Light beam scanning device and light beam scanning system

Abstract

The invention discloses a light beam scanning device and a light beam scanning system, and relates to the technical field of light beam scanning. The light beam scanning device comprises N1 groups (N1 > = 2) of first-class polarized light beam adjusters which are arranged in a laminated manner in a first direction, a target scanning angle in a second direction is greater than a preset scanning angle, and at least two groups of first-class polarized light beam adjusters in the N1 groups of first-class polarized light beam adjusters have opposite deflection directions. Due to the fact that the deflection angle of the emergent light beam in the first direction is essentially a result obtained after superposition modulation of N1 deflection angles corresponding to N1 sets of first-class polarized light beam adjusters, variables influencing the scanning angle in the first direction are remarkably increased. The influence of the scanning angle in the second direction on the scanning angle in the first direction is effectively weakened through the synergistic effect of the at least two groups of first-class polarized beam adjusters with opposite deflection directions, so that the decoupling of the scanning angles in the two orthogonal directions is realized.

Description

Technical Field

[0001] The present application relates to the field of light beam scanning technology, and in particular to a light beam scanning device and a light beam scanning system. Background Art

[0002] Beam scanning technology achieves rapid, comprehensive, and high-precision information acquisition of a target area by precisely controlling and positioning the direction of a light beam. In traditional beam scanning technology, when scanning in two orthogonal directions (e.g., a first direction and a second direction), if the target scanning angle in the second direction is larger, there will be a significant deviation between the actual scanning angle in the first direction and the target scanning angle. This means that conventional beam scanning devices suffer from the problem of coupling the scanning angles in the two orthogonal directions. Therefore, decoupling the scanning angles in the two orthogonal directions in a beam scanning device has become a key challenge that needs to be addressed in the field of beam scanning technology. Summary of the Invention

[0003] Based on the above problems, the present application provides a light beam scanning device and a light beam scanning system, which can achieve decoupling of scanning angles in two orthogonal directions.

[0004] In a first aspect, the present application discloses a light beam scanning device, comprising N1 groups of first-type polarization beam adjusters stacked in a first direction, the first-type polarization beam adjusters being used to adjust the chirality and deflection angle of circularly polarized light; the first-type polarization beam adjusters being used to adjust the scanning angle of an incident light beam in the first direction; wherein N1 is greater than or equal to 2;

[0005] The target scanning angle in the second direction is greater than the preset scanning angle. Among the N1 groups of first-type polarization beam adjusters, at least two groups of the first-type polarization beam adjusters have opposite deflection directions. The first direction and the second direction are orthogonal directions.

[0006] Based on the same inventive concept, the second aspect of the present application discloses a light beam scanning system, including the light beam scanning device described in the first aspect.

[0007] Compared with the prior art, this application has the following beneficial effects:

[0008] The light beam scanning device disclosed in this application includes N1 groups of first-class polarization beam adjusters stacked in a first direction. When the target scanning angle in the second direction is greater than a preset scanning angle, at least two of the N1 groups of first-class polarization beam adjusters have opposite deflection directions. Because the deflection angle of the outgoing light beam in the first direction is essentially the result of the superposition and modulation of the N1 deflection angles corresponding to the N1 groups of first-class polarization beam adjusters, the variables that affect the scanning angle in the first direction are significantly increased. Through the synergistic effect of at least two groups of first-class polarization beam adjusters with opposite deflection directions, the influence of the scanning angle in the second direction on the scanning angle in the first direction is effectively weakened, thereby achieving decoupling of the scanning angles in the two orthogonal directions. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0010] Figure 1 A schematic diagram of the structure of a conventional light beam scanning device in a YOZ cross section provided in an embodiment of the present application;

[0011] Figure 2 A schematic diagram illustrating the working principle of a polarization modulator provided in an embodiment of the present application;

[0012] Figure 3 A schematic diagram of a liquid crystal polarization grating provided in an embodiment of the present application;

[0013] Figure 4A A schematic structural diagram of a conventional optical scanning system provided in an embodiment of the present application;

[0014] Figure 4B A schematic diagram of a light transmission path of an incident light beam processed by a conventional light beam scanning device provided in an embodiment of the present application;

[0015] Figure 5 A schematic diagram of the structure of a target beam scanning device in a YOZ cross section provided in an embodiment of the present application;

[0016] Figure 6 A schematic diagram of a light transmission path of an incident light beam processed by a target light beam scanning device provided in an embodiment of the present application;

[0017] Figure 7 A schematic diagram of a light transmission path of an incident light beam processed by another target light beam scanning device provided in an embodiment of the present application;

[0018] Figure 8 This is a schematic structural diagram of a target beam scanning system disclosed in an embodiment of the present application. DETAILED DESCRIPTION

[0019] In order to help those skilled in the art better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of this application.

[0020] The inventors have found through research that the problem of mutual coupling of scanning angles exists when conventional beam scanning devices scan in two orthogonal directions, which is caused by the structure of the conventional beam scanning device. Figures 1-4B , and elaborates on the intrinsic reasons why two orthogonal scanning angles in traditional beam scanning devices produce mutual coupling.

[0021] Figure 1 A schematic diagram of the structure of a conventional light beam scanning device in the YOZ section provided in an embodiment of the present application. Figure 1 As shown, a conventional light beam scanning device includes four polarization modulators (PMs) and four liquid crystal polarization gratings (LCPGs). The four polarization modulators are PM1, PM2, PM3, and PM4; the four liquid crystal polarization gratings are LCPG1, LCPG2, LCPG3, and LCPG4.

[0022] Figure 1 PM1 and LCPG1 are devices for adjusting the deflection angle of the incident light beam in the Y direction; PM2, LCPG2, PM3, LCPG3, PM4 and LCPG4 are devices for adjusting the deflection angle of the incident light beam in the X direction.

[0023] Figure 2 A schematic diagram of the working principle of a polarization modulator provided in an embodiment of the present application. Figure 2 As shown in FIG, a polarization modulator is an optical device that modulates the characteristics of an optical signal by changing the polarization state of light. The operating state of the polarization modulator is switched between OFF and ON.

[0024] Combine Figure 2As shown in (a), if the incident light beam is linearly polarized light, when the working state of the polarization modulator is OFF (the AC voltage shown in the figure is 0V), the outgoing light beam is linearly polarized light with the polarization state rotated by 90°.

[0025] Combine Figure 2 As shown in (b), if the incident light beam is linearly polarized light, when the working state of the polarization modulator is ON (the AC voltage shown in the figure is ±10V), the polarization state of the linearly polarized light of the outgoing light beam remains unchanged.

[0026] If the incident light beam is circularly polarized light, when the polarization modulator is in the OFF state, the chirality of the incident light beam is changed; if the incident light beam is circularly polarized light, when the polarization modulator is in the ON state, the chirality of the incident light beam remains unchanged.

[0027] Figure 3 A schematic diagram of a liquid crystal polarization grating provided in an embodiment of the present application. Figure 3 (a) is a top view of the liquid crystal polarization grating (LCPG top view); Figure 3 (b) is a cross-sectional view of a liquid crystal polarization grating (LCPG cross-sectional view). Figure 3 The letter p represents the rotation period of the liquid crystal polarization grating; the letter θ is the deflection angle of the incident light beam after passing through the liquid crystal polarization grating.

[0028] Figure 3 The pattern of pink ovals in (a) represents the liquid crystal distribution in a liquid crystal polarization grating. This distribution determines the rotation period of the grating and whether it adjusts the deflection angle in the X or Y direction.

[0029] It should be noted that for an incident light beam with a fixed wavelength, when the rotation period in the liquid crystal polarization grating is determined, the deflection angle θ of the outgoing light beam corresponding to the incident light beam can be determined according to the formula sinθ=λ / p; where λ is the wavelength of the incident light beam.

[0030] Figure 3 The red solid line with an arrow shown in (b) represents the circularly polarized light incident on the liquid crystal polarization grating; the gray arrows around the red solid line represent the rotation direction (i.e. chirality) of the circularly polarized light. Figure 3 As shown in (b), when two circularly polarized light beams of the same wavelength are incident on a liquid crystal polarization grating, the absolute values ​​of the deflection angles of the corresponding outgoing light beams are the same, regardless of whether the rotation directions of the two circularly polarized light beams are the same. If the chirality of the two circularly polarized light beams is different, the circularly polarized light with right-handedness will become circularly polarized light with left-handedness after passing through the liquid crystal polarization grating; and the circularly polarized light with left-handedness will become circularly polarized light with right-handedness after passing through the liquid crystal polarization grating.

[0031] It should be noted that in this application, the light beam incident on a certain optical device is defined as the incident beam of the device, and the light beam emitted after the action of the optical device is called its exit beam. In the application scenario of cascaded optical systems, the exit beam of the preceding optical device (such as optical device A) can be used as the incident beam of the subsequent optical device (such as optical device B). The incident beam and exit beam in this application are relative to a specific optical device or a specific optical device. Those skilled in the art can understand the specific meaning of the incident beam and exit beam based on the context.

[0032] Figure 4A is included Figure 1 An optical scanning system of a conventional optical scanning device. Figure 4A PM1, LCPG1, PM2, LCPG2 to LCPG4 are Figure 1 PM1, LCPG1, PM2, LCPG2, and LCPG4 shown in; Figure 4A It also includes optical devices such as light source, polarizer, and quarter wave plate.

[0033] Combine Figure 4A As shown, the light emitted by the light source is the incident beam of the traditional optical scanning system; the incident beam is first processed by the polarizer with the horizontal polarization direction to become horizontal linear polarized light; the horizontal linear polarized light is transmitted at 90° and processed by the 1 / 4 wave plate with the 45° optical axis, and then converted into the first circularly polarized light ( Figure 1 The first circularly polarized light is right-handed circularly polarized light); the first circularly polarized light enters the polarization modulator PM1 (which can be set to any angle). By controlling the working state of the polarization modulator PM1 to be OFF or ON, the chirality of the first circularly polarized light can be changed or kept unchanged to obtain the second circularly polarized light; the second circularly polarized light is incident on the liquid crystal polarization grating LCPG1, and LCPG1 changes the deflection angle of the second circularly polarized light and the chirality of the second circularly polarized light through its own characteristics ( Figure 4A The effect of LCPG1 on the deflection angle of the second circularly polarized light is not shown in the figure), thereby obtaining a third circularly polarized light; the third circularly polarized light enters the polarization modulator PM2 (which can be set to any angle), and by controlling the working state of the polarization modulator PM2 to be OFF or ON, the chirality of the third circularly polarized light can be changed or kept unchanged, thereby obtaining a fourth circularly polarized light; the fourth circularly polarized light is incident on the liquid crystal polarization grating LCPG2, and LCPG2 changes the deflection angle of the fourth circularly polarized light and the chirality of the fourth circularly polarized light through its own characteristics ( Figure 4A The effect of LCPG1 on the deflection angle of the fourth circularly polarized light is not shown in the figure), thereby obtaining the fifth circularly polarized light; and so on, until the circularly polarized light is processed by the liquid crystal polarization grating LCPG4 and the outgoing beam of the optical scanning system is output.

[0034] Table 1 is Figure 1 The parameters of each liquid crystal polarization grating in the conventional beam scanning device are shown in Table 1. As can be seen from Table 1, LCPG1 has a rotation period of 6.3 μm and a deflection angle of 5°, which are used to adjust the scanning angle in the Y direction; LCPG2 has a rotation period of 3.95 μm and a deflection angle of 8°, which are used to adjust the scanning angle in the X direction; LCPG3 has a rotation period of 1.995 μm and a deflection angle of 16°, which are used to adjust the scanning angle in the X direction; and LCPG4 has a rotation period of 1.038 μm and a deflection angle of 32°, which are used to adjust the scanning angle in the X direction.

[0035] Table 1

[0036]

[0037] Table 2 shows the specific values ​​of the scanning angles in two orthogonal directions obtained by adjusting the drive signal of the polarization modulator corresponding to each liquid crystal polarization grating based on the parameters of each liquid crystal polarization grating shown in Table 1, thereby controlling the deflection direction of each liquid crystal polarization grating. The "+" sign in Table 2 indicates that the deflection direction of the liquid crystal polarization grating is positive, and the "-" sign in Table 2 indicates that the deflection direction of the liquid crystal polarization grating is negative.

[0038] Table 2

[0039]

[0040] As shown in Table 2, when Figure 1 The deflection directions of the four liquid crystal polarization gratings are "+, -, -, +" respectively. When the scanning angle of the conventional beam scanning device in the X direction is 6.63°, the scanning angle in the Y direction is 5.04°. Figure 1 The deflection directions of the four liquid crystal polarization gratings are "+, +, -, +" respectively. When the scanning angle of the conventional beam scanning device in the X direction is 23.3°, the scanning angle in the Y direction is 5.45°. Figure 1 The deflection directions of the four liquid crystal polarization gratings are "+, -, +, +" respectively. When the scanning angle of the conventional beam scanning device in the X direction is 42.0°, the scanning angle in the Y direction is 6.72°; when Figure 1 The deflection directions of the four liquid crystal polarization gratings are "+, +, +, +" respectively. When the scanning angle of the traditional light beam scanning device in the X direction is 71.5°, the scanning angle in the Y direction is 15.5°.

[0041] From the above content, we can see that Figure 1In a conventional beam scanning device, when the X-direction scanning angle is large, the Y-direction scanning angle increases accordingly. When the X-direction scanning angle is 71.5°, the Y-direction scanning angle reaches 15.5°. The Y-direction scanning angle is greatly affected by the X-direction scanning angle. However, when using a beam scanning device, users usually expect the Y-direction scanning angle to remain fixed when scanning at any angle in the X-direction, such as maintaining the Y-direction scanning angle at approximately ±5°. Figure 1 The conventional beam scanning device shown in does not meet the expected usage.

[0042] It should be noted that Figure 1 The deflection directions of the four liquid crystal polarization gratings in are "+, -, -, +", respectively, which means that when the deflection direction of LCPG1 is positively deflected toward the Y axis, the deflection direction of LCPG2 is negatively deflected toward the X axis, the deflection direction of LCPG3 is negatively deflected toward the X axis, and the deflection direction of LCPG1 is positively deflected toward the X axis.

[0043] Figure 4B A schematic diagram of a light transmission path of an incident light beam processed by a conventional light beam scanning device provided in an embodiment of the present application. Figure 4B It is shown in Figure 1 When the parameters of each liquid crystal polarization grating in the conventional light beam scanning device shown in are shown in Table 1 and the deflection directions of each liquid crystal polarization grating are shown in Table 2, the light of the incident light beam of the conventional light beam scanning device in the Y direction is transmitted forward along the Y axis.

[0044] After analyzing the structure of a conventional light beam scanning device and the data in Tables 1 and 2, the inventors discovered that the only liquid crystal polarization grating used to adjust the deflection angle in the Y direction is LCPG1. Consequently, when the deflection angle in the X direction is large, the light wave vector in the Y direction is affected by the light wave vector in the X direction, resulting in a large deviation between the actual scanning angle in the Y direction and the target scanning angle. In other words, the actual scanning angle in the Y direction is affected by the scanning angle in the X direction.

[0045] To solve the above problems, the present application discloses a light beam scanning device (hereinafter referred to as a target light beam scanning device), which includes N1 groups (N1≥2) of first-type polarization light beam adjusters stacked in a first direction. When the target scanning angle in the second direction is greater than a preset scanning angle, at least two groups of first-type polarization light beam adjusters in the N1 groups have opposite deflection directions.

[0046] The first direction and the second direction are orthogonal directions. For example, if the first direction is the Y direction in a three-dimensional coordinate system, the second direction is the X direction in the three-dimensional coordinate system; if the first direction is the X direction in the three-dimensional coordinate system, the second direction is the Y direction in the three-dimensional coordinate system.

[0047] The first type of polarization beam adjuster is used to adjust the chirality and deflection angle of circularly polarized light, and to adjust the scanning angle of the incident light beam in the first direction.

[0048] The polarization beam adjuster can be composed of a polarization modulator and a liquid crystal polarization grating, or it can be composed of a polarization modulator and a volume holographic grating. The subsequent embodiments of this application use the example of a polarization beam adjuster composed of a polarization modulator and a liquid crystal polarization grating to describe in detail different implementations of the light beam scanning device disclosed in this application.

[0049] During use of the light beam scanning device disclosed in the present application, a target scanning angle in a second direction is greater than a preset scanning angle, and at least two of the N1 groups of first-type polarization beam adjusters have opposite deflection directions. The two groups of first-type polarization beam adjusters have opposite deflection directions, meaning that the deflection angles of the incident light beam after passing through the two groups of first-type polarization beam adjusters are opposite. Thus, by using at least two groups of first-type polarization beam adjusters with opposite deflection directions, the scanning angle of the incident light beam in the second direction is adjusted, compensating for the influence of the light wave vector in the first direction on the light wave vector in the second direction, thereby achieving decoupling of the scanning angles in two orthogonal directions in the light beam scanning device.

[0050] It will be understood that when a light beam scanning device performs light beam scanning in two orthogonal directions, each direction corresponds to a target scanning angle and an actual scanning angle. The target scanning angle corresponding to the first direction is the desired scanning angle achieved in the first direction; the actual scanning angle corresponding to the first direction is the scanning angle of the incident light beam after passing through the light beam scanning device. The target scanning angle corresponding to the second direction is the desired scanning angle achieved in the second direction; the actual scanning angle corresponding to the second direction is the scanning angle of the incident light beam after passing through the light beam scanning device.

[0051] In one optional implementation, N1=2, meaning the light beam scanning device disclosed herein includes two groups of first-type polarization beam adjusters stacked in a first direction. The target scanning angle in the second direction is greater than the preset scanning angle, and the two groups of first-type polarization beam adjusters have opposite deflection directions. The two groups of first-type polarization beam adjusters are a first polarization beam adjuster and a second polarization beam adjuster. The deflection direction of the first polarization beam adjuster is opposite to the actual scanning angle in the first direction, while the deflection direction of the second polarization beam adjuster is the same as the actual scanning angle in the first direction. The rotation period of the liquid crystal polarization grating in the first polarization beam adjuster is greater than the rotation period of the liquid crystal polarization grating in the second polarization beam adjuster.

[0052] For example, the first direction is the Y direction, and the deflection direction of the actual scanning angle in the first direction is the +Y direction; when the target scanning angle in the second direction is greater than the preset scanning angle, the deflection direction of the first polarization beam adjuster is the +Y direction, and the deflection direction of the second polarization beam adjuster is the -Y direction. The rotation period of the liquid crystal polarization grating in the first polarization beam adjuster is P1, and the rotation period of the liquid crystal polarization grating in the second polarization beam adjuster is P2, then P1>P2.

[0053] In one optional implementation, N1=2, i.e., the light beam scanning device disclosed in the present application includes two sets of first-type polarization beam adjusters stacked in a first direction. The target scanning angle in the second direction is smaller than the preset scanning angle, and the deflection directions of the two sets of first-type polarization beam adjusters are both the same as the actual scanning angle in the first direction.

[0054] Exemplarily, the first direction is the Y direction, and the deflection direction of the actual scanning angle in the first direction is the +Y direction; when the target scanning angle in the second direction is less than the preset scanning angle, the deflection directions of the two sets of first-type polarization beam adjusters are both +Y directions.

[0055] It should be noted that the front and rear positions of the first polarization beam adjuster and the second polarization beam adjuster in the first type of polarization beam adjuster in the beam scanning device disclosed in the present application can be arranged at will.

[0056] In one optional implementation, N1 ≥ 3, meaning the light beam scanning device disclosed in this application includes at least three sets of first-type polarization beam adjusters stacked in a first direction. The target scanning angle in the second direction is greater than the preset scanning angle. At least two of the at least three sets of first-type polarization beam adjusters have opposite deflection directions. Furthermore, the difference between the actual scanning angle in the first direction and the target scanning angle in the first direction is less than a preset first difference threshold. The specific value of the first difference threshold can be set based on actual needs and is not limited in this application.

[0057] In one optional implementation, N1 ≥ 3, i.e., the light beam scanning device disclosed in the present application includes at least three groups of first-type polarization beam adjusters stacked in a first direction. The target scanning angle in the second direction is greater than a preset scanning angle, and the at least three groups of first-type polarization beam adjusters include m1 groups of first-type polarization beam adjusters and m2 groups of first-type polarization beam adjusters; wherein m1 + m2 = N1, m1 ≥ 1, and m2 ≥ 1.

[0058] Among them, the deflection direction of each group of first-type polarization beam adjusters in the m1 group of first-type polarization beam adjusters is the same, and the deflection direction of each group of first-type polarization beam adjusters in the m2 group of first-type polarization beam adjusters is the same, and the deflection direction of the m1 group of first-type polarization beam adjusters is opposite to the deflection direction of the m2 group of first-type polarization beam adjusters.

[0059] For example, N1=5, m1=2, and m3=3; that is, two of the five groups of first-type polarization beam adjusters have the same deflection direction; the other three groups have the same deflection direction; and the deflection direction of the two groups of first-type polarization beam adjusters is different from the deflection directions of the other three groups of first-type polarization beam adjusters. For example, the deflection direction of the two groups of first-type polarization beam adjusters is in the +Y direction, while the deflection direction of the other three groups of first-type polarization beam adjusters is in the -Y direction.

[0060] For example, N1=5, m1=1, and m3=4; that is, among the five groups of first-type polarization beam adjusters, one group of first-type polarization beam adjusters has the same deflection direction; the other four groups of first-type polarization beam adjusters have the same deflection direction; and the deflection direction of one group of first-type polarization beam adjusters is different from the deflection directions of the other four groups of first-type polarization beam adjusters. For example, the deflection direction of one group of first-type polarization beam adjusters is in the +Y direction, while the deflection directions of the other four groups of first-type polarization beam adjusters are in the -Y direction.

[0061] This configuration, which divides multiple groups of first-class polarization beam adjusters into two groups with opposite deflection directions, can not only realize independent beam scanning in orthogonal directions in the same optical path, but also achieve vector synthesis of scanning angles based on quantitative ratio adjustment, making the total beam deflection angle flexibly adjustable in different directions to meet the needs of diverse scenarios.

[0062] In one optional implementation, N1 ≥ 3, i.e., the light beam scanning device disclosed in the present application includes at least three groups of first-type polarization beam adjusters stacked in a first direction. A target scanning angle in the second direction is less than a preset scanning angle, and a deflection direction of each of the at least three groups of first-type polarization beam adjusters is the same as the target scanning angle in the first direction.

[0063] This solution, which uses multiple sets of first-type polarization beam adjusters with the same deflection direction to perform angle superposition to achieve beam scanning at a target scanning angle in the second direction, has the advantage of a simple structure and avoids the disadvantages of large device processing complexity and large control losses caused by the control of positive and negative deflection directions; it can improve the stability and integration efficiency of the system in practical applications.

[0064] In an optional implementation, the preset scanning angle in the aforementioned embodiment ranges from 40 degrees to 60 degrees. For example, in this application, the preset scanning angle is set to 45 degrees.

[0065] In an optional implementation, the deflection direction of the first type of polarization beam adjuster may be controlled by adjusting a driving signal of a polarization modulator in the first type of polarization beam adjuster.

[0066] Specifically, by adjusting the ON or OFF state of the polarization modulator in the first type of polarization beam adjuster, the chirality of the circularly polarized light is controlled, thereby controlling the deflection direction of the output light beam corresponding to the liquid crystal polarization grating in the first type of polarization beam adjuster, and further controlling the deflection direction of the first type of polarization beam adjuster.

[0067] In an optional implementation, the beam scanning device disclosed in the present application includes N2 (N2≥2) groups of second-type polarization beam adjusters stacked in a second direction, and the second-type polarization beam adjusters are used to adjust the scanning angle of the incident light beam in the second direction; the second-type polarization beam adjusters are used to adjust the chirality and deflection angle of circularly polarized light.

[0068] By adjusting the deflection direction of each of the N2 sets of second-type polarization beam adjusters, the difference between the actual scanning angle in the second direction and the target scanning angle in the second direction is less than a preset second difference threshold. The specific value of the second difference threshold can be set according to actual needs and is not limited in this application.

[0069] Figure 5 A schematic diagram of the structure of a target beam scanning device in the YOZ section provided in an embodiment of the present application. Figure 5 The target beam scanning device includes two sets of first-type polarization beam adjusters stacked in a first direction and three sets of second-type polarization beam adjusters stacked in a second direction. Both the first-type polarization beam adjusters and the second-type polarization beam adjusters are composed of a polarization modulator and a liquid crystal polarization grating. The first-type polarization beam adjusters are used to adjust the scanning angle of the incident light beam in the first direction, while the second-type polarization beam adjusters are used to adjust the scanning angle of the incident light beam in the second direction. Figure 5 The first direction is the Y direction, and the second direction is the X direction.

[0070] Combine Figure 5As shown, the two groups of first-type polarization beam adjusters are the first polarization beam adjuster (PM5+LCPG5) and the second polarization beam adjuster (PM6+LCPG6); the second-type polarization beam adjusters are the third polarization beam adjuster (PM7+LCPG7), the fourth polarization beam adjuster (PM8+LCPG8) and the fifth polarization beam adjuster (PM9+LCPG9); the third polarization beam adjuster, the fourth polarization beam adjuster and the fifth polarization beam adjuster are arranged in sequence along the transmission direction of the incident light beam.

[0071] Figure 6 Shown Figure 5 The target beam scanning device shown is a schematic diagram of the light transmission path when processing the incident light beam. Figure 6 As shown in , when the target scanning angle in the second direction is greater than the preset scanning angle, that is, the target scanning angle in the X direction is greater than the preset scanning angle, the drive signal of the polarization modulator in the first type of polarization beam adjuster is adjusted so that the deflection direction of "PM1+LCPG1" is in the -Y direction, and the deflection direction of "PM2+LCPG2" is in the +Y direction, ultimately achieving the goal of achieving a difference between the actual scanning angle in the first direction and the target scanning angle being less than a first difference threshold. For example, the preset scanning angle is 45°; the difference threshold is 1°.

[0072] Figure 7 Shows another Figure 5 The schematic diagram of the light transmission path when the target beam scanning device processes the incident light beam. Figure 7 As shown, when the target scanning angle in the second direction is smaller than the preset scanning angle, that is, the target scanning angle in the X direction is larger than the preset scanning angle, the driving signal of the polarization modulator in the first type of polarization beam adjuster is adjusted so that the deflection directions of "PM1+LCPG1" and "PM2+LCPG2" are both in the +Y direction, and finally the goal is achieved that the difference between the actual scanning angle in the first direction and the target scanning angle is smaller than the first difference threshold.

[0073] It can be understood that after determining the target scanning angle in the second direction, by adjusting the driving signal of the polarization modulator in the second type of polarization beam adjuster and controlling the deflection direction of the second type of polarization beam adjuster, i.e., the third polarization beam adjuster (PM3+LCPG3), the fourth polarization beam adjuster (PM4+LCPG4) and the fifth polarization beam adjuster (PM5+LCPG5), the goal of achieving a difference between the target scanning angle in the second direction and the actual scanning angle being less than the second difference threshold can be achieved.

[0074] Figure 5 The scanning angle θ of the outgoing light corresponding to the target optical scanning device in the first direction (Y direction) y and the scanning angle θ in the second direction (X direction)x Determined by the following set of equations. The set of equations is: x =atan(k x / k z );θ y =atan(k y / k z );

[0075] Among them, k x =G3+G4+G5; k y =G1+G2;k z =(k 2 -k 2 x -k 2 y ) 1 / 2 ;k=2π / λ; G1=±2π / P1; G2=±2π / P2; G3=±2π / P3; G4=±2π / P4; G5=±2π / P5.

[0076] In the above formula, λ is the wavelength of the incident light beam; P1 is the rotation period of the liquid crystal polarization grating LCPG1; P2 is the rotation period of the liquid crystal polarization grating LCPG2; P3 is the rotation period of the liquid crystal polarization grating LCPG3; P4 is the rotation period of the liquid crystal polarization grating LCPG4; P5 is the rotation period of the liquid crystal polarization grating LCPG5; G3 is the wave vector applied to the incident light beam by the third polarization beam adjuster; G4 is the wave vector applied to the incident light beam by the fourth polarization beam adjuster; and G5 is the wave vector applied to the incident light beam by the fifth polarization beam adjuster.

[0077] The signs of G1, G2, G3, G4, and G5 are determined by the drive signals of the corresponding polarization modulators; for example, the signs of ± in G3 = ±2π / P3 are based on Figure 5 The driving signal of the polarization modulator PM3 is determined by G4 = ±2π / P4; the ± sign is based on Figure 5 It is determined by the driving signal of the polarization modulator PM4.

[0078] In the known Figure 5 The rotation period P3 of the liquid crystal polarization grating in the third polarization beam adjuster, the rotation period P4 of the liquid crystal polarization grating in the fourth polarization beam adjuster, the rotation period P5 of the liquid crystal polarization grating in the fifth polarization beam adjuster, and the target scanning angle θ in the first direction y0 After the wavelength λ of the incident light beam is determined, the rotation period of the liquid crystal polarization grating in the first polarization beam adjuster can be determined based on formula (1). The expression of formula (1) is:

[0079]

[0080] The meanings of the letters in formula (1) refer to the description of the above embodiment and will not be repeated here.

[0081] In the known Figure 5 The rotation period P3 of the liquid crystal polarization grating in the third polarization beam adjuster, the rotation period P4 of the liquid crystal polarization grating in the fourth polarization beam adjuster, the rotation period P5 of the liquid crystal polarization grating in the fifth polarization beam adjuster, and the target scanning angle θ in the first direction y0 After determining the wavelength λ of the incident light beam, the rotation period of the liquid crystal polarization grating in the second polarization beam adjuster can be determined based on formula (2). Formula (2) is expressed as:

[0082]

[0083] The meanings of the letters in formula (1) refer to the description of the above embodiment and will not be repeated here.

[0084] From formula (1) and formula (2), we can know that Figure 5 In the two sets of first-type polarization beam adjusters stacked in the first direction, the rotation period P1 of the liquid crystal polarization grating in the first polarization beam adjuster is greater than the rotation period P2 of the liquid crystal polarization grating in the second polarization beam adjuster, that is, P2 <P1。

[0085] It should be emphasized that Figure 5 The deflection angles of the multiple layers of liquid crystal polarization gratings with the same deflection direction in the target beam scanning device are set to a multiple relationship. For example, Figure 5 The deflection angles of the third, fourth, and fifth liquid crystal polarization gratings stacked in the second direction are set to 1°, 2°, and 4°, respectively. This configuration enables beam scanning at eight scanning angles in the second direction: -7°, -5°, -3°, -1°, 1°, 3°, 5°, and 7°.

[0086] Table 3

[0087]

[0088] Table 3 is Figure 5 Parameters of each liquid crystal polarization grating in the target beam scanning device shown in FIG. Figure 5The rotation period of LCPG5 is 18.97μm, and the deflection angle is 1.66°, which is used to adjust the scanning angle in the Y direction; the rotation period of LCPG6 is 9.54μm, and the deflection angle is 3.31°, which is used to adjust the scanning angle in the Y direction; the rotation period of LCPG7 is 3.95μm, and the deflection angle is 8°, which is used to adjust the scanning angle in the X direction; the rotation period of LCPG8 is 1.995μm, and the deflection angle is 16°, which is used to adjust the scanning angle in the X direction; the rotation period of LCPG9 is 1.038μm, and the deflection angle is 32°, which is used to adjust the scanning angle in the X direction.

[0089] Table 4

[0090]

[0091] Table 4 describes the specific values ​​of the scanning angles in the X and Y directions obtained by adjusting the drive signal of the polarization modulator corresponding to each liquid crystal polarization grating based on the parameters of each liquid crystal polarization grating shown in Table 2, thereby controlling the deflection direction of each liquid crystal polarization grating. The "+" sign in Table 2 indicates that the deflection direction of the liquid crystal polarization grating is positive, and the "-" sign in Table 2 indicates that the deflection direction of the liquid crystal polarization grating is negative.

[0092] Combined with Table 4, when Figure 5 The deflection directions of the five liquid crystal polarization gratings are "+, +, -, -, +" respectively. When the scanning angle of the target beam scanning device in the X direction is 6.62°, the scanning angle in the Y direction is 5.00°; when Figure 5 The deflection directions of the five liquid crystal polarization gratings are "+, +, +, -, +" respectively. When the scanning angle of the target beam scanning device in the X direction is 23.3°, the scanning angle in the Y direction is 5.41°; when Figure 5 The deflection directions of the five liquid crystal polarization gratings are "+, +, -, +, +", respectively. When the scanning angle of the target beam scanning device in the X direction is 42°, the scanning angle in the Y direction is 6.67°; when Figure 5 The deflection directions of the five liquid crystal polarization gratings are "-, +, +, +, +" respectively. When the scanning angle of the target beam scanning device in the X direction is 70.9°, the scanning angle in the Y direction is 5.02°.

[0093] It can be seen from Table 4 that the Figure 5In the target beam scanning device shown in FIG, two sets of first-type polarization beam adjusters are stacked in the Y direction. When the scanning angle in the X direction reaches 70°, simply controlling the deflection directions of the two sets of first-type polarization beam adjusters in opposite directions ensures that the Y-direction scanning angle remains relatively stable, such as approximately 5°. Therefore, the beam scanning device disclosed in this application can achieve decoupling of scanning angles in two orthogonal directions.

[0094] Based on the same inventive concept, the present application also discloses a light beam scanning system. Figure 8 This is a schematic diagram of the structure of a target beam scanning system disclosed in an embodiment of the present application. Figure 8 As shown, the target beam scanning system 800 disclosed in the present application includes a light source 801, a polarizing device 802 and a beam scanning device 803;

[0095] The light source 801 is used to emit an initial light beam; the polarizing device 802 is used to convert the initial light beam into an incident light beam with a circular polarization state; the content of the light beam scanning device 803 can be found in the introduction of the above embodiment and will not be repeated here.

[0096] It should be noted that the various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the method embodiment, since it is basically similar to the method embodiment, the description is relatively simple. For the relevant parts, refer to the partial description of the method embodiment. The method embodiment described above is merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components indicated as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. A person of ordinary skill in the art can understand and implement it without expending creative work.

[0097] The above is merely one specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A light beam scanning device, characterized in that: The light beam scanning device includes N1 groups of first-type polarization beam adjusters stacked in a first direction, the first-type polarization beam adjusters being used to adjust the chirality and deflection angle of circularly polarized light; the first-type polarization beam adjusters being used to adjust the scanning angle of the incident light beam in the first direction; N1 ≥ 2; The target scanning angle in the second direction is greater than the preset scanning angle. Among the N1 groups of first-type polarization beam adjusters, at least two groups of the first-type polarization beam adjusters have opposite deflection directions. The first direction and the second direction are orthogonal directions.

2. The light beam scanning device according to claim 1, wherein: The first type of polarization beam adjuster includes a polarization modulator and a liquid crystal polarization grating.

3. The light beam scanning device according to claim 2, wherein: N1=2, the N1 group of first-type polarization beam adjusters includes a first polarization beam adjuster and a second polarization beam adjuster; The rotation period of the liquid crystal polarization grating in the first polarization beam adjuster is greater than the rotation period of the liquid crystal polarization grating in the second polarization beam adjuster. The deflection direction of the first polarization beam adjuster is opposite to the direction of the actual scanning angle in the first direction, and the deflection direction of the second polarization beam adjuster is the same as the direction of the actual scanning angle in the first direction. The actual scanning angle in the first direction is the scanning angle of the incident light beam in the first direction after passing through the light beam scanning device.

4. The light beam scanning device according to claim 3, wherein: The light beam scanning device further includes: three groups of second-type polarization beam adjusters stacked in the second direction, the second-type polarization beam adjusters being used to adjust the scanning angle of the incident light beam in the second direction; the three groups of second-type polarization beam adjusters including a third polarization beam adjuster, a fourth polarization beam adjuster, and a fifth polarization beam adjuster; the third polarization beam adjuster, the fourth polarization beam adjuster, and the fifth polarization beam adjuster being arranged in sequence along the transmission direction of the incident light beam; The rotation period of the liquid crystal polarization grating in the first polarization beam adjuster is determined by formula (1), In formula (1), P1 is the rotation period of the liquid crystal polarization grating in the first polarization beam adjuster, k is the wave vector of the incident light beam itself, and θ y0 is the target scanning angle in the first direction, G3 is the wave vector applied by the third polarization beam adjuster to the incident light beam; G4 is the wave vector applied by the fourth polarization beam adjuster to the incident light beam; G5 is the wave vector applied by the fifth polarization beam adjuster to the incident light beam.

5. The optical scanning device according to claim 3, wherein: The light beam scanning device further includes: three groups of second-type polarization beam adjusters stacked in the second direction, the second-type polarization beam adjusters being used to adjust the scanning angle of the incident light beam in the second direction; the three groups of second-type polarization beam adjusters including a third polarization beam adjuster, a fourth polarization beam adjuster, and a fifth polarization beam adjuster; the third polarization beam adjuster, the fourth polarization beam adjuster, and the fifth polarization beam adjuster being arranged in sequence along the transmission direction of the incident light beam; The rotation period of the liquid crystal polarization grating in the second polarization beam adjuster is determined by formula (2), In formula (2), P2 is the rotation period of the liquid crystal polarization grating in the second polarization beam adjuster, k is the wave vector of the incident light beam itself, and θ y0 is the target scanning angle in the first direction, G3 is the wave vector applied by the third polarization beam adjuster to the incident light beam; G4 is the wave vector applied by the fourth polarization beam adjuster to the incident light beam; G5 is the wave vector applied by the fifth polarization beam adjuster to the incident light beam.

6. The light beam scanning device according to claim 2, wherein: N1≥3, the N1 group of first-type polarization beam adjusters includes m1 group of first-type polarization beam adjusters and m2 group of first-type polarization beam adjusters; m1+m2=N1, m1≥1, m2≥1; The deflection direction of each group of the first-type polarization beam adjusters in the m1 group is the same, and the deflection direction of each group of the first-type polarization beam adjusters in the m2 group is the same, and the deflection direction of the first-type polarization beam adjusters in the m1 group is opposite to the deflection direction of the first-type polarization beam adjusters in the m2 group.

7. The light beam scanning device according to claim 2, wherein: N1≥3, at least two of the N1 groups of first-type polarization beam adjusters have opposite deflection directions, Among the N1 groups of first-type polarization beam adjusters, at least two groups of the first-type polarization beam adjusters have opposite deflection directions, and the difference between the actual scanning angle in the first direction and the target scanning angle in the first direction is less than a preset first difference threshold; the actual scanning angle in the first direction is the scanning angle of the incident light beam in the first direction after passing through the light beam scanning device.

8. The light beam scanning device according to claim 1, wherein: The light beam scanning device further comprises: N1=2, the target scanning angle in the second direction is smaller than the preset scanning angle, and the deflection direction of each group of the first-type polarization beam adjusters in the N1 groups is the same as the direction of the actual scanning angle in the first direction; the actual scanning angle in the first direction is the scanning angle of the incident light beam in the first direction after passing through the light beam scanning device.

9. The light beam scanning device according to claim 1, wherein: The light beam scanning device further comprises: N1≥3. When the target scanning angle in the second direction is less than the preset scanning angle, the deflection direction of each group of the first-type polarization beam adjusters in the N1 groups is the same as the direction of the actual scanning angle in the first direction; the actual scanning angle in the first direction is the scanning angle of the incident light beam in the first direction after passing through the light beam scanning device.

10. The light beam scanning device according to claim 1, wherein The light beam scanning device further comprises: N2 groups of second-type polarization beam adjusters are stacked in the second direction, and the second-type polarization beam adjusters are used to adjust the scanning angle of the incident light beam in the second direction; the second-type polarization beam adjusters are used to adjust the chirality and deflection angle of the circularly polarized light; N2≥2.

11. The light beam scanning device according to claim 10, wherein: Adjust the deflection direction of each group of the N2 groups of second-type polarization beam adjusters so that the difference between the actual scanning angle in the second direction and the target scanning angle in the second direction is less than a preset second difference threshold; the actual scanning angle in the second direction is the scanning angle of the incident light beam in the second direction after passing through the light beam scanning device.

12. The light beam scanning device according to any one of claims 10 or 11, characterized in that: adjusting a driving signal of a polarization modulator in the first type of polarization beam adjuster to control a deflection direction of the first type of polarization beam adjuster; and adjusting a driving signal of a polarization modulator in the second type polarization beam adjuster to control a deflection direction of the second type polarization beam adjuster.

13. The light beam scanning device according to any one of claims 1 to 11, characterized in that: The preset scanning angle ranges from 40 degrees to 60 degrees.

14. A beam scanning system, characterized in that: The system comprises a light source, a polarizing device and a beam scanning device; the beam scanning device is the beam scanning device according to any one of claims 1 to 13; The light source is used to emit an initial light beam; The polarizing device is used to convert the initial light beam into an incident light beam with a polarization state of circular polarization; The light beam scanning device is used to control the scanning direction of the incident light beam.

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