Fmcw lidar beam path control device and fmcw lidar beam path control method using the same

Abstract

The present invention relates to an FMCW lidar beam path control device and an FMCW lidar beam path control method using the same. According to one embodiment of the present invention, an FMCW lidar beam path control device may be provided, comprising: a light source unit that emits output light; a polarizing optical system that separates the output light emitted from the light source unit into a first output light and a second output light based on a predetermined separation ratio; a reflecting unit that reflects the incident first output light to the polarizing optical system in the form of reflected light; a power meter that measures the optical power of the second output light and the reflected light; and a controller that tilts the reflecting unit so that the difference between the optical power of the second output light and the optical power of the reflected light is minimized.

Description

Technology Field

[0001] The present invention relates to an FMCW lidar beam path control device and an FMCW lidar beam path control method using the same. Background Technology

[0002] Lidar is a technology that irradiates a target with a laser, measures the time it takes for the laser to be reflected from the target and enter a detector to determine the distance to the target, and based on this, acquires a three-dimensional image of the target. In Lidar technology, laser transmission and reception methods include pulse, FMCW, and FSK (frequency shift keying), and the method of extracting the speed and distance of the target varies depending on each method.

[0003] Pulsed LiDAR technology requires high-power lasers or high-sensitivity detectors for long-distance measurements, resulting in high costs, potential impact on eye safety, and the risk of mutual interference between multiple LiDAR signals.

[0004] In contrast, FMCW (frequency modulated continuous wave) lidar is a lidar that simultaneously transmits a continuous wave signal and receives a reflected wave signal from a target. In this case, FMCW lidar extracts relative distance and relative velocity information of the target using the beat frequency, which is the difference frequency component between the transmitted and received signals. Since it uses a laser interferometer for target signal detection, it is not affected by the external environment and can be implemented relatively simply, leading to extensive research in various fields.

[0005] However, since the transmitting and receiving beams of an FMCW lidar must meet and interfere at the same optical axis, the receiving beam must be focused into the core of an optical fiber with a diameter of 10 µm or less. In addition, when the receiving beam is received into the core of the optical fiber, the angle must also be parallel to the extension direction of the optical fiber to enable reception of the receiving beam without loss.

[0006] To improve the signal-to-noise ratio (SNR) and the resulting maximum measurement distance performance of such FMCW lidar, there is a growing need for an FMCW lidar beam path control device that aligns the optical fiber core, transmitting beam, and receiving beam so that they meet on the same optical axis. The problem to be solved

[0007] One embodiment of the present invention was invented against the background described above and aims to provide an FMCW lidar beam path control device capable of aligning the optical fiber core, the transmitting beam, and the receiving beam so that they meet at the same optical axis for an FMCW lidar. means of solving the problem

[0008] According to one aspect of the present invention, an FMCW LiDAR beam path control device may be provided, comprising: a light source unit emitting output light; a polarizing optical system that separates the output light emitted from the light source unit into a first output light and a second output light based on a predetermined separation ratio; a reflecting unit that reflects the incident first output light to the polarizing optical system in the form of reflected light; a power meter that measures the optical power of the second output light and the reflected light; and a controller that tilts the reflecting unit so as to minimize the difference between the optical power of the second output light and the optical power of the reflected light.

[0009] Additionally, an FMCW LiDAR beam path control device may be provided, which further includes a recognition unit that recognizes the position and size of the first output light and the reflected light through which the first output light and the reflected light pass, and the controller controls the tilting angle of the reflection unit so that the first output light and the reflected light identified by the recognition unit are positioned at the same location.

[0010] Additionally, the diameters of the first output light and the reflected light identified in the recognition unit are respectively referred to as the first diameter and the second diameter, and the controller controls the tilting angle of the reflection unit so that when the first output light and the reflected light are incident on the recognition unit, the light with the smaller diameter between the first diameter and the second diameter overlaps within the light with the larger diameter between the first diameter and the second diameter. An FMCW lidar beam path control device may be provided.

[0011] In addition, the above-mentioned predetermined separation ratio may be provided as an FMCW lidar beam path control device in which the intensities of the first output light and the second output light are equal to each other.

[0012] Additionally, an FMCW LiDAR beam path control device may be provided, further comprising a circulator configured to be connected to the light source unit, the polarizing optical system, and the power meter, respectively, so as to transmit output light or reflected light to any one of the light source unit, the polarizing optical system, and the power meter, wherein the circulator comprises: a first port which is a passage for receiving the output light emitted from the light source unit; and a second port which transmits the output light toward the polarizing optical system and receives the reflected light, wherein at the second port, the direction of propagation of the output light and the direction of propagation of the reflected light are opposite to each other.

[0013] Additionally, an FMCW LiDAR beam path control device may be provided, wherein the circulator further includes a third port that emits the reflected light transmitted from the second port toward the power meter.

[0014] Additionally, an FMCW lidar beam path control device may be provided, which further includes a light control unit that provides a space for the first output light to pass in one direction and for the reflected light to pass in the other direction opposite to the one direction, wherein the light control unit is provided in multiple numbers and the multiple light control units are arranged so that the reflected light passes sequentially.

[0015] Additionally, an FMCW lidar beam path control method may be provided, wherein the plurality of light control units comprises a first light control unit and a second light control unit, and the first light control unit and the second light control unit are arranged such that the first output light and the reflected light pass through the center of the first light control unit and the center of the second light control unit in the left-right direction perpendicular to the one direction.

[0016] In addition, an FMCW lidar beam path control method performed by an FMCW lidar beam path control device may be provided, comprising: a light output step of outputting an output light from a light source unit; a light separation step of separating the output light into a first output light and a second output light based on a predetermined separation ratio; a light reflection step of reflecting the incident first output light in the form of reflected light to a polarizing optical system; an alignment verification step of confirming the alignment of the output light path by comparing the light power of the second output light and the reflected light; and an adjustment step of tilting a reflection unit so as to minimize the difference between the light power of the second output light and the light power of the reflected light.

[0017] In addition, an FMCW lidar beam path control method performed by an FMCW lidar beam path control device may be provided, comprising: a light output step of outputting an output light from a light source unit; a light separation step of separating the output light into a first output light and a second output light based on a predetermined separation ratio; a light reflection step of receiving the first output light and reflecting it in the form of reflected light to a polarizing optical system; an alignment verification step of verifying the alignment of the output light path by comparing the position and size of the first output light and the reflected light passed through the recognition unit; and an adjustment step of tilting a reflection unit so that the first output light and the reflected light confirmed by the recognition unit are placed at the same position. Effects of the invention

[0018] According to one embodiment of the present invention, for an FMCW lidar, the optical fiber core, the transmitting beam, and the receiving beam can be aligned to meet at the same optical axis, which has the effect of being possible. Brief explanation of the drawing

[0019] FIG. 1 is a diagram showing an FMCW lidar beam path control device according to one embodiment of the present invention. Figure 2 is a diagram showing the way light travels according to the angle of light incident on the optical fiber. Figure 3 is an enlarged view of part A of Figure 2. Figure 4 is an enlarged view of part B of Figure 3. Figure 5 is a diagram showing the case where the output light and reflected light are not aligned in the recognition unit. Figure 6 is a diagram showing the state in which output light and reflected light are aligned and combined in the recognition unit. Figure 7 is a flowchart illustrating the FMCW lidar beam path control method. Figure 8 is a flowchart showing the alignment verification step of the FMCW lidar beam path control method. Specific details for implementing the invention

[0020] Hereinafter, specific embodiments for implementing the technical concept of the present invention will be described in detail with reference to the drawings.

[0021] In addition, in describing the present invention, if it is determined that a detailed description of related known components or functions may obscure the essence of the invention, such detailed description is omitted.

[0022] Furthermore, when it is mentioned that one component is 'transmitted,' 'provided,' or 'connected' to another component, it should be understood that while the transmission, provision, or connection may be direct to that other component, there may also be other components present in between.

[0023] The terms used in this specification are used merely to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise.

[0024] Furthermore, it should be noted in advance that the representations of parts, etc. in this specification are described based on the drawings, and may be depicted differently if the orientation of the object changes. For the same reason, some components in the attached drawings are exaggerated, omitted, or schematically depicted, and the size of each component does not entirely reflect its actual size.

[0025] Additionally, terms including ordinal numbers, such as first, second, etc., may be used to describe various components, but such components are not limited by such terms. These terms are used solely for the purpose of distinguishing one component from another.

[0026] The meaning of "comprising" as used in the specification is to specify certain characteristics, regions, integers, steps, actions, elements, and / or components, and does not exclude the existence or addition of other specific characteristics, regions, integers, steps, actions, elements, components, and / or groups.

[0027] Hereinafter, the specific configuration of an FMCW LiDAR beam path control device (1) according to one embodiment of the present invention will be described with reference to the drawings.

[0028] The FMCW lidar beam path control device (1) can cause the core, output light, and receiving light of the optical fiber (f) for the FMCW lidar to meet at the same optical axis. This FMCW lidar beam path control device (1) may include a light source unit (100), an optical fiber (200), a circulator (300), a polarizing optical system (400), a light control unit (500), a reflection unit (600), a power meter (700), a recognition unit (800), a camera (900), and a controller (1000).

[0029] The light source unit (100) can emit output light. The light source unit (100) can emit laser pulsed light and CW light. Additionally, the light source unit (100) can emit light having various wavelengths. For example, the light source unit (100) may be a laser diode (LD).

[0030] The optical fiber (200) can provide a path for light to be transmitted. This optical fiber (200) can be extended in one direction. Additionally, the diameter of the core of the optical fiber (200) can be 10 µm or less.

[0031] The circulator (300) can transmit output light or reflected light, which is transmitted or received light, to either the polarizing optical system (400) or the power meter (700). Such a circulator (300) can be connected to the light source unit (100), the polarizing optical system (400), and the power meter (700), respectively. In other words, the circulator (300) can be positioned at the center of the light source unit (100), the polarizing optical system (400), and the power meter (700) to provide a path for transmitting light. Additionally, the circulator (300) may include a circulator body (310), a first port (320), a second port (330), and a third port (340).

[0032] The circulator body (310) can maintain the direction in which light is introduced and provide a space through which light is transmitted. This circulator body (310) can support the first port (320), the second port (330), and the third port (340). Additionally, the circulator body (310) can be positioned adjacent to the optical fiber (200).

[0033] The first port (320) can provide a channel for receiving output light. This first port (320) can be connected to a light source unit (100). In other words, the first port (320) can provide a channel for transmitting output light emitted from the light source unit (100).

[0034] The second port (330) can transmit output light to the polarizing optical system (400) and receive reflected light from the polarizing optical system (400). This second port (330) can be connected to the polarizing optical system (400). In other words, the second port (330) can provide a passage for the output light introduced from the first port (320) to be transmitted, and can receive reflected light introduced from the polarizing optical system (400). Additionally, the direction of travel of the output light transmitted from the second port (330) and the direction of travel of the reflected light may be opposite to each other.

[0035] The third port (340) can transmit reflected light transmitted from the second port (330) to the power meter (700). This third port (340) can be connected to the power meter (700). In other words, the third port (340) can provide a passage for the reflected light introduced from the second port (330) to be transmitted, and can receive reflected light introduced from the power meter (700). Additionally, the direction of travel of the output light transmitted from the second port (330) and the direction of travel of the reflected light transmitted from the third port (340) may be opposite to each other.

[0036] The polarizing optical system (400) can separate the output light emitted from the light source unit (100) into a first output light and a second output light based on a predetermined separation ratio. The predetermined separation ratio performed in the polarizing optical system (400) can be configured so that the intensities of the first output light and the second output light have the same ratio to each other. In other words, the ratio of the first output light to the second output light can be one to one.

[0037] The light control unit (500) may provide a space that guides the first output light to pass in one direction and the reflected light to pass in the other direction opposite to the one direction. The light control unit (500) may be provided in multiple numbers. The multiple light control units (500) may be arranged so that the reflected light passes sequentially. Additionally, the light control unit (500) may include a first light control unit (510) and a second light control unit (520).

[0038] The first light control unit (510) can provide a path through which the first output light and reflected light are transmitted. The first output light and reflected light may be arranged to pass through the center of the first light control unit (510) in the left-right direction perpendicular to the one direction in which the first output light is transmitted. A hole having a predetermined diameter may be formed in the center of such the first light control unit (510). The first output light may pass through the polarizing optical system (400) and the center of the first light control unit (510), and the first output light that has passed through the center of the first light control unit (510) may sequentially pass through the center of the second light control unit (520). Meanwhile, the reflected light may pass through the center of the second light control unit (520) and the center of the first light control unit (510), and the reflected light that has passed through the center of the first light control unit (510) may sequentially pass through the polarizing optical system (400).

[0039] The second light control unit (520) can provide a path through which the first output light and reflected light are transmitted. The first output light and reflected light may be arranged to pass through the center of the second light control unit (520) in a left-right direction that is perpendicular to one direction. A hole having a predetermined diameter may be formed in the center of this second light control unit (520).

[0040] The reflection unit (600) can reflect the incident first output light in the form of reflected light from the polarizing optical system (400). The path along which the reflected light is reflected can be adjusted by controlling the tilting angle of the reflection unit (600) by the controller (1000). Additionally, the reflection unit (600) may include a reflection part (610) and an actuator (620).

[0041] The reflector (610) can reflect the first output light in the form of reflected light. For example, such a reflector (610) may be a mirror, but the present invention is not limited thereto, and other materials capable of reflecting light other than a mirror may be used. Additionally, the reflector (610) can receive the first output light transmitted in one direction and reflect it so that it is transmitted in the opposite direction of the one direction, thereby returning it in the form of reflected light. The first output light may reach the center of the reflector (610) in the left-right direction perpendicular to the one direction in which the first output light is transmitted, and reflected light may be reflected at the point where the first output light reaches.

[0042] The actuator (620) can change the tilting angle of the reflector (610) by changing the position of the reflector (610). This actuator (620) can be controlled by a controller (1000). The actuator (620) can be operated so that the reflector (610) tilts to the right or left when the reflected light is positioned further to the left or right than the first output light. Additionally, the actuator (620) can be driven by a predetermined logic based on the position and size of the first output light and the reflected light recognized by the recognition unit (800). For example, the actuator (620) can tilt the reflector (610) to the right when the reflected light is moved further to the left than the first output light, and can tilt the reflector (610) downward when the reflected light is moved further upward than the first output light.

[0043] The power meter (700) can measure the light power of the second output light and the reflected light. This light power may be light energy. This power meter (700) may be placed adjacent to the circulator (300). Additionally, the power meter (700) may be connected to the first port (320), the second port (330), and the third port (340).

[0044] The recognition unit (800) can recognize the position and size of the first output light and the reflected light. The first output light and the reflected light can pass through this recognition unit (800). Additionally, the diameters of the first output light and the reflected light identified by the recognition unit (800) can be named the first diameter and the second diameter, respectively. The position and size information of the first output light and the reflected light recognized by the recognition unit (800) can be transmitted to the controller (1000).

[0045] The camera (900) can acquire an image of the first output light and reflected light passing through the recognition unit (800). The camera (900) can capture an image of the first output light and reflected light when they overlap. Additionally, the camera (900) can acquire an image of the first output light and reflected light passing through the first light control unit (510).

[0046] The controller (1000) can tilt the reflection unit (600) so that the difference between the optical power of the second output light and the optical power of the reflected light is minimized. The controller (1000) can control the tilting angle of the reflection unit (600) so that the first output light and the reflected light confirmed by the recognition unit (800) are placed at the same position. Additionally, the controller (1000) can control the tilting angle of the reflection unit (600) so that when the first output light and the reflected light are simultaneously incident on the recognition unit (800), the diameters of the first output light (Tx) and the reflected light (Rx) overlap to the size (l) of the smaller diameter between the first diameter and the second diameter. In other words, the tilting angle of the reflection unit (600) can be controlled so that the light having the smaller diameter between the first diameter and the second diameter overlaps within the light having the larger diameter between the first diameter and the second diameter. As a more detailed example, the first diameter and the second diameter may overlap concentrically with each other. The controller (1000) may be implemented by a computing device including a microprocessor, and since the method of implementation is obvious to those skilled in the art, further detailed description is omitted.

[0047] Below, the operation and effect of the FMCW LiDAR beam path control device (1) having the configuration described above will be explained.

[0048] An FMCW lidar beam path control device (1) according to one embodiment of the present invention can align the beam path so that the core of the optical fiber (200), the output light (Tx), and the reflected light (Rx) meet at the same optical axis. In other words, this FMCW lidar beam path control device (1) can control the core of the optical fiber (200), the output light (Tx), and the reflected light (Rx) to be positioned at the same optical axis by changing the tilting angle of the reflector (610).

[0049] In addition, by controlling the FMCW lidar beam path control device (1) so that the core, output light (Tx), and reflected light (Rx) of the optical fiber (200) are positioned on the same optical axis, the signal-to-noise ratio (SNR) of the FMCW lidar and the corresponding maximum measurement distance performance can be improved.

[0050] Additionally, the controller (1000) of the FMCW LiDAR beam path control device (1) can tilt the reflection unit (600) so that the difference between the optical power of the second output light and the optical power of the reflected light is minimized. In other words, by measuring the optical power of the second output light having the same optical power as the first output light separated from the polarizing optical system (400) and measuring the optical power of the reflected light that is reflected back from the first output light, the optical power before reflection and the optical power after reflection can be compared. This controller (1000) can adjust the angle of the reflection unit (600) until the optical power becomes equal.

[0051] Hereinafter, an FMCW lidar beam path control method (S10) according to an embodiment of the present invention will be described with reference to the drawings. In describing the FMCW lidar beam path control method (S10), the differences when compared with the FMCW lidar beam path control device (1) described above will be explained mainly, and the same descriptions and reference numerals will be adopted from the descriptions above.

[0052] Referring to FIGS. 7 and 8, the FMCW lidar beam path control method (S10) can be performed by an FMCW lidar beam path control device (1). This FMCW lidar beam path control method (S10) can align the beam path so that the core of the optical fiber (200), the output light (Tx), and the reflected light (Rx) meet at the same optical axis. Additionally, the FMCW lidar beam path control method (S10) may include an optical output step (S100), an optical separation step (S200), an optical reflection step (S300), an alignment verification step (S400), and an adjustment step (S500).

[0053] In the light output step (S100), output light can be output from the light source unit (100). The output light transmitted in this light output step (S100) can be transmitted to the circulator (300). Additionally, the execution of the light output step (S100) can be controlled by the controller (1000).

[0054] In the light separation step (S200), the output light may be separated into a first output light and a second output light based on a predetermined separation ratio. For example, in the light separation step (S200), the output light may be separated into a first output light and a second output light having the same intensity. The light separation step (S200) may be performed in a polarizing optical system (400).

[0055] In the light reflection step (S300), the first output light is received and can be reflected to the polarizing optical system (400) in the form of reflected light. This light reflection step (S300) can be performed in the reflection unit (600). Additionally, the light reflection step (S300) can be performed multiple times.

[0056] The alignment verification step (S400) can verify the alignment of the output light path by comparing the optical power of the second output light and the reflected light. This alignment verification step (S400) can verify the alignment of the output light path by comparing the position and size of the first output light and the reflected light that passed through the recognition unit (800). Additionally, the alignment verification step (S400) may be performed multiple times. The alignment verification step (S400) may include a power measurement step (S410) and a size measurement step (S420).

[0057] In the power measurement step (S410), the optical power of the second output light and the reflected light can be measured. This power measurement step (S410) can be performed in a power meter (700). Additionally, the optical power information of the second output light and the reflected light measured in the power measurement step (S410) is transmitted to the controller (1000) to verify whether the difference between the optical power of the second output light and the optical power of the reflected light has been minimized. The power measurement step (S410) can be performed multiple times.

[0058] In the size measurement step (S420), either the position and size of the first output light and the reflected light, or an image of the first output light and the reflected light, may be recognized. This size measurement step (S420) may be performed in the recognition unit (800) and the camera (900). Additionally, the position and size of the first output light and the reflected light, and the image information of the first output light and the reflected light measured in the size measurement step (S420), are transmitted to the controller (1000) to verify whether the first output light and the reflected light are positioned at the same location and whether the first output light and the reflected light are positioned coaxially. The size measurement step (S420) may be performed multiple times.

[0059] The adjustment step (S500) can tilt the reflection unit (600) so that the difference between the optical power of the second output light and the optical power of the reflected light is minimized. This adjustment step (S500) can tilt the reflection unit (600) so that the first output light and the reflected light confirmed by the recognition unit (800) are placed at the same position. Additionally, the adjustment step (S500) can be performed by a controller (1000), and the controller (1000) can control the driving of the actuator (620). The adjustment step (S500) can be performed multiple times.

[0060] Although the embodiments of the present invention have been described above as specific embodiments, they are merely examples and the present invention is not limited thereto, but should be interpreted as having the broadest scope in accordance with the technical concept disclosed in this specification. Those skilled in the art may implement patterns of shapes not specified by combining or substituting the disclosed embodiments, and this also does not deviate from the scope of the present invention. Furthermore, those skilled in the art may easily modify or alter the disclosed embodiments based on this specification, and it is evident that such modifications or alterations also fall within the scope of the rights of the present invention. Explanation of the symbols

[0061] 1: FMCW LiDAR Beam Path Controller 100: Light source 200: Optical fiber 300: Circulator 310: Circulator body 320: Port 1 330: Port 2 340: Third Port 400: Polarizing optical system 500: Light control unit 510: 1st Light Control Unit 520: 2nd light control unit 600: Reflection unit 610: Reflective part 620: Actuator 700: Power meter 800: Recognition unit 900: Camera 1000: Controller

Claims

Claim 1 An FMCW LiDAR beam path control device comprising: a light source unit emitting output light; a polarizing optical system that separates the output light emitted from the light source unit into a first output light and a second output light based on a predetermined separation ratio; a reflecting unit that reflects the incident first output light to the polarizing optical system in the form of reflected light; a power meter that measures the optical power of the second output light and the reflected light; and a controller that tilts the reflecting unit so that the difference between the optical power of the second output light and the optical power of the reflected light is minimized. Claim 2 An FMCW LiDAR beam path control device according to claim 1, further comprising a recognition unit through which the first output light and the reflected light pass to recognize the position and size of the first output light and the reflected light, wherein the controller controls the tilting angle of the reflection unit so that the first output light and the reflected light identified by the recognition unit are positioned at the same location. Claim 3 In claim 2, the diameters of the first output light and the reflected light identified in the recognition unit are respectively referred to as the first diameter and the second diameter, and the controller controls the tilting angle of the reflection unit such that when the first output light and the reflected light are incident on the recognition unit, the light with the smaller diameter between the first diameter and the second diameter overlaps within the light with the larger diameter between the first diameter and the second diameter, thereby forming an FMCW lidar beam path control device. Claim 4 In claim 1, the predetermined separation ratio is a ratio in which the intensity of the first output light and the second output light are equal to each other, FMCW lidar beam path control device. Claim 5 An FMCW LiDAR beam path control device according to claim 1, further comprising a circulator configured to be connected to the light source unit, the polarizing optical system, and the power meter, respectively, so as to transmit output light or reflected light to any one of the light source unit, the polarizing optical system, and the power meter, wherein the circulator comprises: a first port which is a passage for receiving the output light emitted from the light source unit; and a second port which transmits the output light toward the polarizing optical system and receives the reflected light, wherein at the second port, the direction of propagation of the output light and the direction of propagation of the reflected light are opposite to each other. Claim 6 An FMCW LiDAR beam path control device according to claim 1, further comprising a light control unit that provides a space for guiding the first output light to pass in one direction and the reflected light to pass in another direction opposite to the one direction, wherein the light control unit is provided in a plurality of units and the plurality of light control units are arranged so that the reflected light passes sequentially. Claim 7 In claim 5, the FMCW LiDAR beam path control device further comprises a third port that emits the reflected light transmitted from the second port toward the power meter. Claim 8 In claim 7, the plurality of light control units comprises a first light control unit and a second light control unit, wherein the first light control unit and the second light control unit are arranged such that the first output light and the reflected light pass through the center of the first light control unit and the center of the second light control unit in a left-right direction perpendicular to the one direction, FMCW LiDAR beam path control device. Claim 9 An FMCW lidar beam path control method performed by an FMCW lidar beam path control device, comprising: a light output step of outputting output light from a light source unit; a light separation step of separating the output light into a first output light and a second output light based on a predetermined separation ratio; a light reflection step of reflecting the incident first output light in the form of reflected light to a polarizing optical system; an alignment verification step of verifying the alignment of the output light path by comparing the light power of the second output light and the reflected light; and an adjustment step of tilting a reflection unit so as to minimize the difference between the light power of the second output light and the light power of the reflected light. Claim 10 An FMCW lidar beam path control method performed by an FMCW lidar beam path control device, comprising: a light output step of outputting an output light from a light source unit; a light separation step of separating the output light into a first output light and a second output light based on a predetermined separation ratio; a light reflection step of receiving the first output light and reflecting it in the form of reflected light to a polarizing optical system; an alignment verification step of verifying the alignment of the output light path by comparing the position and size of the first output light and the reflected light passed through a recognition unit; and an adjustment step of tilting a reflection unit so that the first output light and the reflected light confirmed by the recognition unit are placed at the same position.

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