RANGING DEVICE AND MOBILE PLATFORM

A ranging device includes a transmitter, a collimation element, a converging element, a detector, and at least one of a first pre-shaping element or a second pre-shaping element. The transmitter is configured to emit a light pulse sequence. The collimation element is configured to collimate the light pulse sequence. The converging element is configured to converge at least part of reflected light reflected by an object. The detector is configured to receive and convert the at least part of the reflected light to an electrical signal, and determine at least one of a distance or an orientation of the object with respect to the ranging device according to the electrical signal. An effective aperture of the collimation element is greater than an effective aperture of the first pre-shaping element, and an effective aperture of the converging element is greater than an effective aperture of the second pre-shaping element.

TECHNICAL FIELD

The present disclosure relates to the technical field of ranging and, more particularly, to a ranging device and a mobile platform.

BACKGROUND

Ranging devices play a significant role in many fields, such as for a mobile carrier or a non-mobile carrier, for remote sensing, obstacle avoidance, surveying and mapping, modeling, environmental perception, etc. In particular, the mobile carrier, such as a robot, a manually controlled aircraft, an unmanned aerial vehicle, a vehicle, or a ship, can navigate in a complex environment by the ranging device to achieve path planning, obstacle detection, obstacle avoidance, etc.

The ranging device usually uses a semiconductor laser as a light source. However, because of a large divergence angle and a large difference in fist and slow axis BPP (a product of beam parameters in slow axis and fast axis direction) of the semiconductor laser, beam collimation or compression is required in many applications. Traditional narrow beam collimation is mostly realized by using a cylindrical Los or a cylindrical lens array near a light-emission surface, and wide beam collimation is usually realized by using a single aspheric lens or a cemented spherical lens group. However, for some cases where wide beams and large apertures (>30 mm) are required, because light spot size is too large, required lens aperture will increase accordingly, which is a challenge tor high-index lens processing. In many cases, corresponding lens parameters can be designed, but it cannot be processed or processing cost is relatively high, which affects a mass production of products. In addition, large-aperture optical systems using large-aperture lenses also have the following detects: 1) Single large-aperture lens has poor optical performance and poor system performance; 2) If multiple large-aperture lenses are used, the optical system is bulky and costly; 3) If a large-aperture aspheric lens is used, processing is difficult and cost is high.

Therefore, it is needed to improve the ranging device to solve the above technical problems.

SUMMARY

In accordance with the disclosure, there is provided a ranging device including a transmitter, a collimation element, a converging element, a detector, and at least one of a first pre-shaping element or a second pre-shaping element. The transmitter is configured to emit a light pulse sequence. The collimation element is configured to collimate the light pulse sequence. The converging element is configured to converge at least part of reflected light reflected by an object. The detector is configured to receive and convert the at least part of the reflected light to an electrical signal, and determine at least one of a distance or an orientation of the object with respect to the ranging device according to the electrical signal. An effective aperture of the collimation element is greater than an effective aperture of the first pre-shaping element, and an effective aperture of the converging element is greater than an effective aperture of the second pre-shaping element.

Also in accordance with the disclosure, there is provided a mobile platform including a platform body and a ranging device mounted at the platform body. The ranging device includes a transmitter, a collimation element, a converging element, a detector, and at least one of a first pre-shaping element or a second pre shaping element. The transmitter is configured to emit a light pulse sequence. The collimation element is configured to collimate the light pulse sequence. The converging element is configured to converge at least part of reflected light reflected by an object. The detector is configured to receive and convert the at least part of the reflected light to an electrical signal, and determine at least one of a distance or an orientation of the object with respect to the ranging device according to the electrical signal. An effective aperture of the collimation element is greater than an effective aperture of the first pre-shaping element, and an effective aperture of the converging element is greater than an effective aperture of the second pre-shaping element.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In order to make the objectives, technical solutions, and advantages of the present disclosure more obvious, exemplary embodiments according to the present disclosure will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are sonic of rather than all the embodiments of the present disclosure. It should be noted that the present disclosure is not limited by the exemplary embodiments described herein. Based on the embodiments of the present disclosure described in the present disclosure, all other embodiments obtained by those of ordinary skill in the art without inventive effort shall fall within the scope of the present disclosure.

In the following description, a lot of specific details are given in order to provide a more thorough understanding of the present disclosure. However, it is obvious to those skilled in the art that the present disclosure can be implemented without one or more of these details. In some other examples, some technical features known in the art are not described in order to avoid confusion with the present disclosure.

It should be noted that the present disclosure can be implemented in different forms and should not be construed as being limited to the embodiments described here. Rather, these embodiments are provided so that the disclosure will be thorough and complete, and the scope of the present disclosure will be fully conveyed to those skilled in the art.

The terms used herein is for the purpose of describing specific embodiments only and is not as a limitation of the present disclosure. As used herein, the singular forms of “a,” “an,” and “the” are intended to include plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the terms “comprising,” and/or “including”, when used in this specification, determine the existence of the described features, integers, steps, operations, elements and/or components, but do not exclude the existence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups. As used herein, the term “and/or” includes any and all combinations of related listed items.

In order to provide a thorough understanding of the present disclosure, detailed steps and detailed structures will be presented in the following description to explain the technical solutions of the present disclosure. Some embodiments of the present disclosure are described in detail as follows. However, in addition to these detailed descriptions, the present disclosure may also have other embodiments.

In order to solve the above problems, the present disclosure provides a ranging device, which includes a transmitter, a collimation element, a converging element, a first pre-shaping element and/or a second pre-shaping element. The transmitter is configured to emit a light pulse sequence. The collimation element is located on transmission light path of the transmitter, and is configured to collimate the light pulse sequence emitted by the transmitter and emit the collimated light pulse sequence out of the ranging device. The converging element is configured to converge at least part of reflected light reflected by an object to a detector. The detector is configured to receive at least part of the reflected light and convert to an electrical signal, and determine distance and/or orientation of the object from the ranging device according to the electrical signal. The first pre-shaping element is arranged on the transmission light path and between the collimation element and a light-emission surface of the transmitter, and the second pre-shaping element is arranged on reception light path of the reflected light and between the converging element and photosensitive surface of the detector. Effective aperture of the collimation element is greater than effective aperture of the first pre-shaping element, and effective aperture of the converging element is greater than effective aperture of the second pre-shaping element.

It should be noted that the effective aperture of each element (e.g., collimation element, pre-shaping element, etc.) herein refers to aperture of each element that actually receives a light beam.

The ranging device in the embodiments of the present disclosure combines small aperture pre-shaping element and collimation element and/or a converging element as an optical system for light beam collimation, which can achieve excellent optical performance with a large-aperture lens at a lower cost, and reduce aberration of the optical system, etc., thereby improving performance of the ranging device.

Hereinafter, a ranging device and a mobile platform in the present disclosure will be described in detail with reference to the accompanying drawings. In the case of no conflict, the embodiments and features in the embodiments can be combined with each other.

The ranging device in the embodiments of the present disclosure may be an electronic equipment such as a laser radar or a laser ranging equipment. In some embodiments, the ranging device is configured to sense external environment information, and data recorded in form of points by scanning external environment can be referred to as point cloud data. Each point in the point cloud data includes coordinates of a three-dimensional point and characteristic information of the corresponding three-dimensional point, such as distance information, orientation information, reflection intensity information, speed information, etc. of an environmental target. In one implementation manner, the ranging device can detect distance of a detected object to the ranging device by measuring time of light propagation, that is, time-of-flight (TOF), between the ranging device and the detected object. The ranging device can also detect the distance from the detected object to the ranging device by other techniques, such as a ranging method based on phase shift measurement or a ranging method based on frequency shift measurement, which is not limited herein.

For better understanding, a ranging workflow will be described with examples in conjunction with a ranging device100shown inFIG. 1.

As shown inFIG. 1, the ranging device100includes a transmission circuit110, a reception circuit120, a sampling circuit130, and a computation circuit140.

The transmission circuit110can emit a light pulse sequence (e.g., a laser pulse sequence). The reception circuit120can receive the light pulse sequence reflected by a detected object and perform photoelectric conversion on the light pulse sequence to obtain an electrical signal, and then the electrical signal is processed and output to the sampling circuit130. The sampling circuit130can sample the electrical signal to obtain a sampling result. The computation circuit140can determine distance between the ranging device100and the detected object based on the sampling result of the sampling circuit130.

For example, the ranging device100also includes a control circuit150, which can control other circuits, for example, can control operation time of each circuit and/or set parameters for each circuit.

It should be noted that although the ranging device shown inFIG. 1includes a transmission circuit, a reception circuit, a sampling circuit, and a computation circuit, and is configured to emit a light beam for detection, the embodiments of the present disclosure are not limited thereto. Number of any one of the transmission circuit, the reception circuit, the sampling circuit, and the computation circuit may also be at least two, which are configured to emit at least two light beams in same direction or in different directions. The at least two light beams may be emitted simultaneous or may be emitted at different times. In some embodiments, light emitting chips in the at least two transmission circuits are packaged in same module. For example, each transmission circuit includes a laser emitting chip, and dies of the laser emitting chips in the at least two transmission circuits are packaged together and housed in same package space.

In some implementations, in addition to the circuits shown inFIG. 1, the ranging device100may also include a scanner for changing propagation direction of at least one light pulse sequence emitted by the transmission circuit.

A module including the transmission circuit110, the reception circuit120, the sampling circuit130, and the computation circuit140, or a module including the transmission circuit110, the reception circuit120, the sampling circuit130, the computation circuit140, and the control circuit150may be referred to as a ranging module, which can be independent of other modules, such as the scanner.

A coaxial light path can be used in the ranging device, that is, the light beam emitted by the ranging device and the reflected light beam share at least part of the light path within the ranging device. For example, after at least one laser pulse sequence emitted by the transmission circuit changes its propagation direction and emits through the scanner, the laser pulse sequence reflected by the detected object passes through the scanner and then enters the reception circuit. An off-axis light path can also be used in the ranging device, that is, the light beam emitted by the ranging device and the reflected light beam are respectively transmitted along different light paths within the ranging device.FIG. 2shows a schematic diagram of a ranging device using a coaxial light path according to an embodiment of the present disclosure.

A ranging device200includes a ranging module210, which includes a transmitter203(which may include the transmission circuit described above), a collimation element204, a detector205(which may include the reception circuit, the sampling circuit, and the computation circuit described above), and a light path changing element206. The ranging module210is configured to emit the light beam, receive the reflected light, and convert the reflected light into the electrical signal. The transmitter203can be configured to emit the light sequence. In some embodiments, the transmitter203may emit the laser pulse sequence. For example, a laser beam emitted by the transmitter203is a narrow-bandwidth beam with a wavelength outside visible light range.

The collimation element204is arranged on the transmission light path of the transmitter, and is configured to collimate the light beam emitted from the transmitter203and collimate the light beam emitted from the transmitter203into parallel light output to the scanner. In the coaxial light path, the collimation element is also configured to converge at least part of the reflected light reflected by the detected object. The collimation element204may be a collimating lens or another element capable of collimating the light beam.

In the embodiments shown inFIG. 2, the transmission light path and the reception light path within the ranging device are merged before the collimation element204by the light path changing element206, so that the transmission light path and the reception light path can share the same collimation element, such as sharing a same transceiver lens, which makes the light path more compact. For example, the light path changing element is located within a back focal length of the collimation element204, which is configured to change the transmission light path of the light pulse sequence emitted by the transmitter or the reception light path of the reflected light passing through the collimation element204, so that the transmission light path and the reception light path are merged. For example, the light path changing element206includes a reflector and/or a prism. The reflector includes at least one of a flat reflector or a concave reflector.

In some other implementations, the transmitter203and the detector205may respectively use their own collimation elements. For example, the transmitter203uses the collimation element, while the detector uses the converging element with a converging effect, and the light path changing element206is arranged on the light path behind the collimation element.

In the embodiment shown inFIG. 2, since beam aperture of the light beam emitted by the transmitter203is small, and beam aperture of the reflected light received by the ranging device is large, the light path changing element can use a small-area reflector to merge the transmission light path and the reception light path. In some other implementations, the light path changing element may also use a reflector with a through hole, where the through hole is used to transmit emitted light of the transmitter203and the reflector is used to reflect the reflected light to the detector205, which can reduce block of the reflected light from a support of a small reflector in case of using the small reflector.

In the embodiments shown inFIG. 2, the light path changing element is deviated from an optical axis of the collimation element204, which is configured to project the light pulse sequence emitted by the transmitter to an edge field of view of the transceiver lens. In some other implementations, the light path changing element may also be located on the optical axis of the collimation element204.

The ranging device200also includes a scanner202arranged on the transmission light path of the ranging module210. The scanner202is configured to change transmission direction of a collimated light beam219emitted by the collimation element204and project it to external environment. The reflected light is projected to the collimation element204, and is converged on the detector205through the collimation element204.

In some embodiments, the scanner202may include at least an optical element for changing propagation path of the light beam, and the optical element may change the propagation path of the light beam by reflecting, refracting, diffracting, etc. For example, the scanner202includes a lens, a reflector, a prism, a galvanometer, a grating, a liquid crystal, an optical phased array, or any combination of the above. In some embodiments, at least some of the optical elements are movable, for example, the at least some of the optical elements are driven to move by a drive module, and the movable optical element can reflect, refract or diffract the light beam to different directions at different times. In some embodiments, the multiple optical elements of the scanner202can rotate or vibrate around a common rotation axis209, and each rotating or vibrating optical element is configured to continuously change the propagation direction of an incident light beam. In some embodiments, the multiple optical elements of the scanner202may rotate at different rotation speeds or vibrate at different speeds. In some other embodiments, the at least some of the optical elements of the scanner202may rotate at substantially the same rotation speed. In some embodiments, the multiple optical elements of the scanner may also rotate around different axes. In some embodiments, the multiple optical elements of the scanner may also rotate in the same direction or in different directions; or vibrate in the same direction or in different directions, which is not limited herein.

In some embodiments, the scanner202includes a first optical element214and a driver216connected to the first optical element214. The driver216is configured to drive the first optical element214to rotate around the rotation axis209, such that the first optical element214changes the direction of the collimated light beam219, and the first optical element214projects the collimated light beam219to different directions. In some embodiments, angle between the direction of the collimated light beam219changed by the first optical element and the rotation axis209varies with the rotation of the first optical element214. In some embodiments, the first optical element214includes a pair of opposing non-parallel surfaces through which the collimated light beam219passes. In some embodiments, the first optical element214includes a prism that varies in thickness along at least a radial direction. In some embodiments, the first optical element214includes a wedge angle prism that refracts the collimated light beam219.

In some embodiments, the scanner202also includes a second optical element215that rotates around the rotation axis209, and the rotation speed of the second optical element215is different from the rotation speed of the first optical element214. The second optical element215is configured to change the direction of the light beam projected by the first optical element214. In some embodiments, the second optical element215is connected to another driver217that drives the second optical element215to rotate. The first optical element214and the second optical element215can be driven by the same or different drivers, so that the rotation speed and/or rotation direction of the first optical element214and the second optical element215are different, thereby projecting the collimated light beam219to different directions in outside space, and a larger space can be scanned. In some embodiments, a controller218controls the drivers216and217to drive the first optical element214and the second optical element215, respectively. The rotation speeds of the first optical element214and the second optical element215may be determined according to area and pattern expected to be scanned in actual applications. The drivers216and217may include motors or other drivers.

In some embodiments, the second optical element215includes a pair of opposing non-parallel surfaces through which the light beam passes. In some embodiments, the second optical element215includes a prism that varies in thickness along at least a radial direction. In some embodiments, the second optical element215includes a wedge angle prism.

In some embodiments, the scanner202also includes a third optical element (not shown) and a driver for driving the third optical element to move. For example, the third optical element includes a pair of opposing non-parallel surfaces through which the light beam passes. In some embodiments, the third optical element includes a prism that varies in thickness along at least a radial direction. In some embodiments, the third optical element includes a wedge angle prism. At least two of the first, second, and third optical elements rotate at different rotation speeds and/or rotation directions.

Each optical element in the scanner202can rotate to project light to different directions, such as directions of projected light211and projected light213, so that a space around the ranging device200is scanned. When the projected light211projected by the scanner202hits a detected object201, part of the light is reflected by the detected object201to the ranging device200in a direction opposite to the projected light211. Reflected light212reflected by the detected object201is incident to the collimation element204after passing, through the scanner202.

The detector205and the transmitter203are arranged on the same side of the collimation element204, and the detector205is configured to convert at least part of the reflected light passing through the collimation element204into an electrical signal. In some embodiments, the detector105may include an avalanche photodiode, which is a highly sensitive semiconductor device capable of converting an optical signal into an electrical signal using photocurrent effect.

In some embodiments, each optical element is plated with an anti-reflection coating. For example, thickness of the anti-reflection coating is equal to or close to wavelength of the light beam emitted by the transmitter203, which can increase intensity of the transmitted light beam.

In some embodiments, a filter layer is plated on an element surface located an beam propagation path in the ranging device, or a filter is provided on the beam propagation path, which is configured to at least transmit wavelength band of the beam emitted by the transmitter and reflect other wavelength bands, so as to reduce noise caused by ambient light to receiver.

In some embodiments, the transmitter203may include a laser diode, and emit a nanosecond level laser pulse through the laser diode. Further, laser pulse receiving time can be determined, for example, by detecting rising edge time and/or falling edge time of an electrical signal pulse. As such, the ranging device200can calculate time of flight (TOF) using pulse receiving time information and pulse sending time information, so as to determine the distance between the detected object201and the ranging device200.

The ranging module described above also includes a first pre-shaping element and/or a second pre-shaping element, such as a pre-collimating lens. The ranging module including the pre-shaping element will be described below with reference toFIGS. 3-7. The technical features in these embodiments are equally applicable to the aforementioned ranging module shown inFIG. 2under the premise of no conflict.

In some embodiments, the light path changing element206is located within the back focal length of the collimation element204, which is configured to change the reception light path of the reflected light passing through the collimation element204, so that the transmission light path and the reception light path are merged. For example, in the embodiments shown inFIG. 3, the transmission light path of the light pulse sequence emitted by the transmitter203is incident to the collimation element204through the light path changing element206, while reception light path of the reflected light converged by the collimation element204is changed by the light path changing element and then received by the detector205. In some other embodiments, the light path changing element206is located within the back focal length of the collimation element204, which is configured to change the transmission light path of the light pulse sequence emitted by the transmitter. For example, as shown inFIG. 5, the light pulse sequence emitted by the transmitter203is incident to the collimation element204through the light path changing element206, and at least part of the reflected light converged by the collimation element204passes through an outer edge of the light path changing element206and is received by the detector205.

It should be noted that in the present disclosure, a back focal point (also referred to as a backward focal point) refers to a focal point of the optical element or the optical system (such as the collimation element, the converging element, the pre-shaping element) close to the transmitter or close to the detector, while a back focal length (also referred to as a backward focal length) refers to the distance between a back surface apex of the optical element or the optical system and the back focal point; a front focal point (also referred to as a forward focal point) refers to a focal point of the optical element or the optical system (such as the collimation element, the converging element, the pre-shaping element) away from the transmitter or away from the detector, while a front focal length (also referred to as a forward focal length) refers to the distance between a front surface apex of the optical element or the optical system and the front focal point.

In some embodiments, the light path changing element206is arranged on the same side of the collimation element204as the transmitter203and the detector205, and the collimation element204includes the transceiver lens. In some embodiments, at least one of the light path changing element206, the detector205, and the transmitter203is arranged at one side of the optical axis of the collimation element204. For example, in the embodiments shown inFIG. 3, the transmitter203is arranged on the optical axis of the collimation element204, and the detector205is arranged at one side of the optical axis of the collimation element204. In the embodiments shown inFIG. 5, the detector205is arranged on the optical axis of the collimation element204, and the transmitter203is arranged at one side of the optical axis of the collimation element204. Furthermore, center axis of the light pulse sequence emitted by the transmitter203and center axis of the reflected light received by the detector can approximately 90°. Reflective surface of the light path changing element206is at 45° with the central axis of the light pulse sequence emitted by the transmitter203, and at 45° with the central axis of the reflected light received by the detector. The above is only an example, and it is not limited to this example. In some other embodiments, the detector205, the transmitter203, and the light path changing element206can also be arranged at other angles. As another example, in the embodiments shown inFIG. 6, the detector205and the transmitter203are both arranged at one side of the optical axis of the collimation element204.

In some embodiments, as shown inFIG. 6, the light path changing element206is deviated from the optical axis of the collimation element204, which is configured to project the light pulse sequence emitted by the transmitter203to the edge field of view of the collimation element204. As such, block of the reflected light by the light path changing element206can be reduced as much as possible, and more reflected light can be received by the detector, so as to achieve longer distance or weaker signal detection.

In some embodiments, the light path changing element includes the reflector, and at least part of one of the light pulse sequence emitted by the transmitter and the reflected light reflected by the detected object is transmitted from an outer edge of the reflector, and at least part of the other light is reflected by the reflector. For example, in the embodiments shown inFIG. 5, since the beam aperture of the light beam emitted by the transmitter203is small, and the beam aperture of the reflected light received by the ranging device is large, the light path changing element can use a small-area reflector to merge the transmission light path and the reception light path, and at least part of the light pulse sequence emitted by the transmitter203is reflected to the collimation clement204by the reflector, while at least part of the reflected light reflected by the detected of is projected to the detector205from the outer edge of the reflector.

In some other implementations, the light path changing element includes a reflector provided with a light-emission area. At least part of one of the light pulse sequence emitted by the transmitter and the reflected light reflected by the detected object passes through the light-emission area, and at least part of the other light is reflected by an edge of the reflector. The light-emission area includes an opening provided at the reflector. For example, as shown inFIGS. 3 and 6, the light path changing element206can also use the reflector with the opening, and the opening is configured to transmit at least part of the light pulse sequence emitted by the transmitter203, and the reflector is configured to reflect at least part of the reflected light to the detector205, so that block of the reflected light from a support of a small reflector in case of using the small reflector. For example, the light-emission area includes an anti-reflection coating provided at the reflector, which can increase intensity of the transmitted light beam. For example, a central area of the reflector is the light-emission area made of light-emission material, where the light-emission material is plated with the anti reflection coating, and the edge of the reflector is plated with a high-reflection coating, so as to reflect the light pulse sequence emitted by the transmitter or the reflected light.

In some embodiments, as shown inFIG. 3, at least part of the light pulse sequence emitted by the transmitter203passes through the light-emission area, and a light spot area of the light pulse sequence irradiated to the light path changing element206is greater than or equal to an area of the light-emission area. When the light spot area is larger than the area of the light-emission area, part of the light pulse sequence is blocked and cannot be used for detection.

In some other implementations, the transmitter203and the detector205may respectively use their own collimation elements. For example, as shown inFIG. 7, the transmitter203uses the collimation element204located on the transmission light path of the transmitter203, which is configured to collimate the light pulse sequence emitted by the transmitter203and then emit it, while the detector205uses a converging element2041with a converging effect. The converging element2041is configured to converge at least part of the reflected light reflected by the detected object to the detector205, and the light path changing element206is arranged on the light path behind the collimation element.

In the embodiments with off-axial transceiver as shown inFIG. 7, the ranging module210includes a transmission module2101and a reception module2102. The ranging module210also includes a first pre-shaping element2032and/or a second pre-shaping element2052. The first pre-shaping element2032is arranged on the transmission light path between the collimation element204and the light-emission surface of the transmitter203, and the second pre-shaping clement2052is arranged on the reception light path of the reflected light between the converging element2041and the photosensitive surface of the detector205. Effective aperture of the collimation element204is greater than effective aperture of the first pre-shaping element2032, and effective aperture of the converging element2041is greater than effective aperture of the second pre-shaping element2052. For example, only the first pre-shaping element may be provided on the transmission light path, or only the second pre-shaping element may be provided on the reception light path, or the first pre-shaping element2032and the second pre-shaping element2052may be respectively provided on the transmission light path and the reception light path.

The light pulse sequence e .witted by the transmitter203is first collimated and/or compressed by the first pre-shaping element2032, thereby increasing energy utilization rate of the transmitter, and then the light pulse sequence is collimated and/or compressed again by a collimation element with a large aperture, so that collimation characteristic of the light pulse sequence emitted by the transmitter is significantly improved. On the reception light path of the reflected light, the reflected light is converged by the converging element (or the collimation element on coaxial transceiver light path), and then the reflected light is converged again by the second pre-shaping element, thereby improving reception rate of the reflected light, which is conducive to improve a signal-to-noise ratio of the ranging device. In addition, due to the large effective aperture of the converging element, more reflected light reflected by the detected objects can be received, which is conducive to achieve longer distance or weaker signal detection of the ranging device.

An effective focal length of the collimation element204is greater than an effective focal length of the first pre-shaping element2032, for example, the of focal length of the collimation element204is greater than or equal to 10 times the effective focal length of the first pre-shaping element2032. Further, a backward focal length of the collimation element204is greater than or equal to 10 times a forward focal length of the first pre-shaping element2032. In some embodiments, an effective focal length of the converging element2041is greater than an effective focal length of the second pre-shaping element2052, for example, the effective focal length of the converging element2041is greater than or equal to 10 times the effective focal length of the second pre-shaping element2052. Further, as shown inFIG. 7, a backward focal length of the converging element2041is greater than or equal to 10 times a forward focal length of the second pre shaping element2052, or, as shown inFIG. 3, the transmission light path and the reception light path can share the same collimation element204, and the backward focal length of the collimation element204is greater than or equal to 10 times the forward focal length of the second pre-shaping element2052. The above numerical ranges are examples only, and other suitable numerical ranges can also be applied to the embodiments of the present disclosure.

The first pre-shaping element and the second pre-Shaping element may include a short focal length lens. For example, a focal length range of the first pre-shaping element is between 10 μm and 10 mm, and/or a focal length range of the second pre-shaping element is between 10 μm and 10 mm, or another suitable focal length range, which can also be applied to the structures shown inFIGS. 3-6. For example, as shown inFIG. 7, an effective focal length range of a first optical system is between 20 mm and 200 mm, and/or an effective focal length range of a second optical system is between 20 mm and 200 mm. The above numerical ranges are examples only, and other suitable numerical ranges can also be applied to the embodiments of the present disclosure.

Generally, in an optical system that includes multiple lenses, an effective focal length is a distance from a principal plane of the system to corresponding front and back focal points. In the optical system, a system focal length is usually expressed as the effective focal length. A front focal length of the optical system is a distance from the front focal point of the system to an apex of a first optical surface, and a back focal length is a distance from an apex of a last optical surface of the system to the back focal point.

For example, the first pre-shaping element2032includes an aspheric lens, and the second pre-shaping element2052includes an aspheric lens. The first pre-shaping element2032and the second pre-shaping element2052can be the same lens or different lenses, and the first pre-shaping element2032and the second pre-shaping element2052can also be another type of lens, such as a cylindrical lens, a spherical lens, a spherical lens group, or a combination of the lenses described above.

The ranging module210described above includes the first pre-shaping element2032and/or the second pre-shaping element2052. Positional relationships among various elements are specifically described with reference toFIGS. 3 and 4, but it is understandable that the positional relationships are also applicable to other structural types of the ranging module in the embodiments of the present disclosure.

In the embodiments with coaxial transceiver as shown inFIG. 3, the ranging module210shares the same collimation element through the light path changing element206to merge the transmission light path and the reception light path within the ranging device before the collimation element204, so that the transmission light path and the reception light path can share the same collimation element204, for example, share the same transceiver lens, which makes the light path more compact.

For example, as shown inFIG. 3, the first optical system includes the collimation element204and the first pre-shaping element2032, and the light-emission surface of the transmitter203is located between a backward focal. point of the collimation element204and the first pre-shaping element2032. For example, the light-emission surface of the transmitter203is located on a focal plane of the first optical system, such as, the light-emission surface of the transmitter203is located on a back focal plane of the first optical system, especially the light-emission surface of the transmitter is arranged on the back focal plane of the first optical system. The “focal plane” herein refers to a plane that passes the focal point of the corresponding optical system and is perpendicular to the optical axis of the optical system. The light-emission surface of the transmitter is arranged on the focal plane of the first optical system, which has a better collimation effect on the light pulse sequence emitted by the transmitter.

In the embodiments shown inFIG. 7, the second optical system includes the converging element2041and the second pre-shaping element2052, or, in the embodiments shown inFIG. 3, the second optical system includes the collimation element204and the second pre-shaping element2052. The detector includes the photosensitive surface located on a focal plane of the second optical system. For example, the photosensitive surface of the detector205is arranged on a back focal point of the second optical system, especially the photosensitive surface of the detector205is arranged on a back focal plane of the second optical system, so as to achieve a relatively better convergence effect and improve detection accuracy of the detector.

Distance from the transmitter203to the light path changing element206is not necessarily equal to distance from the detector205to the light path changing element206. As shown inFIG. 3, when a focal length of the first optical system is equal to a focal length of the second optical system, the transmitter203is arranged on the back focal plane of the first optical system. When the first pre-shaping element2032and the second pre shaping element2052are substantially the same element, since the distance from the transmitter203to the light path changing element206is equal to the distance from the detector205to the light path changing element206, then the detector is equivalent to being arranged on the hack focal plane of the second optical system, in which case the convergence effect of the reflected light is better.

Specifically, referring toFIG. 4, positional relationships among the transmitter, the first pre-shaping element, and the collimation element and positional relationships among the detector, the second pre-shaping element, and the collimation element (or the converging element) in the optical system are explained and described. AlthoughFIG. 4only shows part of the elements on the transmission light path inFIG. 3, it can be understood that the following positional relationships are also applicable to the corresponding elements on the reception light path, and is also applicable to other embodiments.FIG. 4shows a forward focal point11of the first pre-shaping element2032, a backward focal point12of the first optical system including the collimation element204and the first pre-shaping element2032, and a backward focal point13of the collimation element204. Correspondingly, the backward focal length of the collimation element204is f1, and the forward focal length of the first pre-shaping element2032is f2. Distance between the forward focal point11of the first pre-shaping element2032and the backward focal point13of the collimation element204is Δ, where Δ is greater than f2, and f1is greater than f2. Distance between the light-emission surface of the transmitter203and the first pre-shaping element2032is L, and center distance between the collimation element204and the first pre-shaping element2032is d.

For example, at least two of emission optical axis of the transmitter203(that is, the central axis of the light pulse sequence emitted by the transmitter), optical axis of the first pre-shaping element2032, and the optical axis of the collimation element204are coaxial. The distance between the light-emission surface of the transmitter203and the first pre-shaping element2032is smaller than the focal length of the first pre-shaping element2032, and in particular, is smaller than the forward focal length of the first pre-shaping element2032. For example, the distance L between the light-emission surface of the transmitter203and the first pre-shaping element2032satisfies the following formula:

Similarly, distance between the photosensitive surface of the detector205and the second pre-shaping element2052inFIG. 3can be calculated by the above formula. Since the detector205is located at one side of the optical axis of the collimation element204inFIG. 3, it can be rotated around an intersection of a central axis of the reception light path and a central axis of the transmission light path in direction of the transmitter, so that the central axis of the reception light path coincides with the central axis of the transmission light path, and equivalent calculation can be performed. It is only needed to replace Δ with an equivalent distance between a forward focal point of the second pre-shaping element and the backward focal point of the collimation element204on the optical axis of the collimation element, and replace f2with the forward focal length of the second pre-shaping element, where the equivalent distance is greater than the forward focal length of the second pre-shaping element. At least two of a receiving optical axis of the detector205(that is, the central axis of the reflected light reflected by the detected object received by the detector), an optical axis of the second pre-shaping elements2052, and the optical axis of the collimation element204are coaxial. The distance between the photosensitive surface of the detector205and the second pre-shaping element2052is smaller than the local length of the second pre-shaping element2052, in particular, is smaller than the forward focal length of the second pre-shaping element2052.

A focal length f (or an effective focal length) of the first optical system satisfies the following formula:

The distances in the formula are all positive, and the focal length f of the entire first optical system, under the premise that f1and f2are known, changes accordingly when the distance d between the first pre-shaping element2032and the collimation element204is adjusted, where f increases if d decreases, and f decreases if d increases. Therefore, value of the focal length f of the optical system depends on value of the distance d between the pre-shaping element and the collimation element, and similarly, the value of the distance d depends on the focal length f of the optical system, so that the center distance d between the first pre-shaping clement2032and the collimation element204is limited.

Similarly, the focal length f of the second optical system can be calculated by the above formula. The center distance d between the second pre-shaping element and the collimation element is also equivalent to the distance on the optical axis of the collimation element, and then the for local length f2of the pre-shaping element2052and the backward focal length f1of the collimation element204are substituted into the above formula to calculate the focal length f of the second optical system.

As shown inFIG. 4again, an effective divergence angle β of the light pulse sequence emitted by the transmitter203satisfies the following formula:

D is the effective aperture of the collimation element, f is the focal length of the first optical system, and the effective divergence angle refers to a divergence angle of the light pulse sequence actually incident to the collimation element. For example, since the collimation element is provided with the optical element such as the light path changing element206, the light path changing element206can only cause part of the light pulse sequence to be incident to the collimation element204.

It should be noted that the effective aperture herein refers to the maximum aperture of the corresponding optical element (such as the collimation element, the converging element, the pre-shaping element) that is actually used to collimate the light pulse sequence emitted by the transmitter and the reflected light received by the detector.

In some embodiments, as shown inFIGS. 3 and 5-7, the effective divergence angle of the light pulse sequence emitted b the transmitter203is smaller than an effective reception angle of the detector205, so that the detector205can receive more reflected light.

An effective photosensitive size of the detector205is greater than or equal to twice the size of an Airy disk of the second optical system. For example, the effective photosensitive size of the detector is greater than or equal to twice the diameter of the Airy disk D1of the second optical system, and the diameter of the Airy disk D1can be obtained by the following formula:

D is the effective aperture of the second optical system, f is the effective focal length of the second optical system, and λ is the wavelength of the light pulse sequence emitted by the transmitter.

Airy disk is a light spot formed at the focal point due to diffraction when a point light source is imaged through an ideal lens. The center is a bright round spot, surrounded by a set of weaker light and dark concentric ring stripes. A central bright spot bounded by the first dark ring is called Airy disk. The effective photosensitive size of the detector205is greater than or equal to twice the size of the Airy disk of the second optical system, so that the detector205can receive more light in addition to the Airy disk formed by the reflected light on the photosensitive surface, which can improve photosensitive performance of the detector.

For example, the effective photosensitive size of the detector205is greater than an effective light-emission size of the transmitter203, where the effective photosensitive size refers to the size of the photosensitive surface of the detector205actually used for light-sensing, such as area, etc., while the effective light-emission size refers to the size of the light-emission surface of the transmitter actually used to emit the laser pulse sequence, such as area, etc.

Shape of the photosensitive surface of the detector205includes a circle, an ellipse, a rectangle, or another suitable shape, which is not specifically limited herein.

In the embodiments shown inFIGS. 3 and 5-7, the transmitter203and the first pre shaping element2032are integrally packaged; and/or, the detector205and the second pre-shaping element2052are integrally packaged. The transmitter and the detector are each packaged together with the corresponding pre-shaping element thereto by a mature packaging process, so that integration is higher, production difficulty is reduced, and mass production is facilitated.

In some embodiments, as shown inFIGS. 3 and 5-7, the ranging device also includes a substrate (not shown) and a housing2031. The substrate is configured to carry the transmitter203, and the substrate (not shown) is configured to be mounted on a circuit board. The housing2031is provided on the surface of the substrate or the circuit hoard, so as to form an accommodation space between the substrate and the housing. The housing is at least partially provided with the light-emission area, and the transmitter203is provided in the accommodation space. The first pre-shaping element2032is provided at the light-emission area, and the light emitted from the transmitter203is emitted through the first pre-shaping element2032. For example, the first pre-shaping element2032is fixed at the light-emission area by form-sealed bonding or welding, or another suitable manner.

Similarly, the detector and the second pre-shaping element can also be packaged in the manner described above. The ranging device also includes a substrate (not shown) and a housing2051. The substrate is configured to carry the detector205, and the substrate (not shown) is configured to be mounted on a circuit board. The housing2051is provided on the surface of the substrate or the circuit board, so as to form an accommodation space between the substrate and the housing. The housing is at least partially provided with the light-emission area, and the detector205is provided in the accommodation space. The second pre-shaping element2052is provided at the light-emission area, and the light emitted from the detector205is emitted through the second pre-shaping element2052. For example, the second pre-shaping element2052is fixed at the light-emission area by form-sealed bonding or welding, or another suitable manner.

In some other embodiments, the ranging device also includes a bracket (not shown), and the first pre-shaping element2032is arranged at the bracket, so that the first pre-shaping element is fixed by the bracket. Similarly, the ranging device also includes a bracket (not shown), and the second pre-shaping element is arranged at the bracket, so that the second pre-shaping element, is fixed by the bracket.

In some other embodiments, the ranging device also includes a first seal body (not shown). The transmitter203is embedded in the first seal body, and the first pre-shaping element is arranged on an outer surface of the first seal body, which is configured to preliminarily compress the light pulse sequence emitted by the transmitter. The first pre-shaping element may be arranged on the outer surface of the first seal body by bonding or welding, or the first seal body and the first pre-shaping element can be integrally formed. Similarly, the detector and the second pre-shaping element can also be integrally packaged in the manner described above. The ranging device also includes a second seal body (not shown). The detector205is embedded in the second seal body, and the second pre-shaping element is arranged on an outer surface of the second seal body, which is configured to preliminarily compress the light pulse sequence omitted by the transmitter. The second pre-shaping element may be arranged on the outer surface of the second seal body by bonding or welding, or the second seal body and the second pre-shaping element can be integrally formed.

Thus, the description of the ranging device according to the embodiments of the present disclosure has been done. Other components and structures may also be included for a complete ranging device, which will not be repeated herein.

In summary, the ranging device according to the embodiments of the present disclosure combines the large-aperture collimation element (or the converging element) with the small-aperture pre-shaping element to form the optical system, which can be equivalent to a large aspheric lens capable of achieving excellent optical performance under a large-aperture lens at a lower cost, reducing aberration of the optical system, etc., which is beneficial to improve the performance of the ranging device such as a laser radar. Through preliminary collimation of the emitted light pulse sequence by the pre-shaping element (such as a pre-collimating lens) and re-convergence and compression of the reflected light reflected by the detected object, energy utilization rate of the transmitter (such as a laser) can be increased, and the collimation characteristic of the light pulse sequence emitted by the transmitter can be improved, and meanwhile, reception of the reflected light is more efficient, which is conducive to improve the signal-to-noise ratio of the system. In addition, since the laser/detector can be packaged together by a mature packaging process, the integration is higher, the production difficulty is reduced, and the mass production is facilitated. Therefore, compared with other conventional systems of small-aperture lenses and large-aperture lenses, the solution of the embodiments of the present disclosure overcomes the problems of complex structure and high production difficulty in the conventional systems.

The distance and orientation detected by the ranging device200can be used for remote sensing, obstacle avoidance, surveying and mapping, modeling, navigation, etc. In some embodiments, the ranging device according to the embodiments of the present disclosure can be applied to a mobile platform, and the ranging device can be mounted at a platform body of the mobile platform. The mobile platform with the ranging device can measure external environment, for example, to measure distance between the mobile platform and an obstacle for obstacle avoidance and other purposes, and to perform two-dimensional or three-dimensional surveying and mapping of the external environment. In some embodiments, the mobile platform includes at least one of an unmanned aerial vehicle, a car, a remote control vehicle, a robot, a camera, or a boat. When the ranging device is applied to an unmanned aerial vehicle, the platform body is a vehicle body of the unmanned aerial vehicle. When the ranging device is applied to a car, the platform body is a vehicle body of the car. The car can be a self-driving car or a semi-self-driving car, which is not limited here. When the ranging device is applied to a remote control vehicle, the platform body is a vehicle body of the remote control vehicle. When the ranging device is applied to a robot, the platform body is the robot. When the ranging device is applied to a camera, the platform body is the camera itself.

Although the exemplary embodiments have been described herein with reference to the accompanying drawings, it should be understood that the exemplary embodiments described above are merely exemplary, and are not intended to limit the scope of the present disclosure thereto. Those of ordinary skill in the art can make various changes and modifications therein without departing from the scope and spirit of the present disclosure. All these changes and modifications are intended to be included within the scope of the present disclosure as claimed in the appended claims.

Those of ordinary skill in the art may realize that the units and algorithm steps of the examples described in the embodiments disclosed herein can be implemented by electronic hardware or a combination of computer software and electronic hardware. Whether these functions are executed by hardware or software depends on the specific application and design constraints of the technical solutions. Professionals and technicians can use different methods for each specific application to implement the described functions, but such implementation should not be considered beyond the scope of the present disclosure.

It should be understood that, in some embodiments provided by the present disclosure, the disclosed device and method can be implemented in other manners. For example, the example device described above is only illustrative. For example, the division of the modules or units is only a logical function division, and there may be other divisions in actual implementation, e.g., multiple units or components may be combined or integrated into another device, or some features may be omitted or not performed.

In the specification provided here, a lot of specific details are described. However, it can be understood that the embodiments of the present disclosure can be implemented without these specific details. In some embodiments, well-known methods, structures, and technologies are not shown in detail, so as not to obscure the understanding of this specification.

Similarly, it should be understood that in order to simplify the present disclosure and help the understanding of one or more of the various aspects of the disclosure, the various features of the present disclosure are sometimes grouped together into a single embodiment, figure, or description thereof in the description of the exemplary embodiments of the present disclosure. However, the method of the present disclosure should not be construed as reflecting the intention that the claimed disclosure requires more features than those explicitly stated in each claim. More precisely, as reflected in the corresponding claims, the point of the disclosure is that the corresponding technical problems can be solved with features that are less than all the features of a single disclosed embodiment. Therefore, the claims following the specific embodiments are thus explicitly incorporated into the specific embodiments, where each claim itself serves as a separate embodiment of the present disclosure.

Those skilled in the art can understand all features, other than those mutually exclusive, disclosed in this specification (including the accompanying claims, abstract, and drawings) and all processes or units of any method or device disclosed can be employed in any combination. Unless expressly stated otherwise, each feature disclosed in this specification (including the accompanying claims, abstract, and drawings) may be replaced by an alternative feature providing the same, equivalent, or similar purpose.

In addition, those skilled in the art can understand that although some embodiments described herein include certain features included in other embodiments rather than other features, the combination of features of different embodiments means that they are within the scope of the present disclosure and form different embodiments. For example, in the claims, any one of the claimed embodiments can be used in any combination.

The various component embodiments of the present disclosure may be implemented by hardware, or by software module running on one or more processors, or by a combination thereof. Those skilled in the art should understand that a microprocessor or a digital signal processor (DSP) may be used in practice to implement some or all of the functions of some modules according to the embodiments of the present disclosure. The present disclosure can also be implemented as a device program (for example, a computer program and a computer program product) for executing part or all of the methods described herein. Such a program implementing the present disclosure may be stored on a computer-readable medium, or may have the form of one or more signals. Such signals can be downloaded from an Internet website, or provided in carrier signals, or provided in any other form.

It should be noted that the embodiments described above illustrate rather than limit the present disclosure, and those skilled in the art can design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference symbols placed between parentheses shall not be constructed as a limitation to the claims. The present disclosure can be implemented by means of hardware including several different elements and by means of a suitably programmed computer. In the unit claims listing several devices, several of these devices may be embodied in the same hardware item. The use of the words first, second, and third, etc. do not indicate any order. These words can be interpreted as names.