KR20190082171A - An Improved Holographic Reconstruction Apparatus and Method - Google Patents

Abstract

Disclosed are an improved holographic recovery apparatus and a method thereof. According to the present invention, the holographic recovery apparatus comprises: a first light splitter splitting a single wavelength light of a light source unit into first and second transmitted split lights; a plurality of optical mirrors reflecting the first transmitted split light; a second light splitter splitting the second transmitted split light into first and second reflective split lights; a reference light objective lens passing the second reflective split light; a position adjustment mirror receiving the first reflective split light passing through the reference light objective lens; a recording medium recording an interference pattern formed when the first transmitted split light passing through the object to be measured or the first reflective split light reflected from the object to be measured passes through an object light objective lens, and the second reflective split light reflected from the position adjustment mirror passes through the reference light objective lens to be transferred to the second light splitter; and a processor receiving and storing an image file generated by converting the interference pattern. Moreover, light transmission or a reflective object hologram is selectively acquired in accordance with a mode. Various embodiments are possible.

Description

[0001] Improved Holographic Reconstruction Apparatus and Method [0002]

The present invention relates to an improved holographic reconstruction apparatus and method.

More specifically, the present invention relates to an integrated system that integrates a transmission type system for measuring an object transmitting light and a reflection type system for measuring an object that reflects light, And more particularly, to an improved hologram reconstruction apparatus and method capable of measuring a digital hologram irrespective of characteristics.

As is well known, holography is a method of imaging aimed at improving the resolving power of an electron microscope, whereas conventional photography only records the distribution of light and dark surfaces of an object, whereas holography is all information The principle is that the coherent light from a laser light source divides the beam splitter into two parts, one of which is reflected by the object, Reflected light reaches the holographic photosensitive material. This ray is called object light. The other one beam is diffused into the lens and illuminated directly onto the holographic photosensitive material. This light beam is referred to as a reference light (hereinafter referred to as "reference light"). In this way, the object light and the reference light interfere with each other on the holographic photosensitive material, resulting in an extremely delicate and complicated interference pattern of about 500 to 1500 per 1 mm. A photograph recording this interference pattern is called a hologram. When the hologram is made to have the same light as the reference light, the interference fringe acts as a diffraction grating to diffract the light at a position different from the direction in which the reference light is incident. When such a diffracted light is collected, Become like. In this manner, the first object light is reproduced in the hologram.

Therefore, when you look inside the reproduced wavefront, the first object appears, but the object appears to be inside. Moving the point of view again changes the position of the object, so it looks as if you are looking at a stereoscopic picture. In addition, since the original wavefront of the object is reproduced, it can also interfere with the wavefront from an object that is slightly deformed. Therefore, the characteristics of such a holography are applied and used in various fields.

For example, a digital holography microscope is a microscope that measures the shape of an object using a digital holography technique. A general microscope usually measures the intensity of light reflected or transmitted from an object by irradiating an ordinary light source onto the object, The digital holography microscope is a device for measuring the interference and diffraction phenomenon of light that occurs when light is reflected on an object, digitally recording it, and restoring the shape information of the object from the information.

In other words, the digital holography technique generates light of a single wavelength such as a laser and divides it into two lights using a light splitter, and directs one light (reference light) directly to the image sensor, while the other light As the light transmitted or reflected from the object to be measured is compared with the image sensor in view of the object to be measured, the reference light and the object light interfere with each other in the image sensor, and the interference fringe information of the light is recorded And the shape of the object to be measured is restored using the computer with the recorded interference fringe information.

On the other hand, in the case of a conventional optical holography technique other than digital holography, the interference fringe information of the light is recorded as a special film, and in order to restore the shape of the measurement object, the reference light is reflected on a special film on which interference fringes are recorded The shape of the virtual object to be measured is restored in the place where the object is originally located.

The digital holography microscope measures the interference fringe information of the light by a digital image sensor and stores the information in a digital manner when compared with the conventional optical holography method. The digital interference fringe information is stored in a numerical calculation method using a computer device So that the shape of the object to be measured is restored.

In a conventional digital holography microscope, a laser light source of a single wavelength may be used first. However, in the case of using a single laser light source, there is a problem that the measurement resolution of the object, that is, the minimum measurement unit is limited to the wavelength of the laser light source used. In the case of using a laser light source of two wavelengths or multiple wavelengths in a conventional digital holography microscope, the cost is increased by using light sources having different wavelengths, or sequentially obtaining hologram images using light sources of different wavelengths There is a problem that it is difficult to measure three-dimensional change information of an object to be measured in real time.

In addition, in the above-described conventional digital holography technique, a CGH (Computer Generated Hologram) is generated by a computer to restore the shape of an object to be measured, and then displayed on a spatial light modulator (SLM) , A three-dimensional hologram image of the object is obtained by diffraction of reference light. In this case, since it is required to use a spatial light modulator (SLM) of a high price (several tens of thousands or more), there is considerable difficulty in practical use.

A number of patent documents for solving the problems of the conventional digital holography technique are disclosed as follows.

According to these patent documents, the measurement resolution of the object to be measured is increased, and holograms of the object to be measured varying with time are measured and recorded in real time to restore the three-dimensional shape information of the object in real time However, the following problems still arise.

More specifically, Patent Document 1, entitled " Digital Holographic Microscope and Digital Hologram Image Generation Method ", entitled " Digital Holographic Microscope and Digital Hologram Image Generation Method ", is a two-wavelength digital holography microscope apparatus, which comprises a mixed light source unit 100, An interference pattern acquisition unit 300, an object unit 400, 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 unit 110 and a light source unit lens 120. The mixed light source unit 110 emits mixed light having a wavelength band distributed in various non- The lens 120 optically adjusts the mixed light generated by the mixed light source unit 110 and enters the wavelength division unit 200.

The wavelength division unit 200 includes a first light splitter 210, a first light guide plate 220, a second light guide plate 230, and a first reflector 240. The first light splitter 210 receives the mixed light from the mixed light source unit 100 and divides the mixed light into two lights. At this time, the first optical splitter 210 divides the incident mixed light into different directions. The first light guide plate 220 receives one of the light beams divided by the first light splitter 210 and acquires a first light beam having a predetermined single wavelength. Here, the light input to the first light guide plate 220 is filtered while passing through the first light guide plate 220, and a first light ray having a single wavelength determined according to the characteristics of the first light guide plate 220 is obtained. The second light guide plate 230 receives the other one of the light beams split by the first light splitter 210 in the same manner as the first light guide plate 220 and receives light of the second light guide plate 230 having a wavelength different from that of the first light beam. Obtain a ray of light. The second light beam is sent to the interference fringe obtaining unit 300. The first reflector 240 receives the first light beam obtained from the first light guide plate 220 and reflects the first light beam to the interference fringe obtaining unit 300.

The interference fringe obtaining unit 300 includes a second light splitter 310, a third light splitter 320, a second reflector 330, a third reflector 340, and a third reflector 350. The second light splitter 310 receives the first light beam input from the wavelength division unit 200 and divides the first light beam into the first object light and the first reference light. At this time, the second light splitter 210 divides the incident first rays into different directions and proceeds. The third light splitter 320 receives the second light ray in the same manner as the second light splitter 310 and divides the second light ray into the second object light and the second reference light. The second reflector 330 receives the first reference beam and transmits the first reference beam reflected by the second beam splitter 310 to the second beam splitter 310. The third light guide plate 340 receives the first reference light divided by the second light splitter 310 and transmits the first reference light to the second reflector 330 and receives the first reflected reference light to be transmitted to the second light splitter 310 . The third light guide plate 340 prevents the second object light from reaching the second reflector 330 when the second object light is incident on the second light splitter 310 and partly proceeds toward the second reflector 330 . For this purpose, the third light guide plate 340 is a light guide plate having the same characteristics as the first light guide plate 220 in transmitting light. The third reflector 350 receives the second reference light and transmits the second reflected reference light to the third optical splitter 320. The second reflector 330 and the third reflector 350 are connected to the controller 700 The angle of the hologram can be adjusted according to the control of the optical system. Thus, an off-axis hologram can be realized.

On the other hand, the first object light and the second object light obtained as described above are converted into the first reflected object light and the second reflected object light through the following process and sent to the image sensor unit 500. The second light splitter 310 separates the first object light divided as described above into an object to be measured which is placed on the object 400, And causes the light to enter the object to be measured. In this case, the reflected light that reflects the first object light incident from the measurement object is referred to as a first reflected object light. The reflected light that reflects the second object light incident on the object to be measured is referred to as a 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 it to the third optical splitter 320. The third light splitter 320 transmits the first reflected object light and the second reflected object light received as described above to the image sensor unit 500 again.

The first and second reflection reference beams obtained as described above are sent to the image sensor unit 500 through the following process. Specifically, the second optical splitter 310 receives the first reflected reference light reflected by the second reflector 330 and transmits the first reflected reference light to the third optical splitter 320. The third light splitter 320 receives the first reflection reference light sent from the second light splitter 310 and the second reflection reference light reflected from the third reflector 350 as described above, Lt; / RTI > Accordingly, after the first reflected object light, the first reflected reference light, the second reflected object light, and the second reflected reference light are both transmitted in the direction of the image sensor unit 500 in the third optical splitter 320, An interference fringe is generated.

Meanwhile, the second reflector 330 and the third reflector 350 may have different angles according to the control of the controller 700 to form an off-axis system in which light beams of different wavelengths form different interference fringes. Can be adjusted in various directions.

That is, as the angles of the second reflector 330 and the third reflector 350 are different from each other, the first and second reflectors 330 and 350 reflect the first and second reflectors 330 and 350, When 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 arriving at the image sensor unit 500 to form an interference fringe, So that the interference fringes are differently formed.

The object unit 400 includes an object mount 410 and an objective lens 420. The object mount 410 allows the object to be measured by fixing the object to the mount while the objective lens 420 is placed on the object to be measured The first object light and the second object light are optically adjusted.

The image sensor unit 500 projects the interference fringes obtained from the interference fringe obtaining unit 300 to a digital image sensor, measures the projected interference fringes using the digital image sensor, . Normally, the recording of the interference fringe is referred to as a hologram. As such a digital image sensor, various image sensors such as a CCD can be used.

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

The controller 700 controls the position and angle of the second reflector 330 and the third reflector 350 in order to implement the above-described off-axis system and obtain interference fringes. The interference fringe obtaining unit 300 Controls the objective part 400 to adjust the objective lens 420 to adjust the first object light and the second object light incident on the measurement object, and the interference fringe is measured, Controls the image sensor unit 500 to convert the information into a discrete signal, and controls the image storage unit 600 to store the interference fringe information converted into the discrete signal.

The object shape restoring unit 800 includes a phase information obtaining unit 810, a thickness information obtaining unit 820 and a shape restoring unit 830. The phase information obtaining unit 810 obtains the phase information using the interference fringe information Acquires the phase information of the interference fringe for the first light beam and the phase information of the interference fringe for the second light beam, respectively, and the thickness information obtaining unit 820 obtains the thickness information of the measurement object using the phase information , The shape restoring unit 830 restores the real time three-dimensional shape of the measurement object 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. The interference fringe is formed when the object light and the reference light overlap each other due to the optical path difference between the object light and the reference light.

In the above-described Patent Document 1, a mixed light source having wavelength bands distributed in a plurality of unspecified bands is used. Therefore, in order to obtain at least two single wavelengths, a first light beam and a second light beam having wavelengths different from each other A first luminescent plate, a second luminescent plate, and a first reflector should be used for the division. The interference fringe acquisition section may further include a third light splitter for splitting the second light beam, a third reflector for reflecting the second light beam, and a third light guide plate for shielding the second light beam from being incident on the second reflector, Should be used. Therefore, there is still a problem that the structure of the entire device becomes complicated, the optical noise of the entire device increases due to the increase of optical element usage, and the total manufacturing cost is high.

Accordingly, there is a need for a new method for solving the above-described problems while using a light source of a single wavelength, and a large number of patent documents corresponding thereto are disclosed.

However, the optical systems of most of the disclosed patent documents can broadly be classified into a transmission type system for measuring an object transmitting light, or a reflection type system for reflecting light, in order to measure a digital hologram.

More specifically, Patent Documents 2, 3, 5 and 6 are reflection type measuring devices using two wavelengths, and only an object reflecting light can be measured. In Patent Document 2, a laser having two different wavelengths is required The optical interferometer system is complicated, Patent Document 3 uses two image sensors, uses white light with low coherence, and the optical interferometer system is complicated like Patent Document 2, and Patent Document 5 is similar to Patent Document 2 , A laser having two different wavelengths is required and the optical interferometer system is complicated. In addition, the hologram can not be generated due to the constitution of the proposed system, and Patent Document 6 has two different wavelengths as in Patent Document 2 There is a complex problem of optical interferometer system.

Patent Document 4 discloses a transmission type measuring apparatus using one wavelength, which can measure only an object that transmits light, but it requires two image capturing operations, which causes a time delay error.

In order to solve this problem, it was necessary to use a transmission type system and a reflection type system in accordance with the optical characteristics of an object to be measured, such as a light-transmitting object or a light-reflecting object. However, In order to measure the hologram, it is necessary to purchase expensive equipment, which is several hundreds of millions of won per unit, so that there is a problem of additional cost.

[Prior Patent Literature]

[Patent Literature]

1. Korean Registered Patent No. 10-1634170 (Registered on June 22, 2016)

2. Korean Registered Patent No. 10-1152798 (registered on May 29, 2012)

3. Korean Patent No. 10-1139178 (Registered on April 16, 2012)

4. Korean Patent No. 10-1203699 (registered on November 15, 2012)

5. Korean Registered Patent No. 10-1441245 (Registered on May 1, 2014)

6. Korean Registered Patent No. 10-1716452 (Registered on Mar. 3, 2017)

SUMMARY OF THE INVENTION It is an object of the present invention to provide a transmissive system for measuring an object transmitting light and a reflection type reflector for measuring an object reflecting light, And an object of the present invention is to provide an improved holographic restoration device capable of measuring a digital hologram regardless of the optical characteristics of an object measured by a single integrated system incorporating a system.

It is another object of the present invention to provide a method and apparatus for measuring a digital hologram regardless of the optical characteristics of an object to be measured, including a transmission mode for measuring an object transmitting light, a reflection mode for measuring an object reflecting light, The present invention provides an improved holographic reconstruction method capable of selecting a holographic reconstruction method.

According to an aspect of the present invention, there is provided an improved holographic reconstruction apparatus including: a light source for emitting a single wavelength light; A first light splitter for dividing the single wavelength light emitted from the light source into a first transmission split light and a second transmission split light; A plurality of optical mirrors for reflecting the first transmissive split light beams divided by the first optical beam splitter; A second light splitter for splitting the second transmitted light split by the first optical splitter into a first split split light and a second split split light; A first objective lens for passing the first split split light split by the first split split light or the first split split light that is reflected by the plurality of optical mirrors and transmitted through the object; A reference light objective lens for passing the second divided reflection light split by the second light splitter; A position adjustment mirror through which the second reflective divided light having passed through the reference light objective lens is transmitted; And a second transmission section that transmits the first transmission split light transmitted through the object to be measured or the first reflection split light reflected from the surface of the measurement object and the second reflection split light that has passed through the reference light objective lens, A recording medium for recording an interference fringe formed by passing through the object optical objective lens and the reference light objective lens to the second optical splitter; And a processor for receiving and storing an image file generated by transforming the interference fringes transmitted from the recording medium, wherein the processor is configured to convert a light transmission hologram and a light reflection hologram into a transmission mode And the reflective mode.

According to another aspect of the present invention, there is provided an improved holographic reconstruction method including: a) selecting (S1) two measurement modes of an object hologram of an object to be measured; b) measuring (S2) the object hologram according to the selected mode; c) removing the DC, virtual image, and aberration information of the measured object hologram (S3); d) extracting phase information of the object hologram (S4); And e) reconstructing the three-dimensional shape information and the quantitative size (thickness) information of the object to be measured (S5).

According to the improved holographic reconstruction apparatus and method of the present invention through the solution of the above-mentioned problems, the following effects are provided.

1. It is possible to solve a complicated optical device structure required for restoration of a one-shot type digital holography using a single object hologram image of the related art, and a considerably high cost problem associated therewith.

2. Holographic reconstruction is possible with simple structure and low cost.

3. It has versatility that can be applied to both the reflection type and transmission type hologram restoration apparatus of the prior art.

4. Especially, it is unnecessary to use the reference light when restoring the hologram, and it is possible to quantitatively reconstruct a three-dimensional image of the object to be measured in real time.

5. Detection, confirmation, or display of various fields including detection of defects in ultra-fine structures such as TFTs and semiconductors, detection of refractive errors of transparent objects such as medical devices requiring display of precise three-dimensional images, and other lenses It is possible to apply to the device.

6. One integrated system incorporating the reflection type and transmission type hologram restoration apparatus of the prior art can select the transmission mode and the reflection mode selectively to measure the digital hologram regardless of the optical characteristics of the object to be measured, The problem can be solved.

Further advantages of the present invention can be clearly understood from the following description with reference to the accompanying drawings, in which like or similar reference numerals denote like elements.

1 is a block diagram illustrating a two-wavelength digital holography microscope apparatus in accordance with the disclosed prior art.
2 is a schematic block diagram showing an improved holographic reconstruction apparatus according to a preferred embodiment of the present invention.
3 is a flowchart illustrating an improved holographic reconstruction method according to an embodiment of the present invention.
FIG. 4 is a flowchart illustrating a detailed implementation step of step S3 of the improved holographic reconstruction method of FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the same components are denoted by the same reference numerals as possible in the accompanying drawings. In the following description of the present invention, a detailed description of related configurations or functions is omitted when it is determined that a detailed description is unnecessary.

2, which shows an improved holographic reconstruction apparatus according to an embodiment of the present invention, an improved holographic reconstruction apparatus 1 according to an embodiment of the present invention measures an object transmitting light, In-one type digital holographic microscope that selectively performs a transmissive mode in which light is reflected and a reflective mode in which an object that reflects light is measured.

An improved holographic reconstruction apparatus (1) according to an embodiment of the present invention includes a light source unit (10) emitting a single wavelength light; A first light splitter (20) for splitting the single wavelength light emitted from the light source part (10) into a first transmission split light (T1) and a second object transmission light (T2); A plurality of optical mirrors (30, 31) for reflecting the first transmission split light (T1) divided by the first light splitter (20); A second light splitter (60) for splitting the second transmission split light (T2) divided by the first light splitter (20) into a first reflection split light (R1) and a second reflection split light (R2); The first transmission split light (T1) transmitted through the measurement object (40) after being reflected by the plurality of optical mirrors (30, 31) or the first transmission split light An object-optical objective lens 50 for passing the reflected split light R1; A reference light objective lens (51) for passing the second split split light (R2) divided by the second light splitter (60); A position adjusting mirror (70) through which the second reflected split light (R2) passing through the reference light objective lens (51) is transmitted; The first transmissive divided light beam T1 transmitted through the measurement object 40 or the first reflected light beam R1 reflected from the surface of the measurement object 40 and the reference light objective lens 51 The second reflected split light R2 reflected by the position adjusting mirror 70 passes through the object optical objective lens 50 and the reference light objective lens 51 and passes through the second light splitter 60, A recording medium (80) for recording interference fringes formed by being transmitted to the recording medium (80); And a processor 90 for receiving and storing an image file generated by converting the interference fringes transmitted from the recording medium 80.

The processor 90 of the holographic reconstruction apparatus 1 according to the embodiment of the present invention is implemented as an apparatus capable of performing arithmetic operations such as a microprocessor and a PC (Personal Computer) For example, an image sensor such as a CCD (Charge Coupled Device) or a CMOS (Complimentary Metal-Oxide Semiconductor).

The improved holographic reconstruction apparatus 1 according to an embodiment of the present invention includes a processor 90 for converting a light transmission hologram and a light reflection hologram into a transmission mode and a reflection mode And can be obtained selectively. That is, the processor 90 of the integrally improved holographic reconstruction apparatus 1 according to an embodiment of the present invention adjusts the position of the position adjusting mirror 70 to adjust the position of the light in the transmissive mode and the reflection mode Corrects the difference in light path. Accordingly, the light-transmitting object hologram or the light-reflecting object hologram can be transferred to the processor 90 through the recording medium 80 (e.g., a CCD) and acquired in the form of an image file.

 More specifically, in the holographic reconstruction apparatus 1 according to the embodiment of the present invention, in the transmissive mode in which a light-transmitting object is measured, light emitted from the laser as the light source unit 10 is incident on the first light splitter 20 Divided into a first transmissive divisional light T 1 and a second transmissive divisional light T 2.

The first transmission split light T 1 is reflected by each of the plurality of optical mirrors 30 and 31 to be transmitted to the measurement target object 40 and then passes through the measurement target object 40, 50 to the second light splitter 60. In the embodiment of the present invention, it is to be understood that a plurality of optical mirrors 30 and 31 are illustrated as being implemented by two optical mirrors, but those skilled in the art can realize that the optical mirrors 30 and 31 may be implemented by three or more optical mirrors. On the other hand, the second transmissive split light T 2 passes through the second light splitter 60 and the reference light objective lens 51, is reflected by the position-adjusting optical mirror 70, passes through the reference light objective lens 51 again, And is directed to the light splitter 60.

The first and second transmissive split lights T1 and T2 which are combined in the second optical splitter 60 form an interference fringe (light transmitting object hologram) for a portion of the measurement object 40 that transmits light . Here, the first transmission split light (T1) corresponds to the object light of the light transmitting object hologram, and the second transmission split light (T2) corresponds to the reference light of the light transmitting object hologram.

Meanwhile, in the reflective mode in which an object that reflects light is measured, light emitted from the laser as the light source unit 10 is transmitted through the first light splitter 20 to the first transmission split light T1 and the second transmission split light T2, .

The second transmitted light T 2 is divided into a first divided light beam R 1 and a second divided light beam R 2 by the second light splitter 60. The first reflected split light R 1 passes through the object optical objective lens 50 and is reflected by the measurement object 40 and passes through the object optical objective lens 50 to the second optical splitter 60. The second reflected split light R2 passes through the reference light objective lens 51 and is reflected by the position adjusting optical mirror 70. The reflected light then passes through the reference light objective lens 51 again to be incident on the second light splitter 60, .

The first and second split light beams R1 and R2 that are incident on the second light splitter 60 are reflected by the interference fringe (light reflection object hologram) for the portion of the measurement object 40 that reflects light Respectively. Here, the first reflection divided light R1 corresponds to the object light of the light reflection object hologram, and the second reflection divided light R2 corresponds to the reference light of the light reflection object hologram.

At this time, the position of the position adjusting mirror 70 is adjusted by the processor 90 implemented by, for example, a PC, thereby correcting the difference in light path of light occurring in the transmissive mode and the reflective mode. The light-transmitting object hologram and the light-reflecting object hologram are respectively transferred to the PC as the processor 90 through the CCD, which is the recording medium 80, and are obtained in the form of an image file.

When the light transmission mode is selected and measured by the holographic reconstruction apparatus 1 according to the embodiment of the present invention, the obtained light-transmitting object hologram is divided into a portion through which the light of the measurement object 40 is transmitted It is the interference pattern. The thus obtained light-transmitting object hologram can be expressed as a complex conjugate hologram as shown in Equation (1).

Equation 1:

는 획득한 빛 투과 물체 홀로그램을 나타내고,

는 빛 투과 물체 홀로그램의 물체광과 기준광을 나타내고,

는 빛 투과 물체 홀로그램의 물체광과 기준광의 복소 공액을 나타낸다.Here, x and y represent spatial coordinates,

Represents the obtained light-transmitting object hologram,

Represents the object light and reference light of the light-transmitting object hologram,

Represents the complex conjugate of the reference light and the object light of the light-transmitting object hologram.

On the other hand, when the light reflection mode is selected and measured, the obtained light reflection object hologram is an interference fringe for a portion of the measurement object 40 that reflects light. The thus obtained light reflection object hologram can be expressed as a complex conjugate hologram as shown in Equation (2).

Equation 2:

는 획득한 빛 반사 물체 홀로그램을 나타내고,

는 빛 반사 물체 홀로그램의 물체광과 기준광을 나타내고,

는 빛 반사 물체 홀로그램의 물체광과 기준광의 복소 공액을 나타낸다.Here, x and y represent spatial coordinates,

Represents the obtained light reflecting object hologram,

Represents the object light and the reference light of the light reflection hologram hologram,

Represents the complex conjugate of the reference light and the object light of the light reflection hologram hologram.

Hereinafter, a specific method of restoring the three-dimensional shape of the object from the obtained two types of object holograms will be described.

2 to 4, in order to remove the DC and virtual image information in the light-transmitting object hologram (S21 in FIG. 3) obtained by selecting the transmissive mode by the processor 90 as described above, A 2D Fourier transform is performed (S3 in FIG. 3).

In the transmissive mode, the frequency spectrum of the light-transmitting object hologram obtained by the two-dimensional Fourier transform is a real image of the light-transmitting object hologram, an imaginary image of the light-transmitting object hologram, and direct current (DC) (S31 in Fig. 4). In order to remove virtual image and direct current (DC) information of the separated light-transmitting object hologram, for example, an automatic real image spot-position extraction algorithm is extracted from the real image spot- And extracts the phase information (S3 in Fig. 3 and S32 in Fig. 4).

Thereafter, reference light information of the light-transmitting object hologram is extracted using a frequency filtering algorithm (S33 in FIG. 4).

In order to calculate the compensation term (Term) of the extracted reference light information, a wavenumber vector constant of the extracted reference light information is calculated (S34 in FIG. 4). And calculates a compensation term (Term) of the extracted reference light information using the calculated wavenumber vector constant (S35 in FIG. 4). In this case, the term (Term) of the extracted reference light information is the conjugate term of the light transmitting object hologram.

Then, in order to compensate for the curvature aberration of the object optical objective 51 used in hologram measurement, curvature information is extracted from the light transmitting object hologram (S36 in FIG. 4). For this purpose, for example, an automatic frequency curvature compensation algorithm is used to generate a term of a curvature information compensation term.

The compensation term of the extracted reference light information and the curvature information compensation term are multiplied by the light transmitting object hologram to obtain the compensated light transmitting object hologram (S5 in FIG. 3 and S37 in FIG. 4).

On the other hand, also in the case of the reflection type mode, the light reflection object hologram acquired by the two-dimensional Fourier transform is also obtained by applying the same method as the transmission mode described above to compensate the light reflection object hologram. The compensated light-transmitting object hologram and the compensated light-reflecting object hologram obtained in this way can be expressed by the following equations (3) and (4), respectively.

Equation (3)

Equation 4:

및

는 각각 보상된 빛 투과 물체 홀로그램, 및 보상된 빛 반사 물체 홀로그램이고,

는 빛 투과 물체 홀로그램의 물체광 및 기준광이며,

는 빛 반사 홀로그램의 물체광 및 기준광이고,

는 빛 투과 물체 홀로그램의 기준광 정보의 보상 항이고,

는 빛 투과 물체 홀로그램의 수차(curvature) 정보 보상 항이며,

는 빛 반사 물체 홀로그램의 기준광 정보의 보상 항이고,

는 빛 반사 물체 홀로그램의 수차(curvature) 정보 보상 항을 의미한다.here,

And

Is a compensated light-transmitting object hologram, and a compensated light-reflecting object hologram, respectively,

Is an object light and reference light of a light-transmitting object hologram,

Is the object light and reference light of the light reflection hologram,

Is a compensation term of the reference light information of the light-transmitting object hologram,

Is a curvature information compensation term of the light transmitting object hologram,

Is a compensation term of the reference light information of the light reflection object hologram,

Means the compensation information of the curvature information of the hologram of the light reflection object hologram.

The compensated light-transmitting object hologram represented by Equation (3) is converted into information of a reconstruction image plane using an Angular Spectrum Propagation Algorithm.

And extracts the phase information from the transformed compensated object hologram through an inverse 2D Fourier transform. The phase information obtained at this time is obtained by adding the remaining information excluding the phase information of the portion of the acquired light-transmitting object hologram, through which the light of the measurement object 40 is transmitted, (i.e., the information of the light, Aberration information) is removed, and only the phase information of the light-transmitting portion of the measurement object 40 is included.

The same method is applied to the compensated light reflecting object hologram to extract the phase information. The phase information obtained at this time is obtained by adding the remaining information excluding the phase information of the part of the acquired light reflection object hologram that reflects the light of the measurement object 40 (that is, information of the light, Aberration information) is removed, and only the phase information of the portion that reflects the light of the measurement object 40 is included.

 The phase information of the portion of the measurement object 40 through which the extracted light is transmitted and the phase information of the portion that reflects the extracted light are obtained by using a 2D phase unwrapping algorithm, And calculates the quantitative thickness information of the measurement object 40 (S5 in FIG. 3). This quantitative thickness information can be expressed as shown in Equation (5).

Equation 5:

*

은 측정 대상 물체(40)의 정량적인 두께 정보이고,

는 물체 홀로그램 획득 시 사용한 광원의 파장이며,

는 측정 대상 물체(40)의 빛을 투과하는 부분의 위상 정보이고,

는 측정 대상 물체(40)의 빛을 반사하는 부분의 위상 정보이며,

는 측정 대상 물체(40)와 공기의 굴절률 차이를 의미한다. 계산된 물체의 정량적인 두께 정보를 이용하여 물체의 3차원 형상을 복원한다.here,

Is the quantitative thickness information of the measurement object 40,

Is the wavelength of the light source used to acquire the object hologram,

Is the phase information of the light-transmitting portion of the measurement object 40,

Is phase information of a portion of the measurement object 40 that reflects light,

Means the refractive index difference between the object to be measured 40 and air. The 3D shape of the object is restored by using the quantitative thickness information of the calculated object.

3 is a flowchart illustrating an improved holographic reconstruction method according to an embodiment of the present invention.

2 and 3, an improved holographic reconstruction method according to an embodiment of the present invention includes: a) selecting (S1) two measurement modes of an object hologram of an object to be measured 40; b) measuring (S2) the object hologram according to the selected measurement mode; c) removing the measured direct current, virtual image, and aberration information of the object hologram (S3); d) extracting phase information of the object hologram (S4); And e) reconstructing the three-dimensional shape information and the quantitative size (thickness) information of the measurement object 40 (S5).

In the holographic reconstruction method according to an embodiment of the present invention, the step b) includes a step S21 of measuring an object hologram in a light transmission mode or a step S22 of measuring an object hologram in a light reflection mode can do.

The light-transmitting object hologram obtained in the measurement step S21 of the light transmission mode is a complex conjugate hologram corresponding to the interference fringe for the light-transmitting portion of the measurement object 40, .

Equation 1:

는 획득한 빛 투과 물체 홀로그램을 나타내고,

는 빛 투과 물체 홀로그램의 물체광과 기준광을 나타내며,

는 빛 투과 물체 홀로그램의 물체광과 기준광의 복소 공액을 나타낸다.Here, x and y represent spatial coordinates,

Represents the obtained light-transmitting object hologram,

Represents the object light and reference light of the light-transmitting object hologram,

Represents the complex conjugate of the reference light and the object light of the light-transmitting object hologram.

On the other hand, the light reflection object hologram obtained in the measurement step S22 of the light reflection mode is a complex conjugate hologram corresponding to the interference fringe for the light reflection portion of the measurement object 40, .

Equation 2:

는 획득한 빛 반사 물체 홀로그램을 나타내고,

는 빛 반사 물체 홀로그램의 물체광과 기준광을 나타내며,

는 빛 반사 물체 홀로그램의 물체광과 기준광의 복소 공액을 나타낸다.Here, x and y represent spatial coordinates,

Represents the obtained light reflecting object hologram,

Represents the object light and the reference light of the light reflection hologram,

Represents the complex conjugate of the reference light and the object light of the light reflection hologram hologram.

In the holographic reconstruction method according to an embodiment of the present invention, when the measured object hologram is a light-transmitting object hologram, the step c) includes: c1) removing the DC and holographic information from the light- The frequency spectrum of the light-transmitting object hologram obtained by performing 2D Fourier transform is separated into a real image, an imaginary image, and a direct current information of the light-transmitting object hologram step; c2) In order to remove virtual image and direct current (DC) information of the separated light-transmitting object hologram, the real image spot-position is converted into an automatic real image spot-position extraction algorithm ; c3) extracting the reference light information of the light-transmitting object hologram using a frequency filtering algorithm; c4) calculating a wavenumber vector constant of the extracted reference light information; c5) calculating a term (Term) of the extracted reference light information by using the calculated wavenumber vector constant; c6) extracting curvature information from the light-transmitting object hologram to compensate for curvature aberration of the object optical objective 50 used in the measurement of the object hologram; And c7) converting the compensation term and the light-transmitting object hologram in which the aberration information is compensated to information of a reconstruction image plane using an Angular Spectrum Propagation Algorithm .

In this case, the step c6) includes the steps of generating a curvature information compensation term using an automatic frequency curvature compensation algorithm; And obtaining the compensated light-transmitting object hologram by multiplying the light-transmitting object hologram by the compensation term of the extracted reference light information and the aberration information compensation term.

On the other hand, also in the case of the reflection type mode, the light reflection object hologram acquired by the two-dimensional Fourier transform is also obtained by applying the same method as the transmission mode described above to compensate the light reflection object hologram.

In the holographic reconstruction method according to an embodiment of the present invention, the compensated light-transmitting object hologram or the compensated light-reflecting object hologram may be expressed by Equation (3) or (4).

Equation (3)

Equation 4:

는 보상된 빛 투과 물체 홀로그램이고,

는 보상된 빛 반사 물체 홀로그램이고,

는 빛 투과 물체 홀로그램의 물체광 및 기준광이며,

는 빛 반사 홀로그램의 물체광 및 기준광이고,

는 빛 투과 물체 홀로그램의 기준광 정보의 보상 항이며,

는 빛 투과 물체 홀로그램의 수차(curvature) 정보 보상 항이고,

는 빛 반사 물체 홀로그램의 기준광 정보의 보상 항이며,

는 빛 반사 물체 홀로그램의 수차(curvature) 정보 보상 항을 의미한다.here,

Is a compensated light-transmitting object hologram,

Is a compensated light reflection object hologram,

Is an object light and reference light of a light-transmitting object hologram,

Is the object light and reference light of the light reflection hologram,

Is a compensation term of the reference light information of the light-transmitting object hologram,

Is a curvature information compensation term of the light transmitting object hologram,

Is a compensation term of the reference light information of the light reflection object hologram,

Means the compensation information of the curvature information of the hologram of the light reflection object hologram.

In the holographic reconstruction method according to an embodiment of the present invention, the step d) is performed by extracting phase information through an inverse 2D Fourier transform on the transformed object hologram, The phase information obtained here is obtained by extracting the remaining information (that is, information of the light, an object, etc.) excluding the phase information of the light-transmitting object hologram or the light-reflecting object hologram, (Aberration information of the optical objective lens 50) from the measurement object 40 is removed.

In the holographic reconstruction method according to an embodiment of the present invention, the step (e) may include extracting phase information of the light-transmitting portion of the measurement object 40 or extracted phase information of the light- Compensating the distorted phase information using a two-dimensional phase unwrapping algorithm; Calculating quantitative thickness information of the measurement object (40) using the compensated phase information; And reconstructing the three-dimensional shape of the measurement object 40 using the calculated quantitative thickness information of the object.

The calculated thickness information may be expressed by the following equation (5).

Equation 5:

은 측정 대상 물체(40)의 정량적인 두께 정보이고,

는 물체 홀로그램 획득 시 사용한 광원의 파장이며,

는 물체의 빛을 투과하는 부분의 위상 정보이고,

는 물체의 빛을 반사하는 부분의 위상 정보이고,

는 물체와 공기의 굴절률 차이를 의미한다.here,

Is the quantitative thickness information of the measurement object 40,

Is the wavelength of the light source used to acquire the object hologram,

Is the phase information of the portion through which the light of the object is transmitted,

Is the phase information of a part that reflects light of an object,

Means the refractive index difference between the object and the air.

As described above, in the improved holographic reconstruction apparatus 1 and method according to the present invention, the processor 90 directly generates the digital reference hologram calculated from the object hologram, Dimensional information can be restored. Therefore, a complicated optical device structure required for restoration of a one-shot type digital holography using a single object hologram image of the prior art, and thus a considerably high cost problem can be solved.

Further, according to the improved holographic reconstruction apparatus 1 and method according to the present invention, since the reconstruction apparatus additionally uses only the processor 90, it becomes possible to restore the holographic structure at a low cost with a very simple overall configuration .

In addition, in the improved holographic reconstruction apparatus 1 and method according to the present invention, other components except for the processor 90 and the positioning mirror 70 are substantially the same as the reflection type and transmission type holographic reconstruction apparatus of the prior art It has general versatility that can be easily applied to both the reflection type and transmission type hologram restoration apparatus of the prior art.

In addition, unlike the conventional art, the improved holographic reconstruction apparatus 1 and method according to the present invention do not require the use of the reference light during hologram reconstruction, and provide a quantitative three-dimensional image reconstruction This is possible.

Further, in the improved holographic reconstruction apparatus 1 and method according to the present invention, it is possible to quantitatively reconstruct a three-dimensional image of the measurement object 40 in real time without using the reference light as described above, , A device for detecting defects in ultrafine structure, a medical device requiring display of a precise three-dimensional image, and a refractive index error detection of a transparent object such as another lens, etc. It is possible.

Furthermore, in the improved holographic reconstruction apparatus 1 and method according to the present invention, the transmission mode and the reflection mode are selectively selected and measured by one integrated system incorporating the reflection type and transmission type hologram reconstruction apparatus of the related art Since the digital hologram can be measured regardless of the optical characteristics of the object, it is possible to solve the additional cost problem.

Although the present invention has been described by way of examples, the present invention is not limited thereto, and modifications and variations are possible within the scope of the technical idea of the present invention.

10: light source part 20: first light splitter
30: first optical mirror 31: second optical mirror
40: object to be measured 50: object optical objective lens
51: reference light objective lens 60: second light splitter
70: Position adjusting mirror 80: Recording medium
90: Processor

Claims (1)

In the holographic reconstruction apparatus,
A light source portion emitting a single wavelength light;
A first light splitter for dividing the single wavelength light emitted from the light source into a first transmission split light and a second transmission split light;
A plurality of optical mirrors for reflecting the first transmissive split light beams divided by the first optical beam splitter;
A second light splitter for splitting the second transmitted light split by the first optical splitter into a first split split light and a second split split light;
A first objective lens for passing the first split split light split by the first split split light or the first split split light that is reflected by the plurality of optical mirrors and transmitted through the object;
A reference light objective lens for passing the second divided reflection light split by the second light splitter;
A position adjustment mirror through which the second reflective divided light having passed through the reference light objective lens is transmitted;
And a second transmission section that transmits the first transmission split light transmitted through the object to be measured or the first reflection split light reflected from the surface of the measurement object and the second reflection split light that has passed through the reference light objective lens, A recording medium for recording an interference fringe formed by passing through the object optical objective lens and the reference light objective lens to the second optical splitter; And
And a processor for receiving and storing an image file generated by converting the interference fringes transmitted from the recording medium,
By the above process, a light transmission hologram and a light reflection hologram are selectively acquired according to a transmission mode and a reflection mode
A holographic restoration device.

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