Apparatus for laser surveying of an environment

Abstract

A device (1) for surveying an environment by time-of-flight measurement of a laser beam (4 i ) reflected from the environment (2), comprising a beam deflection device (13) with at least one mirror surface (18-25) which can be rotated or oscillated about an axis of rotation (26) which is not perpendicular to the mirror surface, and a first laser transmitter (111) associated with a first laser receiver (141) and a second laser transmitter (112) associated with a second laser receiver (142), the emission and reception directions (301, 311, 302; 312) in each case being parallel to one another in pairs and at different angles (α1, α2) to the axis of rotation (26), wherein in each case the first laser receiver (141) is spaced apart (PX) from the first laser transmitter (111) and the second laser receiver (142) is spaced apart (PX) from the second laser transmitter (112) in the direction of the axis of rotation (26).

Description

Technical Field

[0001] The present invention relates to an apparatus for surveying an environment by measuring the time of flight of a laser beam, particularly a pulsed laser beam, reflected from the environment. The apparatus comprises: a beam deflection device having at least one mirror surface rotatable or oscillating about a rotation axis not perpendicular to the mirror surface; the beam deflection device having a mirror prism, each prism side forming a mirror surface and the prism axis being the rotation axis; a first laser emitter configured to emit a first emitted laser beam via the beam deflection device in a first time-related emission direction; and a first laser receiver configured to receive the first emitted laser beam reflected from the environment and received back via the beam deflection device in a first time-related reception direction as a first received laser beam, wherein the first emission and reception directions are parallel to each other at the corresponding emission and reception times of the emitted and received laser beams and form a first angle with the rotation axis. Background Technology

[0002] This type of device is known, for example, from EP3182159B1, and is particularly used for aerial surveying of landscapes. Multiple laser pulses are emitted from a laser scanner on an aircraft from high altitude to numerous target points on the ground via a beam deflection device. A point model of the terrain (“3D point cloud”), target distances, and distances from these targets are created based on time-of-flight measurements of the target reflections—the location and position of the laser scanner and the corresponding deflection angles are known. In this process, the emitted laser beam, directed at a rotating or vibrating reflector surface, is thus periodically rotated (“scanned”) within a range of scanning angles, forming a scanning fan for scanning the landscape. The received laser beam, reflected by the environment, is received back along the same path; that is, in each case, the reflector surface used to emit laser pulses in a specific direction is simultaneously used to deflect laser pulses received from the same direction to the laser receiver.

[0003] Such laser scanners must meet a wide range of requirements. On the one hand, it is desirable to create point clouds as quickly and completely as possible during survey flights; on the other hand, the surveys should be as error-free as possible simultaneously. Dust, moisture, or clouds within the near-range can cause interfering reflections, complicating or distorting the creation of the landscape model. The object of this invention is to provide a device for laser scanning that can generate environmental point clouds particularly quickly and meaningfully without nearby target errors. Summary of the Invention

[0004] This objective is achieved by a device of the type described at the beginning, characterized by: a second laser emitter configured to emit a second emitted laser beam in a second time-related emission direction via a beam deflection device; and a second laser receiver configured to receive the second emitted laser beam reflected from the environment and received back in a second time-related reception direction via a beam deflection device as a second received laser beam, wherein the second emission and reception directions are parallel to each other at the corresponding emission and reception times of the emitted and received laser beams and form a second angle with the rotation axis, and wherein, in each case, in the direction of the rotation axis, the first laser receiver is spaced apart from the first laser emitter, and the second laser receiver is spaced apart from the second laser emitter.

[0005] The laser scanning apparatus of the present invention can simultaneously emit two or more divergent scanning fans (further details below) using a single beam deflection device. On the one hand, this allows twice the number of environmental measurement points to be created for a point cloud at the same time. On the other hand, if the apparatus moves over the environment in a feed direction deviating from the plane of the scanning fan, in each case, the same point in the environment will be struck by the scanning fan at a different angle, so that a surface that happens to be in the plane of one scanning fan can also be correctly detected by the other scanning fan. For example, in aerial surveying, if one scanning fan points towards the nadir while the other points diagonally forward or backward, vertical building facades can also be correctly plotted in the point cloud. Simultaneously, due to the parallax caused by the mutual spacing of the laser emitter and receiver in the direction of rotation axis, the survey is less susceptible to interference from "erroneous" environmental targets at close range, such as aircraft chassis components, clouds, etc. Due to this parallax, the apparatus can only detect targets from a specific minimum distance, which depends on the beam spread of the emitted laser beam, the receiving aperture of the laser receiver, and the aforementioned distance between the emitter and receiver.

[0006] As a result, the device of the present invention enables particularly rapid, complete and interference-free surveying of the environment in a simple manner, namely, a single beam deflection device extending in the direction of the rotation axis, with the laser emitter and receiver distributed along the rotation axis.

[0007] Preferably, the laser emitter is directed toward the beam deflection device such that the emitted laser beams substantially intersect each other at the beam deflection device. The statement "substantially at the beam deflection device" means the area immediately adjacent to the beam deflection device with respect to the average measurement distance of the environment. For example, in the case of an airborne laser scanner, the environment is surveyed from an altitude of several 100 meters or kilometers, and the relatively negligible short range can be as high as a few meters.

[0008] By making the emitted laser beams intersect as close as possible to the beam deflection device, when viewed in the direction of the rotation axis, the impact points of the emitted laser beams on the reflector surface of the beam deflection device are as close as possible to each other, so that the length of the beam deflection device in the direction of the rotation axis can be reduced.

[0009] According to another preferred feature of the invention, the angular orientation of the laser emitter and receiver, particularly the distance between the laser receiver and the beam deflection device, is selected such that the received laser beams intersect each other between the beam deflection device and the laser receiver. In the same manner, this minimizes the required impact area of ​​the received laser beams on the beam deflection device in the direction of its rotation axis. Furthermore, a common focusing optics unit can be arranged in the intersection region of the received laser beams, such that only one focusing optics unit is needed for all received laser beams, and their size can be reduced to the intersection region.

[0010] In a first preferred embodiment of the invention, the first and second transmitting and receiving directions are located in a common plane parallel to the axis of rotation at the corresponding transmitting and receiving times of the laser beam and the laser beam, respectively. When the device is mounted on the feed direction of a transport platform, such as an aircraft, with its axis of rotation, the scanning fans thus overlap in the feed direction, allowing the same location in the environment of the scanning fans to be scanned at different angles.

[0011] In a second preferred embodiment of the invention, the laser emitter and laser receiver are oriented in such a way that, when viewed from away from the beam deflection device and the environment, those emitting and receiving laser beams that are close to each other are deflected relative to each other. This increases near-range insensitivity and therefore increases sensitivity to device interference. Without this measure, it is possible that the emitted laser beam from the laser emitter could be reflected by a nearby target, such as a cloud, along the receiving direction assigned to the laser receiver of the other laser emitter, and thus result in erroneous points in the point cloud.

[0012] In a first particularly preferred variant, the mirror prism has a groove extending around its periphery, wherein, when viewed in the direction of the prism axis, the laser emitter is located on one side of the groove and the laser receiver is located on the other side of the groove. In a second preferred variant, the mirror prism has a rib extending around its periphery, wherein, when viewed in the direction of the prism axis, the laser emitter is located on one side of the rib and the laser receiver is located on the other side of the rib. This significantly increases the selectivity of the device's near-range insensitivity. Furthermore, this groove or rib prevents the emitted laser beam from being interferingly scattered into the received laser beam at the near range of the device.

[0013] In both variations, when viewed along the prism axis, the laser receiver is preferably located at a greater distance from the groove or rib than the laser emitter. In other words, a large portion of the longitudinal length of the mirror prism is available for the area irradiated by the laser beam, enabling the use of a large receiving aperture, thus resulting in high measurement sensitivity and, consequently, a wide measurement range. Simultaneously, the longitudinal portion of the mirror prism used for transmitting the laser beam is minimized, resulting in a reduced length for the mirror prism.

[0014] The device according to the invention can be extended to any number of laser emitters and receivers, such as three, four, five, etc., using the aforementioned principle, each laser emitter and receiver pointing at the beam deflection device at a different angle. Therefore, another preferred embodiment of the invention is characterized by: a third laser emitter configured to emit a third emitted laser beam in a third time-related emission direction via the beam deflection device, and a third laser receiver configured to receive the third emitted laser beam reflected from the environment and received back via the beam deflection device in a third time-related reception direction as a third received laser beam, wherein the third emission and reception directions are parallel to each other at the corresponding emission and reception times of the emitted and received laser beams and form a third angle with the axis of rotation, and wherein the third laser receiver is spaced apart from the third laser emitter in the direction of the axis of rotation.

[0015] For detecting vertical surfaces or elevations in the covered terrain, it is particularly advantageous that the first and second transmission and reception directions, as well as the second and third transmission and reception directions, in each case form an angle at the corresponding transmission and reception times of the transmitted and received laser beams, said angle being in the range of 1° to 30°, preferably 5° to 15°, and particularly preferably 5° to 10°.

[0016] If all mirror surfaces are preferably provided to be parallel to the axis of rotation, and the second transmitting and receiving directions are perpendicular to the axis of rotation, this results in horizontal movement of the device relative to the environment not in the scanning fan plane—in the first scanning fan in the direction of lowest point, in the second scanning fan in the direction of tilting forward, and in the third scanning fan in the direction of tilting backward. This allows for particularly good generation of point clouds across buildings with vertical surfaces.

[0017] In each of the above embodiments, it is particularly advantageous if the beam deflection device has at least one compensating mirror in the beam path from the received laser beam to the laser receiver, which is adjustable about an adjustment axis parallel to the axis of rotation. Such a compensating mirror can be used to compensate for time shifts, and thus for directional shifts in the mirror surfaces of the beam deflection device(s), which occur between the emission of a laser pulse from the beam deflection device and its return to the receiver at the beam deflection device. During this time, the corresponding mirror surface has rotated slightly, and therefore it will "see" the received laser beam in a direction different from the direction in which the emitted laser beam was "sent". This directional shift depends on the measurement distance and the angular velocity of the mirror surface, and can be compensated accordingly by the compensating mirror. Therefore, regardless of the angular velocity and measurement distance, the emission and reception directions of the associated laser emitter and laser receiver can be kept constantly parallel to each other, which significantly simplifies setup. However, it should be understood that, instead of a compensating mirror, the laser receiver can also be slightly angularly adjusted relative to the laser emitter or the portion of the emission deflection device assigned to it, which is included herein under the term "substantially parallel emission and reception directions of the laser emitter and receiver".

[0018] It is particularly advantageous to provide a common compensating mirror for all received laser beams. Since the directional offset is the same for all received laser beams, such a single compensating mirror can be used, thus simplifying the construction of the device.

[0019] As described above, a preferred application of the device of the present invention is that it is installed on an aircraft constructed for the main flight direction, wherein the rotation axis of the aircraft is not perpendicular to the main flight direction, but preferably substantially parallel to the main flight direction. Attached Figure Description

[0020] The invention will now be explained in more detail with reference to exemplary embodiments shown in the accompanying drawings. The drawings show: Figure 1 The present invention is a device installed on an aircraft for surveying terrain. Figure 2 yes Figure 1 A block diagram of one of the multiple transmit and receive channels of the device, in which the beam path is schematically depicted; Figure 3 and 4 It has no shell. Figure 1 The device, firstly, is a front view viewed along the axis of rotation ( Figure 3 ), one is a side view ( Figure 4 The beam path is schematically drawn in each case; and Figure 5 For example Figure 4 That side view shows Figure 1 The parallax of the laser transmitter and receiver in the transmit / receive channel of the device is shown, with the beam path schematically depicted. Detailed Implementation

[0021] Figure 1 An apparatus 1 for surveying the environment 2 from a vehicle 3 is shown. The environment 2 to be surveyed can be, for example, a landscape (topography), but can also be a road surface and facade along a road, the inner surface of a hall, tunnel or mine, or the sea surface or seabed, etc. The vehicle 3 can be a manned or unmanned land, air or water vehicle.

[0022] For the purpose of surveying environment 2, device 1 uses two or more (here: three) laser measuring beams 41, 42, 43 (typically 4) i (i = 1, 2, ...)) Scanning environment 2. Each laser measurement beam 4 i Pivoting back and forth to form the corresponding scanning sector 5 i Furthermore, the vehicle 3 moves forward in the direction of travel F to scan the environment 2 in the adjacent scan zone 6 (only one is shown). If the vehicle 3 is an aircraft, then the direction of travel F is the main flight direction for which the aircraft is constructed.

[0023] The direction of travel F is not in the scanning sector 5 i In the plane shown, the direction of travel F is perpendicular to the plane of scan fan 52, such that scan fan 52 is located in the direction of the lowest point of vehicle 3, and scan fan 53 points forward at an angle, while scan fan 51 points backward and downward at an angle toward environment 2. However, scan fan 5... i Alternatively, they could be rotated about the vertical axis g of the vehicle 3, such that their intersection line 7 with the environment 2 is... i That is, the "scanning line" in the scanning strip 6 is laid flat and tilted relative to the direction of travel F of the projection. In the same way, the scanning fan can rotate about the pitch axis p and / or roll axis r of the vehicle 3.

[0024] Scanning sector 5 i It doesn't have to be planar. For example, due to the laser measurement beam 4 discussed later... i The deflection mechanism, with the rearward and forward scanning sectors 51, 53 situated on a weakly curved conical surface; see exemplary curvature of scan lines 71, 73. This is negligible for the purposes of this invention; the term "planar" scanning sector 5... i and scanning sector 5 i The term "scanning sector plane" in this specification is understood to include such a weakly curved scanning sector.

[0025] 4 per laser measurement beam i Includes the laser beam 8 emitted from device 1 to environment 2.i and the received laser beam 9 reflected back to device 1 from the environment. i According to the laser pulse S i，n Time-of-flight measurements of (n = 1, 2, ...), where laser pulse S i，n Included in the corresponding emitted laser beam 8 i And each point P in environment 2 i，n The laser beam is reflected and received back in device 1 as the receiving laser beam 9. i Environmental reflected laser pulse E i，n The current position Pos from device 1 can be calculated using known relationships. i,n To the corresponding scan point P in environment 2 i，n Distance measurement value d i，n d i,n = c·ΔTP i,n / 2 = c·(t) E,i,n - t S,i,n ) / twenty one) in, t S，i，n …Emit laser beam 8 i The emitted laser pulse S i，n Launch time, t E，i，n ………Receive laser beam 9 i Received laser pulse E i，n The reception time, and c………speed of light.

[0026] Given the laser pulse S i，n The launch time is the corresponding position pos of device 1 in the local or global x / y / z coordinate system 10 of environment 2. i，n The corresponding orientation of device 1 in coordinate system 10. i，n And laser measurement beam 4 i At point P i，n ang in the direction relative to the corresponding angular position of vehicle 3 i，n Then, based on the corresponding distance measurement value d i，n Calculate scan point P i，n The position in coordinate system 10, wherein the orientation ori i，n For example, this can be represented by the tilt angle, roll angle, and deflection angle of vehicle 3 around its lateral, longitudinal, and vertical axes p, r, and g. A large number of such survey and calculation scan points P... i，n Environment 2 is imaged in the form of "scanned point cloud" in coordinate system 10.

[0027] Figure 2The time-of-flight measurement principle of device 1 is illustrated in one of the three transmit / receive channels of device 1, where each channel is responsible for scanning sector 5. i The same principle applies to each transmit / receive channel of device 1, i.e., each scan sector 5. i .

[0028] according to Figure 2 The emitted laser pulse S in the i-th transmit / receive channel i，n Laser emitter 11 i The laser beam 8 is emitted via a reflector 12 and a deflection device 13, such as an oscillating reflector, a rotating polygonal mirror wheel, a rotating reflector pyramid, or a rotating reflector prism. i The corresponding environmental point P on the same path i，n After reflection, the laser pulse E is either reflected by the deflection device 13 or used as an ambient reflection or to receive the laser pulse E. i，n To receive laser beam 9 i The signal is received back in the form of laser and incident on laser receiver 14. i Up. Laser pulse S i，n launch time t S，i，n and laser pulses E reflected from the environment i，n Reception time t E，i，n The distance is provided to the measuring device 15, which uses it to calculate the corresponding distance d using equation (1). i，n .

[0029] Emit laser pulse S i，n The pulse repetition rate (PRR) is constant or can be modulated, for example, to resolve MTA (multi-path) ambiguity in order to facilitate the reception of pulse E. i，n and the emitted pulse S i，n The allocation of each other, as is known in the art.

[0030] Figure 3 and 4 The mechanical and optical components of all three transmit / receive channels of device 1 are shown. For clarity, in Figure 3 and 4 The housing 16 of the device 1 that stores all these components has been removed. Figure 2 ).

[0031] exist Figure 3 and 4 In the example, the beam deflection device 13 for all transmit / receive channels is a common reflector prism 17, whose prism sides 18-25 are each formed for deflecting the transmit and receive laser beams 8. i and 9 iThe mirror prism 17 has a mirror surface, and its prism axis is the axis of rotation 26 about which the mirror surface 18-25 rotates. The mirror prism 17 can have any number of prism sides, such as three, four, etc., thus having mirror surfaces 18-25, and can be regular or irregular prisms. Therefore, the prism sides or mirror surfaces 18-25 can all have the same size and be equidistant from the prism axis 26, or they can be unequal.

[0032] The reflecting prism 17 rotates at an angular velocity ω. Because the device 1 serves as the source of the emitted laser pulse S... i，n The emitted and received laser pulses E in device 1 i，n The flight time ΔT of the received laser pulse i，n The beam deflection device 13 during flight time ΔT i，n During this period, it continues to move at an angular velocity ω, such that when receiving the laser beam 9 i At that time, the corresponding reflector surfaces 19-25 (here: 24) no longer have the same position. In order to use the emitted laser pulse S i，n Measurement of environmental point P i，n It can still be used in laser receiver 14 i Precisely from the emitted laser beam 8 i Orientation R i，n Receive the corresponding laser pulse E i，n The beam deflection device 13 also includes a compensating mirror 27, which can be adjusted by means of an actuator 29 about an adjustment axis 28 parallel to the rotation axis 26. The actuator 29 can be adjusted, for example, by the angular velocity ω and the last measured point P. i，n The current average target distance d i，n To control and compensate for the aforementioned effects.

[0033] Instead of using the compensating reflector 27, the choice depends on the angular velocity ω and the current average target distance d. i，n 8 laser beams are being emitted i and receiving laser beam 9 i The aforementioned angular offset can also be achieved through the corresponding laser emitter 11 i And its associated laser receiver 14 i This is achieved through the corresponding angular offset between them, for example, through laser emitter 11. i and / or laser receiver 14 i A rotary bearing surrounding the rotation axis 26 is used, which is adjusted by an actuator 29. In another variation, it is used for the laser emitter 11. i The longitudinal portion 17 of the reflecting prism 17 a It can be used relative to the laser receiver 14 i The longitudinal portion 17 of the reflecting prism 17b Rotate at an angle, for example, the longitudinal portion 17 a 17 b Mounted on a common axis, they are angularly rotatable relative to each other about a rotation axis 26 to compensate for the differences in laser beam emission and reception 8. i 9 i The aforementioned angular offset between them. For this purpose, actuator 29 again determines the angular velocity ω of the reflecting prism 17 and the current average target distance d. i，n To adjust the two longitudinal sections 17 of the reflecting prism 17 a 17 b The angular offset between them.

[0034] For each transmit / receive channel i, i.e., for each scan sector 5 i In each case, device 1 includes a laser emitter 11. i and associated laser receiver 14 i That is, in the example shown, the laser emitter and laser receiver are paired with {11,14} 11}、{11,14 22} and {11,14 33}. Used for laser emitter 11 i The launching direction of device 1 is 30°. i In each case, it is essentially parallel to, more specifically, in each case, the transmitting and receiving laser beams are respectively 8 i 9 i The transmission and reception of laser pulses S in i,n E i,n launch time t S,i,n ("transmission time") and associated reception time t E,i n The observation at the location of (“reception time”) is used to determine the corresponding scanning sector 5. i The laser emitter and laser receiver pair of laser receiver 14 i The receiving direction 31 of device 1 i Here, the angular offset of the reflector 27 or the laser emitter and laser receiver 11 is compensated for. i 14 i Or the corresponding longitudinal portion 17 of the reflecting prism 17 a 17 b The mutual rotation compensation deflection device 13 around the rotation axis 26 during the pulse flight time d i,n Further rotation during the period.

[0035] In transmitting and receiving laser beams 8 i 9 i All laser emitters observed at the corresponding emission and reception times 11i Launch direction 30 i In each case, the angle α with respect to the axis of rotation 26 is different. i And therefore at different angles α with the mirror surface 18-25 used in each case. i See also Figure 4 The same applies to laser receiver 14. i Receiving direction 31 i Therefore, they are paired and parallel.

[0036] In transmitting and receiving laser beams 8 i 9 i At the corresponding emission and reception times, the angles α1-α2 between the emission direction 301 of the first laser emitter 111 and the emission direction 302 of the second laser emitter 112, and the angles α2-α3 between the emission direction 302 of the second laser emitter 112 and the emission direction 303 of the third laser emitter 113 are considered again, and therefore the corresponding angles between the reception directions 311, 312, and 313 are also considered, for example, 1° to 30° in each case, preferably 5° to 15°, particularly preferably 5° to 10°, and particularly preferably, for example, about 7°.

[0037] It is understandable that the laser emitter 11 i and laser receiver 14 i Alternatively, the reflector surface 18-25 of the deflection device 13 can be pointed directly, instead of via the deflection and compensation reflectors 12, 27, or via several deflection and / or compensation reflectors.

[0038] Laser emitter 11 i and the corresponding associated laser receiver 14 i They are spaced apart when viewed along the direction of rotation axis 26, i.e., they have a parallax PX in the direction of rotation axis 26. As a result, laser receiver 14 i Laser beam 8 is emitted to surrounding targets (such as chassis components of vehicle 3, clouds, etc.) located at a short range N from device 1. i Their reflexes are insensitive, or in other words, "blind".

[0039] like Figure 5 As shown, the size N of this short-range device 1, which is insensitive to the measurement target, depends on the parallax PX and the beam of emitted laser 8. i The inevitable beam broadening W and laser receiver 14 i The receiving aperture A. In Figure 3 and 4 In the example, the receiving aperture A is the laser receiver 11. iThe viewing angle is determined by the dimensions of the reflector surface 18-25, the dimensions of the compensation reflector 27, and the location of each receiving laser beam 9. i The aperture of the focusing optical unit 32 in the beam path and each laser receiver 14 i The intersection point formed by the dimensions of the light-detecting surface is determined. Device 1 is only sensitive to measurements from a distance N, where N is the ambient point P. i,n Distance from device 1, where environmental point P i,n Located in the corresponding laser receiver 14 adjusted by the receiving aperture A i Within the field of view B. Conversely, targets at close range N are thus concealed, such as jamming clouds 33. In an exemplary embodiment, a laser beam 8 is emitted. i The beam spread is 0.1-1 milliradians, the receiving aperture A is 1-10 milliradians, and the parallax PX is 5-50cm, preferably 10cm-20cm.

[0040] To further improve the short-range insensitivity of device 1 and increase the selectivity of short-range N, the reflector prism 17 may optionally be equipped with ribs 34 extending around its periphery. The larger the diameter of the ribs 34, the better the selectivity of short-range N; moreover, the ribs 34 can be used to completely block stray light from very close targets, such as stray reflections from the housing 16 of device 1 or from components of vehicle 3.

[0041] Instead of the peripheral rib 34, a peripheral groove can also be machined into the reflector prism 17 to increase the selectivity between the transmitting and receiving channels of the device 1. Such a groove can also be interpreted as meaning that the reflector prism 17 consists of a sequence of several individual reflector prisms that are axially connected in series on the same rotation axis 26 and rotate together around the rotation axis 26.

[0042] For the high sensitivity of device 1, and therefore for the measurement of the distant environment 2, laser receiver 11 i The maximum possible receiving aperture A is desired, namely, the maximum possible mirror surface 18-25, the maximum possible focusing optical unit 32, and the corresponding large compensating mirror 27. (As from...) Figure 4 As can be seen from the image, when viewed in the direction of the rotation axis 26, the laser receiver 14... i Especially located in the laser emitter 11 i At a distance b from the groove or rib 34 that is further away from them than distance a, i.e. b > a, Preferably b>>a.

[0043] As a result, compared with the laser beam used to emit 8 iIn contrast, a larger axial region of the reflecting prism 17 is reserved for receiving the laser beam 9. i Conversely, laser emitter 11 i 8 emitted laser beams i The laser beam is powerfully focused and requires only a very small impact point on the mirror prism 17, so that only the short axis portion of the mirror prism 17 needs to be reserved for emitting the laser beam 8i.

[0044] In order to make the laser beam 8 emitted on the reflector prism 17 i Minimal required area, laser emitter 11 i The reflector prism 17 (with or without the deflector 12) is arranged in such a way that the laser beam 8 is emitted. i Basically, the beam crosses at the beam deflection device 13, that is, in its immediate vicinity, at the crossover point K. s The intersection point is K, viewed from the direction of rotation axis 26. s The closer to the reflector surface 18-25 of the reflector prism 17, the shorter the axial portion of the reflector prism 17, which is the laser beam 8 emitted from the reflector prism 17. i The deflection required.

[0045] Laser receiver 14 i Alternatively, it can be arranged in such a way that the laser beam 9 is received i They intersect each other, more specifically, on the one hand, also near the beam deflection device 13, in order to minimize the axial length of the reflector prism 17 required for this purpose, and on the other hand, in order to arrange the focusing optical unit 32 in the intersection region K of the laser beam receiving area. E In this way, the size of the focusing optical unit 32 can be reduced to the size of the intersection region K. E Therefore, it is minimized.

[0046] If all mirror surfaces 18-25 of the beam deflection device 13 are parallel to the rotation axis 26, and the second transmitting and receiving directions 302, 312 are perpendicular to the rotation axis 26, then the second scanning fan 52 extends from the vehicle 3 along the lowest point direction, assuming the rotation axis 26 is horizontal. If the rotation axis 26 is located in the travel direction F of the vehicle 3, then in this case, the scanning fan 52 is located in a vertical plane transverse to the travel direction F. Then the first and third scanning fans 51, 53 are tilted forward and backward, respectively.

[0047] To prevent the laser beam 9 from approaching when viewed from the beam deflection device 13 i (Here: those emitting laser beams 81 and receiving laser beams 93) iUnexpected backscattering, which could lead to their accidental reflection by nearby targets 33, can be addressed by the following optional measures. Laser emitter and laser receiver 11 i 14 i Oriented in such a way that, when viewed from a distance away from the beam deflection device 13 (here, looking downwards), the emitted and received laser beams 8 are close to each other between the beam deflection device 13 and the environment 2. i 9 i They are at a certain angle to each other. This can avoid... Figure 4 The laser pulse S shown at the bottom center i，n Backscattered to uncorrelated laser receiver 14 j The situation in the receiving channel (j≠i).

[0048] It should be understood that laser emitter 11 i and its launch direction 30 i (and the corresponding laser receiver 14) i and the receiving direction parallel to it 31 i Then it is no longer located in the plane parallel to the rotation axis 26, but deviates from that plane. Even a slight deviation from the plane of the rotation axis 26 is sufficient to achieve deflected transmission and reception of the laser beam 8 within the desired short range of the device 1. i 9 j The normal distance between them approximately corresponds to the parallax PX, and thus establishes the connection between non-proximity (i.e., parallel) laser beams (82, 92) or divergent (83, 91) transmitting and receiving laser beams. i 9 i The parallax PX is the same as the short-range insensitivity.

[0049] It should be understood that in all the embodiments shown, instead of the rotating mirror surfaces 18-25, and especially instead of the rotating mirror prism 17, periodically oscillating mirror surfaces 18-25 may also be used, for example, corresponding to... Figure 3 and 4 A single oscillating mirror of one of the mirror surfaces 18 and 25 in the arrangement shown.

[0050] Therefore, the present invention is not limited to the embodiments shown, but includes all variations, modifications and combinations thereof that fall within the scope of the appended claims.

Claims

1. A method for transmitting a laser beam (4) reflected from the environment (2). i An apparatus (1) for surveying the environment (2) by measuring the time of flight of a 1000 tonnes, comprising: A beam deflection device (13) has at least one mirror surface (18-25) that is rotatable or oscillating about a rotation axis (26) not perpendicular to the mirror surface. The beam deflection device (13) has a mirror prism (17) whose prism sides each form a mirror surface (18-25), and whose prism axis is the rotation axis (26). A first laser emitter (111) is configured to emit a first emitted laser beam (81) in a first time-related emission direction (301) via the beam deflection device (13), and The first laser receiver (141) is configured to receive the first emitted laser beam (81) reflected by the environment (2) and received back via the beam deflection device (13) in a first time-related receiving direction (311) as the first received laser beam (91). Wherein, the first transmitting and receiving directions (301, 311) are in the transmitting and receiving laser beam (8 i 9 i The corresponding transmission and reception times are parallel to each other and form a first angle (α1) with respect to the rotation axis (26). The device (1) further includes a second laser emitter (112) configured to emit a second emitted laser beam (82) in a second time-dependent emission direction (302) via the beam deflection device (13), and The second laser receiver (142) is configured to receive the second emitted laser beam (82) reflected from the environment (2) and received back via the beam deflection device (13) in a second time-dependent receiving direction (312) as the second received laser beam (92). Wherein, the second transmitting and receiving directions (302, 312) are in the transmitting and receiving laser beam (8 i 9 i The corresponding transmission and reception times are parallel to each other and form a second angle (α2) with the rotation axis (26). In each case, in the direction of the rotation axis (26), the first laser receiver (141) is spaced PX from the first laser emitter (111), and the second laser receiver (142) is spaced PX from the second laser emitter (112), and The reflector prism (17) has a groove extending around its periphery, wherein, when viewed in the direction of the prism axis (26), the laser emitter (11) i The laser receiver (14) is located on one side of the groove. i Located on the other side of the groove, Alternatively, the reflector prism (17) carries ribs (34) extending around its periphery, wherein, when viewed in the direction of the prism axis (26), the laser emitter (11) i The laser receiver (14) is located on one side of the rib (34), and the laser receiver (14) is located on the other side of the rib (34). i It is located on the other side of the rib (34).

2. The apparatus according to claim 1, characterized in that, The emitted laser beam (8) i They intersect each other at the beam deflection device (13).

3. The apparatus according to claim 1, characterized in that, The receiving laser beam (9) i ) in the beam deflection device (13) and the laser receiver (14) i They intersect with each other.

4. The apparatus according to claim 3, characterized in that, The focusing optical unit (32) is arranged in the receiving laser beam (31) i The intersection region (K) E )middle.

5. The apparatus according to any one of claims 1 to 4, characterized in that, The first and second transmitting and receiving directions (30) i 31 i ) in the transmitting and receiving laser beams (8 i 9 i At the corresponding transmission and reception times, they are located in a common plane parallel to the rotation axis (26).

6. The apparatus according to any one of claims 1 to 4, characterized in that, The laser emitter (11) i ) and laser receiver (14 i The laser beams (8) that emit and receive each other are oriented in such a way that they are close to each other when viewed from away from the beam deflection device (13) and the environment (2). i 9 j They are skewed relative to each other.

7. The apparatus according to any one of claims 1-4, characterized in that, When viewed in the direction of the prism axis (26), relative to the laser emitter (11) i Compared to the laser receiver (14), i It is located at a distance (b) further away from the rib (34).

8. The apparatus according to any one of claims 1 to 4, characterized in that... A third laser emitter (113) is configured to emit a third emitted laser beam (83) in a third time-dependent emission direction (303) via the beam deflection device (13), and The third laser receiver (143) is configured to receive the third emitted laser beam (83) reflected from the environment (2) and received back via the beam deflection device (13) in a third time-related receiving direction (313) as the third received laser beam (93). Wherein, the third transmitting and receiving directions (303, 313) are in the transmitting and receiving laser beam (8 i 9 i The corresponding transmission and reception times are parallel to each other and form a third angle (α3) with the rotation axis (26), and The third laser receiver (143) is spaced PX apart from the third laser emitter (113) in the direction of the rotation axis (26).

9. The apparatus according to claim 8, characterized in that, In each case, the first transmitting and receiving direction (301, 311) and the second transmitting and receiving direction (302, 312), and the second transmitting and receiving direction (302, 312) and the third transmitting and receiving direction (303, 313), in the transmitting and receiving laser beam (8) i 9 i An angle (α1-α2, α2-α3) is formed at the corresponding transmission and reception times, and the angle is in the range of 1° to 30°.

10. The apparatus according to claim 9, characterized in that, All mirror surfaces (18-25) are parallel to the rotation axis (26), and the second transmitting and receiving directions (302, 312) are perpendicular to the rotation axis (26).

11. The apparatus according to any one of claims 1 to 4, characterized in that, The beam deflection device (13) is located at the receiving laser beam (9) i ) to the laser receiver (14) i The beam path of the beam has at least one compensating mirror (27), which is adjustable about an adjustment axis (28) parallel to the rotation axis (26).

12. The apparatus according to claim 11, characterized in that, For all receiving laser beams (9 i Provide public compensation reflectors (27).

13. The apparatus according to any one of claims 1 to 4, characterized in that, The device is mounted on an aircraft (3) configured for the main flight direction (F), wherein the rotation axis (26) of the aircraft is not perpendicular to the main flight direction (F).

14. The apparatus according to any one of claims 1 to 4, characterized in that, The device is mounted on an aircraft (3) configured for the main flight direction (F), the rotation axis (26) of which is parallel to the main flight direction (F).

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