dividing the second light source, a third reflector 350 for reflecting the second light source, and a second light source for the second reflector 330 The third filter plate 340 for blocking the incident to the additional should be used.

Therefore, the structure of the microscope is complicated, and this entails various problems such as an increase in manufacturing cost and an increase in design complexity. Therefore, a new method is needed to solve the above-mentioned problems while using a single wavelength light source.

Republic of Korea Patent Publication No. 10-2016-0029606 Republic of Korea Patent Publication No. 10-2010-0095302 Republic of Korea Patent Publication No. 10-2012-0014355 Republic of Korea Patent No. 10-1139178 Republic of Korea Patent No. 10-1441245 U.S. Patent No. 7,649,160

The present invention is to solve the problems of the prior art as described above, it is intended to accurately generate the three-dimensional shape information of the object to be measured by the acquisition of only one hologram.

In particular, the present invention seeks to generate three-dimensional shape information of an object to be measured with improved accuracy by generating information about the reference light and curvature aberration information of the object light objective lens from one hologram and correcting the obtained object hologram in consideration of this.

In addition, the present invention seeks to solve the complex optical device structure and thus significant high cost problems.

Furthermore, the present invention seeks to detect defects of these structures with a high probability by accurately acquiring three-dimensional shapes of ultra-fine structures such as TFTs and semiconductors.

Three-dimensional shape information of the object to be measured from an image including intensity information of the object hologram generated by interference of the reference light reflected from the optical mirror and the object light reflected from the object to be measured according to an embodiment of the present invention The method for generating a method includes: identifying at least one frequency component included in the image; Extracting a real image component corresponding to a real image among the at least one frequency component; Generating a real image hologram including a correction light having a conjugate relationship with the reference light based on the real components and real information of the object to be measured; Generating an intermediate hologram from which the information of the reference light is removed from the actual hologram based on the corrected light; Generating curvature aberration correction information from the intermediate hologram; Generating a correction hologram in which errors due to curvature aberration are removed from the intermediate hologram based on the curvature aberration correction information; And generating the 3D shape information of the object to be measured from the correction hologram.

The generating of the curvature aberration correction information may include generating 3D shape information of the measurement target object from the intermediate hologram; Determining at least one parameter for determining the curvature aberration correction information based on the 3D shape information of the measurement target object generated from the intermediate hologram; And generating the curvature aberration correction information based on the parameter.

The three-dimensional shape of the object to be measured generated from the intermediate hologram includes at least a portion of a hemispherical curved surface, and determining the at least one parameter comprises at least a portion of the hemispherical curved surface. Determining the coordinates of the center point of the; And determining a radius of the hemispherical curved surface from at least a portion of the hemispherical curved surface.

The determining of the at least one parameter may further include generating a cut surface for cutting the hemispherical curved surface, and determining the coordinates of the center point is a curve generated by the hemispherical curved surface on the cut surface. The step of determining the coordinates of the center point from and determining the radius of the curved surface may determine the radius from the curve.

The cut surface may be parallel to the traveling direction of the object light.

According to the present invention, it is possible to accurately generate three-dimensional shape information of an object to be measured by acquiring only one hologram.

In particular, by generating information about the reference light and curvature aberration information of the object light objective lens from one hologram and correcting the obtained object hologram in consideration of this, it is possible to generate three-dimensional shape information of an object to be measured with improved accuracy.

In addition, it is possible to solve the complicated optical device structure and thus a considerable high cost problem.

Furthermore, by accurately acquiring the three-dimensional shape of ultra-fine structures such as TFTs and semiconductors, defects in these structures can be detected with a high probability.

Additional advantages of the present invention can be clearly understood from the following description with reference to the accompanying drawings in which identical or similar reference numerals indicate identical components.

1 is a block diagram showing in detail a two-wavelength digital holography microscope device according to the disclosed prior art.
2A is a block diagram showing a schematic configuration of a holographic reconstruction apparatus according to a first embodiment of the present invention.
2B is a block diagram showing a schematic configuration of a holographic reconstruction apparatus according to a second embodiment of the present invention.
3A and 3B are views for explaining the appearance of an exemplary measurement object.
4 is an example of an image of a portion of an object to be measured.
FIG. 5 is a diagram showing frequency components of an image of a part of the measurement target object illustrated in FIG. 4.
6A, 6B, 6C, and 6D are diagrams for explaining a method of extracting frequency components corresponding to a real image from the frequency components illustrated in FIG. 5.
7A is a diagram showing the intensity of digital reference light.
7B is a diagram showing the phase of the reference light.
7C is a diagram showing the intensity of the correction light.
7D is a diagram showing the phase of the correction light.
8 is a diagram illustrating an exemplary actual hologram.
9 and 10 are diagrams for explaining a method for a processor to determine a curvature aberration correction term from an intermediate hologram according to an embodiment of the present invention.
11A, 11B, and 11C are diagrams showing examples of three-dimensional shapes of objects to be measured generated from holograms.
12 is a flowchart illustrating a method of generating 3D shape information of an object to be measured performed by a holographic reconstruction apparatus according to an embodiment of the present invention.
13 and 14 are flow charts of a noise removal method of the holographic restoration apparatus 1 according to the embodiments of the present invention.

The present invention can be applied to various transformations and can have various embodiments, and specific embodiments will be illustrated in the drawings and described in detail in the detailed description. Effects and features of the present invention and methods for achieving them will be clarified with reference to embodiments described below in detail with reference to the drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various forms.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, and the same or corresponding components will be denoted by the same reference numerals when describing with reference to the drawings, and redundant description thereof will be omitted. .

In the following examples, terms such as first and second are not used in a limiting sense, but for the purpose of distinguishing one component from other components. In the following embodiments, singular expressions include plural expressions, unless the context clearly indicates otherwise. In the examples below, terms such as include or have are meant to mean the presence of features or components described in the specification, and do not preclude the possibility of adding one or more other features or components in advance. In the drawings, the size of components may be exaggerated or reduced for convenience of description. For example, since the size and shape of each component shown in the drawings are arbitrarily shown for convenience of description, the present invention is not necessarily limited to what is illustrated.

2A is a block diagram showing a schematic configuration of a holographic reconstruction apparatus 1A according to a first embodiment of the present invention.

In the present invention, the 'Holography (Holography) reconstruction device' may mean a device that acquires a hologram (hereinafter referred to as 'object hologram') for an object to be measured and analyzes and / or displays the obtained object hologram. .

For example, the holographic restoring apparatus 1A may be a device that is disposed on a semiconductor manufacturing line, obtains an object hologram of the produced semiconductor, and determines whether the semiconductor is integrity from the obtained object hologram. However, this is exemplary and the spirit of the present invention is not limited thereto.

Meanwhile, in the present invention, 'object hologram' is a hologram that can be generated from an image obtained by the holographic reconstruction apparatus 1A, and may mean a hologram before various processing by the holography reconstruction apparatus 1A is performed. have. Detailed description thereof will be described later.

Referring to FIG. 2A, the holographic reconstruction apparatus 1A according to the first embodiment of the present invention includes a light source unit 10 emitting single wavelength light and a collimator 20 for collimating single wavelength light emitted from the light source unit 10 ), An optical splitter 30 for dividing the single wavelength light passing through the collimator 20 into object light O and reference light R, and an object through which the object light O divided by the light splitter 30 passes The optical objective lens 40, the reference light objective lens 60 passing through the reference light R divided by the optical splitter 30, and the optical mirror 70 reflecting the reference light R passing through the reference light objective lens 60 ), The object light (O) reflected from the surface of the object to be measured (50) passing through the object light objective lens (40) and the reference light (R) reflected by the optical mirror (70) are respectively the object light objective lens (40). ) And an image sensor 80 and an image sensor 8 for recording an image formed by passing through the reference light objective lens 60 and being transferred to the optical splitter 30 0) may include a processor 90 for processing the acquired image.

At this time, the processor 90 may generate 3D information of the object to be measured 50 from the image acquired by the image sensor 80. The detailed description of the operation of the processor 90 will be described later.

2B is a block diagram showing a schematic configuration of a holographic reconstruction apparatus 1B according to a second embodiment of the present invention.

Referring to FIG. 2B, the holographic restoration apparatus 1B according to the second embodiment of the present invention includes a light source unit 10 emitting single wavelength light and a collimator 20 for collimating single wavelength light emitted from the light source unit 10 ), A light splitter 30 for dividing the single wavelength light passing through the collimator 20 into object light O and reference light R, and the object light O divided by the light splitter 30 is an object to be measured After passing through (50), the object light objective lens (40) passing through the object transmitted light (T) containing the information of the object to be measured (50), and the object transmitted light (T) passing through the object light objective lens (40) is reflected. A second optical mirror 72, a reference light objective lens 60 through which the reference light R divided by the light splitter 30 passes, and a first light reflecting the reference light R passing through the reference light objective lens 60 The optical mirror 70, the reference light R reflected by the first optical mirror 70 and the object transmitted light T reflected by the second optical mirror 72 are respectively transmitted. The second optical splitter 32, the image sensor 80 and the image sensor 80 for recording an image formed by the reference light (R) and the object light transmitted light (T) transmitted to the second optical splitter 32 It may include a processor 90 for processing the acquired image.

Of course, even in this second embodiment, the processor 90 may generate three-dimensional information of the object to be measured 50 from the image acquired by the image sensor 80. The detailed description of the operation of the processor 90 will be described later.

2A and 2B, the holographic reconstruction apparatus 1A according to the first embodiment of the present invention and the holographic reconstruction apparatus 1B according to the second embodiment of the present invention respectively measure the object light O The fact that the object 50 reflects (the embodiment of FIG. 2A) or the object light O transmits the object 50 to be measured (the embodiment of FIG. 2B) and thus some components (eg, It has substantially the same configuration except for the further use of the second optical mirror 72 and the second light splitter 32 of the embodiment of FIG. 2B and the placement of some components accordingly).

In particular, it should be noted that the image is acquired by the image sensor 80, and the processor 90 has the same characteristic in that it generates the reference light R from the acquired image.

Hereinafter, holographic reconstruction apparatuses 1A and 1B according to the first and second embodiments of the present invention will be collectively described as holographic reconstruction apparatus 1.

Meanwhile, the processor 90 of the holographic restoring apparatus 1 according to an embodiment of the present invention may include all kinds of apparatus capable of processing data. For example, the processor 90 may refer to a data processing device embedded in hardware having physically structured circuits to perform functions represented by codes or instructions included in a program.

As an example of such a data processing device embedded in hardware, a microprocessor, a central processing unit (CPU), a processor core, a multiprocessor, and an application-specific integrated (ASIC) Circuit), FPGA (Field Programmable Gate Array), and the like, but the scope of the present invention is not limited thereto.

In addition, the image sensor 80 according to an embodiment of the present invention may be implemented with at least one image sensor, such as a Charge Coupled Device (CCD) or a Complimentary Metal-Oxide Semiconductor (CMOS), for example.

3A and 3B are views for explaining the appearance of an exemplary object to be measured 50.

As shown in FIGS. 3A and 3B, the object to be measured 50 may include rectangular parallelepiped structures 51A to 51I arranged on one surface at predetermined intervals. In other words, the object to be measured 50 may include cuboid-shaped structures 51A to 51I protruding in the Z direction on a plane parallel to the X-Y plane.

Hereinafter, the holographic reconstruction apparatus 1 irradiates the object light O in a direction perpendicular to the surface on which the structures 51A to 51I of the rectangular parallelepiped structure of the object to be measured 50 are disposed, and the image of the object to be measured 50 It will be described on the premise of obtaining.

First, the image sensor 80 according to an embodiment of the present invention may acquire an image of the object 50 to be measured.

In the present invention, the 'image' of the object to be measured 50 is the intensity information at each position of the object hologram U0 (x, y, 0) with respect to the object to be measured 50 (ie | (U0 (x, y, 0) | 2 ), and may be expressed as Equation 1 below.

[Equation 1]

Figure 112018094955308-pat00001

Here, the object hologram Uo (x, y, 0) represents phase information at each x and y point of the object to be measured, and x and y are coordinates in the space where the object to be measured is placed and perpendicular to the object light O O (x, y) and R (x, y) denote object light O and reference light R, respectively, and O * (x, y) and R * (x, y) represents the complex conjugate of the object light O and the reference light R, respectively.

For example, the image sensor 80 may acquire an image as shown in FIG. 4 for a portion of the measurement target object 50 shown in FIGS. 3A and 3B (eg, a portion including 51A and 51B). You can.

Since the image acquired by the image sensor 80 includes intensity information at each position of the object hologram U0 (x, y, 0), as described above, the image sensor 80 acquires the general It may be different from the image of the object to be measured 50 (that is, photographed only with object light O).

Referring to Equation 1, the object hologram U0 (x, y, 0) does not include the object light 0 including the phase information of the object 50 to be measured at each point and the phase information of the object to be measured. It may be generated by the interference of the reference light (R).

In addition, the object hologram (U0 (x, y, 0)) is in addition to the phase information (ie, height information of the object) at each point (ie, each x, y point) of the object to be measured 50, the object light objective lens 40 ) May further include errors and noises caused by aberration (eg, speckle noise due to use of a photon of a laser).

Accordingly, the processor 90 according to an embodiment of the present invention may perform various calculation processes as described below to remove the above-described error and noise from the image acquired by the image sensor 80.

The processor 90 according to an embodiment of the present invention may check frequency components of an image acquired by the image sensor 80. For example, the processor 90 may perform a 2D Fourier Transform on the image to check frequency components of the image.

In other words, the processor 90 uses the frequency components included in the image including the intensity information for each position of the object hologram U0 (x, y, 0) (ie, | (U0 (x, y, 0) | 2 ). In this case, the image may include a frequency component corresponding to a real image, a frequency component corresponding to an Imaginary Image, and a DC component.

Of course, the image may further include various components in addition to the three components described above (the frequency component corresponding to the real image, the frequency component corresponding to the virtual image, and the DC component). For example, the image may further include frequency components due to noise. However, this is exemplary and the spirit of the present invention is not limited thereto.

The processor 90 according to an embodiment of the present invention can extract only the components corresponding to the actual condition among the identified frequency components. At this time, the processor 90 may extract components corresponding to the actual image in various ways.

For example, the processor 90 extracts components having a peak value (hereinafter referred to as peak components) among the frequency components included in the image, and a peak component corresponding to a real image among the extracted peak components. Components within the frequency difference of firing can be extracted as components corresponding to the actual image.

At this time, the processor 90 may determine components corresponding to the actual image in various ways based on a peak component corresponding to the actual image. For example, the processor 90 may determine, among the frequency components corresponding to the real image, frequency components in the cross region including the peak component as components corresponding to the real image. At this time, the length of the cross region from the peak component may be determined based on a distance difference value between a frequency component corresponding to the real image and a frequency component corresponding to the origin. For example, however, this is exemplary and the spirit of the present invention is not limited thereto. The processor 90 includes a peak component corresponding to the actual image,

In an optional embodiment, the processor 90 may extract only components corresponding to the real image among frequency components included in the hologram using an automatic real image spot-position extraction algorithm.

In the present invention, 'extracting' a specific frequency component may mean extracting a frequency and a magnitude (or intensity) of the frequency component.

FIG. 5 is a diagram showing frequency components of an image for a portion of the object to be measured 50 shown in FIG. 4.

As described above, the processor 90 may check frequency components of the image acquired by the image sensor 80, and accordingly, the processor 90 may include a frequency component 911 corresponding to a real image and a frequency component corresponding to a virtual image. Various frequency components including 912 and DC component 913 may be identified.

In addition, the processor 90 may extract only the frequency component 911 corresponding to the actual condition among the identified components. At this time, the processor 90 removes noise from the frequency component corresponding to the actual image. Specifically, the processor 90 removes the frequency component located in the direction of the interference fringe and the normal direction of the interference fringe as noise, thereby corresponding to the real image as shown in FIGS. 6A, 6B, 6C, and 6D, for example. The frequency components in the cross region centered on the peak component can be determined as components corresponding to the actual image. At this time, the direction of the cross region is rotated according to the direction of the interference fringe.

The processor 90 according to an embodiment of the present invention may generate digital reference light from frequency components corresponding to a real image extracted by the above-described process. Looking at this in more detail, the processor 90 may calculate the propagation direction and wave number of the digital reference light based on the frequency components corresponding to the actual image. In other words, the processor 90 may calculate the wavenumber vector of the digital reference light.

In addition, the processor 90 generates a digital reference light based on the propagation direction and wave number (or wave vector) of the digital reference light, and the conjugate term of the digital reference light (R (x, y)) generated as in Equation 2 below By obtaining, the correction light Rc (x, y) can be generated.

[Equation 2]

Rc (x, y) = conj [R (x, y)]

At this time, R (x, y) represents digital reference light generated based on frequency components corresponding to the real image, and Rc (x, y) represents correction light.

The processor 90 extracts a normal line of the interference fringe and direction lines (Line1, Line2) parallel to the interference fringe corresponding to the peak component 911P from the frequency components 911 corresponding to the actual image. The processor 90 determines regions including Line1 and Line2 as noise regions (Noise1, Noise2, Noise3, and Noise4). The processor 90 may extract frequency components distributed in regions excluding noise regions. The processor 90 may extract frequency components corresponding to the reality in which noise is removed using a pattern excluding the noise region. As illustrated in FIG. 6C, the processor 90 may remove noise using a cross-shaped pattern (Pattern1) excluding frequency components distributed in Line1 and Line2. At this time, the processor 90 generates a cross-shaped pattern (Pattern1) based on a constant ratio of the distance difference value between the origin component 913 and the actual frequency component 911, for example, 1/3 times R. Can decide.

The processor 90 may set various patterns to remove the noise region. As illustrated in FIG. 6D, noise is removed from a frequency component corresponding to the real image by using a pattern (Pattern2) that is wider as it approaches the peak component of the frequency component 911 corresponding to the real image.

Since the digital reference light R (x, y) and the correction light Rc (x, y) are in a conjugate relationship, the intensity is the same as shown in FIGS. 7A and 7C, as shown in FIGS. 7B and 7D. Likewise, the phases can be reversed. Here, FIG. 7A is a diagram showing the intensity of the digital reference light R (x, y), FIG. 7B is a diagram showing the phase of the reference light, and FIG. 7C is the intensity of the correction light Rc (x, y). Fig. 7D is a diagram showing the phase of the correction light.

The generated correction light Rc (x, y) may be used for correction of a real hologram Um (x, y, 0) described later.

Meanwhile, the 'digital reference light' is light having the same properties as the reference light R generated by the above-described light splitter 30 from light of a single wavelength, and the processor 90 restores the image obtained by the image sensor 80. It can be a virtual light.

The processor 90 according to an embodiment of the present invention may generate a real image hologram based on frequency components corresponding to the real image extracted by the above-described process. For example, the processor 90 may generate an actual hologram as shown in FIG. 8 by performing an inverse 2D Fourier transform on frequency components corresponding to the actual image.

In this case, the hologram may be represented by Equation 3 below.

[Equation 3]

Um (x, y, 0) = O (x, y) R * (x, y)

Here, Um (x, y, 0) denotes a hologram, O (x, y) denotes object light O, and R * (x, y) denotes a complex conjugate of reference light R.

On the other hand, such a real hologram (Um (x, y, 0)), in addition to information about the height of the object to be measured 50, information about the reference light (R) and the error due to the aberration of the object light objective lens 40 It can contain.

Therefore, the processor 90 according to an embodiment of the present invention takes into account the error caused by the reference light R and the error caused by the aberration of the object light objective lens 40 from the real hologram Um (x, y, 0). A correction hologram Uc (x, y, 0) can be generated.

For example, the processor 90 may include a term (Rc (x, y)) for correction light and a term for correction of curvature aberration (Rca (x) in the actual hologram (Um (x, y, 0)) as shown in Equation 4 below. , y)) to generate a correction hologram Uc (x, y, 0).

[Equation 4]

Uc (x, y, 0) = Um (x, y, 0) Rc (x, y) Rca (x, y)

Here, Uc (x, y, 0) represents a correction hologram in which information about the reference light R and aberration information of the object light objective lens 40 are removed, and Um (x, y, 0) represents a real hologram, Rc (x, y) represents a term for correction light, and Rca (x, y) represents a term for curvature aberration correction.

Meanwhile, the processor 90 according to an embodiment of the present invention may generate the term Rca (x, y) for the curvature aberration correction described above in various ways.

For example, the processor 90 can actually measure the hologram Um (x, y, 0) multiplied by only the term Rc (x, y) for the correction light from the hologram (hereinafter, the intermediate hologram) 3 of the object to be measured 50 A dimensional shape may be generated, and a term Rca (x, y) for curvature aberration correction may be generated from the generated 3D shape.

Looking at this in more detail, the processor 90 may determine at least one parameter for determining a curvature aberration correction term from the three-dimensional shape of the measurement target object 50 generated from the intermediate hologram. At this time, the parameter may include, for example, a coordinate and a radius of a center point defining a hemispherical curved surface.

9 and 10 are diagrams for describing a method in which the processor 90 according to an embodiment of the present invention determines a curvature aberration correction term from an intermediate hologram.

For convenience of description, it is assumed that the image sensor 80 acquires an image of the cuboid-shaped structure 51D of FIG. 3B, and the processor 90 generates an intermediate hologram for the structure 51D according to the above-described process. do. It is also assumed that the three-dimensional shape 920 of the structure 51D generated from the intermediate hologram for the structure 51D is as shown in FIG. 9.

Under the assumptions described above, the processor 90 according to an embodiment of the present invention may determine at least one parameter for determining a curvature aberration correction term from the three-dimensional shape 920. For example, the processor 90 may determine the coordinates (Cx, Cy) of the center point of the hemispherical curved surface and the radius (r) of the curved surface as parameters from a curve on the II section of the three-dimensional shape 920 as shown in FIG. 10. . At this time, the processor 90 according to an embodiment of the present invention may determine the position and / or direction of the cutting surface such that the cutting surface such as the I-I cross section includes the center point of the three-dimensional shape 920 (ie, the center point of the hemispherical shape). In addition, the processor 90 may determine that a cutting surface such as an I-I cross section is parallel to the traveling direction of the object light 0.

The processor 90 according to an embodiment of the present invention may generate (or determine) a curvature aberration correction term based on at least one parameter determined by the above-described process. For example, the processor 90 refers to the coordinates (Cx, Cy) of the center point of the curved surface and the radius (r) of the curved surface to generate a curved surface in 3D space, and is reflected in the phase correction of each x, y point from the generated curved surface. A curvature aberration correction term may be generated (or determined) by generating information.

In an optional embodiment, the processor 90 may determine a correction term from an intermediate hologram of an object to be measured (e.g., an object having the same z value in all x, y coordinates) whose shape is known in advance.

In the case of an object to be measured in advance of the shape, since the z value at each x and y point is known in advance, the processor 90 determines the three-dimensional shape of the object to be measured generated from the intermediate hologram and the shape of the object to be measured. The correction term can also be determined by checking the difference in z values at each x and y point. However, this is exemplary and the spirit of the present invention is not limited thereto.

The processor 90 according to an embodiment of the present invention may generate a three-dimensional shape of the object 50 to be measured based on the correction hologram Uc (x, y, 0). In other words, the processor 90 may calculate the height of the object at each x and y point in the z direction.

For example, the processor 90 may convert the corrected hologram Uc (x, y, 0) into information on a reconstructed image plane. In this case, the reconstructed image plane means a virtual image display plane corresponding to a distance between the object to be measured and the image sensor by the processor, and may be a virtual plane calculated and simulated by the processor 90.

The processor 90 may calculate the height in the z direction of the object at points x and y as shown in FIGS. 11A, 11B, and 11C from the restored information in consideration of the reconstructed image plane. FIG. 11A shows the result of restoring without removing noise from the frequency component, and FIG. 11B shows the result of removing noise using the cross-shaped pattern (Pattern1), and FIG. 11C shows the result of removing noise using Pattern2. . A1, A2, and A3 represent the height value in the Z direction as a flat graph. It can be seen that A1 has no noise, so that the height value in the z direction is large, and A2 and A3 have little change in the height value in the z direction.

When the processor 90 uses a cross-shaped pattern, the frequency component may be extracted according to the following equation.

Figure 112018094955308-pat00002

Here, ms is the size of the cross-region pattern, xc is the X coordinate of the peak component, and yc is the Y coordinate of the peak component. R is a number proportional to the distance between the actual and corresponding frequency components and origin components. For example, R may be distance / 3, distance / 2, and the like.

The size (ms) of the cross-region pattern is determined based on the distance between the origin component and the actual and corresponding frequency components, but the size of the cross-region pattern is adjustable for efficient removal of noise components. The size of the cross-region pattern can be optimized through an iterative noise removal process.

11A, 11B, and 11C, three-dimensional shapes of two cuboid-shaped structures 51A and 51B disposed on the object to be measured 50 are exemplarily illustrated.

12 is a flowchart illustrating a method of generating three-dimensional shape information of an object to be measured 50 performed by the holographic restoration apparatus 1 according to an embodiment of the present invention. Hereinafter, descriptions of contents overlapping with those described in FIGS. 1 to 11 will be omitted, but will be described with reference to FIGS. 1 to 11 together.

The holographic restoration apparatus 1 according to an embodiment of the present invention may acquire an image of the object to be measured 50 (S1201).

In the present invention, the 'image' of the object to be measured 50 is the intensity information at each position of the object hologram U0 (x, y, 0) with respect to the object to be measured 50 (ie | (U0 (x, y, 0) | 2), and may be expressed as Equation 1 above.

For example, the holographic restoration apparatus 1 acquires an image as shown in FIG. 4 for a portion of the object to be measured 50 shown in FIGS. 3A and 3B (for example, a portion including 51A and 51B). can do.

Since the image obtained by the holographic reconstruction apparatus 1 includes intensity information at each position of the object hologram U0 (x, y, 0) as described above, the holographic reconstruction apparatus 1 is obtained It may be different from the image of the object to be measured 50, which is one general (ie, only photographed with object light O).

Referring to Equation 1, the object hologram U0 (x, y, 0) does not include the object light 0 including the phase information of the object 50 to be measured at each point and the phase information of the object to be measured. It may be generated by the interference of the reference light (R).

In addition, the object hologram (U0 (x, y, 0)) is in addition to the phase information (ie, height information of the object) at each point (ie, each x, y point) of the object to be measured 50, the object light objective lens 40 ) May further include errors and noises caused by aberration (eg, speckle noise due to use of a photon of a laser).

Therefore, the holographic reconstruction apparatus 1 according to an embodiment of the present invention may perform the calculation process of steps S1202 to S1207 to remove the above-described error and noise from the image obtained by the holographic reconstruction apparatus 1. .

The holographic reconstruction apparatus 1 according to an embodiment of the present invention may identify frequency components of an image obtained by the holographic reconstruction apparatus 1 (S1202). For example, the holography reconstruction apparatus 1 may be two-dimensional for an image. By performing a Fourier Transform (2D Fourier Transform), it is possible to check the frequency components of the image.

In other words, the holographic restoration apparatus 1 is a frequency included in an image including intensity information for each position of the object hologram U0 (x, y, 0) (that is, | (U0 (x, y, 0) | 2). Components may be identified, wherein the image may include a frequency component corresponding to a real image, a frequency component corresponding to an imaginary image, and a DC component.

Of course, the image may further include various components in addition to the three components described above (the frequency component corresponding to the real image, the frequency component corresponding to the virtual image, and the DC component). For example, the image may further include frequency components due to noise. However, this is exemplary and the spirit of the present invention is not limited thereto.

The holographic reconstruction apparatus 1 according to an embodiment of the present invention can extract only components corresponding to the real image from the identified frequency components. (S1203) At this time, the holography reconstruction apparatus 1 corresponds to the real image in various ways. Ingredients can be extracted.

For example, the holographic reconstruction apparatus 1 extracts components having a peak value (hereinafter referred to as peak components) among the frequency components included in the image, and a peak corresponding to a real image among the extracted peak components Components within the frequency difference between the component and the firing can be extracted as components corresponding to the actual condition.

At this time, the holographic reconstruction apparatus 1 may determine components corresponding to the actual image in various ways based on a peak component corresponding to the actual image. For example, the holographic reconstruction apparatus 1 may determine frequency components in a cross region centered on a peak component corresponding to the real image as components corresponding to the real image. However, this is exemplary and the spirit of the present invention is not limited thereto.

In an optional embodiment, the holographic reconstruction apparatus 1 may extract only components corresponding to the real image from among the frequency components included in the hologram using an automatic real image spot-position extraction algorithm.

In the present invention, 'extracting' a specific frequency component may mean extracting a frequency and a magnitude (or intensity) of the frequency component.

Referring back to FIG. 5, the holographic reconstruction apparatus 1 may check frequency components of an image obtained by the holographic reconstruction apparatus 1, and accordingly, the holography reconstruction apparatus 1 may correspond to a frequency component 911 corresponding to a real image. ), Various frequency components including the frequency component 912 and the DC component 913 corresponding to the virtual image may be identified.

In addition, the holographic reconstruction apparatus 1 may extract only the frequency component 911 corresponding to the real image from the identified components. At this time, the holographic reconstruction apparatus 1 may determine, as illustrated in FIG. 6, frequency components 911B in the cross region centered on the peak component 911A corresponding to the real image as components corresponding to the real image.

The holographic reconstruction apparatus 1 according to an embodiment of the present invention may generate digital reference light from frequency components corresponding to a real image extracted by the above-described process. (S1204) Looking at this in more detail, the holographic reconstruction apparatus ( 1) can calculate the propagation direction and wave number of the digital reference light based on the frequency components corresponding to the actual image. In other words, the holographic reconstruction apparatus 1 can calculate the wavenumber vector of the digital reference light.

In addition, the holographic reconstruction apparatus 1 generates digital reference light based on the propagation direction and wave number (or wave vector) of the digital reference light, and the digital reference light R (x, y) generated as in Equation 2 described above. The correction light Rc (x, y) can be generated by obtaining the conjugate term.

Since the digital reference light R (x, y) and the correction light Rc (x, y) are in a conjugate relationship, the intensity is the same as shown in FIGS. 7A and 7C, as shown in FIGS. 7B and 7D. Likewise, the phases can be reversed. Here, FIG. 7A is a diagram showing the intensity of the digital reference light R (x, y), FIG. 7B is a diagram showing the phase of the reference light, and FIG. 7C is the intensity of the correction light Rc (x, y). Fig. 7D is a diagram showing the phase of the correction light.

The generated correction light Rc (x, y) may be used for correction of a real hologram Um (x, y, 0) described later.

Meanwhile, the 'digital reference light' is light having the same properties as the reference light R generated by the above-described optical splitter 30 from light of a single wavelength, and the holographic restoration device 1 is obtained by the holographic restoration device 1 It may be a virtual light reconstructed from an image.

The holographic reconstruction apparatus 1 according to an embodiment of the present invention may also generate a real hologram based on frequency components corresponding to the real image extracted by the above-described process. (S1204) For example, the holographic reconstruction apparatus 1 8 may generate an actual hologram as shown in FIG. 8 by performing an inverse 2D Fourier transform on frequency components corresponding to the actual image. In this case, the hologram may be represented by Equation 3 described above.

The holographic reconstruction apparatus 1 according to an embodiment of the present invention may generate an intermediate hologram to generate a term Rca (x, y) for curvature aberration correction. (S1205) For example, the holographic reconstruction apparatus 1 ) Can actually generate an intermediate hologram by multiplying the hologram Um (x, y, 0) by the term Rc (x, y) for the correction light. The generated intermediate hologram can be used to generate curvature aberration correction information in step S1206.

The holographic restoring apparatus 1 according to an embodiment of the present invention generates a three-dimensional shape of the object to be measured 50 from the intermediate hologram generated in step S1205, and the terms for curvature aberration correction from the generated three-dimensional shape ( Rca (x, y)). (S1206) Looking at this in more detail, the holographic reconstruction apparatus 1 determines a curvature aberration correction term from the three-dimensional shape of the measurement object 50 generated from the intermediate hologram. At least one parameter. At this time, the parameter may include, for example, a coordinate and a radius of a center point defining a hemispherical curved surface.

Referring again to FIGS. 9 and 10, a method for determining a correction term for curvature aberration from an intermediate hologram by the holographic reconstruction apparatus 1 according to an embodiment of the present invention will be described. For convenience of explanation, the holographic reconstruction apparatus 1 acquires an image of the rectangular parallelepiped structure 51D of FIG. 3B, and the holographic reconstruction apparatus 1 acquires an intermediate hologram for the structure 51D according to the above-described process. It is assumed to have been created. It is also assumed that the three-dimensional shape 920 of the structure 51D generated from the intermediate hologram for the structure 51D is as shown in FIG. 9.

Under the assumptions described above, the holographic reconstruction apparatus 1 according to an embodiment of the present invention may determine at least one parameter for determining a curvature aberration correction term from the three-dimensional shape 920. For example, the holographic reconstruction apparatus 1 determines the coordinates (Cx, Cy) of the center point of the hemispherical curved surface and the radius (r) of the curved surface as parameters from a curve on the II section of the three-dimensional shape 920 as shown in FIG. 10. You can. At this time, the holographic restoration apparatus 1 according to an embodiment of the present invention may determine the position and / or direction of the cutting surface such that the cutting surface such as the II section includes the center point of the three-dimensional shape 920 (that is, the center point of the hemispherical shape). . Also, the holographic restoration apparatus 1 may determine that a cutting surface such as an I-I cross section is parallel to the traveling direction of the object light 0.

The holographic restoration apparatus 1 according to an embodiment of the present invention may generate (or determine) a curvature aberration correction term based on at least one parameter determined by the above-described process. For example, the holography restoration apparatus 1 generates a curved surface in three-dimensional space with reference to the coordinates (Cx, Cy) of the center point of the curved surface and the radius (r) of the curved surface, and corrects the phase of each x, y point from the generated curved surface. A method of correcting a curvature aberration may be generated (or determined) in a manner of generating information to be reflected.

In an alternative embodiment, the holographic reconstruction apparatus 1 may determine a correction term from an intermediate hologram of an object to be measured (for example, an object having the same z value in all x, y coordinates) whose shape is known in advance.

Since the z-value at each x and y point is known in advance in the case of the object to be measured in advance, the holography reconstruction apparatus 1 can measure the three-dimensional shape of the object to be measured and the object to be measured from the intermediate hologram. The correction term can also be determined by checking the difference in z values at each x and y point of the shape. However, this is exemplary and the spirit of the present invention is not limited thereto.

The holographic restoring apparatus 1 according to an embodiment of the present invention takes into consideration the error caused by the aberration of the object light 40 and the influence by the reference light R and the actual hologram (Um (x, y, 0)) It is possible to generate a corrected hologram Uc (x, y, 0). (S1207) For example, the holographic reconstruction apparatus 1 is configured to generate a real hologram Um (x, y, 0) as in Equation 4 described above. A correction hologram Uc (x, y, 0) can be generated by multiplying the term Rc (x, y) for the correction light and the term Rca (x, y) for curvature aberration correction. In this case, the term Rc (x, y) for the correction light may be generated in step S1204, and the term Rca (x, y) for curvature aberration correction may be generated in step S1206.

The holographic restoration apparatus 1 according to an embodiment of the present invention may generate three-dimensional shape information of the object to be measured 50 based on the corrected hologram Uc (x, y, 0). (S1208) In other words, the holographic reconstruction apparatus 1 can calculate the height of the object at each x and y point in the z direction.

For example, the holography reconstruction apparatus 1 may convert the corrected hologram Uc (x, y, 0) into information on the reconstructed image surface. At this time, the reconstructed image plane means a virtual image display plane corresponding to a distance between the object to be measured and the image sensor by the processor, and may be a virtual plane calculated and simulated by the holographic reconstruction apparatus 1. .

The holographic reconstruction apparatus 1 may calculate the height in the z direction of the object at the x and y points from the reconstructed information in consideration of the reconstructed image plane. 11, three-dimensional shapes of two rectangular parallelepiped structures 51A and 51B disposed on the object to be measured 50 are exemplarily illustrated.

13 and 14 are flow charts of a noise removal method of the holographic restoration apparatus 1 according to the embodiments of the present invention.

The holographic reconstruction apparatus 1 according to an embodiment of the present invention can extract only components corresponding to a real image from the identified frequency components. (S1203)

In S12031, the holographic reconstruction apparatus 1 determines a first frequency component corresponding to a real image included in an image, a second frequency component corresponding to a virtual image, and a third frequency component corresponding to an origin.

In S12032, the holographic restoration apparatus 1 calculates the direction of the interference fringe and the normal direction from the first frequency component, and determines the frequency components located in the direction and normal direction of the interference fringe as noise.

In S12033, the holographic reconstruction apparatus 1 removes noise from the first frequency component to extract a frequency component corresponding to the real image.

In another embodiment, the holography restoring apparatus 1 may set a pattern to remove noise and use the pattern to extract frequency components corresponding to the real image.

In S12034, the holographic reconstruction apparatus 1 determines the first frequency component corresponding to the real image included in the image, the second frequency component corresponding to the virtual image, and the third frequency component corresponding to the origin.

In S12035, the holographic reconstruction apparatus 1 generates a cross-region pattern including the peak component of the first frequency component. In S12036, the holographic reconstruction apparatus 1 extracts, among the first frequency components, frequency components included in the cross-region pattern.

The mathematical formula to which the cross-region pattern is applied is as follows. The holographic reconstruction apparatus 1 may extract frequency components included in the cross-region pattern according to the following equation.

Figure 112018094955308-pat00003

Here, ms is the size of the cross-region pattern, xc is the X coordinate of the peak component, and yc is the Y coordinate of the peak component. R is a number proportional to the distance between the actual and corresponding frequency components and origin components. For example, R may be distance / 3, distance / 2, and the like.

The size (ms) of the cross-region pattern is determined based on the distance between the origin component and the actual and corresponding frequency components, but the size of the cross-region pattern is adjustable for efficient removal of noise components. The size of the cross-region pattern can be optimized through an iterative noise removal process.

In another embodiment, the holographic reconstruction apparatus 1 may give different weights according to the position of the filtering region with hemispherical filtering in order to more effectively remove noise. For example, the holographic reconstruction apparatus 1 may multiply a weight less than 1 as it moves away from the center.

Figure 112018094955308-pat00004

Here, R is a number proportional to the distance (distance) between the frequency component and the origin component corresponding to the actual image. For example, R may be distance / 3, distance / 2, and the like.

The embodiment according to the present invention described above may be implemented in the form of a computer program that can be executed through various components on a computer, and such a computer program can be recorded on a computer-readable medium. At this time, the medium may be to store a program executable by a computer. Examples of the medium include magnetic media such as hard disks, floppy disks and magnetic tapes, optical image sensors such as CD-ROMs and DVDs, and magneto-optical mediums such as floptical disks, And program instructions including ROM, RAM, flash memory, and the like.

Meanwhile, the computer program may be specially designed and configured for the present invention or may be known and available to those skilled in the computer software field. Examples of computer programs may include machine language codes such as those produced by a compiler, as well as high-level language codes that can be executed by a computer using an interpreter or the like.

The specific implementations described in the present invention are examples, and do not limit the scope of the present invention in any way. For brevity of the specification, descriptions of conventional electronic configurations, control systems, software, and other functional aspects of the systems may be omitted. In addition, the connection or connecting members of the lines between the components shown in the drawings are illustrative examples of functional connections and / or physical or circuit connections, and in the actual device, alternative or additional various functional connections, physical It can be represented as a connection, or circuit connections. In addition, unless specifically mentioned, such as "essential", "important", etc., it may not be a necessary component for the application of the present invention.

Accordingly, the spirit of the present invention is not limited to the above-described embodiments, and should not be determined, and the scope of the spirit of the present invention as well as the claims to be described later, as well as all ranges that are equivalent to or equivalently changed from the claims Would belong to

1, 1A, 1B: Holographic restoration device
10: light source unit
20: collimator
30,32: Optical splitter
40: object light objective lens
50: object to be measured
60: reference light objective lens
70,72: optical mirror
80: image sensor
90: processor

Claims (4)

  1. delete
  2. In the method of generating three-dimensional shape information of the object to be measured from the image including the intensity (Intensity) information of the object hologram generated by the interference of the reference light reflected from the optical mirror and the object light affected by the object to be measured,
    Identifying a first frequency component set corresponding to a real image included in the image, a second frequency component set corresponding to an origin, and a third frequency component set corresponding to a virtual image;
    Extracting real image components corresponding to a real image of the measurement target object including a peak component of the first frequency component using a distance difference value between the first frequency component and the second frequency component;
    Generating a real image hologram including a correction light having a conjugate relationship with the reference light based on the real components and real information of the object to be measured;
    Generating an intermediate hologram from which the information of the reference light is removed from the actual hologram based on the corrected light;
    Generating curvature aberration correction information from the intermediate hologram;
    Generating a correction hologram in which errors due to curvature aberration are removed from the intermediate hologram based on the curvature aberration correction information; And
    And generating the 3D shape information of the object to be measured from the correction hologram.
    Extracting the actual components corresponding to the actual image is
    The direction and normal direction of the interference fringe are determined from the first frequency component, and the frequency components located in the direction and normal direction of the interference fringe are determined as noise,
    A method of removing three-dimensional shape information by removing noise included in a frequency component of an object to be measured, removing the noise from the first frequency component.
  3. In the method of generating three-dimensional shape information of the object to be measured from the image including the intensity (Intensity) information of the object hologram generated by the interference of the reference light reflected from the optical mirror and the object light affected by the object to be measured,
    Identifying a first frequency component set corresponding to a real image included in the image, a second frequency component set corresponding to an origin, and a third frequency component set corresponding to a virtual image;
    Extracting real image components corresponding to a real image of the measurement target object including a peak component of the first frequency component using a distance difference value between the first frequency component and the second frequency component;
    Generating a real image hologram including a correction light having a conjugate relationship with the reference light based on the real components and real information of the object to be measured;
    Generating an intermediate hologram from which the information of the reference light is removed from the actual hologram based on the corrected light;
    Generating curvature aberration correction information from the intermediate hologram;
    Generating a correction hologram in which errors due to curvature aberration are removed from the intermediate hologram based on the curvature aberration correction information; And
    And generating the 3D shape information of the object to be measured from the correction hologram.
    Extracting the actual components corresponding to the actual image is
    The pattern region is determined in consideration of the peak component of the first frequency component and the direction of the interference fringe, overlaps the image and pattern region, and extracts the frequency component included in the pattern region as real components corresponding to the real image. , A method for generating 3D shape information by removing noise included in a frequency component of an object to be measured.
  4. In the method of generating three-dimensional shape information of the object to be measured from the image including the intensity (Intensity) information of the object hologram generated by the interference of the reference light reflected from the optical mirror and the object light affected by the object to be measured,
    Identifying a first frequency component set corresponding to a real image included in the image, a second frequency component set corresponding to an origin, and a third frequency component set corresponding to a virtual image;
    Extracting real image components corresponding to a real image of the measurement target object including a peak component of the first frequency component using a distance difference value between the first frequency component and the second frequency component;
    Generating a real image hologram including a correction light having a conjugate relationship with the reference light based on the real components and real information of the object to be measured;
    Generating an intermediate hologram from which the information of the reference light is removed from the actual hologram based on the corrected light;
    Generating curvature aberration correction information from the intermediate hologram;
    Generating a correction hologram in which errors due to curvature aberration are removed from the intermediate hologram based on the curvature aberration correction information; And
    And generating the 3D shape information of the object to be measured from the correction hologram.
    Extracting the actual components corresponding to the actual image is
    The frequency component of the object to be measured is selected by selecting a pattern region set to give a weight in consideration of the distance from the peak component of the first frequency component, and extracting frequency components included in the pattern region as real components corresponding to the real image A method for generating 3D shape information by removing noise included in the image.
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