Far-field simulator and optical test system including same, and beam alignment method using far-field simulator

Abstract

Disclosed is a far-field simulator for simulating a beam as having been propagated from a remote point. The far-field simulator comprises: a beam splitter configured to split an incident beam into a first beam and a second beam; a far-field simulation unit which is disposed on the optical path of the first beam that has passed through the beam splitter and configured to increase the curvature of the wavefront of the passing first beam, and that simulates the first beam as having been propagated from a remote point; an interference pattern acquisition unit formed to be struck by the first beam that has passed through the far-field simulation unit and the second beam split by the beam splitter, and configured to acquire interference patterns of the first and second beams; and an alignment unit configured to align the far-field simulation unit, so that the first beam that has passed through the far-field simulation unit has a flatness in a predetermined range, on the basis of the interference patterns acquired by the interference pattern acquisition unit.

Description

Long-distance simulator and optical test system including same, beam alignment method using long-distance simulator

[0001] The present invention relates to a long-distance simulator that simulates a beam in a form propagated from a distant point, an optical test system including the same, and a beam alignment method using the long-distance simulator.

[0002] A far-field simulator (FFS) is a device that generally simulates a beam propagated over a long distance. Such far-field simulators can be particularly useful in technologies that transmit optical signals via space propagation between satellites.

[0003] Specifically, satellite payloads are equipped with various optical devices related to optical communications, which transmit optical signals between satellites via spatial propagation. Since testing an actual satellite is impossible during the design process for such optical communications, a method is needed to simulate the satellite's operating environment and test the optical communications of the optical devices on the payload in this simulated environment, thereby achieving a more accurate design.

[0004] Meanwhile, long-range simulators must maintain a high level of flatness in the wavefront of the beam emitted, as they simulate beams transmitted from long distances. However, the wavefront sensor, which is positioned at the rear of a conventional long-range simulator and used for optical system alignment to maintain the flatness of the wavefront of the beam emitted from the simulator, is extremely expensive, posing various limitations in the development of satellites that perform optical communications.

[0005] One object of the present invention is to provide a long-distance simulator configured to replace a wavefront sensor for alignment of a long-distance simulator, an optical test system including the same, and a beam alignment method using the long-distance simulator.

[0006] In order to achieve the object of the present invention, a long-distance simulator according to one embodiment of the present invention includes: a beam splitter configured to split an incident beam into a first beam and a second beam; a long-distance simulator arranged on an optical path of the first beam passing through the beam splitter and configured to increase a curvature of a wavefront of the passing first beam so as to simulate the first beam in a form propagated from a distant point; an interference pattern acquisition unit configured to acquire interference patterns of the first and second beams by forming an incident portion of the first beam passing through the long-distance simulator and the second beam split by the beam splitter; and an alignment unit configured to align the long-distance simulator such that the first beam passing through the long-distance simulator has a flatness within a preset range based on the interference pattern acquired by the interference pattern acquisition unit.

[0007] According to an example related to the present invention, the alignment unit may be configured to align the long-distance copy unit so that the interference pattern acquired from the interference pattern acquisition unit becomes a null state in which no interference pattern appears.

[0008] According to an example related to the present invention, the optical path of the first beam split by the beam splitter and incident on the interference pattern acquisition unit through the long-distance copying unit is formed to be longer than the optical path of the second beam split by the beam splitter and incident on the interference pattern acquisition unit, and the beam splitter may be configured to split the first beam at a higher ratio than the second beam so as to reduce the difference in intensity between the first beam and the second beam incident on the interference pattern acquisition unit.

[0009] According to an example related to the present invention, the optical path of the first beam, which is split by the beam splitter and passes through the long-distance copying unit and is incident on the interference pattern acquisition unit, is formed to be longer than the optical path of the second beam, which is split by the beam splitter and is incident on the interference pattern acquisition unit, and the long-distance copying unit may further include a beam reducer, which is arranged on the optical path of the first beam between the long-distance copying unit and the interference pattern acquisition unit and is configured to reduce the width of the first beam that has passed through the long-distance copying unit.

[0010] According to an example related to the present invention, the optical path of the first beam split by the beam splitter and incident on the interference pattern acquisition unit through the long-distance copying unit is formed to be longer than the optical path of the second beam split by the beam splitter and incident on the interference pattern acquisition unit, and the long-distance copying unit may further include an optical filter unit that is arranged on the optical path of the second beam between the beam splitter and the interference pattern acquisition unit and is formed to reduce the intensity of the second beam incident on the interference pattern acquisition unit.

[0011] According to an example related to the present invention, the long-distance copying unit may include a first lens formed to focus the first beam passing through the beam splitter; a pinhole formed to pass the first beam focused in the form of a point light source while passing through the first lens; and a second lens formed to even out the wavefront of the first beam diverging through the pinhole to form a collimated beam.

[0012] According to an example related to the present invention, the alignment unit may be configured to finely adjust the relative position of the pinhole between the first lens and the second lens so that the interference pattern acquired by the interference pattern acquisition unit becomes a null state in which no interference pattern appears.

[0013] An optical test system according to another embodiment of the present invention includes: the long-distance simulator; and an optical test section configured to test an optical communication environment by receiving the first beam in an aligned state emitted from the long-distance simulator, wherein the optical test section includes a test for a PAT (Pointing, Acquisition and Tracking) algorithm designed to correct disturbance in an optical communication environment.

[0014] In another embodiment of the present invention, a beam alignment method using a long-distance simulator comprises the steps of: splitting an incident beam into a first beam and a second beam using a beam splitter;

[0015] The method comprises: a step of increasing the curvature of the wavefront of the first beam passing through the beam splitter using a long-distance copying unit to copy the first beam in a form in which the first beam is propagated from a distant point; a step of obtaining an interference pattern of the first beam passing through the long-distance copying unit and the second beam split by the beam splitter, which are each incident on an interference pattern obtaining unit; a step of aligning the beam splitter based on the interference pattern obtained by the interference pattern obtaining unit; and a step of aligning the long-distance copying unit such that the first beam has a flatness in a preset range using an alignment unit that aligns the long-distance copying unit based on the interference pattern obtained by the interference pattern obtaining unit.

[0016] According to an example related to the present invention, the long-distance copying unit includes a first lens, a pinhole, and a second lens sequentially arranged on the optical path of the first beam passing through the beam splitter, and the step of aligning the beam splitter comprises: tipping and / or tilting the beam splitter so that a tilt pattern defined by the slope of the wavefronts of the first and second beams is visible in the interference pattern acquisition unit, and finely adjusting the posture of the beam splitter so that the interference pattern does not appear in a null state; and the step of aligning the long-distance copying unit comprises: adjusting the distance and each position between the first lens that focuses the first beam split in the beam splitter and the second lens that evenly forms the wavefront of the first beam passing through the first lens so that the interference pattern acquired in the interference pattern acquisition unit is in the null state; And it may include a step of arranging the pinhole at the focus of the first beam that passes through the first lens and is focused between the first and second lenses, and finely adjusting the position of the pinhole so that the number of photons acquired by the interference pattern acquisition unit has a maximum value, thereby aligning the center of the pinhole and the optical axes of the first and second beams.

[0017] The effects of the present invention obtained through the above-described solution are as follows.

[0018] The long-distance simulator includes a beam splitter that splits an incident beam into a first beam and a second beam, a long-distance simulator that increases the curvature of the wavefront of the first beam split by the beam splitter to simulate the first beam in the form of propagation from a distant point, an interference pattern acquisition unit that acquires an interference pattern formed when the first beam passing through the long-distance simulator and the second beam split by the beam splitter are incident, and an alignment unit that aligns the long-distance simulator so that the first beam passing through the long-distance simulator has a flatness within a preset range based on the acquired interference pattern.

[0019] This configuration of a long-range simulator enables alignment of optical systems without the need for expensive wavefront sensors. This significantly reduces cost constraints on the development of satellites for optical communications, thereby stimulating related research and development. Furthermore, the interference pattern acquisition unit can be implemented simply by displaying interference patterns, even without an electronic system, allowing for a wider range of configurations of long-range simulators and optical test systems including them.

[0020] Figure 1 is a conceptual diagram of a long-distance simulator and an optical test system equipped therewith according to one embodiment of the present invention.

[0021] Figure 2 is a conceptual diagram of the long-distance copying unit illustrated in Figure 1.

[0022] FIG. 3 is a flowchart showing a beam alignment method using a long-distance simulator according to another embodiment of the present invention.

[0023] FIG. 4 is a conceptual drawing of a long-distance simulator and an optical test system including the same for explaining the steps of aligning the beam splitter illustrated in FIG. 3.

[0024] FIG. 5 is a drawing showing an example of a tilt pattern appearing in the interference pattern acquisition unit shown in FIG. 4 during the process of aligning the beam splitter shown in FIG. 3.

[0025] FIG. 6 is a conceptual drawing of a long-distance copying machine and an optical test system including the same for explaining the step of adjusting the distance between the first and second lenses and their respective positions in the step of aligning the long-distance copying unit illustrated in FIG. 3.

[0026] FIG. 7 is a drawing showing examples of interference patterns appearing in the interference pattern acquisition unit shown in FIG. 6 during the process of adjusting the distance between the first and second lenses and their respective positions in the step of aligning the long-distance copy unit shown in FIG. 3.

[0027] FIG. 8 is a conceptual drawing of a long-distance copying machine and an optical test system including the same for explaining the process of aligning the center of the pinhole and the optical axes of the first and second beams by finely adjusting the position of the pinhole in the step of aligning the long-distance copying unit illustrated in FIG. 3.

[0028] Hereinafter, a long-distance simulator (100) and an optical test system (10) including the same, and a beam alignment method using the long-distance simulator (100) related to the present invention will be described in more detail with reference to the drawings.

[0029] In this specification, identical or similar reference numbers are assigned to identical or similar components even in different embodiments, and redundant descriptions thereof are omitted.

[0030] Singular expressions include plural expressions unless the context clearly indicates otherwise.

[0031] Fig. 1 is a conceptual diagram of a long-distance simulator (100) and an optical testing system (10) equipped therewith according to one embodiment of the present invention. Fig. 2 is a conceptual diagram of a long-distance simulator (120) illustrated in Fig. 1.

[0032] Referring to FIGS. 1 and 2, the optical test system (10) includes a long-distance simulator (100) and an optical test section (12).

[0033] The long-distance simulator (100) is configured to align the long-distance simulator (120) based on the interference pattern acquired from the interference pattern acquisition unit (130) and emit the first beam (B1) in the aligned state. Through the long-distance simulator (100), an optical system in an optical communication environment used over long distances, such as 10 km, 20 km, or 1000 km, can be simulated. A more detailed description of the long-distance simulator (100) will be provided later.

[0034] The optical test unit (12) is configured to test the optical communication environment by receiving the aligned first beam (B1) emitted from the long-distance copy unit (120).

[0035] For example, the optical test section (12) may include a test for a PAT (Pointing, Acquisition and Tracking) algorithm designed to compensate for disturbances in an optical communication environment.

[0036] In addition, the optical test unit (12) configured for testing the PAT algorithm may include, for example, a first high-speed steering mirror (not shown), a second high-speed steering mirror (not shown), an optical lens (not shown), and an image acquisition device (not shown). The first high-speed steering mirror, the second high-speed steering mirror, the optical lens, and the image acquisition device may be sequentially arranged along the optical path (B1a) of the first beam (B1) emitted from the long-distance copy unit (120).

[0037] The first high-speed steering mirror may be configured to receive the first beam (B1) and generate jitter. The jitter is a phenomenon in which a digital pulse signal waveform is distorted on the time axis, and refers to a deviation in timing that provides an operating moment. In addition, a mirror (M2, M3) may be provided between the long-distance copy machine (100) and the first high-speed steering mirror to reflect the incident first beam (B1) in a specific direction so that the first beam (B1) emitted from the long-distance copy machine (100) proceeds toward the first high-speed steering mirror, thereby forming an optical path (B1a) of the first beam (B1).

[0038] The second high-speed steering mirror may be configured to correct the jitter by receiving the first beam (B1) reflected from the first high-speed steering mirror.

[0039] The optical lens may be arranged on the optical path (B1a) of the first beam (B1) reflected from the second high-speed steering mirror, so as to form an optical path (B1a) of the first beam (B1) directed toward the image acquisition device.

[0040] The above image acquisition device is configured to acquire image information about the first beam (B1) incident through the optical lens. The optical test unit (12) may be configured to perform a test on the PAT algorithm based on the image information about the first beam (B1) obtained through the image acquisition device.

[0041] Meanwhile, the optical test system (10) may include a light source unit (11) arranged in front of a long-distance simulator (100) as shown in FIG. 1 and configured to generate a beam and transmit it to a long-distance simulator (120).

[0042] The light source unit (11) may include, for example, a light source generation unit (11a), a beam isolator (11b), and a collimator (11c).

[0043] The light source generating unit (11a) can be configured to generate a beam that travels in a specific direction, such as a laser.

[0044] The beam isolator (11b) can be configured to allow light generated from the light source generation unit (11a) to pass through when it moves in the direction of travel, and to block the beam that is reflected and returns toward the light source generation unit (11a).

[0045] The collimator (11c) can be configured to make the incident beam from the beam isolator (11b) incident and the passing incident beam parallel. Accordingly, the beam emitted from the light source unit (11) can be configured to proceed along the optical path in a collimated state and be incident on the long-distance copy unit (120).

[0046] The long-distance simulator (100) includes a beam splitter (110), a long-distance simulator (120), an interference acquisition unit, and an alignment unit (140).

[0047] The beam splitter (110) is configured to split the incident beam (B0) into a first beam (B1) and a second beam (B2). The first beam (B1) may be referred to as an output beam or a test beam in that it is given optical characteristics for testing through a long-distance simulator (100) and then outputted and used for optical testing thereafter. The difference in intensity between the first and second beams (B1, B2) determines the contrast of the interference pattern. Accordingly, the splitting ratio of the beam splitter (110) may be selected so as to make the intensities of the first and second beams (B1, B2) as similar as possible.

[0048] The long-distance copying unit (120) is arranged on the optical path (B1a) of the first beam (B1) passing through the beam splitter (110), and is configured to increase the curvature of the wavefront of the passing first beam (B1), thereby copying the first beam (B1) in a form propagated from a distant point. Here, the wavefront means a continuous surface on which waves with the same phase occur successively at a certain time. In addition, when the curvature of the wavefront is infinite, the wavefront becomes flat in a nearly straight shape.

[0049] Additionally, the long-distance copy unit (120) may include a first lens (121), a pinhole (122), and a second lens (123).

[0050] The first lens (121) can be formed to focus the first beam (B1) that has passed through the beam splitter (110) as illustrated in FIG. 2.

[0051] The pinhole (122) may be formed to pass the first beam (B1) focused in the form of a point light source through the first lens (121). The pinhole (122) may be formed to remove the spatial high frequency component of the wavefront by passing the first beam focused in the form of a point light source through the first lens (121).

[0052] The second lens (123) can be configured to make the wavefront of the first beam (B1) that passes through the pinhole (122) even and diverge into a collimated beam. The collimated beam refers to a beam that is emitted when the optical system through which the first beam (B1) passes is aligned.

[0053] The interference pattern acquisition unit (130) is formed so that the first beam (B1) that has passed through the long-distance copy unit (120) and the second beam (B2) that has been split by the beam splitter (110) are incident thereon, thereby acquiring interference patterns of the first and second beams (B1, B2). In addition, the long-distance copy unit (100) may include a first beam splitter (171) that is arranged on the optical path (B1a) of the first beam (B1) between the long-distance copy unit (120) and the interference pattern acquisition unit (130) and reflects a portion of the incident first beam (B1) toward the interference pattern acquisition unit (130) and transmits the other portion as an output beam. In addition, the long-distance copy machine (100) may include a second beam splitter (172) that is arranged on the optical path (B2a) of the second beam (B2) between the beam splitter (110) and the interference pattern acquisition unit (130) to reflect a portion of the incident second beam (B2) toward the interference pattern acquisition unit (130) and transmit the first beam (B1) incident from another direction toward the interference pattern acquisition unit (130).

[0054] In addition, the interference pattern acquisition unit (130) may be implemented with other types of configurations that can display interference patterns on the surface, such as paper, plastic, metal, cloth, or film of a specific size, even if it is not an electronic device such as a camera. In addition, the interference pattern acquisition unit (130) may include relay optics or imaging optics that transmit an image and adjust or form a magnification.

[0055] The alignment unit (140) is configured to align the long-distance copy unit (120) so that the first beam (B1) passing through the long-distance copy unit (120) has a flatness within a preset range based on the interference pattern acquired from the interference pattern acquisition unit (130).

[0056] For example, the alignment unit (140) can be configured to align the long-distance copy unit (120) so that the interference pattern acquired from the interference pattern acquisition unit (130) becomes a null state in which the interference pattern does not appear.

[0057] Meanwhile, the alignment unit (140) can be configured to finely adjust the relative position of the pinhole (122) between the first lens (121) and the second lens (123) so that the interference pattern acquired from the interference pattern acquisition unit (130) becomes a null state in which no interference pattern appears.

[0058] In addition, the alignment unit (140) may be configured to perform a fine adjustment function for the optical system configuration such as the pinhole (122), the first lens (121), the second lens (123), the beam splitter, and the mirror (M1) that adjusts the optical path by reflecting the incident first beam (B1) in a specific direction. As the optical system is aligned by the alignment unit (140), the wavefront aberration of the interference pattern acquired by the interference pattern acquisition unit (130) can be changed to a state where there is almost no wavefront aberration. The wavefront aberration shows the difference in the optical paths of the two beams (B1, B2), and can be used to determine the slight angular change that occurs during alignment, the abnormal state of the optical system surface, etc. The null state of the wavefront aberration means that there is almost no phase difference between the two beams, which means that the alignment state is very precise.

[0059] The alignment unit (140) is composed of mounts that are respectively connected to the optical systems constituting the long-distance copy machine (100), and can provide the optical systems with a high degree of freedom for attitude adjustment.

[0060] Meanwhile, as illustrated in FIG. 1, the optical path (B1a) of the first beam (B1) that is split by the beam splitter (110) and passes through the long-distance copying unit (120) to be incident on the interference pattern acquisition unit (130) can be formed to be longer than the optical path (B2a) of the second beam (B2) that is split by the beam splitter (110) and is incident on the interference pattern acquisition unit (130).

[0061] Here, the beam splitter (110) may be configured to split the first beam (B1) at a higher ratio than the second beam (B2) so as to reduce the difference in intensity between the first beam (B1) and the second beam (B2) incident on the interference pattern acquisition unit (130).

[0062] Meanwhile, the long-distance copy machine (100) may further include a beam reducer (150).

[0063] The beam reducer (150) is arranged on the optical path (B1a) of the first beam (B1) between the long-distance copying unit (120) and the interference pattern acquisition unit (130), and can be configured to reduce the width of the first beam (B1) that has passed through the long-distance copying unit (120).

[0064] Meanwhile, the long-distance copy machine (100) may further include an optical filter unit (160).

[0065] The optical filter unit (160) may be formed to be disposed on the optical path (B2a) of the second beam (B2) between the beam splitter (110) and the interference pattern acquisition unit (130) and to lower the intensity of the second beam (B2) incident on the interference pattern acquisition unit (130). At this time, the optical filter unit (160) may be formed to adjust the intensity of the second beam (B2) to correspond to the intensity of the first beam (B1). The optical filter unit (160) may be formed, for example, as an ND filter (Neutral Density Filter).

[0066] According to the configuration of the long-distance simulator (100) described above, it is possible to provide a long-distance simulator (100) that enables alignment of the optical system even without the expensive wavefront sensor that has been used in the past. Accordingly, the cost constraints that arise when developing a satellite that performs optical communication are greatly reduced, thereby further activating research and development related to long-distance optical communication. In addition, in the case of the interference pattern acquisition unit (130), even if it is not electronic, it can be implemented by only displaying the interference pattern, so that the long-distance simulator (100) that does not have a wavefront sensor and the optical test system (10) including the same can be configured in more diverse ways.

[0067] Hereinafter, a beam alignment method using a long-distance simulator (100) according to another embodiment of the present invention will be described with reference to FIGS. 3 to 8.

[0068] FIG. 3 is a flowchart showing a beam alignment method using a long-distance simulator (100) according to another embodiment of the present invention. FIG. 4 is a conceptual diagram showing a long-distance simulator (100) and an optical test system (10) equipped with the same for explaining a step (S140) of aligning a beam splitter (110) shown in FIG. 3. FIG. 5 is a diagram showing an example of a tilt pattern appearing in the interference pattern acquisition unit (130) shown in FIG. 4 during the process of aligning the beam splitter (110) shown in FIG. 3. FIG. 6 is a conceptual diagram showing a long-distance simulator (100) and an optical test system (10) equipped with the same for explaining a step of adjusting the distance between the first and second lenses (123) and their respective positions in a step (S150) of aligning the long-distance simulator (120) shown in FIG. 3. FIG. 7 is a drawing showing examples of interference patterns appearing in the interference pattern acquisition unit (130) shown in FIG. 6 during the process of adjusting the distance between the first and second lenses (121, 123) and their respective positions in the step (S150) of aligning the long-distance copying unit (100) shown in FIG. 3. FIG. 8 is a drawing conceptually showing a long-distance copying unit (100) and an optical test system (10) equipped therewith for explaining the process of aligning the center of the pinhole (122) and the optical axes of the first and second beams (B1, B2) by finely adjusting the position of the pinhole (122) in the step (S150) of aligning the long-distance copying unit (120) shown in FIG. 3.

[0069] Referring to FIGS. 3 to 8, a beam alignment method using a long-distance simulator (100) includes a step of dividing into a first beam (B1) and a second beam (B2) (S110), a step of simulating the first beam (B1) in a form propagated from a distant point (S120), a step of obtaining an interference pattern of the first beam (B1) and the second beam (B2) (S130), a step of aligning the beam splitter (110) based on the obtained interference pattern (S140), and a step of aligning the long-distance simulator (120) so that the first beam (B1) has a flat surface within a preset range (S150).

[0070] First, the beam alignment method using a long-distance simulator (100) is divided into a first beam (B1) and a second beam (B2) in the step (S110), which divides the incident beam (B0) into the first beam (B1) and the second beam (B2) using a beam splitter (110).

[0071] Next, the step (S120) of simulating the first beam (B1) in a form propagated from a distant point increases the curvature of the wavefront of the first beam (B1) that has passed through the beam splitter (110) using a long-distance simulating unit (120) to simulate the first beam (B1) in a form propagated from a distant point. The long-distance simulating unit (120) may include a first lens (121), a pinhole (122), and a second lens (123) sequentially arranged on the optical path (B1a) of the first beam (B1) that has passed through the beam splitter (110).

[0072] Next, in the step (S130) of obtaining interference patterns of the first beam (B1) and the second beam (B2), the interference patterns of the first beam (B1) that passes through the long-distance copying unit (120) and is incident on the interference pattern obtaining unit (130) and the second beam (B2) that is split by the beam splitter (110) are obtained.

[0073] Next, the step (S140) of aligning the beam splitter (110) based on the obtained interference pattern aligns the beam splitter (110) based on the interference pattern obtained by the interference pattern obtaining unit (130). Referring to FIG. 4, the first beam (B1) is a test beam that is emitted from a long-distance simulator (100) and used for an optical test, and may be formed to have a longer optical path than the optical path (B2a) of the second beam (B2). In addition, the second beam (B2) may have a shorter optical path than the first beam (B1), and may mean a reference beam for use in aligning the optical system using the interference pattern.

[0074] In addition, the step (S140) of aligning the beam splitter (110) may be performed by tipping and / or tilting the beam splitter (110) so that the tilt pattern shown in FIG. 5, which is defined as the inclination of the wavefront of the first and second beams (B1, B2) in the interference pattern acquisition unit (130), is visible, and the attitude of the beam splitter (110) may be finely adjusted so that it becomes a null state where the interference pattern does not appear.

[0075] Lastly, the step (S150) of aligning the long-distance copy unit (120) so that the first beam (B1) has a flatness of a preset range is to align the long-distance copy unit (120) so that the first beam (B1) has a flatness of a preset range, using the alignment unit (140) that aligns the long-distance copy unit (120) based on the interference pattern acquired by the interference pattern acquisition unit (130).

[0076] In addition, the step (S150) of aligning the long-distance copy unit (120) is a step of adjusting the distance and each position between the first lens (121) that focuses the first beam (B1) split in the beam splitter (110) and the second lens (123) that evenly forms the wavefront of the first beam (B1) passing through the first lens (121) so that the interference pattern obtained by the interference pattern obtaining unit (130) is in the null state as shown in FIG. 6, and as shown in FIG. 8, a pinhole (122) is placed between the first and second lenses (121, 123) at the focus of the first beam (B1) that passes through the first lens (121) and is focused, and the position of the pinhole (122) is finely adjusted so that the number of photons obtained by the interference pattern obtaining unit (130) has the maximum value, so that the center of the pinhole (122) and the first and second beams (B1, B2) It may include a step of aligning the optical axis.

[0077] Also, referring to FIG. 7, in the process of adjusting the distance and respective positions between the first and second lenses (121, 123) in the step (S150) of aligning the long-distance copy unit (120), if the distance between the first and second lenses (123) does not match, a concentric interference pattern mainly appears as shown in (a) of FIG. 7. In addition, if the optical axis and the centers of the first and second lenses (121, 123) do not match, an interference pattern of the form shown in (b) of FIG. 7 appears, and if the cases of (a) and (b) of FIG. 7 are mixed, an interference pattern of the form shown in (c) of FIG. 7 may appear.

[0078] The foregoing description is merely exemplary, and various modifications may be made by those skilled in the art to which the present invention pertains without departing from the scope and technical spirit of the described embodiments. The above-described embodiments may be implemented individually or in any combination.

Claims

1. A beam splitter configured to split an incident beam into a first beam and a second beam; A long-distance copying unit arranged on the optical path of the first beam passing through the beam splitter and configured to increase the curvature of the wavefront of the passing first beam, thereby copying the first beam in a form propagated from a distant point; An interference pattern acquisition unit formed so that the first beam passing through the long-distance copy unit and the second beam split by the beam splitter are incident, thereby acquiring interference patterns of the first and second beams; and A long-distance copying machine including an alignment unit configured to align the long-distance copying unit so that the first beam passing through the long-distance copying unit has a flatness within a preset range based on the interference pattern acquired from the interference pattern acquisition unit.

2. In paragraph 1, A long-distance copying machine characterized in that the alignment unit is configured to align the long-distance copying unit so that the interference pattern acquired by the interference pattern acquisition unit is in a null state in which the interference pattern does not appear.

3. In paragraph 1, The optical path of the first beam, which is split by the beam splitter and passes through the long-distance copying unit and is incident on the interference pattern acquisition unit, is formed to be longer than the optical path of the second beam, which is split by the beam splitter and is incident on the interference pattern acquisition unit. A long-distance simulator characterized in that the beam splitter is configured to split the first beam at a higher ratio than the second beam so as to reduce the difference in intensity between the first beam and the second beam incident on the interference pattern acquisition unit.

4. In paragraph 1, The optical path of the first beam, which is split by the beam splitter and passes through the long-distance copying unit and is incident on the interference pattern acquisition unit, is formed to be longer than the optical path of the second beam, which is split by the beam splitter and is incident on the interference pattern acquisition unit. A long-distance simulator further comprising a beam reducer arranged on the optical path of the first beam between the long-distance simulator and the interference pattern acquisition unit, and configured to reduce the width of the first beam passing through the long-distance simulator.

5. In paragraph 1, The optical path of the first beam, which is split by the beam splitter and passes through the long-distance copying unit and is incident on the interference pattern acquisition unit, is formed to be longer than the optical path of the second beam, which is split by the beam splitter and is incident on the interference pattern acquisition unit. A long-distance simulator further comprising an optical filter section arranged on the optical path of the second beam between the beam splitter and the interference pattern acquisition section, and formed to reduce the intensity of the second beam incident on the interference pattern acquisition section.

6. In paragraph 1, The above long-distance copying unit, A first lens formed to focus the first beam passing through the beam splitter; A pinhole formed to pass the first beam focused in the form of a point light source through the first lens; and A long-distance simulator characterized by including a second lens configured to make the wavefront of the first beam emitted through the pinhole uniform and into a collimated beam.

7. In paragraph 6, A long-distance copy machine characterized in that the alignment unit is configured to finely adjust the relative position of the pinhole between the first lens and the second lens so that the interference pattern acquired by the interference pattern acquisition unit becomes a null state in which no interference pattern appears.

8. The long-distance copy machine according to any one of the clauses 1 to 7; and An optical test unit is provided to test an optical communication environment by receiving the first beam in an aligned state emitted from the long-distance copy machine. The above optical test section, An optical test system comprising a test for a Pointing, Acquisition and Tracking (PAT) algorithm designed to compensate for disturbances in an optical communication environment.

9. A step of dividing an incident beam into a first beam and a second beam using a beam splitter; A step of increasing the curvature of the wavefront of the first beam passing through the beam splitter using a long-distance copying unit to copy the first beam in a form propagated from a distant point; A step of acquiring an interference pattern of the first beam that has passed through the long-distance copying unit and the second beam that has been split by the beam splitter, each incident on the interference pattern acquisition unit; A step of aligning the beam splitter based on the interference pattern obtained from the interference pattern obtaining unit; and A beam alignment method using a long-distance copying machine, comprising a step of aligning the long-distance copying unit so that the first beam has a flatness within a preset range, using an alignment unit that aligns the long-distance copying unit based on the interference pattern acquired from the interference pattern acquisition unit.

10. In paragraph 9, The above long-distance copying unit includes a first lens, a pinhole, and a second lens sequentially arranged on the optical path of the first beam passing through the beam splitter, The step of aligning the above beam splitter is: The beam splitter is tipped and / or tilted so that a tilt pattern defined by the slope of the wavefront of the first and second beams is visible in the interference pattern acquisition unit, and the attitude of the beam splitter is finely adjusted so that it becomes a null state where the interference pattern does not appear. The step of aligning the above long-distance copy unit is: A step of adjusting the distance and position of each of a first lens that focuses the first beam split by the beam splitter and a second lens that evenly forms the wavefront of the first beam passing through the first lens so that the interference pattern acquired by the interference pattern acquisition unit becomes the null state; and A beam alignment method using a long-distance simulator, comprising the step of aligning the center of the pinhole and the optical axes of the first and second beams by placing the pinhole at the focus of the first beam that passes through the first lens and is focused between the first and second lenses and finely adjusting the position of the pinhole so that the number of photons acquired by the interference pattern acquisition unit is the maximum.

Images