Light interference blocking structure

Abstract

The invention relates to a light interference blocking structure. A system applied to a biaxial optical system including an optical transmitter and a receiver is provided. The light interference blocking structure according to the present invention can more effectively achieve development of a LiDAR sensor by applying a design of preventing total reflection to a cover of the LiDAR sensor, thereby reducing noise that may reduce sensor performance, improving accuracy and precision of a sensor signal, and ultimately increasing a signal-to-noise ratio (SNR).

Description

Technical Field

[0001] The following disclosure relates to a system applied to a dual-axis optical system including an optical transmitter and a receiver. Background Art

[0002] A light detection and ranging (Li DAR) sensor is a sensor that provides three-dimensional data and measures the distance to an object, typically by measuring the round-trip time of light using a laser. LiDAR sensors can be classified into a coaxial type in which the optical axes of the transmitter and receiver are aligned and a dual-axis type in which the optical axes of the transmitter and receiver are separated.

[0003] More specifically, a LiDAR sensor according to the related art includes a light source that repeatedly outputs laser pulses, a transmission lens that sends the emitted laser pulses, a scanner for obtaining 3D data in a wide area, a receiving lens that collects signals reflected by a target, a detector that detects the collected signals, and a signal processing unit that calculates the distance from the transmission lens and the receiving lens to the target based on the collected signals.

[0004] At this time, since the transmitter and the receiver of the dual-axis type LiDAR sensor according to the related art are not completely optically shielded, proximity noise may occur due to the same reason, which may degrade performance. More specifically, the cover of the LiDAR according to the related art has only a smooth flat or curved surface, which has a problem of not being able to prevent total reflection of light incident on the cover. In the case where the light incident on the cover is totally reflected, the light generated from the transmitter may move through the cover as a medium and directly be incident on the receiver without being reflected by the target, such as Figure 1 As shown, problems with accuracy and precision may arise when measuring the distance to a target.

[0005] [Related technical literature]

[0006] [Patent Document]

[0007] (Patent Document 1) Korean Patent Publication No. 10-2022-0004456 “LiDAR Device” Summary of the invention

[0008] Embodiments of the present invention are directed to providing a light interference blocking structure that can more effectively implement the development of a LiDAR sensor by applying a design that prevents total reflection to a cover of the LiDAR sensor, thereby reducing noise that may degrade sensor performance, improving the accuracy and precision of sensor signals, and ultimately increasing the signal-to-noise ratio (SNR).

[0009] In one general aspect, a light interference blocking structure for a light detection and ranging (LiDAR) system including a transmitter that emits light in one direction and a receiver that receives light in the one direction includes: a cover portion, which is a window arranged along the one direction of the LiDAR system; and a total reflection preventing portion, which protrudes from the cover portion toward the LiDAR system, wherein the total reflection preventing portion includes a protrusion and a groove, which have a uniform shape and are formed to prevent total internal reflection of incident light.

[0010] The cover portion may have a flat surface, and the total reflection preventing portion may be formed along an edge of the cover portion and have at least one first inclined surface forming a predetermined inclined angle with one surface of the cover portion.

[0011] The first inclined surface of the total reflection preventing portion may satisfy the following expression:

[0012] θ d1 >θ i -θ c

[0013] Among them, θ d1 is the inclination angle formed by the first inclined surface and the one surface of the cover portion, θ i is the incident angle of the light, θ c is the critical angle of the material of the cover part.

[0014] The cover portion may have a curved surface, and the total reflection preventing portion may be formed along an edge of the cover portion and have at least one second inclined surface forming a predetermined inclined angle with one surface of the cover portion.

[0015] The second inclined surface of the total reflection preventing portion may satisfy the following expression:

[0016] θ d2 >θ i -θ c +(θ r1 +θ r2 )

[0017] Among them, θ d2 is the inclination angle formed by the second inclined surface and the one surface of the cover portion, θ i is the incident angle of the light, θ c is the critical angle of the material of the cover part, θ r1 is the tangent angle at the light incident point on the inner curved surface of the cover portion, θ r2 is the tangential angle at the light emission point on the outer curved surface of the cover portion.

[0018] The total reflection preventing portion may have at least one third inclined surface whose slope connecting both ends forms a predetermined inclined angle with one surface of the cover portion, and the third inclined surface may be formed as a curved surface having a predetermined curvature.

[0019] The third inclined surface may include a convex inclined surface convex with respect to the cover portion, and a concave inclined surface connecting the convex inclined surfaces and concave with respect to the cover portion.

[0020] The light interference blocking structure may further include a shielding wall installed between the transmitter and the receiver, wherein the shielding wall may include a material that does not transmit light.

[0021] The total reflection preventing portion may be formed in a region facing the shield wall.

[0022] The total reflection preventing portion may be formed along an edge of the cover portion, and may be formed only at an edge of a region where the transmitter is located among regions partitioned by the shielding wall. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic diagram illustrating a noise generation process in a light detection and ranging (LiDAR) system according to the related art.

[0024] Figure 2 is a cross-sectional view showing a light interference blocking structure according to the present invention.

[0025] Figure 3 is a top view showing a light interference blocking structure according to the present invention.

[0026] Figure 4 and Figure 5 2 is a schematic diagram showing a coupling relationship between a cover portion and a total reflection preventing portion according to the present invention.

[0027] Figure 6 is a partial perspective view showing an example of a total reflection preventing portion according to the present invention.

[0028] Figure 7 is a top view showing a shielding wall of a light interference blocking structure according to the present invention.

[0029] Figure 8 is a cross-sectional view showing a shielding wall of a light interference blocking structure according to the present invention.

[0030] Fig. 9 is a top view showing a first example of the light interference blocking structure according to the present invention.

[0031] Fig.10 is a cross-sectional view showing a first example of the light interference blocking structure according to the present invention.

[0032] Fig.11 is a top view showing a second example of the light interference blocking structure according to the present invention.

[0033] [Detailed description of main components]

[0034] 1000: Light interference blocking structure

[0035] 100: Cover part

[0036] 200: Total reflection prevention part

[0037] 210: First inclined surface

[0038] 220: Second inclined surface

[0039] 230: Third inclined surface

[0040] 231: Concave inclined surface

[0041] 232: Raised inclined surface

[0042] 300: Shielding wall

[0043] Tx: Transmitter

[0044] Rx: Receiver DETAILED DESCRIPTION

[0045] The technical spirit of the present invention will be described in more detail below with reference to the accompanying drawings. The terms and words used in this specification and claims should not be interpreted as general meanings or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical ideas of the present invention based on the principle that the inventor can appropriately define the concepts of the terms in order to describe his invention in the best mode.

[0046] In the following, reference will be made to Figure 2 and Figure 3 The basic configuration of the light interference blocking structure 1000 according to the present invention is described in more detail.

[0047] like Figure 2 As shown, the light interference blocking structure 1000 according to the present invention is applied to a light detection and ranging (Li DAR) system including a transmitter Tx that emits light in one direction and a receiver Rx that receives light in one direction, and the light interference blocking structure 1000 according to the present invention may include a cover portion 100, which is a window provided in one direction of the LiDAR system. That is, the cover portion 100 can cover both the side where the transmitter Tx generates light and the side where the receiver Rx receives light. At this time, the cover portion 100 can be formed of a light-transmitting material such as glass or silicon. The cover portion 100 can protect the transmitter Tx and the receiver Rx of the LiDAR system from external forces.

[0048] At this time, the light interference blocking structure 1000 according to the present invention may further include a total reflection preventing portion 200 protruding from the cover portion 100 toward the LiDAR system. The total reflection preventing portion 200 may be formed integrally with the cover portion 100, may protrude from the cover portion 100 toward the LiDAR system, and may have a specific shape in which predetermined protrusions and grooves are formed at the protruding end. At this time, due to the shape of the total reflection preventing portion 200, the light generated from the transmitter Tx and incident on the cover portion 100 may not be totally reflected inside the cover portion 100, but may be refracted and moved to the outside of the cover portion 100. Therefore, the light emitted from the transmitter Tx may not be directly transmitted to the receiver Rx, but may be transmitted to the receiver Rx after being reflected by the target. The light interference blocking structure 1000 according to the present invention may include a total reflection preventing portion 200 to reduce noise that may reduce the performance of the LiDAR system and improve the accuracy and precision of the sensor signal.

[0049] In addition, if Figure 3 As shown, the total reflection preventing portion 200 may be formed along the edge of the cover portion 100. The transmitter Tx and the receiver Rx may be Figure 3 , and the light generated by the transmitter Tx can move radially based on the light generation point inside the transmitter Tx. The radially moving light can be reflected by the shell of the LiDAR system, etc. and incident on the cover portion 100, and the light incident on the cover portion 100 can be totally reflected and move inside the cover portion 100 according to the incident angle of the light and directly incident on the receiver Rx. In this regard, a total reflection prevention portion 200 can be formed at the edge of the cover portion 100, so that even if the light incident on the cover portion 100 is totally reflected by a portion in which the total reflection prevention portion 200 is not formed, the light incident on the cover portion 100 can be refracted by the total reflection prevention portion 200 located at the edge without being totally reflected, and moves to the outside of the cover portion 100 when guided toward the receiver Rx.

[0050] In the following, reference will be made to Figure 4 and Figure 5 The shape restriction of the total reflection preventing portion 200 according to the present invention is described in more detail.

[0051] like Figure 4As shown, the cover portion 100 may have a flat surface, and the total reflection preventing portion 200 may have at least one first inclined surface 210 forming a predetermined inclination angle with one surface of the cover portion 100. That is, the total reflection preventing portion 200 may have a sawtooth shape of a groove or protrusion presenting a triangular prism shape, and a surface of the total reflection preventing portion 200 corresponding to the first inclined surface 210 may have the largest area. More specifically, the inclination angle of the first inclined surface 210 of the total reflection preventing portion 200 may satisfy the following Expression 1.

[0052] Expression 1: θ d1 >θ i -θ c (θ d1 : An inclination angle formed by the first inclined surface 210 and one surface of the cover portion 100, θ i : The incident angle of light, θ c : Critical angle of the material of the cover portion 100).

[0053] Here, θ c θ may be a constant value determined by the material of the cover portion 100. For example, in the case where the cover portion 100 is formed of polycarbonate, θ c It can be 39.68 degrees (≈40 degrees). In addition, θ can be predetermined according to the specifications and structure of the cover part 100 and the LiDAR system. i For example, assuming that the inclination angle θ of the first inclined surface 210 is d1 is determined to be 20 degrees, θ c is 40 degrees, when the incident angle θ i1 When the value of is 50 degrees, the right side of the expression is 10 degrees, and the above Expression 1 is satisfied, so the light can be refracted without total reflection and move to the outside of the cover portion 100. On the other hand, when the incident angle θ i2 When the value of is 60 degrees, the right side of the expression is 20 degrees, which does not satisfy the above Expression 1, and therefore, the light may be totally reflected and act as noise. In other words, when the LiDAR system is operated, θ may be determined after predetermining the range of the incident angle of light incident on the cover portion 100. d1 .

[0054] like Figure 5As shown, the cover portion 100 may have a curved surface, and the total reflection preventing portion 200 may have at least one second inclined surface 220 forming a predetermined inclination angle with one surface of the cover portion 100. That is, the total reflection preventing portion 200 may have a sawtooth shape of a groove or protrusion presenting a triangular prism shape, and a surface of the total reflection preventing portion 200 corresponding to the second inclined surface 220 may have the largest area. More specifically, the inclination angle of the second inclined surface 220 of the total reflection preventing portion 200 may satisfy the following Expression 2.

[0055] Expression 2: θ d2 >θ i -θ c +(θ r1 +θ r2 )(θ d2 : The inclination angle formed by the second inclined surface 220 and one surface of the cover portion 100, θ i : The incident angle of light, θ c : Critical angle of the material of the cover portion 100, θ r1 : tangential angle at the light incident point on the inner curved surface of the cover portion 100, θ r2 : tangential angle at the light emission point on the outer curved surface of the cover portion 100).

[0056] Here, θ c θ may be a constant value determined by the material of the cover portion 100. For example, in the case where the cover portion 100 is formed of polycarbonate, θ c It can be 39.68 degrees (≈40 degrees). In addition, θ i ,θ r1 and θ r2 The correlation between i ,θ r1 and θ r2 The range of may be predetermined according to the specifications and structures of the cover portion 100 and the LiDAR system. For example, assuming that the inclination angle θ of the second inclined surface 220 is d2 is determined to be 20 degrees, θ c is 40 degrees, then when the tangential angle θ of the light incident point r11 is -20 degrees, the incident angle θ i3 When the value is 60 degrees, determine the tangential angle θ at the light emission point r21 is 7 degrees, the right side of the expression is 7 degrees, and the above expression 2 is satisfied, so the light can be refracted without total reflection and move to the outside of the cover portion 100. In addition, the tangential angle θ at the light incident point is r12 is 30 degrees and the incident angle θ i4 When the value is 70 degrees, θ r22θ is determined to be −45 degrees, the right side of the expression is 15 degrees, and the above Expression 2 is also satisfied, so the light can be refracted without total reflection and move to the outside of the cover portion 100. In other words, when the LiDAR system is operated, θ can be determined after predetermining the range of the incident angle of light incident on the cover portion 100 and the shape of the curved surface of the cover portion 100. d2 .

[0057] In the following, reference will be made to Figure 6 An example of the shape of the total reflection preventing portion 200 according to the present invention is described in more detail.

[0058] In the example, Figure 6 As shown, the total reflection preventing portion 200 may have at least one third inclined surface 230, and the slope connecting the two ends of the third inclined surface forms a predetermined inclination angle with one surface of the cover portion 100. At this time, the total reflection preventing portion 200 may be formed in a sawtooth shape, and the third inclined surface 230 may be an inclined surface with a maximum area. At this time, the inclination angle of the third inclined surface 230 may follow the inclination angle θ of the first inclined surface 210 according to the shape of the cover portion 100. d1 Or the inclination angle θ of the second inclined surface 220 d2 .

[0059] In addition, the third inclined surface 230 may be formed as a curved surface having a predetermined curvature. More specifically, the third inclined surface 230 may include a convex inclined surface 232 convex relative to the cover portion 100 and a concave inclined surface 231 connecting the convex inclined surface 232 and having a smaller area than the convex inclined surface 232.

[0060] In the following, reference will be made to Figure 7 and Figure 8 The shielding wall 300 of the light interference blocking structure 1000 according to the present invention is described in more detail.

[0061] like Figure 7 As shown, the light interference blocking structure 1000 according to the present invention may further include a shielding wall 300, which is a wall installed between the transmitter Tx and the receiver Rx. Here, the shielding wall 300 may contain a material that does not transmit light and may be formed of a metal material. The light interference blocking structure 1000 according to the present invention may include the shielding wall 300 to block the transmission of light, thereby preventing the light emitted from the transmitter Tx from being emitted to the receiver Rx. Therefore, as Figure 8 As shown, proximity noise detected when a laser pulse emitted from a transmitter Tx is reflected from lens surfaces of the transmitter Tx and the receiver Rx or proximity noise caused by internal scattering in a housing or the like included in the LiDAR system can be removed.

[0062] In the following, reference will be made to Fig. 9 and Fig.10 A first example of the light interference blocking structure 1000 according to the present invention is described in more detail.

[0063] like Fig. 9 As shown, in the first example of the light interference blocking structure 1000 according to the present invention, the light interference blocking structure 1000 according to the present invention may include a shielding wall 300 installed between the transmitter Tx and the receiver Rx, the shielding wall 300 and the cover portion 100 may be arranged to be spaced apart from each other at a predetermined interval, and the total reflection preventing portion 200 may be formed in a region of the cover portion 100 facing the shielding wall 300 in addition to being formed in an edge region of the cover portion 100. Therefore, even when noise is totally reflected along a surface of the cover portion 100 where the total reflection preventing portion is not formed and reaches the vicinity of the shielding wall 300, the total reflection of the noise may be auxiliary prevented by the total reflection preventing portion 200 formed in the region corresponding to the shielding wall 300, and finally, light that may generate noise may be guided toward the outside of the cover portion 100, that is, toward a target, such as Fig.10 shown.

[0064] In the following, reference will be made to Fig.11 The second example of the light interference blocking structure 1000 according to the present invention is described in more detail.

[0065] like Fig.11 As shown, the total reflection preventing portion 200 can be formed along the edge of the cover portion 100, and can be formed only at the edge of the area where the transmitter Tx is located among the areas divided by the shielding wall 300. In fact, the total reflection preventing portion 200 according to the present invention is intended to prevent the light generated from the transmitter Tx from reaching the receiver Rx. Therefore, high noise removal performance can be expected only by blocking the noise occurring near the transmitter Tx. That is, by applying the second example of the light interference blocking structure 1000 according to the present invention, the effect of maintaining noise removal performance and improving manufacturing efficiency can be expected.

[0066] The light interference blocking structure according to the present invention having the configuration as described above can more effectively realize the development of the LiDAR sensor by applying a design that prevents total reflection to the cover of the LiDAR sensor, thereby reducing noise that may reduce sensor performance, enhancing the accuracy and precision of the sensor signal, and ultimately increasing the signal-to-noise ratio (SNR).

[0067] Therefore, the spirit of the present invention should not be limited to the described embodiments, but the claims and all modifications equivalent to the claims are intended to fall within the scope and spirit of the present invention.

[0068] Cross-references to related applications

[0069] This application claims the priority of Korean Patent Application No. 10-2023-0138142 filed on October 17, 2023 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety.

Claims

1. A light interference blocking structure for a light detection and ranging LiDAR system including a transmitter emitting light in one direction and a receiver receiving light in the one direction, the light interference blocking structure comprising: a cover portion, wherein the cover portion is a window disposed along the one direction of the LiDAR system; as well as a total reflection preventing portion, the total reflection preventing portion protruding from the cover portion toward the LiDAR system, Wherein, the total reflection preventing portion includes protrusions and grooves having a uniform shape and formed to prevent total internal reflection of incident light.

2. The light interference blocking structure according to claim 1, in, The cover portion has a flat surface, and The total reflection preventing portion is formed along an edge of the cover portion and includes at least one first inclined surface forming a predetermined inclined angle with one surface of the cover portion.

3. The light interference blocking structure according to claim 2, in, The at least one first inclined surface of the cover portion and the flat surface of the cover portion form a triangular prism shape.

4. The light interference blocking structure according to claim 2, wherein: The first inclined surface of the total reflection preventing portion satisfies the following expression: i d1 >θ i -θ c Among them, θ d1 is the inclination angle formed by the first inclined surface and the one surface of the cover portion, θ i is the incident angle of the light, and θ c is the critical angle of the material of the cover part.

5. The light interference blocking structure according to claim 1, in, The cover portion has a curved surface, and The total reflection preventing portion is formed along an edge of the cover portion and includes at least one second inclined surface forming a predetermined inclined angle with one surface of the cover portion.

6. The light interference blocking structure according to claim 5, in, The at least one second inclined surface of the cover portion and the one surface of the cover portion form a triangular prism shape.

7. The light interference blocking structure according to claim 5, wherein: The second inclined surface of the total reflection preventing portion satisfies the following expression: i d2 >θ i -θ c +(θ r1 +θ r2 ) Among them, θ d2 is the inclination angle formed by the second inclined surface and the one surface of the cover portion, θ i is the incident angle of the light, θ c is the critical angle of the material of the cover part, θ r1 is the tangential angle at the light incident point on the inner curved surface of the cover portion, and θ r2 is the tangential angle at the light emission point on the outer curved surface of the cover portion.

8. The light interference blocking structure according to claim 1, in, The total reflection preventing portion includes at least one third inclined surface, a slope connecting the first end and the second end of the at least one third inclined surface forms a predetermined inclined angle with one surface of the cover portion, and Wherein, the third inclined surface is formed as a curved surface with a predetermined curvature.

9. The light interference blocking structure according to claim 8, in, The at least one third inclined surface of the cover portion and the one surface of the cover portion form a triangular prism shape.

10. The light interference blocking structure according to claim 8, wherein: The third inclined surface comprises: a raised inclined surface, the raised inclined surface being raised relative to the cover portion; and A concave inclined surface is connected to the convex inclined surface and is concave relative to the cover portion.

11. The light interference blocking structure according to claim 1, further comprising: a shielding wall installed between the transmitter and the receiver, The shielding wall contains a material that does not transmit the light.

12. The light interference blocking structure according to claim 11, wherein: The total reflection preventing portion is formed in a region of the cover portion facing the shield wall.

13. The light interference blocking structure according to claim 11, wherein: The total reflection preventing portion is formed along an edge of the cover portion.

14. The light interference blocking structure according to claim 13, wherein: The total reflection preventing portion is formed in a region of the cover portion facing the shield wall.

15. The light interference blocking structure according to claim 13, wherein: The cover portion covers a side of the light interference blocking structure where the transmitter generates light and a side of the light interference blocking structure where the receiver receives light.

16. The light interference blocking structure according to claim 13, wherein: The total reflection preventing portion is formed only at an edge of a region of the cover portion where the transmitter is provided, among regions of the cover portion partitioned by the shield wall.

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