KR-20260062653-A - Apparatus and Method for Reducing Noise in LIDAR

KR20260062653AKR 20260062653 AKR20260062653 AKR 20260062653AKR-20260062653-A

Abstract

An apparatus according to an embodiment of the present disclosure comprises, in a lidar apparatus, a laser that emits a pulsed laser; an optical element that outputs or reflects the emitted pulsed laser to a distance measuring target; and a single photon detector that detects at least one of the light reflected from the distance measuring target and the light reflected from the optical element, wherein the single photon detector operates in a free running mode, and a gate mode is applied during the off time of the single photon detector determined based on the distance from the laser to the outermost optical element and the distance from the outermost optical element to the single photon detector with respect to the optical path of the lidar.

Inventors

이학순
곽재영
박철우

Assignees

에스케이텔레콤 주식회사

Dates

Publication Date: 20260507
Application Date: 20241029

Claims (9)

In a lidar device, A laser that emits a pulsed laser; A light element that outputs or reflects the above-mentioned emitted pulsed laser to a distance measuring target; and It includes a single photon detector that detects at least one of the light reflected from the distance measuring target and the light reflected from the light element, and The single photon detector operates in a free running mode, wherein a gate mode is applied during the off time of the single photon detector determined based on the distance from the laser to the outermost optical element and the distance from the outermost optical element to the single photon detector, relative to the optical path of the lidar. device.
In paragraph 1, The above off time is, A device that calculates a first value by the sum of the distance from the laser to the outermost optical element and the distance from the outermost optical element to the single photon detector, calculates a second value by dividing the first value by the speed of light, and determines the second value as the off time.
In paragraph 2, The start point of the above off time indicates the point in time when the pulse laser is emitted from the laser, device.
In paragraph 1, The above off time is, A third value is calculated by summing the distance from the laser to the outermost optical element and the distance from the outermost optical element to the single photon detector, a fourth value is calculated by dividing the first value by the speed of light, a fifth value is calculated by adding the laser pulse width time to the fourth value, and the fifth value is determined as the off time. device.
In paragraph 4, The start point of the above off-time indicates the point in time when a pulse laser is emitted from the laser, device.
In paragraph 1, When there are multiple optical elements that reflect the pulsed laser, the off time is determined from the start time of the off time to the time of the laser pulse width, and The above off time is applied to each of the plurality of optical elements, device.
In paragraph 6, The start point of the above off time indicates the point in time when the pulsed laser emitted from the laser is reflected from the corresponding optical element and incident on the single photon detector. method.
In paragraph 1, The above gate mode is, Applied by setting the bias voltage applied to the above single photon detector lower than the breakdown voltage, device.
In a method for reducing noise in LiDAR, In a laser, the process of emitting a pulsed laser; In a photonic device, a process of outputting or reflecting the emitted pulsed laser to a distance measuring target; and The process includes detecting at least one of the light reflected from the distance measurement target and the light reflected from the light element in a single photon detector. The single photon detector operates in a free running mode, wherein a gate mode is applied during the off time of the single photon detector determined based on the distance from the laser to the outermost optical element and the distance from the outermost optical element to the single photon detector, relative to the optical path of the lidar. method.

Description

Apparatus and Method for Reducing Noise in LIDAR The present disclosure relates to an apparatus and method for reducing noise in a lidar. The content described in this section merely provides background information regarding the present invention and does not constitute prior art. A typical coaxial LiDAR optical system has the advantage of maintaining a uniform amount of light across the field of view of the LiDAR when a scanner is applied, as the optical axes of the transmitter and receiver are the same. However, the coaxial structure reduces light reception efficiency because the laser must pass through an optical path at the center of the receiver's optical system. In particular, at short distances, there may be no incident light on the detector, which can lead to performance degradation. Furthermore, while single-photon detectors are used to increase the detection range of LiDAR, this presents a problem where even minute amounts of light directly reflected from the scanner, hole mirror, or cover act as significant noise for the single-photon detector. Figure 1 is an example of a lidar including a single photon detector. Figure 2 is an example diagram showing the gain during linear mode and Geiger mode operation. FIG. 3 is a first exemplary diagram of a single-photon detector-based lidar according to an embodiment of the present disclosure. FIG. 4 is an exemplary diagram showing a method for applying a gate mode according to an embodiment of the present disclosure. FIG. 5 is a second exemplary illustration of a single-photon detector-based lidar according to another embodiment of the present disclosure. FIG. 6 is an exemplary diagram illustrating a method for applying a gate mode according to another embodiment of the present disclosure. FIG. 7 is a third exemplary illustration of a single-photon detector-based lidar according to an embodiment of the present disclosure. FIG. 8 is a fourth exemplary diagram of a single-photon detector-based lidar according to an embodiment of the present disclosure. FIG. 9 is a fifth exemplary diagram of a single-photon detector-based lidar according to an embodiment of the present disclosure. Some embodiments of the present disclosure are described in detail below with reference to the exemplary drawings. It should be noted that in assigning reference numerals to the components of each drawing, the same components are given the same reference numeral whenever possible, even if they are shown in different drawings. Furthermore, in describing the present disclosure, if it is determined that a detailed description of related known components or functions could obscure the essence of the present disclosure, such detailed description is omitted. In addition, terms such as first, second, A, B, (a), (b), etc. may be used to describe the components of the present disclosure. These terms are intended only to distinguish the components from other components, and the nature, order, or sequence of the components is not limited by these terms. Throughout the specification, when a part is described as 'comprising' or 'equipped' with a certain component, unless specifically stated otherwise, this means that it does not exclude other components but may include additional components. Furthermore, terms such as '…part' or 'module' described in the specification refer to a unit that processes at least one function or operation, and this may be implemented in hardware, software, or a combination of hardware and software. The detailed description set forth below, together with the accompanying drawings, is intended to describe exemplary embodiments of the present disclosure and is not intended to represent the only embodiment in which the present disclosure can be practiced. To increase detection range, single-photon detectors are used in LiDAR. However, in this case, even minute amounts of light directly reflected from hole mirrors, scanner mirrors, or covers can act as significant noise for the single-photon detector. This noise can appear as band-shaped noise on the 3D point cloud and affect the performance of the system. Furthermore, since single-photon detectors have a dead time, they may not operate again for a certain period after being activated once. Consequently, there is a problem where even minute amounts of light directly reflected from within the lidar act as significant noise. When a single-photon detector is applied to a rangefinder included in a lidar, the rangefinder generally operates in free-running mode because the measurement distance is not fixed. A single-photon detector has the advantage of having a gain that is hundreds of thousands of times greater than that of a general detector, and it responds even when only one photon is incident. General detectors operate in linear mode, while single-photon detectors operate in Geiger mode. Single-photon detectors are widely used in long-range lidar, long-range distance measuring devices, and long-range optical communication d