WO2025178281A1 - 2d conversion optical array structure and light scanning device - Google Patents

Abstract

A 2D conversion optical array structure and a light scanning device are provided. The 2D conversion optical array structure comprises a plurality of horizontal light-splitting paths for horizontally splitting a beam introduced from a light source. Each of the horizontal light-splitting paths has a multilayer structure in which a plurality of vertical light-splitting paths is stacked in a vertical direction. The light scanning device comprises: a light source; a 2D conversion optical array structure for generating horizontally and vertically split beams from a beam emitted from the light source; and a detector for detecting beams reflected from an object after being emitted from the 2D conversion optical array structure.

Description

2D transformation optical array structure and optical scanning device

The present invention relates to a 2D transformation optical array structure and an optical scanning device. More specifically, the present invention relates to a 2D transformation optical array structure including an optical multilayer structure and an optical scanning device utilizing the same.

For example, an optical scanning device such as a Light Detection And Ranging (LiDAR) sensor is a radar system that measures the location coordinates of a reflector by measuring the time it takes for laser light to be reflected and returned. LiDAR sensors are applied to various devices such as automobiles, robots, and drones. Recently, LiDAR sensors are installed on aircraft or satellites and used for topographic surveying, and are also utilized in speed guns, autonomous mobile robots, and self-driving cars.

For example, LiDAR sensors can generate information about objects based on the time-of-flight (ToF) measurement method of light. For example, a LiDAR sensor transmits light toward an object and receives it back through the sensor, measuring the time-of-flight using high-speed electrical circuits. The LiDAR sensor then calculates the distance to the object from the time-of-flight and, using the calculated distance for each position of the object, generates additional information about the object.

However, when measuring using the ToF method, information on speed is not produced in real time, and if the emitted laser pulse is weakened by an atmospheric environment such as fog, the measurement intensity and measurement sensitivity may decrease.

For optical scanning, the transmitted light can be split into phased arrays. However, even with the phased array splitting, sufficiently high-precision position/velocity information may not be generated.

For example, Korean Patent Publication No. 10-2020-0127364 discloses a ToF type lidar sensor.

One object of the present invention is to provide a 2D transformation lens array structure having improved precision and reliability.

An object of the present invention is to provide an optical scanning device having improved precision and reliability.

1. A 2D transformation optical array structure comprising a plurality of horizontally divided optical paths that horizontally divide light introduced from a light source, each of the horizontally divided optical paths having a multilayer structure in which a plurality of vertically divided optical paths are vertically stacked.

2. A 2D transformation optical array structure in the above 1, wherein the multilayer structure further includes barrier layers arranged between the vertically divided optical paths.

3. A 2D transformation optical array structure in the above 1, wherein the horizontal split optical paths include a plurality of sub-horizontal split optical paths branching from each horizontal split optical path end.

4. A 2D conversion optical array structure further comprising a switching element that distributes light to each of the vertically divided optical paths in the above 1.

5. A 2D transformation optical array structure further comprising a lens structure through which vertically divided light generated from the vertically divided optical paths passes in the above 1.

6. In the above 5, the lens structure is a 2D transformation optical array structure including individual lenses corresponding to each of the vertically divided optical paths.

7. A 2D transformation optical array structure in the above 6, wherein at least one of the individual lenses is arranged to be inclined with respect to the horizontal direction.

8. A 2D transformation optical array structure in which the tilt angle sequentially increases or decreases from the individual lens positioned at the lowest position among the individual lenses in the above 6.

9. A 2D transformation optical array structure in the above 8, wherein the inclination angle is maintained in the range of -10 ^o to 10 ^o.

10. A 2D transformation optical array structure in the above 5, wherein at least one of the vertically divided optical paths included in the multilayer structure is arranged to be inclined with respect to the horizontal direction.

11. A 2D transformation optical array structure in which the tilt angle sequentially increases or decreases from the vertically divided optical path arranged at the lowest among the vertically divided optical paths in the above 10.

12. A 2D transformation optical array structure in the above 11, wherein the inclination angle is maintained in the range of -10 ^o to 10 ^o .

13. A 2D transformation optical array structure in which the lens structure corresponding to the multilayer structure in the above 10 is provided as a single lens.

14. An optical scanning device comprising: a light source; a 2D transformation optical array structure according to the above-described embodiments that generates horizontal and vertically divided lights from light emitted from the light source; and a detector that detects lights reflected from an object by lights emitted from the 2D transformation optical array structure.

15. An optical scanning device according to 14 above, wherein the 2D transformation optical array structure is provided as a single optical phased array (OPA) element.

A 2D transformation optical array structure according to embodiments of the present invention includes a plurality of horizontally split optical paths, each of which may include a multilayer structure or stack of vertically split optical paths. Accordingly, two-dimensional (2D) beam steering can be implemented, for example, through a single optical phased array (OPA) element. Accordingly, the split light beams can have different positions in a 2D plane and generate light spots. Continuous optical scanning can be implemented through a sensor including the 2D transformation optical array structure, while increasing the signal processing speed.

According to embodiments of the present invention, the 2D transformation optical array structure can be applied to an optical scanning device such as a lidar sensor. The optical scanning device can include the 2D transformation optical array structure as a horizontal light splitting device and a vertical light splitting device. Transmission light horizontally split by the horizontally split optical paths can be finely split again through the multilayer structure of the vertically split optical paths. Accordingly, the precision and resolution of measurement information of an object can be improved, and velocity information of the object can be scanned and collected in real time.

For example, a mechanical light splitting device such as a separate motor or rotor can be excluded, thereby avoiding inaccuracy in beam scanning due to vibration or shock of the mechanical light splitting device.

FIG. 1 is a schematic plan view illustrating a 2D transformation optical array structure according to exemplary embodiments.

FIG. 2 is a schematic cross-sectional view illustrating a 2D transformation optical array structure according to exemplary embodiments.

FIG. 3 is a schematic diagram illustrating light spot generation through a 2D transformation optical array structure according to exemplary embodiments.

FIGS. 4 to 8 are schematic cross-sectional views illustrating a 2D transformation optical array structure according to some exemplary embodiments.

FIG. 9 is a schematic block diagram illustrating an optical scanning device according to exemplary embodiments.

FIG. 10 is a schematic block diagram illustrating an optical scanning device according to exemplary embodiments.

Embodiments of the present invention provide a 2D transformation optical array structure including a plurality of optical paths. Embodiments of the present invention provide an optical scanning device including the 2D transformation optical array structure and a detector.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. However, the following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the contents of the invention described above, serve to further understand the technical concept of the present invention. Therefore, the present invention should not be interpreted as being limited to the matters described in such drawings.

The terms “first,” “second,” “top,” “bottom,” “upper,” and “lower” used in this specification do not limit absolute positions or orders, but are used in a relative sense to distinguish different components or parts.

The term "row direction" as used in this application may refer to a horizontal direction or X direction, and "column direction" may refer to a vertical direction or Y direction perpendicular to the row direction. A two-dimensional (2D) plane may be defined by the row direction and the column direction.

FIG. 1 is a schematic plan view illustrating a 2D transformation optical array structure according to exemplary embodiments. The 2D transformation optical array structure may be provided as an optical phased array (OPA) element.

Referring to FIG. 1, the 2D conversion optical array structure (100) (hereinafter, may be abbreviated as optical array structure) may include a beam splitter section (130), a phase shift section (140), and an emitting section (150).

For example, light irradiated from a light source (110) can sequentially pass through a beam splitter (130) and a phase modulation unit (140) and be emitted from a radiation unit (150).

The light emitted from the light source (110) may be split into a plurality of horizontally split light paths in the beam splitter unit (130). In some embodiments, the beam splitter unit (130) includes a plurality of horizontally split light paths and may further include sub-horizontally split light paths. A plurality of the sub-horizontally split light paths may be branched from each of the horizontally split light paths.

For example, as illustrated in FIG. 1, the horizontal split optical paths may include a first horizontal split optical path (132a) and a second horizontal split optical path (132b). A plurality of sub-horizontal split optical paths may be branched from each of the first horizontal split optical path (132a) and the second horizontal split optical path (132b).

For example, a first sub-horizontal split optical path (134a) and a second sub-horizontal split optical path (134b) may be branched from a first horizontal split optical path (132a), and a third sub-horizontal split optical path (134c) and a fourth sub-horizontal split optical path (134d) may be branched from a second horizontal split optical path (132b).

In some embodiments, a switching element (120) may be connected to one end of the beam splitter section (130). In some embodiments, a splitter for distributing light to each horizontally divided optical path may be arranged at the one end of the beam splitter section (130). The splitter may have, for example, a multimode interference (MMI) structure.

Light input into each of the sub-horizontal split optical paths (134a to 134d) can be converted to have different phases by a phase modulator (140). The phase modulator (140) can include a phase modulator coupled to or included in each of the sub-horizontal split optical paths (134a to 134d). The phase modulator can perform light modulation through electrical, magnetic, thermal, mechanical, or other means.

The resolution between horizontally distributed lights in the plane direction of FIG. 1 can be increased through the phase modulation unit (140).

Fig. 2 is a schematic cross-sectional view illustrating a 2D transformation optical array structure according to exemplary embodiments. Fig. 2 is a cross-sectional view illustrating a stacked structure of each horizontally divided optical path or sub-horizontally divided optical path.

Referring to FIG. 2, each horizontal split optical path or sub-horizontal split optical path may have a multi-layer structure in the vertical direction.

According to exemplary embodiments, each horizontal split optical path may include a plurality of vertical split optical paths (170) stacked in the vertical or column direction.

A barrier layer (160) may be arranged between the vertically divided optical paths (170) to block light mixing between the vertically divided optical paths (170). The barrier layer (160) may be provided as a substrate layer for the optical paths. For example, the barrier layer (160) may include an inorganic insulating material such as quartz, Si, Ge, SiGe, or an oxide or nitride thereof, or an organic resin material.

As illustrated in FIG. 2, a first barrier layer (160a), a first vertically divided light path (170a), a second barrier layer (160b), a second vertically divided light path (170b), a third barrier layer (160c), a third vertically divided light path (170c), a fourth barrier layer (160d), a fourth vertically divided light path (170d), a fifth barrier layer (160e), and a fifth vertically divided light path (170e) can be sequentially arranged.

The switching element (120) can distribute light into vertically divided optical paths (170) of each layer. For example, the switching element (120) can include a switching integrated circuit (IC), a switching diode, an Acousto-Optic Modulator (AOM), an optical coupler, etc.

According to the embodiment illustrated in FIGS. 1 and 2, four horizontally split lights are generated from light introduced from a light source (110), and each of the horizontally split lights can be split into five vertically split lights. Accordingly, 20 (4*5) split lights can be generated from one light.

However, the number of horizontally split optical paths and vertically split optical paths is not particularly limited, and can be appropriately adjusted in consideration of the detection target, desired precision, detection stability, etc.

According to the embodiments of the present invention described above, horizontal and vertical divisions can be simultaneously generated from a single optical array structure (100), thereby allowing light to be divided into two-dimensional planes. Accordingly, two-dimensional positional information, including the distance and height of an object, can be calculated with higher precision.

Additionally, vertical segmentation via mechanical elements such as motors or rotors is eliminated, and vertical segmentation can be implemented with a single OPA element. Consequently, detection errors caused by vibration and shock can be reduced or suppressed.

FIG. 3 is a schematic diagram illustrating light spot generation through a 2D transformation optical array structure according to exemplary embodiments.

Referring to FIG. 3, the optical array structure (100) may further include a lens structure (180) into which light emitted from vertically divided optical paths (170) is incident.

According to exemplary embodiments, the lens structure (180) may include a plurality of individual lenses arranged corresponding to each vertically divided optical path (170). For example, a first lens (180a), a second lens (180b), a third lens (180c), a fourth lens (180d), and a fifth lens (180e) may be arranged corresponding to a first vertically divided optical path (170a), a second vertically divided optical path (170b), a third vertically divided optical path (170c), a fourth vertically divided optical path (170d), and a fifth vertically divided optical path (170e), respectively.

The focusing characteristics of light emitted from each vertically divided optical path (170) onto the target object (300) can be increased by the above individual lenses. Accordingly, the intensity of reflected light from the target object (300) can be increased, thereby improving the detection intensity through the optical scanning device.

Vertically split lights passing through individual lenses of the lens structure (180) can reach the target object (300) to generate light spots (305). As in the embodiment described with reference to FIGS. 1 and 2, four horizontally split lights can be generated, and each of the horizontally split lights can be split into five vertically split lights. Accordingly, the light can be dispersed into 20 lights on a two-dimensional plane to generate light spots (305).

FIGS. 4 to 8 are schematic cross-sectional views illustrating a 2D transformation optical array structure according to some exemplary embodiments.

Referring to FIG. 4, at least one of the individual lenses (180a to 180e) included in the lens structure (180) may be arranged at an angle with respect to the direction of light incident from the vertically divided optical path (170).

For example, a tilt angle can be applied to the surrounding lenses (180a, 180b, 180d, 180e) centered on the third lens (180c) corresponding to the optical path located in the center among the plurality of vertically divided optical paths (e.g., the third vertically divided optical path (170c)).

In one embodiment, the inclination angle may sequentially increase or decrease from the first lens (180a) positioned at the bottom. For example, the inclination angles of the first lens (180a), the second lens (180b), the third lens (180c), the fourth lens (180d), and the fifth lens (180e) may sequentially be -5 ^o , -2.5 ^o , 0 ^o , 2.5 ^o , and 5 ^{o ,} respectively.

In some embodiments, the difference between the maximum and minimum wide angles generated by the lenses (180a, 180b, 180d, 180e) may be 20 ^° or less. For example, the difference between the maximum and minimum wide angles may be 5 ^° to 20 ^° , or 5 ^° to 15 ^° .

For example, the range of vertically split wide-angles generated through the lenses (180a, 180b, 180d, 180e) can be adjusted so that the inclination angles are maintained in the range of -10 ^o to 10 ^o , or in the range of -5 ^o to 5 ^o . This can prevent a decrease in detection power and precision due to excessive light dispersion while improving the resolution between vertically split lights in the wide-angle range.

Referring to FIG. 5, an inclination angle may be applied to the vertical split optical paths (170).

For example, among the plurality of vertically divided optical paths, a centrally located optical path (e.g., a third vertically divided optical path (170c)) may be provided with an inclination angle (an inclination angle in the vertical direction with respect to the horizontal direction) to the surrounding vertically divided optical paths (170a, 170b, 170d, 170e). In this case, each of the lenses (180a to 180e) may be arranged parallel to each other in the horizontal direction.

In one embodiment, the inclination angle may sequentially increase or decrease from the first vertically divided light path (170a) positioned at the bottom. For example, the inclination angles of the first vertically divided light path (170a), the second vertically divided light path (170b), the third vertically divided light path (170c), the fourth vertically divided light path (170d), and the fifth vertically divided light path (170e) may be -5 ^o , -2.5 ^o , 0 ^o , 2.5 ^o , and 5 ^{o ,} respectively.

As described above, the range of the vertically divided light angle generated through the vertically divided light paths (170a, 170b, 170d, 170e) can be adjusted so that the inclination angles are maintained in the range of -10 ^o to 10 ^o , or in the range of -5 ^o to 5 ^o .

Referring to FIG. 6, the inclination angle of the first vertical split light path (170a) positioned at the bottom is substantially 0 ^o , and the inclination angle can sequentially increase or decrease from the first vertical split light path (170a).

For example, the inclination angles of the first vertically divided optical path (170a), the second vertically divided optical path (170b), the third vertically divided optical path (170c), the fourth vertically divided optical path (170d), and the fifth vertically divided optical path (170e) can be sequentially increased to 0 ^o , 2.5 ^o , 5 ^o , 7.5 ^o , and 10 ^o, respectively.

Referring to FIGS. 7 and 8, when a tilt angle is applied to the vertically divided optical paths (170) as described with reference to FIGS. 5 and 6, the lens structure (180) can be provided as a single lens corresponding to the multilayer structure of one vertically divided optical path.

For example, a single lens may be positioned corresponding to the first to fifth vertically divided optical paths (170a to 170e). Accordingly, mechanical instability caused by the individual lenses being misaligned due to external physical impact can be avoided.

FIG. 9 is a schematic block diagram illustrating an optical scanning device according to exemplary embodiments.

The term "optical scanning device" as used in this application is used as a comprehensive term for a sensor that illuminates a target object with light and detects information about the target object through the reflected light. According to exemplary embodiments, the optical scanning device may include, but is not limited to, a lidar sensor.

Hereinafter, an optical scanning device and a measurement method using the same will be described with reference to FIGS. 9 and 10.

Referring to FIG. 9, the optical scanning device (200) may include a light source (110) and the optical array structure (100) described above.

According to exemplary embodiments, the light source (110) may be a device that irradiates light in the infrared region. By using light in the infrared region, mixing with natural light, including, for example, visible light, can be prevented. However, the light transmitted from the light source (110) is not limited to infrared, and light of multiple different wavelength bands may be emitted simultaneously.

In some embodiments, the wavelength of light emitted from the light source (110) may be between 1500 nm and 2000 nm. In one embodiment, the wavelength may be between 1520 nm and 1580 nm, or between 1520 nm and 1560 nm. In this wavelength range, the deterioration of detection performance due to light scattering can be prevented while reducing the harmfulness to the human eye.

According to exemplary embodiments, continuous light can be irradiated from a light source (110).

In some embodiments, the light source (110) may include a laser light source. For example, the light source (110) may include an edge emitting laser, a vertical-cavity surface emitting laser (VCSEL), a distributed feedback laser, a laser diode, or the like.

In some embodiments, the transmitted light generated from the light source (110) may be amplified by the amplifier (210). Accordingly, the intensity of the transmitted light may be increased, and the intensity of the received light may be prevented from being weakened while passing through the optical array structure.

Light transmitted from a light source (110) or amplified by an amplifier (210) can be split by an optical array structure (100). As described above, the optical array structure (100) can include an OPA element having a multilayer structure. Accordingly, horizontal splitting and vertical splitting can be implemented simultaneously through a single OPA element.

As described above, the transmitted light from the light source (110) or the light amplified through the amplifier (210) can be split into a plurality of horizontal light beams through the horizontal split light paths (132, 134). For example, the transmitted light from the light source (110) can generate a plurality of horizontally split light beams having an angular difference or a phase difference in the X-direction (row direction) plane.

Each of the above horizontally split lights can be vertically split/distributed through a plurality of vertically split light paths (170) included in a multi-layer structure corresponding to each horizontally split light path. For example, the horizontally split lights can be given an angular difference in the y-axis direction by the vertically split light paths (170). Accordingly, the light transmitted from the light source (110) is dispersed in the horizontal direction as well as the vertical direction, thereby generating light spots having two-dimensionally different phases or positions, and the identification characteristics of each light can be enhanced.

As described above, the split light can be continuously incident on the target object (300) through the lens structure (180). The light reflected by the target object (300) can be input to the detector (220). The received light can be converted into an electrical signal by the detector (220). For example, a current can be output by the detector (220).

In exemplary embodiments, the detector (220) may include at least one pixel. For example, the detector (220) may include a plurality of pixels arranged in an array or matrix form. Each of the pixels may function as a light-receiving element and output an electrical signal, such as a current, corresponding to the reflected light. Information such as the direction or position of the target object (300) may be generated based on the position of the pixel that detected the corresponding light among the pixels.

For example, the distance to the target object (300) can be calculated based on the light emission time of the light source (110) and the light detection time of the detector (220).

The above pixel may be a photodetector that operates under an applied bias voltage. For example, the detector (220) may include an avalanche photodiode (APD) or a single photon avalanche diode (SPAD).

The electrical signal generated from the detector (220) can be processed and calculated through the processor (250). For example, the processor (250) can determine location information about the target object (300) using the detection result of the detector (220). The location information about the target object (300) can include at least one of the direction, height, and distance of the target object (300).

Additionally, real-time position changes of the object (300) can be detected through continuous optical scanning. Accordingly, velocity information can be derived together with position information of the object (300).

The processor (250) may also control the operation of the light source (110). For example, the light emission operation may be controlled through the processor (250).

The light source (110) and the amplifier (210) are connected to each other through a first optical path (LP1), and the amplifier (210) and the optical array structure (100) can be connected to each other through a second optical path (LP2). The optical paths (LP1, LP2) are formed of optical fibers and can suppress optical transmission loss.

Fig. 10 is a schematic block diagram illustrating an optical scanning device according to exemplary embodiments. Detailed descriptions of configurations and operations substantially identical or similar to those described with reference to Fig. 9 are omitted.

Referring to Fig. 9, for example, at least one of the horizontal split optical paths (132, 134) may be provided as a reference distribution optical path. A reference light may be generated through the reference distribution optical path, and the remaining horizontal split optical paths (132, 134) may be provided as detection distribution optical paths to generate target lights.

The detector may include a first detector (240) and a second detector (230). The reference light generated through the reference distribution optical path may be directly introduced into the second detector (230). The target light generated through the detection distribution optical paths may be vertically divided through vertically divided optical paths (170) and a lens structure (180), and then reflected by the target object (300) and introduced into the first detector (240).

The above target lights can be more clearly identified based on the reference light recognized through the second detector (230). In addition, the position information of the object (300) can be processed/generated in high resolution through the target signal generated by the target lights based on the reference signal generated based on the reference light through the processor (250).

Through the optical scanning device described above, practical continuous real-time optical scanning can be implemented with a single detector for target lights, and a Frequency Modulated Continuous Wave (FMCW) type lidar sensor can be implemented.

For example, in a TOF (Time of Flight) type lidar sensor based on a single optical pulse, the sensing sensitivity may decrease due to the weakening of the optical pulse depending on the atmospheric environment. However, according to exemplary embodiments, the sensing sensitivity can be effectively maintained through continuous optical scanning, and information on the speed of the target object (300) can be calculated in real time based on continuous measurements.

In some embodiments, the TOF type lidar sensor can also be implemented using the above-described optical scanning device or 2D conversion optical array structure.

Claims (15)

It includes a plurality of horizontally split light paths that horizontally split the light introduced from the light source, A 2D transformation optical array structure, wherein each of the above horizontally divided optical paths has a multilayer structure in which a plurality of vertically divided optical paths are stacked in the vertical direction. A 2D transformation optical array structure according to claim 1, wherein the multilayer structure further includes barrier layers disposed between the vertically divided optical paths. A 2D transformation optical array structure according to claim 1, wherein the horizontal split optical paths include a plurality of sub-horizontal split optical paths branching from each horizontal split optical path end. A 2D transformation optical array structure according to claim 1, further comprising a switching element that distributes light to each of the vertically divided optical paths. A 2D transformation optical array structure according to claim 1, further comprising a lens structure through which vertically split light generated from the vertically split optical paths passes. A 2D transformation optical array structure according to claim 5, wherein the lens structure includes individual lenses corresponding to each of the vertically divided optical paths. A 2D transformation optical array structure according to claim 6, wherein at least one of the individual lenses is arranged to be inclined with respect to the horizontal direction. A 2D transformation optical array structure according to claim 6, wherein the tilt angle sequentially increases or decreases from the individual lens positioned at the lowest position among the individual lenses. A 2D transformation optical array structure according to claim 8, wherein the inclination angle is maintained in a range of -10 ^o to 10 ^o. A 2D transformation optical array structure according to claim 5, wherein at least one of the vertically divided optical paths included in the multilayer structure is arranged to be inclined with respect to the horizontal direction. A 2D transformation optical array structure in which the tilt angle sequentially increases or decreases from the vertically divided optical path arranged at the lowest among the vertically divided optical paths according to claim 10. A 2D transformation optical array structure according to claim 11, wherein the inclination angle is maintained in a range of -10 ^o to 10 ^o. A 2D transformation optical array structure according to claim 10, wherein the lens structure corresponding to the multilayer structure is provided as a single lens. light source; A 2D transformation optical array structure according to claim 1 that generates horizontal and vertical split lights from light emitted from the light source; and An optical scanning device comprising a detector that detects light reflected from an object by light irradiated from the above 2D transformation optical array structure. An optical scanning device according to claim 14, wherein the 2D transformation optical array structure is provided as a single optical phased array (OPA) element.