Scanning hologram-based high-precision depth measuring and sharpness enhancement apparatus

Abstract

The present invention relates to a scanning hologram-based high-precision depth measuring and sharpness enhancement apparatus. Provided, according to the present invention, is a high-precision depth measuring and sharpness enhancement apparatus comprising: a scan beam generation unit for forming a scan beam by modulating the phase of a first beam split from a light source, and converting the first beam into a first curvature beam, and converting a second beam into a second curvature beam, and then having the first and second curvature beams interfere with each other; a scan unit for controlling the scanning position of the scan beam in the horizontal and vertical directions so as to use the scan beam to scan an object which is a reflective object; a light splitter arranged between the scan unit and the object so as to transmit the scan beam to the object and receive a beam reflected from the object and reflect said beam to the outside; a polarized beam splitter arranged between the light splitter and the object so as to divide the scan beam into a s-polarized beam and a p-polarized beam and transmit same to the object; and a photodetector for receiving and detecting the beam reflected from the light splitter.

Description

Scanning Hologram-Based High-Precision Depth Measurement and Sharpness Enhancement Device

[0001] The present invention relates to a high-precision depth measurement and sharpness enhancement device based on a scanning hologram, and more specifically, to a device that, unlike conventional scanning holograms, utilizes the characteristics of polarization to not only enhance the sharpness of an acquired image but also measure the depth of an object with high precision.

[0002] To measure the high-precision depth of an object, a method of acquiring phase information based on the step difference of the object was previously used.

[0003] A conventional scanning hologram recording device for acquiring phase information based on the step difference of an object forms a scan beam by superimposing a spherical wave and a plane wave, scans the object by moving the object in the X and Y directions while the scan beam is fixed, then collects the scan beam reflected from the object and focuses it on a photodetector, and generates an electrical signal proportional to the intensity of the focused light in the photodetector.

[0004] In this case, a very small mask, such as a pinhole, is placed in front of the photodetector to filter and acquire only the light information corresponding to the focal area of ​​the condensing lens. With such a pinhole mask structure, not only is the light-gathering efficiency low, but since scanning is performed by mechanically moving the stage on which the object is mounted in the X and Y directions, there is a disadvantage of taking a long time to acquire phase information of the object's step height, as well as a problem where the acquired phase information of the step height is contaminated by speckle noise.

[0005] The technology forming the background of the present invention is disclosed in Korean Registered Patent No. 1304695 (published September 6, 2013).

[0006] The present invention aims to provide a scanning hologram-based high-precision depth measurement and sharpness enhancement device that utilizes the polarization characteristics of a light source to enable high-precision depth measurement of an object without speckle noise, as well as to enhance the sharpness of the hologram of the object.

[0007] The present invention provides a scanning hologram-based high-precision depth measurement and sharpness enhancement device comprising: a scan beam generation unit that modulates the phase of a first beam split from a light source to convert it into a first curvature beam and converts a second beam into a second curvature beam, and then interferes the first and second curvature beams to form a scan beam; a scan unit that controls the scanning position of the scan beam in horizontal and vertical directions to transmit it to the object, which is a reflective object, so as to scan the object using the scan beam; a light splitter disposed between the scan unit and the object, which transmits the scan beam received from the scan unit to the object and receives the beam reflected from the object and reflects it outward; a polarization beam splitter disposed between the light splitter and the object, which splits the scan beam into an s-polarized beam and a p-polarized beam and transmits it to the object, and changes the sharpness of the hologram through moving the installation position or adjusting the angle; and a light detector that receives and detects the beam reflected from the light splitter.

[0008] In addition, the present invention provides a scanning hologram-based high-precision depth measurement and sharpness enhancement device comprising: a scan beam generation unit that modulates the phase of a first beam split from a light source to convert it into a first curvature beam and converts a second beam into a second curvature beam, and then interferes the first and second curvature beams to form a scan beam; a scanning unit that controls the scanning position of the scan beam in horizontal and vertical directions to transmit it to the object, which is a transmissive object, so as to scan the object using the scan beam; a polarization beam splitter disposed between the scanning unit and the object, which splits the scan beam into an s-polarized beam and a p-polarized beam and transmits it to the object, and changes the sharpness of the hologram through moving the installation position or adjusting the angle; and a light detector that receives and detects the beam transmitted through the object.

[0009] In addition, the scanning hologram-based high-precision depth measurement and sharpness enhancement device may further include an electronic processing unit that processes a signal detected by the photodetector to generate a hologram of the object.

[0010] In addition, the scanning hologram-based high-precision depth measurement and sharpness enhancement device may further include a computer processing unit composed of a numerical restoration unit that reads the hologram information received from the electronic processing unit and restores it using a numerical method, and a numerical processing unit that extracts phase information of the numerical restoration result and performs depth measurement of the object.

[0011] In addition, the numerical processing unit can perform depth measurement of the object by unwrapping the phase information of the numerical restoration result.

[0012] Additionally, the scan beam generating unit may include: a transition means for phase modulating a first beam divided from the light source by frequency shifting or phase shifting; first and second curvature beam generators for converting the phase-modulated first beam and the second beam divided from the light source into a first curvature beam and a second curvature beam, respectively, having a set curvature; and an interference means for generating the scan beam having an interference pattern of a Fresnel plate by interfering the first curvature beam that has passed through the first curvature beam generator and the second curvature beam that has passed through the second curvature beam generator with each other.

[0013] In addition, the above-mentioned transition means is a frequency transition means for frequency transitioning the first beam, and the scan beam can be defined by the following mathematical formula as a Fresnel plate form that is heterodyne modulated over time.

[0014]

[0015] Here, λ is the wavelength of the beam used, (x,y,z) is a spatial coordinate system in which the focal position of the first or second curvature beam is the origin, the direction of propagation of the first or second curvature beam is the z-axis, and the plane axes perpendicular to the z-axis are the x-axis and y-axis, C(z) is a function representing the change in curvature along the z-axis as the curvature of the Fresnel plate formed by the interference of the first curvature beam and the second curvature beam, and Ω represents the frequency of transition.

[0016] In addition, the above-mentioned transition means is a phase transition means for phase transitioning the first beam, and the scan beam can be defined by the following mathematical formula as a phase-transitioned Fresnel plate shape in the region where the first curvature beam and the second curvature beam interfere.

[0017]

[0018] Here, λ is the wavelength of the beam used, (x,y,z) is a spatial coordinate system with the focal position of the first or second curvature beam as the origin, the direction of propagation of the first or second curvature beam as the z-axis, and planar axes parallel to the z-axis as the x-axis and y-axis, C(z) is the curvature of the Fresnel plate formed by the interference of the first and second curvature beams, a function representing the change in curvature along the z-axis, P n represents a set of n different phases used in the above phase transition.

[0019] Additionally, the electronic processing unit may include: a heterodyne detector that generates an in-phase output signal and a quartile output signal using a current signal detected by the photodetector and a heterodyne modulation signal having a frequency Ω generated by a function generator of the signal generation unit; an AD converter that receives the in-phase signal and the quartile signal through each channel and converts them into digital signals; a signal processing unit that generates a complex hologram of an object from the converted digital signal; a storage unit that stores the generated complex hologram; and a scan control unit that generates a control signal to change the scan position of the scan unit whenever hologram processing for any position of the object is completed.

[0020] Additionally, the electronic processing unit may include an AD converter that converts a current signal detected by the photodetector into a digital signal; a signal processing unit that generates a complex hologram of an object using the converted digital current signal and a phase shift value generated by a phase shift signal generator of the signal generation unit; a storage unit that stores the generated complex hologram; and a scan control unit that generates a control signal to change the scan position of the scan unit whenever hologram processing for any position of the object is completed.

[0021] Additionally, the scanning unit may include a horizontal scanning mirror and a vertical scanning mirror to control the scanning position of the scan beam with respect to the object in horizontal and vertical directions.

[0022] Additionally, the scanning unit may include a scanning mirror that controls the scan beam incident from the scan beam generating unit in a horizontal direction and transmits it to the target object to control the scanning position of the scan beam with respect to the target object in horizontal and vertical directions, and a translation stage that moves the target object in a vertical direction from the rear end of the target object.

[0023] The above polarization beam splitter can adjust the horizontal spacing between the split p-polarized beam and s-polarized beam according to the adjustment of the position shift amount (Δx) in the x direction, and perform fine adjustment to match the telecentricity of the optical system according to the adjustment of the position shift amount (Δz) in the z direction.

[0024] In addition, the polarization beam splitter may include a beam displacer made of an anisotropic optical material that separates a scan beam incident through a first plane into an s-polarized beam and a p-polarized beam of mutually orthogonal polarization and emits them side by side through a second plane.

[0025] Additionally, the polarizing beam splitter comprises a combination of two triangular prisms made of different materials with crystal axes perpendicular to each other, and includes a polarizing prism that separates a scan beam incident through a first plane into a first polarizing beam traveling parallel to the scan beam and a second polarizing beam traveling at a set angle with respect to the scan beam at the boundary surface of the two triangular prisms, and emits them through a second plane, wherein if the first polarizing beam is an s-polarizing beam, the second polarizing beam is a p-polarizing beam, and if the first polarizing beam is a p-polarizing beam, the second polarizing beam may be an s-polarizing beam.

[0026] In addition, the polarizing prism can be implemented in the structure of any one of a Rochon prism, a Senarmont prism, or a Wollaston prism.

[0027] In addition, the polarization beam splitter is composed of a combination of two triangular prisms made of different materials with crystal axes perpendicular to each other, and is implemented as a Nomarski prism structure that splits a scan beam incident perpendicularly through a first plane into a first polarization beam and a second polarization beam of mutually orthogonal polarization components, deflects them at the boundary surface, and emits them through a second plane; if the first polarization beam is an s-polarization beam, the second polarization beam is a p-polarization beam, and if the first polarization beam is a p-polarization beam, the second polarization beam may be an s-polarization beam.

[0028] Additionally, the polarizing beam splitter may include: a first polarizing beam splitter that reflects an s-polarized beam component and transmits a p-polarized beam component from an incident scan beam; first and second mirrors sequentially installed on the path of an s-polarized beam reflected from the first polarizing beam splitter to change the beam path by 90 degrees; third to fifth mirrors sequentially installed on the path of a p-polarized beam transmitted from the first polarizing beam splitter to change the beam path by 90 degrees; a sixth mirror capable of angle adjustment and reflecting the angle of the p-polarized beam passing through the fifth mirror at an angle greater than 90 degrees; and a second polarizing beam splitter that receives the s-polarized beam passing through the second mirror and the p-polarized beam passing through the sixth mirror through a first surface and a second surface, respectively, and outputs them at different angles through a third surface.

[0029] Additionally, the polarizing beam splitter may include: a first polarizing beam splitter that reflects an s-polarized beam component and transmits a p-polarized beam component from an incident scan beam; first and second mirrors sequentially installed on the path of an s-polarized beam reflected from the first polarizing beam splitter to change the beam path by 90 degrees; third to sixth mirrors sequentially installed on the path of a p-polarized beam transmitted from the first polarizing beam splitter to change the beam path by 90 degrees; a wedge prism that receives a beam reflected from the sixth mirror and outputs it by changing the propagation angle; and a second polarizing beam splitter that receives an s-polarized beam passing through the second mirror and a p-polarized beam passing through the wedge prism through a first surface and a second surface, respectively, and outputs them at different angles through a third surface.

[0030] Additionally, the polarizing beam splitter may include: a beam splitter that transmits a portion of an incident scan beam and reflects a portion of it; first and second mirrors sequentially installed on the path of the beam reflected from the beam splitter to change the beam path by 90 degrees; third to fifth mirrors sequentially installed on the path of the beam transmitted from the beam splitter to change the beam path by 90 degrees; a polarizer disposed on either the path of the reflected beam or the transmitted beam of the beam splitter to pass only one polarization component of s-polarization and p-polarization or to make it into a linearly polarized beam of a specific angle; a sixth mirror capable of angle adjustment and reflecting the angle of the beam passing through the fifth mirror at an angle greater than 90 degrees; and a polarizing beam splitter that receives the beam passing through the second mirror and the beam passing through the sixth mirror through a first surface and a second surface, respectively, and outputs them at different angles through a third surface.

[0031] Additionally, the polarizing beam splitter may include: a beam splitter that transmits a portion of an incident scan beam and reflects a portion of it; first and second mirrors sequentially installed on the path of the beam reflected from the beam splitter to change the beam path by 90 degrees; third to sixth mirrors sequentially installed on the path of the beam transmitted from the beam splitter to change the beam path by 90 degrees; a polarizer positioned on either the path of the reflected beam or the transmitted beam of the beam splitter to pass only one polarization component of s-polarization and p-polarization or to make it into a linearly polarized beam of a specific angle; a wedge prism that receives the beam reflected from the sixth mirror and outputs it by changing the propagation angle; and a polarizing beam splitter that receives the beam passing through the second mirror and the beam passing through the wedge prism through a first surface and a second surface, respectively, and outputs them at different angles through a third surface.

[0032] According to the present invention, unlike conventional scanning holograms, it is possible to perform high-precision depth measurement of an object without speckle noise by utilizing the polarization characteristics of a light source, and it provides the advantage of increasing the sharpness of the hologram of the object.

[0033] FIG. 1 is a diagram showing the configuration of a scanning hologram-based high-precision depth measurement and sharpness enhancement device according to a first embodiment of the present invention.

[0034] Figure 2 is a diagram in which the transition means of Figure 1 is replaced with a phase transition means.

[0035] FIG. 3 is a diagram illustrating an example of implementation of a beam curvature generator according to an embodiment of the present invention.

[0036] FIGS. 4a to 4i are drawings illustrating specific examples of polarization beam splitters.

[0037] Figure 5 is a diagram illustrating an example in which incident light is spatially separated through a polarization beam splitter.

[0038] FIG. 6 is a flowchart illustrating a numerical processing process for obtaining phase information from hologram information obtained according to an embodiment of the present invention.

[0039] FIGS. 7a and 7b are configuration diagrams of a scanning hologram high-precision depth measurement and sharpness enhancement device according to a second embodiment of the present invention.

[0040] FIG. 8 is a configuration diagram of a scanning hologram high-precision depth measurement and sharpness enhancement device according to a third embodiment of the present invention.

[0041] Figure 9 is a diagram in which the transition means of Figure 8 is replaced with a phase transition means.

[0042] FIG. 10 is a diagram illustrating an embodiment in which light is spatially split according to the polarization characteristics of incident light when a Normalski prism is used among polarizing beam splitters.

[0043] FIG. 11 is a diagram illustrating an embodiment in which the degree to which incident light is spatially diverged according to polarization characteristics varies depending on the length of the path passing through a polarization beam splitter.

[0044] Figures 12a and 12b are drawings showing specific experimental examples in which the sharpness of an image is changed through fine-tuning of the angle and position of a polarizing beam splitter implemented with a Normalski prism.

[0045] FIG. 13 shows a specific embodiment of adjusting a polarization beam splitter and is a diagram illustrating fine adjustment in the horizontal direction.

[0046] FIG. 14 shows a specific embodiment of adjusting a polarization beam splitter and is a diagram explaining the angle adjustment of the polarization beam splitter.

[0047] FIG. 15 is a diagram showing an example in which the image obtained changes depending on the angle adjustment of the polarization beam splitter as an experimental result according to a specific embodiment of adjusting the polarization beam splitter.

[0048] Then, with reference to the attached drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. Furthermore, in order to clearly explain the present invention in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification have been given similar reference numerals.

[0049] Throughout the specification, when a part is described as being "connected" to another part, this includes not only cases where they are "directly connected," but also cases where they are "electrically connected" with other components interposed between them. Furthermore, when a part is described as "including" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0050] The present invention relates to a scanning hologram-based high-precision depth measurement and sharpness enhancement device, and provides a scanning hologram interferometer capable of high-precision depth measurement of an object and acquiring a hologram with enhanced sharpness. The object may correspond to a reflective object, which is a reflective object, or a transmissive object, which is a transmissive object.

[0051] The present invention proposes a scanning hologram-based high-precision depth measurement device that enables high-precision depth measurement of an object by utilizing the polarization characteristics of a light source when acquiring a hologram of an object having a rough surface with a step difference, thereby acquiring phase information according to the step difference of the object without speckle noise.

[0052] FIG. 1 is a diagram showing the configuration of a scanning hologram-based high-precision depth measurement and sharpness enhancement device according to a first embodiment of the present invention, and FIG. 2 is a diagram in which the transition means of FIG. 1 is replaced with a phase transition means.

[0053] First, as shown in FIG. 1, the scanning hologram-based high-precision depth measurement and sharpness enhancement device (100) according to the first embodiment of the present invention largely comprises a scan beam generating unit (110), a scanning unit (120), a polarization beam splitter (130), a light splitter (140), and a light detector (150), and may further include an electronic processing unit (160a), a computer processing unit (170), and a signal generating unit (180a). Here, the remaining parts excluding the electronic processing unit (160a) and the computer processing unit (170) correspond to the optical system part of the present invention.

[0054] First, the scan beam generating unit (110) modulates the phase of the first beam among the first and second beams divided from the light source to convert it into a first curvature beam through the first curvature beam generator (N1), converts the second beam into a second curvature beam through the second curvature beam generator (N2), and then interferes the first and second curvature beams to form a scan beam.

[0055] The scan beam generating unit (110) uses a Mark Zender interferometer structure that divides a light source into first and second beams to generate first and second curvature beams, and then combines the two generated beams.

[0056] The scan beam generating unit (110) includes a first beam splitter (111), a transition means (112), first and second mirrors (M1, M2), first and second beam curvature beam generators (N1, N2), and an interference means (117), and may further include a light source.

[0057] The transition means (112; 112a, 112b) can phase-modulate the first beam split from the light source by frequency-shifting or phase-shifting. In an embodiment of the present invention, FIG. 1 implements the transition means (112) as a frequency-shifting means (112a), and FIG. 2, described later, implements it as a phase-shifting means (112b).

[0058] The first and second curvature beam generators (N1, N2) can convert the first beam, which is phase-modulated by the transition means (112), and the second beam, which is split from the light source, into the first curvature beam and the second curvature beam, respectively, having a set curvature. In this way, the first and second curvature beam generators (N1, N2) can change the incident beam into a beam of a specific curvature.

[0059] The interference means (117) can receive the first curvature beam and the second curvature beam and interfere with each other to generate a scan beam having an interference pattern of a Fresnel plate and transmit it to the scan unit (120).

[0060] Below, the configuration of the scan beam generating unit (110) is explained in more detail through FIG. 1.

[0061] First, the light source is the part that generates electromagnetic waves. The light source can include various means capable of generating electromagnetic waves, such as a laser generator, an LED (light emitting diode), or a low-coherence beam like halogen light with a short coherence length. In the following, a representative example is provided where the light source is implemented as a laser generator.

[0062] The beam output from such a light source is input to the first beam splitter (111). The first beam splitter (111) separates the incident beam into a first beam and a second beam, transmits the first beam to the frequency shifting means (112b), and transmits the second beam to the second mirror (M2). That is, the beam following the path of the first beam in the first beam splitter (111) is transmitted to the frequency shifting means (112b), and the beam following the path of the second beam is reflected by the second mirror (M2) and then transmitted to the second curvature beam generator (N2).

[0063] Here, the first beam splitter (111) may be composed of an optical fiber coupler, a beam splitter, a geometric phase lens, etc., and may be implemented in a manner that transmits a beam to the outside by guiding it through free space. Here, if a means capable of splitting a beam in-line, such as a geometric phase lens, is used, the beam may be split into a first beam and a second beam in-line. In the following, it is assumed that each optical splitter is implemented as a beam splitter.

[0064] The frequency shifting means (112a) shifts the frequency of the first beam and then transmits it to the first mirror (M1). The frequency shifting means can shift the frequency of the first beam by Ω using the frequency generated by the function generator of the signal generation unit (180a) and transmit it to the first mirror (M1). Here, the frequency shifting means (112a) may use a phase optical modulator, but the present invention is not necessarily limited thereto, and it is also possible to perform frequency shifting using an acousto-optic frequency shifter or a PZT.

[0065] Here, the frequency shifting means (112a) is formed between the first beam splitter (111) and the first curvature beam generator (N1) as an example, but the present invention is not necessarily limited thereto. That is, the frequency shifting means (112a) can, of course, be formed between the first beam splitter (111) and the second curvature beam generator (N2).

[0066] The first beam reflected from the first mirror (M1) is transmitted to the first beam curvature generating unit (N1). The second beam reflected from the second mirror (M2) is transmitted to the second beam curvature generating unit (N2).

[0067] Here, the first and second curvature beam generators (N1, N2) receive each beam incident and generate an enlarged beam having a curvature between negative and positive curvature, including the collimated beam. The first and second curvature beam generators (N1, N2) may be set to different curvatures or, if necessary, to the same curvature.

[0068] FIG. 3 is a diagram illustrating an example of implementation of a beam curvature generator according to an embodiment of the present invention. FIG. 3 shows a first curvature beam generator, (b) a second curvature beam generator, and (c) an example of a change in curvature of a beam passing through the first curvature beam generator.

[0069] A specific implementation example of the first curvature beam generator (N1) is a beam expander having a first lens (113) that converts a first beam reflected from a first mirror (M1) into a spherical wave and a second lens (115) that receives the spherical wave and generates a curvature beam (first curvature beam), and the curvature of the beam can be adjusted by adjusting the distance between the first lens (113) and the second lens (115). A specific implementation example of the second curvature beam generator (N2) is a beam expander having a third lens (114) that converts a second beam reflected from a second mirror (M2) into a spherical wave and a fourth lens (116) that receives the spherical wave and generates a curvature beam (second curvature beam), and the curvature of the beam can be adjusted by adjusting the distance between the third lens (114) and the fourth lens (116).

[0070] In this way, the first and second curvature beam generators (N1, N2) may be composed of at least one lens, and the curvature of the first beam and the curvature of the second beam may be changed respectively by adjusting the distance between the lenses.

[0071] In addition, in all embodiments of the present invention, various scaling elements can be determined by adjusting the curvature of the two beams, such as setting the curvature of the first curvature beam and the curvature of the second curvature beam to be the same or different, by utilizing the first curvature beam generator (N1) and the second curvature beam generator (N2) in the method of FIG. 3.

[0072] The first curvature beam generator (N1) converts the first beam into a first curvature beam of a specific curvature and transmits it to the interference means (117). That is, the first curvature beam generator (N1) generates the first curvature beam by modulating the spatial distribution of the first beam.

[0073] The second curvature beam generator (N2) converts the second beam into a second curvature beam of a specific curvature and transmits it to the interference means (117). That is, the second curvature beam generator (N2) generates a second curvature beam by modulating the spatial distribution of the second beam.

[0074] The generated first and second curved beams are transmitted to the scanning unit (120) after interfering with each other while passing through the interference means (117). The interference means (117) can be implemented as a beam splitter and is referred to as a second beam splitter in the drawing.

[0075] The interference means (117) overlaps and interferes the first beam (first curvature beam) that has passed through the first beam curvature generating unit (N1) and the second beam (second curvature beam) that has passed through the second beam curvature generating unit (N2) to form a scan beam having an interference pattern of a Fresnel zone pattern.

[0076] At this time, the depth position on the focal axis of the first curvature beam and the depth position on the focal axis of the second curvature beam can be different from each other. Accordingly, the interference means (117) can form an interference beam (scan beam) in the shape of a Fresnel plate by interfering the first curvature beam and the second curvature beam, which have different focal positions, with each other.

[0077] In this way, the scan beam generating unit (110) converts the first beam and the second beam separated from the light source into first and second curvature beams and then overlaps them with each other through the interference means (117) to form a scan beam.

[0078] At this time, as shown in FIG. 1, when the transition means is composed of a frequency transition means (112a), the generated scan beam can be defined as a Fresnel plate shape that is heterodyne modulated over time as shown in Equation 1 below.

[0079]

[0080] Here, λ is the wavelength of the beam used, (x,y,z) is a spatial coordinate system with the focal position of the first or second curvature beam as the origin, the direction of propagation of the first or second curvature beam as the z-axis, and planar axes perpendicular to the z-axis as the x-axis and y-axis, C(z) is the curvature of the Fresnel plate formed by the interference of the first and second curvature beams, a function representing the change in curvature along the z-axis, and Ω represents the shifted frequency. Also, (x0 2 +y0 2 ) represents a cathartic coordinate system with (x0,y0) being a plane orthogonal to the optical axis of the first or second curvature beam.

[0081] For convenience of explanation, in the following embodiments of the present invention, (x,y,z) is exemplified as a spatial coordinate system in which the focal position of the first curvature beam is the origin and the axes of a plane perpendicular to the direction of travel of the first curvature beam are the x and y axes.

[0082] The scan beam generating unit (110) transmits the generated scan beam to the scanning unit (120). The scanning unit (120) scans an object using an interference beam formed by the interference means (117).

[0083] Referring again to FIG. 1, the scanning unit (120) controls the scanning position of the scan beam in the horizontal and vertical directions to scan the object, which is a reflective object, using the scan beam and transmits it to the object.

[0084] The beam incident on the scanning unit (120) is transmitted to the target object via the horizontal scanning mirror (121) (X scanner) and the vertical scanning mirror (122) (Y scanner). In this way, the scanning unit (120) may include an X scanner and a Y scanner to control the scanning position of the scan beam for the target object in the horizontal and vertical directions.

[0085] The present invention uses a mirror scanner as a scanning means, but the present invention is not necessarily limited thereto and can be replaced with various known scanning means.

[0086] A Fresnel plate-shaped beam is transmitted to a mirror-shaped scanning unit (120), and the scanning unit (120) enables scanning of an object by moving the Fresnel plate-shaped beam across the object. The scanning position can be adjusted according to a control signal from a scan control unit (165) provided in an electronic processing unit (160a).

[0087] The scanning unit (120) can be operated by receiving a scanning control signal from the scanning control unit (165) within the electronic processing unit (160a). In response to the control signal, a scan beam can be projected onto an object according to the movement of the scanning mirror. In this way, the scanning unit (120) can project an interference beam (a scan beam by the scanning unit) between the first and second curvature beams onto an object using the scanning mirror.

[0088] Of course, the scanning unit (120) can be changed to a scanning unit (220) structure utilizing a horizontal scanning mirror (121) (X scanner) and a vertical scanning mirror (122) (Y scanner) as shown in FIGS. 1 and 2, as shown in FIGS. 7a and 7b described later, utilizing a horizontal scanning mirror (221) and a translation stage (222).

[0089] In other words, in the present invention, instead of using two mirror scanners as described above, the object can be positioned on an objective plate and the object can be scanned by moving the objective plate horizontally. In addition, the object can be scanned using various methods, such as using an electron light deflector.

[0090] The optical splitter (140) is positioned between the scanning unit (120) and the target object to transmit the scan beam received from the scanning unit (120) to the target object and to reflect the beam reflected back from the target object back to the optical detector (150). More specifically, the optical splitter (140) may be positioned between the scanning unit (120) and the polarization beam splitter (130).

[0091] A polarization beam splitter (130) is positioned between the optical splitter (140) and the target and can split the scan beam into different polarization beams, namely an s-polarization beam and a p-polarization beam, and transmit them to the target. Additionally, the different polarization beams reflected back from the target can be combined again and incident on the optical splitter (140).

[0092] This polarization beam splitter (130) can change the sharpness of the hologram by moving the installation position or adjusting the angle.

[0093] At this time, the horizontal spacing between the p-polarized beam and the s-polarized beam can be adjusted by adjusting the x-direction positional displacement (Δx) of the polarization beam splitter (130), and fine adjustment can be performed to match the telecentricity of the optical system by adjusting the z-direction positional displacement (Δz).

[0094] In an embodiment of the present invention, the polarizing beam splitter (130) may be implemented with a Normarski prism structure shown in FIG. 4i, and may also be implemented with a structure shown in FIG. 4a to 4h.

[0095] FIG. 10 is a diagram illustrating an embodiment in which light is spatially split according to the polarization characteristics of incident light when a Normalski prism is used among polarizing beam splitters. As shown in FIG. 10, when a beam is incident perpendicularly on a birefringent crystal medium, the waves of the incident beam are divided into two beams of polarization components that are orthogonal to each other within the crystal.

[0096] A beam of one polarization component is an ordinary ray that travels along a normal optical path within the medium, while a beam of the other polarization component is an extra-ordinary ray that travels through the interior of the crystal along a different path from the ordinary ray due to another crystal structure within the medium. The ordinary ray travels relatively faster within the crystal medium compared to the extra-ordinary ray; consequently, a phase difference appears between the two beams as they pass through the crystal medium, and the phase difference between the two beams increases as the thickness of the medium increases. This means that a desired phase difference can be obtained between the two beams by appropriately adjusting the thickness of the birefringent crystal medium through which the two beams pass.

[0097] FIG. 11 is a diagram illustrating an embodiment in which the degree to which incident light is spatially diverged according to polarization characteristics varies depending on the length of the path passing through a polarizing beam splitter, and FIG. 12a and FIG. 12b are diagrams showing specific experimental examples in which the sharpness of an image is changed through fine adjustment of the angle and position of a polarizing beam splitter implemented with a Normalski prism.

[0098] For example, as shown in Fig. 11, when a beam is incident on the left side of a birefringent medium, the special light takes the phase lead as it passes through the thick upper medium, and when it passes through the lower birefringent crystal medium with a 90-degree rotational direction relative to the upper birefringent grating, the general light and the special light have reversed paths and velocities. In these two birefringent crystal media, the phase difference between the two beams can be said to be determined as they pass through the thicker medium. Therefore, when a beam is incident on the right side of the birefringent medium and transmitted, the phase of the general light takes the phase lead, and when a beam is incident on the left side of the birefringent medium, the phase of the special light takes the phase lead.

[0099] According to this, the phase difference can be changed by adjusting the position of the polarization beam splitter, thereby changing the image sharpness. As a result, information on objects with high sharpness can be obtained from surfaces with rough curvature that do not appear in general bright-field observation methods, and specific embodiments are shown in FIGS. 12a and 12b. Such a polarization beam splitter can be implemented by including a Nomarski prism and can be implemented with the structure of FIG. 4 described later. Additionally, a lens may be added depending on the type of prism used.

[0100] The adjustment method of the polarizing beam splitter mentioned above can be illustrated as in FIGS. 13 and 14. As shown in FIG. 13, the x-direction displacement of the prism's position Δx is adjusted to maintain the optical path difference (d) between the two incident beams of S-wave and P-wave on a flat object at (2m+1)λ / 2. In this case, destructive interference occurs between the two incident beams in the flat area, enabling the acquisition of dark area images. Under these conditions, if a change in ΔZ occurs due to surface curvature, a difference arises between the two maintained optical paths, and the interference brightness increases as a result. If the optical path difference increases by λ / 2 compared to the previously maintained optical path difference due to the change in ΔZ, maximum constructive interference occurs in this area, allowing for maximum contrast ratio representation for objects with curvature.

[0101] As shown in Fig. 14, by rotating the prism, the rate of change of OPD of the curved surface of the object can be varied in the dx or dy direction, allowing for adjustment of the intensity of the detection light in the desired direction. When the angle of the prism (shear axis direction) coincides with the direction of maximum slope of the curvature change, a detection image with maximum contrast can be obtained, and image detection can be prevented in mutually perpendicular directions. The change in image sharpness obtained according to the method of Fig. 14 can be confirmed as shown in Fig. 15.

[0102] The light detector (150) can receive and detect a beam reflected from the light splitter (140).

[0103] Here, a focusing lens (145) may be provided at the front end of the photodetector (150). The photodetector (150) can receive a beam focused through the focusing lens (145) and convert it into an electrical signal.

[0104] The condensing lens (145) can spatially condense a beam reflected from the light splitter (140) and transmit it to the light detector (150). A beam reflected from an object at a scan position of a scan beam designated by the scanning unit (120) can be spatially condensed by the condensing lens (145). The condensing lens (145) can be composed of various lenses, such as an image or non-image condenser including a concave reflector and a convex reflector.

[0105] In this way, the condensing lens (145) condenses the beam reflected from the object and passed through the light splitter (140), and the light detector (150) can detect the spatially condensed beam through the condensing lens (145) and convert it into a current signal. At this time, the light detector (150) can generate a current according to the intensity of the spatially condensed beam. The light detector can be implemented using a photodiode, but the present invention is not necessarily limited thereto, and various light detection means such as a light pipe may be applied. In addition, the present invention can directly detect light transmitted to the detection surface of the light detector (150) without a condensing lens.

[0106] Next, the electronic processing unit (160a) processes the signal detected by the photodetector (150) to generate a hologram of the object.

[0107] Referring to FIG. 1, the electronic processing unit (160a) includes a heterodyne detector (161), an AD converter (162), a signal processing unit (163), a storage unit (164), and a scan control unit (165).

[0108] The heterodyne detector (161) processes the current signal received from the photodetector (150) to generate an in-phase output signal and a quarter-phase output signal.

[0109] Specifically, the heterodyne detector (161) generates a homodyne output signal and a quartile output signal using a current signal detected by the photodetector (150) and a heterodyne modulation signal having a frequency Ω generated by the function generator of the signal generation unit (180a).

[0110] The heterodyne detector (161) multiplies the received current signal with a heterodyne modulated signal having a frequency Ω generated by the function generator of the signal generation unit (180a), and then performs low-frequency filtering to generate a first output signal in phase. At the same time, the signal phase of the frequency Ω generated by the function generator is shifted by Ω and multiplied with the received current signal, and then performs low-frequency filtering to generate a second output signal in phase. Accordingly, the heterodyne detector (161) produces two output signals (in-phase output signal and phase in phase output signal).

[0111] Here, the in-phase output signal and the quartile output signal correspond to the pattern of the object's 3D image encoded by the Fresnel plate and can be expressed by Equation 2 and Equation 3, respectively.

[0112]

[0113]

[0114] Here, is the three-dimensional distribution of reflectance for the object, and is a convolution operation. And (x,y) is the scan position of the scan beam specified by the scan unit (120), and C(z) is the curvature of the Fresnel plate formed by the interference of the first curvature beam and the second curvature beam, representing a function that indicates the change in curvature along the z-axis.

[0115] The AD converter (162) receives these in-phase and quarter-phase signals through each channel and converts them into digital signals. The converted digital current signals are provided to the signal processing unit (163) along with the scanning position of the scanning unit (120).

[0116] The signal processing unit (163) generates a complex hologram of an object from the converted digital signal, and the storage unit (164) stores the generated complex hologram.

[0117] And, whenever hologram processing for any position of the object is completed, the scan control unit (165) generates a control signal to change the scan position of the scan unit (120) and transmits it to the scan unit (120).

[0118] To this end, the signal processing unit (163) can form a two-dimensional array according to each scan position by adding mathematical formula 2 and mathematical formula 3 using a complex number addition method as shown in mathematical formula 4 below, and the storage unit (164) can store this.

[0119] In addition, the signal processing unit (163) may form a three-dimensional array according to the respective scan positions for Equation 2 and Equation 3 and transmit it to the storage unit (164), and then, when the scan is finished, read it from the storage unit (164), add the two-dimensional array corresponding to Equation 2 and Equation 3 using the complex number addition method of Equation 4, and then store it back in the storage unit (164). The signal stored in the storage unit (164) refers to Equation 4 below.

[0120]

[0121] In addition, the present invention may obtain the outputs of Equations 2 and 3 by applying the heterodyne signal generated in the signal generation unit (180a) to the reference signal input part of the heterodyne detector and obtaining the in-phase output and the quartile output, but as is known in the field of scanning hologram technology, it is also possible to obtain the reference signal by detecting it by positioning a portion of the light interfered by the interference means, that is, the second beam splitter (117), at the second photodetector.

[0122] In addition, in the first embodiment of the present invention, heterodyne detection is performed before converting to a digital signal through the AD converter (162), but it is also possible to convert the current signal provided by the photodetector (150) and the signal generated by the signal generation unit (180a) into a digital signal through the AD converter (162), and then perform digital heterodyne detection using a digital signal processing method and transmit it to the signal processing unit (163).

[0123] Meanwhile, the spatial distribution of the scan beam may be modulated or distorted in cases such as when there are aberrations in the lens or mirror. In this case, the pattern detected by the photodetector corresponds to a pattern encoded by a Fresnel plate having a modulated or distorted spatial distribution from the cross-sectional image of the object. At this time, the modulated or distorted pattern element can be obtained by convolving the complex conjugate of the desired Fresnel plate with the modulated or distorted Fresnel plate. Furthermore, by forming an inverse filter, such as a power fringe adaptive filter, using the modulated or distorted pattern element, the hologram encoded by the modulated or distorted Fresnel plate can be converted into a hologram encoded by the desired Fresnel plate. It goes without saying that the modulated or distorted Fresnel plate is also a type of Fresnel plate. These details are common to all embodiments of the present invention.

[0124] In addition, in an embodiment of the present invention, an arbitrary phase and amplitude pattern may be positioned in the path of the first curvature beam or the path of the second curvature beam to modulate the spatial distribution of the first curvature beam or the second curvature beam. At this time, the scan beam is a Fresnel plate modulated by an arbitrary phase and amplitude pattern, and accordingly, the pattern detected by the photodetector may be a pattern encoded with the image of the object and the Fresnel plate having a spatial distribution modulated by an arbitrary phase and amplitude pattern. Here, a pattern element modulated by an arbitrary phase and amplitude pattern can be obtained by convolving the complex conjugate of the desired Fresnel plate with the Fresnel plate having a spatial distribution modulated by an arbitrary phase and amplitude pattern. Furthermore, by forming an inverse filter, such as a power print adaptive filter, using the pattern element modulated by the arbitrary phase and amplitude pattern, the hologram encoded by the Fresnel plate modulated by the arbitrary phase and amplitude pattern can be converted into a hologram encoded by the desired Fresnel plate. It goes without saying that a Fresnel plate having a spatial distribution modulated by arbitrary phase and amplitude patterns is also a type of Fresnel plate. This information is also common to all embodiments of the present invention.

[0125] FIGS. 4a to 4i are drawings illustrating specific examples of polarization beam splitters.

[0126] First, FIG. 4a is a first embodiment of a polarization beam splitter, wherein the scan beam splitter (130-1) includes a beam displacer (131a) corresponding to the polarization splitter.

[0127] The beam displacer (131a) separates the scan beam incident through the first plane into mutually orthogonal polarized s-polarized beams and p-polarized beams and emits them side by side through the second plane. At this time, the beam displacer (131a) is made of an anisotropic optical material, and the anisotropic optical material may be calcite, YVO4, α-BBO, TeO2, etc.

[0128] In FIG. 4a, among the two emitted polarized beams, the ray whose polarization vibrates in the same direction as the optical axis of the beam displacer (131a) (see the optical axis indication on the upper plane) is called the ordinary ray, and the ray whose polarization vibrates in a direction perpendicular to the optical axis is called the extra-ordinary ray.

[0129] In the case of FIG. 4a, the p-polarized beam emitted from the beam displacer (131a) corresponds to a normal ray parallel to the optical axis of the beam displacer (131a), and the s-polarized beam corresponds to an abnormal ray perpendicular to the optical axis.

[0130] In this way, when a beam displacer (131a) is implemented using an optical material with an anisotropic crystal structure, it has a birefringence characteristic in which the refractive index changes depending on the polarization, so a beam polarized at 45 degrees or unpolarized can be incident and split into two linearly polarized beams (s-polarized beam, p-polarized beam) with a 90-degree phase difference.

[0131] Next, FIG. 4b is a second embodiment of a polarizing beam splitter, wherein the polarizing beam splitter (130-2) shown in FIG. 4b includes a polarizing prism (131b) of a Rochon prism structure, and a lens may be added to the rear end as needed.

[0132] The polarizing prism (131b) illustrated in FIG. 4b is implemented as a Rochon prism and consists of a combination of two triangular prisms made of different materials with crystal axes perpendicular to each other. Here, the polarizing prism (131b) separates a scan beam incident through a first surface into an s-polarized beam traveling parallel to the scan beam (incident ray) at the boundary between the two triangular prisms and a p-polarized beam traveling at a set angle to the scan beam (incident ray), and emits it through a second surface.

[0133] Here, the incident ray is separated at the boundary between the two triangular prism materials into an extra-ordinary ray that exits at an angle and an ordinary ray that exits parallel to the incident ray, depending on the wavelength of the light and the refraction of the material.

[0134] In the case of Fig. 4b, the s-polarized beam emitted parallel to the incident beam corresponds to the normal beam, and the p-polarized beam traveling at an angle to the incident beam corresponds to the abnormal beam.

[0135] At this time, the two beams can travel parallel to each other through a lens added to the rear end of the polarizing prism (131b).

[0136] Next, FIG. 4c is a third embodiment of a polarizing beam splitter, wherein the polarizing beam splitter (130-3) shown in FIG. 4c includes a polarizing prism (131c) with a Senarmont prism structure, and in this case, a lens may also be added to the rear end as needed.

[0137] The polarizing prism (131c) illustrated in Fig. 4c is implemented as a Senarmont prism and consists of a combination of two triangular prisms made of different materials with crystal axes perpendicular to each other.

[0138] Here, the polarizing prism (131c) separates the scan beam incident through the first plane into a p-polarized beam traveling parallel to the scan beam at the boundary of the two triangular prisms and an s-polarized beam traveling at a set angle with respect to the scan beam, and emits it through the second plane.

[0139] Here, the incident ray is separated at the boundary between the two triangular prism materials into an ordinary ray that exits at an angle according to the wavelength of light and the refraction of the material, and an extra-ordinary ray that exits parallel to the incident ray.

[0140] In Fig. 4c, the p-polarized beam emitted parallel to the incident beam corresponds to the ideal ray, and the s-polarized beam traveling at an angle to the incident beam corresponds to the normal ray.

[0141] Here, the two beams can travel parallel to each other through a lens added to the rear end of the polarizing prism (131c).

[0142] In the case of Fig. 4c, the basic structure and operating principle are the same as Fig. 4b, except that it is implemented with a Senarmont prism, so a repeated explanation thereof is omitted.

[0143] Next, FIG. 4d is a fourth embodiment of a polarizing beam splitter, wherein the polarizing beam splitter (130-4) shown in FIG. 4d includes a polarizing prism (131d) with a Wollaston prism structure, and in this case, a lens may be added to the rear end as needed.

[0144] The polarizing prism (131d) is composed of a combination of two triangular prisms made of different materials with crystal axes perpendicular to each other, and separates a scan beam incident through the first plane into an s-polarized beam and a p-polarized beam that travel symmetrically with respect to the direction of the scan beam at a set angle at the boundary surface of the two triangular prisms and emits them through the second plane.

[0145] In this Wollaston prism structure, if the crystal axis of the first triangular prism that meets the incident ray is perpendicular to the direction of propagation of the incident ray and the crystal axis of the second triangular prism is perpendicular to the first triangular prism, the incident ray is separated into an ordinary ray and an extraordinary ray that exit at an angle according to the wavelength of light and the refractive index of the materials at the boundary surface of the two materials. Here, the two beams can travel parallel to each other through a lens added to the rear end of the polarizing prism (131c).

[0146] FIG. 4e is a fifth embodiment of a polarizing beam splitter, wherein the polarizing beam splitter (130-5) shown in FIG. 4e is implemented by including first and second polarizing beam splitters (PBS1, PBS2) and first to sixth mirrors (M1~M6), and a lens may be further added to the rear end of the second polarizing beam splitter (PBS2).

[0147] The first polarizing beam splitter (PBS1) reflects the s-polarized beam component and transmits the p-polarized beam component from the incident scan beam. The first and second mirrors (M1, M2) are installed sequentially on the path of the s-polarized beam reflected by the first polarizing beam splitter (PBS1) to change the beam path by 90 degrees.

[0148] The third to sixth mirrors (M3 to M6) are sequentially installed in a 'U' shape on the path of the p-polarized beam transmitted from the first polarizing beam splitter (PBS1) to change the beam path. Here, the third to fifth mirrors (M3 to M5) can change the path of the p-polarized beam transmitted from the first polarizing beam splitter (PBS1) by 90 degrees, and the sixth mirror (M6) can be adjusted in angle.

[0149] The second polarizing beam splitter (PBS2) receives an s-polarized beam reflected using the first mirror (M1) and the second mirror (M2) and a p-polarized beam reflected using the third to sixth mirrors (M3~M6) through the first and second surfaces, respectively, and outputs them at different angles through the third surface.

[0150] The second polarization beam splitter (PBS2) reflects the s-polarized beam incident on the first surface and transmits the p-polarized beam incident on the second surface, thereby causing the reflected s-polarized beam and the transmitted p-polarized beam to be emitted through the third surface.

[0151] Here, the two beams can travel parallel to each other through a lens added to the rear end of the second polarizing beam splitter (PBS2).

[0152] FIG. 4f is a sixth embodiment of a polarizing beam splitter, wherein the polarizing beam splitter (130-6) shown in FIG. 4f is implemented by including first and second polarizing beam splitters (PBS1, PBS2), first to sixth mirrors (M1~M6), and a wedge prism (W), and a lens may be further added to the rear end of the second polarizing beam splitter (PBS2).

[0153] Figure 4f is a variation example of Figure 4e.

[0154] In FIG. 4f, the third to sixth mirrors (M3 to M6) are sequentially installed in a 'U' shape along the path of the p-polarized beam transmitted from the first polarizing beam splitter (PBS1) so that the beam path can be changed by 90 degrees. The wedge prism (W) into which the beam reflected from the sixth mirror (M6) is incident has a wedge shape and has an inclined surface formed thereon so that the beam can be deflected.

[0155] The second polarizing beam splitter (PBS2) can finally receive the s-polarized beam passing through the second mirror (M2) and the p-polarized beam passing through the wedge prism (W) through the first and second planes, respectively, and output them at different angles through the third plane. Here, the two beams can travel parallel to each other through a lens added at the rear end of the second polarizing beam splitter (PBS2).

[0156] FIGS. 4g and FIGS. 4h are the seventh and eighth embodiments of a polarizing beam splitter, respectively, and their basic principles are similar to FIGS. 4e and FIGS. 4f. FIGS. 4g and FIGS. 4h have a structure combining one beam splitter (BS) and one PBS (PBS) instead of two polarizing beam splitters (PBS1, PBS2).

[0157] First, FIG. 4g is a seventh embodiment of a polarizing beam splitter, and the polarizing beam splitter (130-7) shown in FIG. 4g is implemented by including a beam splitter (BS), first to sixth mirrors (M1 to M6), and a polarizing beam splitter (PBS), and a lens may be further added to the rear end of the polarizing beam splitter (PBS).

[0158] The beam splitter (BS) transmits a portion of the incident scan beam and reflects a portion. The first and second mirrors (M1, M2) are installed sequentially on the path of the beam reflected from the beam splitter to change the beam path by 90 degrees.

[0159] The third to fifth mirrors (M3 to M5) change the path of the p-polarized beam transmitted from the first polarizing beam splitter (PBS1) by 90 degrees.

[0160] A polarizer (WP) is placed on either the path of the reflected or transmitted beam of the beam splitter (BS) to allow only one of the polarization components of s-polarization and p-polarization to pass through, or to create a linearly polarized beam of a specific angle. For example, the polarizer (WP) may be installed between the beam splitter (BS) and the third mirror (M1) as shown in FIG. 4g, or between the first mirror (M1) and the second mirror (M2) as indicated by the dotted line.

[0161] The polarizing beam splitter (PBS) finally receives the beam passing through the second mirror (M2) and the beam passing through the sixth mirror (M6) through the first and second planes, respectively, and emits them at different angles through the third plane. Here, the two beams can travel parallel to each other through a lens added to the rear end of the polarizing beam splitter (PBS).

[0162] FIG. 4h is an eighth embodiment of a polarizing beam splitter, and the polarizing beam splitter (130-8) shown in FIG. 4h is implemented by including a beam splitter (BS), first to sixth mirrors (M1 to M6), a polarizing beam splitter (PBS), and a wedge prism (W).

[0163] Figure 4h is a variation of Figure 4g, in which a wedge prism (W) is placed between the sixth mirror (M6) and the polarizing beam splitter (PBS) instead of requiring angle adjustment of the sixth mirror (M6). Since the specific principle is the same as in the case of Figure 4f, a redundant explanation is omitted.

[0164] FIG. 4i is a ninth embodiment of a polarizing beam splitter, wherein the polarizing beam splitter (130-9) shown in FIG. 4i can be implemented by including a polarizing prism (131i) of a Nomarski prism structure, and in this case, a lens may be added to the rear end as needed.

[0165] The polarizing prism (131i) of this Normalski prism structure is composed of a combination of two triangular prisms made of different materials with crystal axes perpendicular to each other, and can split a scan beam incident perpendicularly through a first surface into a first polarizing beam and a second polarizing beam with polarization components orthogonal to each other, deflect them at the boundary surface, and emit them through a second surface. Of course, the first polarizing beam may be an s-polarizing beam or a p-polarizing beam, and the second polarizing beam may be the opposite p-polarizing beam or s-polarizing beam. The two emitted beams may travel parallel to each other through a lens.

[0166] The various structures of the polarization beam splitters shown in FIGS. 4a to 4h are applicable to all of the first to third embodiments of the present invention.

[0167] FIG. 5 is a diagram illustrating an example in which incident light is spatially separated through a polarization beam splitter. FIG. 5 shows an embodiment in which a first curvature beam and a second curvature beam are spatially separated through a polarization beam splitter (130) and incident on an object.

[0168] If Δx is the difference in horizontal distance between the centers of different polarized lights spatially separated through the polarizing beam splitter (130), the holographic information obtained from the electronic processing unit (160) can be expressed as Equation 5 below.

[0169]

[0170] This mathematical formula 5 represents holographic information obtained through a scanning holographic high-precision depth measurement and sharpness enhancement device (100) using different polarized light that is spatially separated through a polarizing beam splitter (130).

[0171] The depth difference Δx of different polarized light In this case, mathematical formula 5 can be expressed as mathematical formula 6 below.

[0172]

[0173] In mathematical equations 5 and 6 is acquired hologram information, ε is the reflectance of the spatially distributed object, Δz is the depth difference caused by different polarized light spatially separated by a polarizing beam splitter, is the Fresnel zone pattern at a specific depth position z, and Δx represents the difference in horizontal distance between different polarized lights spatially separated by a polarization beam splitter.

[0174] Specific embodiments of Δx can be shown as in FIGS. 5, 10, 11, and 13. As shown in FIGS. 5, 10, 11, and 13, Δx can be changed according to the change in the optical path length of the light passing through the polarizing beam splitter (130), and accordingly, the acquired holographic information changes as shown in Equation 5. FIG. 11 is a specific example of moving polarized light, where Δx can change depending on which boundary point of the prism the light passes through. FIGS. 12a and 12b show experimental results through the specific embodiments mentioned above. Through FIGS. 12a and 12b, the difference in sharpness depending on whether the polarizing beam splitter (Norsky prism) is applied can be confirmed.

[0175] Again, referring to FIG. 1, the computer processing unit (170) may be configured to include a numerical restoration unit (171) that reads hologram information received from the electronic processing unit (160) and restores it at a specific depth location using a numerical method, and a numerical processing unit (172) that extracts phase information of the numerical restoration result (restored hologram information) by the numerical restoration unit (171) and performs depth measurement of the object.

[0176] Light of different polarizations spatially divided by a polarization beam splitter (130) scans an object, is reflected back, and combined through the polarization beam splitter (130). The combined light is converted into an electrical signal form through a photodetector (150) and then used to generate a hologram of the object in an electronic processing unit (160). The computer processing unit (170) can numerically restore and process the hologram information to obtain phase information of the object.

[0177] More specifically, the computer processing unit (170) reads the hologram stored in the storage unit (164) and transmits it to the numerical restoration unit (171). The numerical restoration unit (171) places the hologram at a specific location ( The hologram is restored using a numerical method. Numerical restoration can be obtained by convolving the complex conjugate of the Fresnel plate generated at the restoration location onto the stored hologram. This method is exemplary, and it goes without saying that the hologram can be restored using various methods known to those skilled in the art.

[0178] Equation 7 below represents the restoration of a hologram using the above method. Equation 7 represents the restoration of hologram information obtained through a scanning hologram high-precision depth measurement and sharpness enhancement device (100) using different polarized light that is spatially separated through a polarizing beam splitter (130).

[0179]

[0180] Here, Is Hologram information restored from, ε is the reflectance of the spatially distributed object, Δz is the depth difference caused by different polarized light spatially separated by a polarizing beam splitter, is a specific depth location The complex conjugate of the Fresnel zone pattern, Δx, represents the difference in horizontal distance between different polarized lights spatially separated by a polarization beam splitter.

[0181] In mathematical equation 7, the depth difference Δx is In the case of It can be expressed as follows. Mathematical Equation 7 According to [source], not only does sharpness increase due to the difference in images separated by Δx in the x-direction In the phase, the depth difference at a position separated by Δx in the x direction is encoded to be less than the wavelength of the light source, making high-precision depth measurement possible.

[0182] The numerical processing unit (172) of the computer processing unit (170) performs processing to extract only the phase information of the restored hologram information or to correct distortion using a numerical method, and includes other numerical correction methods well known to those skilled in the art. The above-mentioned process can be illustrated in FIG. 6.

[0183] FIG. 6 is a flowchart illustrating a numerical processing process for obtaining phase information from hologram information obtained according to an embodiment of the present invention. That is, the scanning hologram-based high-precision depth measurement and sharpness enhancement device (100) obtains information of light reflected from an object in the form of an electrical signal using a light detector (150) in the embodiment of FIG. 1, and obtains hologram information such as the above equation through an electronic processing unit (160). At this time, if the hologram information is numerically restored at a specific location, high-precision depth information at that location can be obtained.

[0184] As shown in FIG. 6, the numerical processing unit (172) can perform high-precision depth measurement by analyzing the phase information of the numerical restoration result obtained from the numerical restoration unit (171), and can adjust the degree of high-precision depth measurement according to the difference in the optical paths of different polarized light passing through the polarization beam splitter (130).

[0185] Here, the numerical processing unit (172) can perform depth measurement of the object by unwrapping the phase information of the numerical restoration result. The unwrapping process can be represented as shown in Equation 8 below.

[0186]

[0187] Here, x is the spatial coordinate system, u is the spatial frequency coordinate system, are each The estimated value of, is the function value of the object, Is The Fourier transform value of, class is the phase information to be restored, and i represents the complex number representation.

[0188] At this time, , It can be expressed as.

[0189] The process from step 1 to step 4 of mathematical formula 8 is performed repeatedly until the difference between the estimated value and the measured value is minimized, and the final result value is used as the unwrap result.

[0190] The unwrap method mentioned above corresponds to a representative example, and in addition to the above example, various methods including the quad-tree decomposition method, the least-square method using FFT, the block least-square method, and the rounding-least-square method may be utilized.

[0191] In this way, the scanning hologram-based high-precision depth measurement and sharpness enhancement device (100) obtains information of light reflected back from an object after passing through a polarizing beam splitter (130) in the form of an electrical signal using a light detector (150), and obtains hologram information through an electronic processing unit (160a). At this time, by numerically restoring the hologram information to a specific location and unwrapping the phase information through a computer processing unit (170), precise height information (step difference or depth information of the object surface) at that location can be obtained. Thus, the present invention enables high-precision depth measurement of an object without speckle noise by utilizing the polarization characteristics of the light source.

[0192] Meanwhile, FIG. 2 is a case in which the transition means is implemented as a phase transition means (112b) differently from FIG. 1, and since components having the same sign as FIG. 1 mean that they perform the same operation, a separate description of components with the same sign is omitted.

[0193] In the case of Fig. 2, the basic structure of the system is the same as in Fig. 1, but the configuration of the transition means (112b), the signal generation unit (180b), and the electronic processing unit (160b) is different.

[0194] The phase shifting means (112b) serves to discontinuously shift the phase of the divided first curvature beam. The operation of the phase shifting means (112b) is based on the phase shift signal generated by the signal generation unit (180b). For example, the phase shifting means (112b) can shift the phase of the laser beam following the path of the first curvature beam in the order of {0, π / 2, π} according to the phase shift signal generated by the signal generation unit (180b).

[0195] A phase optical modulator can be used as such a phase shifting means, but the present invention is not necessarily limited thereto, and various phase shifting means can be used, such as changing the phase of the beam in the order of {0, π / 2, π} using a PZT.

[0196] In this embodiment, the phase is divided into three different phases {0, π / 2, π}, but it is possible to capture images with even more detailed subdivisions, and it is also possible to capture images with only one or two phase changes if you do not want to remove biimage noise or background noise. However, when capturing with only one phase (single phase), a phase modulator is not required.

[0197] In FIG. 2, the phase transition means (112b) is formed on the side of the first divided curvature beam as an example, but the present invention is not necessarily limited thereto. That is, the phase transition means (112b) can, of course, be formed on the side of the second divided curvature beam.

[0198] As shown in FIG. 2, when the transition means is composed of a phase transition means (112b), the scan beam generated by the scan beam generation unit (110) can be defined as a phase-transitioned Fresnel plate shape in the region where the first curvature beam and the second curvature beam are combined, as shown in Equation 9 below.

[0199]

[0200] Here, P n is a set of n different phases used for phase transition in the phase transition means (112b), i.e., It represents, and the definitions for the remaining factors are the same as those shown in Equation 1 above. Here, the three phase transitions shown are for illustrative purposes, and it is obvious that n phase transitions, such as 2, 3, or 4, are possible.

[0201] As shown in Fig. 2, when the frequency shifting means is replaced with a phase shifting means, the electronic processing unit (180b) does not need to be equipped with a heterodyne detector.

[0202] First, the current generated at the scan position of the response command beam specified by the scan unit (120) of FIG. 2 is given by Equation 10. This Equation 10 represents the current signal detected by the photodetector (150) of FIG. 2.

[0203]

[0204] is a current signal detected by a photodetector (150), and is the three-dimensional distribution of reflectance for the object, and is a convolution operation. And, (x,y) is a scan position of a scan beam specified by the scan unit (120), and C(z) is a function representing the change in curvature along the z-axis as the curvature of a Fresnel plate formed by the interference of the first curvature beam and the second curvature beam.

[0205] The electronic processing unit (180b) of FIG. 2 processes a current signal detected by a photodetector to extract holographic information of an object, and to this end, it may include an AD converter (166), a signal processing unit (167), a storage unit (168), and a scan control unit (169).

[0206] The AD converter (166) converts the current signal detected by the photodetector (150) into a digital signal. The converted digital current signal is a phase shift value P generated by the phase shift signal generator of the signal generation unit (180b). n It is provided as a signal processing unit (167) together with.

[0207] The signal processing unit (167) generates a complex hologram of an object using the converted digital current signal and the phase shift value generated by the phase shift signal generator of the signal generation unit (180b), and the storage unit (268) stores the generated complex hologram.

[0208] And, the scan control unit (169) can generate a control signal that changes the scan position of the scan unit (120) whenever holographic processing for any position of the object is completed.

[0209] Here, the signal processing unit (167) synthesizes the converted digital signals in three cases (p1, p2, p3) of the phase values ​​{0, π / 2, π} transitioned at each scanning position using Equation 11, thereby forming a pattern encoded with a 3D image of an object and a Fresnel plate. Acquires.

[0210]

[0211] In Figure 2, the phase is subdivided into three. Here, when the phase is subdivided into three or more, the images for three or more phases are combined in the manner of Equation 11 to obtain a pattern in which the image of the object being photographed and the Fresnel plate are encoded.

[0212] In the case where there are two phases, there is insufficient information for combining the image of the object being photographed and the Fresnel plate in Equation 11, so the encoded pattern of the cross-sectional image of the object being photographed and the real Fresnel plate is combined, and in this case, the reconstructed image is contaminated by paired image noise.

[0213] In the case of FIG. 2, the digital current signal, the scanning position of the scanning unit (120), and the phase transition value P n The data can be stored in the storage unit (168), and after scanning is completed, it can be read from the storage unit (168) and transmitted to the electronic processing unit (167) to perform the signal processing process described above.

[0214] FIGS. 7a and 7b are configuration diagrams of a scanning hologram high-precision depth measurement and sharpness enhancement device according to a second embodiment of the present invention.

[0215] As shown in FIG. 7a and FIG. 7b, the scanning hologram high-precision depth measurement and sharpness enhancement device (200) according to the second embodiment of the present invention mainly comprises a scan beam generating unit (110), a scanning unit (220), a polarization beam splitting unit (130), a light splitter (140), and a light detector (150), and may further include an electronic processing unit (160), a computer processing unit (170), and a signal generating unit (180).

[0216] In the case of FIGS. 7a and FIGS. 7b, the basic structure of the system is the same as FIGS. 1 and FIGS. 2, but the configuration of the scanning unit (220) is different, and the operating principle is as follows.

[0217] In FIGS. 7a and 7b, the scanning unit (220) includes a scanning mirror (221) (X scanner) that controls the scanning beam incident from the scanning beam generating unit (110) in the horizontal direction and transmits it to the target object so as to control the scanning position of the scan beam for the target object in the horizontal and vertical directions, and a translation stage (222) that moves the target object in the vertical direction (y direction) from the rear end of the target object.

[0218] The scan mirror (221) controls the scan beam received from the interference means (117) in a horizontal direction and transmits it to the object. Here, a third mirror (M3) may be added to convert the direction of the beam output from the interference means (117) and transmit it to the scan mirror (221). The translation stage (222) is installed at the rear end of the object to directly move the object receiving the scan beam in a vertical direction, thereby enabling scanning of the object in the y-direction through the scan beam.

[0219] The translation stage (222) is implemented to be movable in the y-axis direction on which the object is placed, and may correspond to a movable object plate. Although such a translation stage (222) is physically separated from the scan mirror (221), it corresponds to a means for controlling the scanning position of the beam for the object, and is therefore included as a component of the scan unit (220) together with the scan mirror (221).

[0220] In this way, the scanning unit (220) can control the scan beam in the horizontal direction (x direction) and the vertical direction (y direction) relative to the object using the scanning mirror (221) and the translation stage (222).

[0221] Here, it goes without saying that the structure of such a modified scan unit is also applicable to the structure of the second embodiment of FIG. 8.

[0222] FIG. 8 is a configuration diagram of a scanning hologram high-precision depth measurement and sharpness enhancement device according to a third embodiment of the present invention. FIG. 8 illustrates an embodiment for high-precision depth measurement of a transmission sample.

[0223] As shown in FIG. 8, the scanning hologram high-precision depth measurement and sharpness enhancement device (300) according to the third embodiment of the present invention mainly comprises a scan beam generating unit (110), a scanning unit (120), a polarization beam splitter (330), and a light detector (340), and may further include an electronic processing unit (160), a computer processing unit (170), and a signal generating unit (180a).

[0224] In the case of Fig. 8, the basic structure of the system is similar to Fig. 1, but differs in that the object is a permeable sample, and since components with the same symbols as in Fig. 1 perform the same operation, a separate description of components with the same symbols is omitted.

[0225] In the case of Fig. 8, as an example for a transmission type sample, a polarization beam splitter can be added between the object and the focusing lens depending on the type of prism used in the polarization beam splitter.

[0226] At this time, the scanning unit (120) controls the scanning position of the scan beam in the horizontal and vertical directions to transmit it to the object, which is a transmissive object, and scans the object. The polarization beam splitter (330) is positioned between the scanning unit (120) and the object and splits the scan beam into an s-polarized beam and a p-polarized beam to transmit it to the object, which is a transmissive object. The photodetector (340) receives the beam transmitted through the object and detects it. At this time, as in the case of the first embodiment, a focusing lens (345) may be provided at the front end of the photodetector (340). The photodetector (340) can receive the beam focused through the focusing lens (345) and convert it into an electrical signal. The electronic processing unit (160), the computer processing unit (170), and the signal generation unit (180) are the same as those described above.

[0227] FIG. 9 is a diagram in which the transition means of FIG. 8 is replaced with a phase transition means. In the case of FIG. 9, the basic structure of the system is the same as FIG. 8, but the configuration of the transition means (112b), the signal generation unit (180b), and the electronic processing unit (160b) is different from FIG. 8. Since the configuration of the transition means (112b), the signal generation unit (180b), and the electronic processing unit (160b) of FIG. 9 is the same as that of the embodiment of FIG. 2, a redundant description is omitted.

[0228] In addition, the embodiments of FIGS. 8 and 9 can also be configured with a combination of a scan mirror and a translation stage as in FIGS. 7a and 7b.

[0229] According to the present invention as described above, unlike conventional scanning holograms, high-precision depth measurement of an object is possible without speckle noise by utilizing the polarization characteristics of a light source.

[0230] The present invention has been described with reference to embodiments illustrated in the drawings, but this is merely illustrative, and those skilled in the art will understand that various modifications and equivalent alternative embodiments are possible therefrom. Accordingly, the true technical scope of protection of the present invention should be determined by the technical spirit of the appended claims.

Claims

1. A scan beam generating unit that modulates the phase of a first beam split from a light source to convert it into a first curvature beam and converts a second beam into a second curvature beam, and then interferes the first and second curvature beams to form a scan beam; A scanning unit that controls the scanning position of the scan beam in horizontal and vertical directions and transmits it to the object, so as to scan the object which is a reflective object using the scan beam; A light splitter disposed between the scanning unit and the target object, which transmits a scan beam received from the scanning unit to the target object and receives a beam reflected from the target object and reflects it outward; A polarization beam splitter disposed between the above-mentioned optical splitter and the above-mentioned target, splitting the scan beam into an s-polarized beam and a p-polarized beam and transmitting them to the target, and changing the sharpness of the hologram through moving the installation position or adjusting the angle; and A scanning hologram-based high-precision depth measurement and sharpness enhancement device comprising a photodetector that receives and detects a beam reflected from the above-mentioned optical splitter.

2. A scan beam generating unit that modulates the phase of a first beam split from a light source to convert it into a first curvature beam and converts a second beam into a second curvature beam, and then interferes the first and second curvature beams to form a scan beam; A scanning unit that controls the scanning position of the scan beam in horizontal and vertical directions and transmits it to the object, so as to scan the object which is a transmissive object using the scan beam; A polarization beam splitter disposed between the above-mentioned scanning unit and the above-mentioned target, which splits the scan beam into an s-polarized beam and a p-polarized beam and transmits them to the target, and changes the sharpness of the hologram through movement of the installation position or adjustment of the angle; and A scanning hologram-based high-precision depth measurement and sharpness enhancement device comprising a photodetector that receives and detects a beam transmitted through the above-mentioned object.

3. In claim 1 or claim 2, A scanning hologram-based high-precision depth measurement and sharpness enhancement device further comprising an electronic processing unit that processes a signal detected by the above-mentioned photodetector to generate a hologram of the object.

4. In Claim 3, A scanning hologram-based high-precision depth measurement and sharpness enhancement device further comprising a computational processing unit composed of a numerical restoration unit that reads the hologram information received from the electronic processing unit and restores it by a numerical method, and a numerical processing unit that extracts phase information of the numerical restoration result and performs depth measurement of an object.

5. In Claim 4, The above numerical processing unit is, A scanning hologram-based high-precision depth measurement and sharpness enhancement device that performs depth measurement of an object by unwrapping the phase information of the above numerical reconstruction result.

6. In claim 1 or claim 2, The above scan beam generating unit is, A transition means for phase modulating a first beam divided from the above light source by frequency shifting or phase shifting; A first and second curvature beam generator that converts the phase-modulated first beam and the second beam split from the light source into a first curvature beam and a second curvature beam, respectively, having a set curvature; and A scanning hologram-based high-precision depth measurement and sharpness enhancement device comprising an interference means for generating a scan beam having an interference pattern of a Fresnel plate by interfering the first curvature beam passed through the first curvature beam generator and the second curvature beam passed through the second curvature beam generator with each other.

7. In Claim 6, The above-mentioned shifting means is a frequency shifting means for frequency shifting the above-mentioned first beam, and The above scan beam is, High-precision depth measurement and sharpness enhancement device based on a scanning hologram defined by the following mathematical formula as a time-dependent heterodyne modulated Fresnel plate: Here, λ is the wavelength of the beam used, (x,y,z) is a spatial coordinate system in which the focal position of the first or second curvature beam is the origin, the direction of propagation of the first or second curvature beam is the z-axis, and the plane axes perpendicular to the z-axis are the x-axis and y-axis, C(z) is a function representing the change in curvature along the z-axis as the curvature of the Fresnel plate formed by the interference of the first curvature beam and the second curvature beam, and Ω represents the frequency of transition.

8. In Claim 6, The above-mentioned transition means is a phase transition means for phase-shifting the above-mentioned first beam, and The above scan beam is, A scanning hologram-based high-precision depth measurement and sharpness enhancement device defined by the following mathematical formula as a phase-shifted Fresnel plate shape in the region where the first and second curvature beams interfere: Here, λ is the wavelength of the beam used, (x,y,z) is a spatial coordinate system with the focal position of the first or second curvature beam as the origin, the direction of propagation of the first or second curvature beam as the z-axis, and planar axes parallel to the z-axis as the x-axis and y-axis, C(z) is the curvature of the Fresnel plate formed by the interference of the first and second curvature beams, a function representing the change in curvature along the z-axis, P n represents a set of n different phases used in the above phase transition.

9. In Claim 7, The above electronic processing unit is, A heterodyne detector that generates an in-phase output signal and a quartile output signal using a current signal detected by the above photodetector and a heterodyne modulation signal having a frequency Ω generated by a function generator of a signal generation unit; An AD converter that receives the above in-phase signal and quarter-phase signal through each channel and converts them into digital signals; A signal processing unit that generates a complex hologram of an object from the above converted digital signal; A storage unit for storing the complex hologram generated above; and A scanning hologram-based high-precision depth measurement and sharpness enhancement device comprising a scan control unit that generates a control signal to change the scan position of the scan unit whenever hologram processing for any position of the object is completed.

10. In claim 8, The above electronic processing unit is, An AD converter that converts the current signal detected by the above photodetector into a digital signal; A signal processing unit that generates a complex hologram of an object using the above-mentioned converted digital current signal and the phase shift value generated by the phase shift signal generator of the signal generation unit; A storage unit for storing the complex hologram generated above; and A scanning hologram-based high-precision depth measurement and sharpness enhancement device comprising a scan control unit that generates a control signal to change the scan position of the scan unit whenever hologram processing for any position of the object is completed.

11. In claim 1 or claim 2, The above scanning unit is, A scanning hologram-based high-precision depth measurement and sharpness enhancement device comprising a horizontal scan mirror and a vertical scan mirror to control the scanning position of the scan beam with respect to the above object in horizontal and vertical directions.

12. In claim 1 or claim 2, The above scanning unit is, A scanning hologram-based high-precision depth measurement and sharpness enhancement device comprising: a scanning mirror that controls the scan beam incident from the scan beam generating unit in the horizontal direction and transmits it to the target object so as to control the scanning position of the scan beam with respect to the target object in the horizontal and vertical directions, and a translation stage that moves the target object in the vertical direction from the rear end of the target object.

13. In claim 1 or claim 2, The above polarization beam splitter is, A scanning hologram-based high-precision depth measurement and sharpness enhancement device that adjusts the horizontal spacing between the divided p-polarized beam and s-polarized beam according to the adjustment of the position displacement amount (Δx) in the x direction, and performs fine adjustment to align the telecentricity of the optical system according to the adjustment of the position displacement amount (Δz) in the z direction.

14. In claim 1 or claim 2, The above polarization beam splitter is, A scanning hologram-based high-precision depth measurement and sharpness enhancement device comprising a beam displacer made of an anisotropic optical material, which separates a scan beam incident through a first plane into mutually orthogonal polarized s-polarized beams and p-polarized beams and emits them side by side through a second plane.

15. In claim 1 or claim 2, The above polarization beam splitter is, It includes a polarizing prism composed of a combination of two triangular prisms made of different materials with mutually perpendicular crystal axes, and separates a scan beam incident through a first surface into a first polarizing beam traveling parallel to the scan beam and a second polarizing beam traveling at a set angle with respect to the scan beam at the boundary surface of the two triangular prisms, and emits them through a second surface. A scanning hologram-based high-precision depth measurement and sharpness enhancement device, wherein if the first polarized beam is an s-polarized beam, the second polarized beam is a p-polarized beam, and if the first polarized beam is a p-polarized beam, the second polarized beam is an s-polarized beam.

16. In claim 1 or claim 2, The above polarization beam splitter is, It is implemented as a Nomarski prism structure composed of a combination of two triangular prisms made of different materials with mutually perpendicular crystal axes, wherein a scan beam incident perpendicularly through a first plane is split into a first polarized beam and a second polarized beam with mutually orthogonal polarization components, deflected at the boundary surface, and emitted through a second plane. A scanning hologram-based high-precision depth measurement and sharpness enhancement device, wherein if the first polarized beam is an s-polarized beam, the second polarized beam is a p-polarized beam, and if the first polarized beam is a p-polarized beam, the second polarized beam is an s-polarized beam.

17. In claim 1 or claim 2, The above polarization beam splitter is, A first polarization beam splitter that reflects the s-polarized beam component and transmits the p-polarized beam component of an incident scan beam; First and second mirrors sequentially installed on the path of an s-polarized beam reflected from the first polarizing beam splitter to change the beam path by 90 degrees; Third to fifth mirrors sequentially installed on the path of the p-polarized beam transmitted from the first polarizing beam splitter to change the beam path by 90 degrees; A sixth mirror capable of angle adjustment and reflecting the p-polarized beam passing through the fifth mirror at an angle greater than 90 degrees; and A scanning hologram-based high-precision depth measurement and sharpness enhancement device comprising a second polarization beam splitter that receives an s-polarized beam passing through the second mirror and a p-polarized beam passing through the sixth mirror through a first surface and a second surface, respectively, and outputs them at different angles through a third surface.

18. In claim 1 or claim 2, The above polarization beam splitter is, A first polarization beam splitter that reflects the s-polarized beam component and transmits the p-polarized beam component of an incident scan beam; First and second mirrors sequentially installed on the path of an s-polarized beam reflected from the first polarizing beam splitter to change the beam path by 90 degrees; Third to sixth mirrors sequentially installed on the path of the p-polarized beam transmitted from the first polarizing beam splitter to change the beam path by 90 degrees; A wedge prism that receives a beam reflected from the sixth mirror and outputs it by changing the propagation angle; and A scanning hologram-based high-precision depth measurement and sharpness enhancement device comprising a second polarization beam splitter that receives an s-polarized beam passing through the second mirror and a p-polarized beam passing through the wedge prism through a first surface and a second surface, respectively, and outputs them at different angles through a third surface.

19. In claim 1 or claim 2, The above polarization beam splitter is, A beam splitter that transmits a portion of the incident scan beam and reflects a portion; First and second mirrors sequentially installed on the path of the beam reflected from the beam splitter to change the beam path by 90 degrees; Third to fifth mirrors sequentially installed on the path of the beam transmitted from the beam splitter to change the beam path by 90 degrees; A polarizer positioned on either the path of the reflected beam or the path of the transmitted beam of the beam splitter, for allowing only the polarization component of either s-polarization or p-polarization to pass through or for making into a linearly polarized beam of a specific angle; A sixth mirror capable of angle adjustment and reflecting the beam passing through the fifth mirror at an angle greater than 90 degrees; and A scanning hologram-based high-precision depth measurement and sharpness enhancement device comprising a polarizing beam splitter that receives a beam passing through the second mirror and a beam passing through the sixth mirror through a first surface and a second surface, respectively, and outputs them at different angles through a third surface.

20. In claim 1 or claim 2, The above polarization beam splitter is, A beam splitter that transmits a portion of the incident scan beam and reflects a portion; First and second mirrors sequentially installed on the path of the beam reflected from the beam splitter to change the beam path by 90 degrees; Third to sixth mirrors sequentially installed on the path of the beam transmitted from the beam splitter to change the beam path by 90 degrees; A polarizer positioned on either the path of the reflected beam or the path of the transmitted beam of the beam splitter, for allowing only the polarization component of either s-polarization or p-polarization to pass through or for making into a linearly polarized beam of a specific angle; A wedge prism that receives a beam reflected from the sixth mirror and outputs it by changing the propagation angle; and A scanning hologram-based high-precision depth measurement and sharpness enhancement device comprising a polarizing beam splitter that receives a beam passing through the second mirror and a beam passing through the wedge prism through a first surface and a second surface, respectively, and outputs them at different angles through a third surface.

Images