Laser measurement system

Abstract

A laser measurement system including a laser transmitter and a laser receiver is provided. The laser transmitter includes a reflective surface and one or more laser sources for projecting an initial laser pulse. The laser receiver includes a first reflective surface for reflecting the initial laser pulse to provide a first reflected laser pulse, and a second reflective surface for reflecting the initial laser pulse to provide a second reflected laser pulse. The laser receiver also includes a photodetection unit for receiving: 1) a first double-reflected laser pulse generated by reflecting the first reflected laser pulse from the reflective surface of the laser transmitter, and 2) a second double-reflected laser pulse generated by reflecting the second reflected laser pulse from the reflective surface of the laser transmitter. The laser receiver determines an orientation angle associated with the laser receiver based on the first and second double-reflected laser pulses.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Patent Application No. 16 / 665,118, filed on October 28, 2019, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] The present invention relates generally to a laser measurement system, and more particularly to a laser measurement system for providing complete positioning and, in some embodiments, orientation information associated with a laser receiver. Background Art

[0004] Preparing a worksite, such as a construction or agricultural site, often involves grading and excavating sections of the site into the desired topology. Positioning measurements are an important aspect of site preparation in order to improve the accuracy of this grading and excavation. Construction machines (e.g., bulldozers, scrapers, excavators, etc.) often use laser measurement systems to facilitate positioning measurements.

[0005] In one conventional approach, a laser measurement system is utilized to facilitate positioning measurements. In such conventional laser measurement systems, a laser diode of a laser transmitter projects laser pulses, while a photodiode of a laser receiver receives the laser pulses. Each of the laser transmitter and the laser receiver is provided with a reflective surface centered around the laser diode and the photodiode, respectively. Based on the reflections of the laser pulses off the reflective surfaces, the distance between the laser transmitter and the laser receiver can be calculated. However, when the laser transmitter is close to the laser receiver, the direct laser pulses and the reflected laser pulses used to calculate the distance between the laser transmitter and the laser receiver are difficult to distinguish. Furthermore, such conventional laser measurement systems do not provide information about the orientation of the laser receiver.

[0006] An example of a conventional laser measurement system is described in U.S. Patent No. 10,145,671, issued on December 4, 2018, the entire disclosure of which is incorporated herein by reference. Summary of the Invention

[0007] According to one or more embodiments, a system and method for operating a laser receiver to measure the position and / or orientation of the laser receiver are provided. An initial laser pulse from a laser transmitter is received and reflected by a first reflective surface of the laser receiver to generate a first reflected laser pulse, and is reflected by a second reflective surface of the laser receiver to generate a second reflected laser pulse. A first double-reflected laser pulse and a second double-reflected laser pulse are detected at a photoelectric detection unit of the laser receiver. The first double-reflected laser pulse is generated by reflecting the first reflected laser pulse from the reflective surface of the laser transmitter. The second double-reflected laser pulse is generated by reflecting the second reflected laser pulse from the reflective surface of the laser transmitter. Based on the first double-reflected laser pulse and the second double-reflected laser pulse, an azimuth angle associated with the laser receiver is determined.

[0008] In one embodiment, the azimuth angle is determined by determining the phase difference between the first and second double-reflected laser pulses.A (eg, tilt) sensor may be used to determine one or more additional orientation angles (eg, pitch and roll).

[0009] In one embodiment, the initial laser pulse is detected at a photoelectric detection unit of the laser receiver, and before the photoelectric detection unit detects the initial laser pulse, the initial laser pulse is received by a first reflective surface of the laser receiver, and after the photoelectric detection unit detects the initial laser pulse, the initial laser pulse is received by a second reflective surface of the laser receiver.

[0010] In one embodiment, an initial laser pulse is modulated by a laser transmitter using a plurality of modulated subcarriers to transmit a horizontal angle associated with the laser transmitter and additional data associated with the laser transmitter. The modulated initial laser pulse can be demodulated by multiplying the phase vectors of the plurality of modulated subcarriers with a multiplier vector to extract the horizontal angle.

[0011] According to one embodiment, the laser receiver includes a photodetection unit and at least one reflection surface, each of the at least one reflection surface having a center point positioned offset from a center point of the photodetection unit.

[0012] In one embodiment, the at least one reflective surface includes a first reflective surface and a second reflective surface, the first reflective surface and the second reflective surface being positioned on opposite sides of a plane intersecting the center of the photodetection unit. The first reflective surface and the second reflective surface of the laser receiver may be positioned symmetrically relative to the plane. The plane may be perpendicular to the surface of the photodetection unit.

[0013] In one embodiment, the laser receiver further comprises a non-reflective area positioned around the photodetection unit. The photodetection unit can be used to receive the initial laser pulse from the laser emitter, and the size of the non-reflective area is at least twice the size of the reflective surface of the laser emitter.

[0014] In one embodiment, the laser receiver includes a (eg, tilt) sensor for determining one or more additional orientation angles (eg, pitch and roll).

[0015] According to one or more embodiments, systems and methods for operating a laser transmitter are provided. An initial laser pulse is projected toward a laser receiver. A first reflected laser pulse is received and reflected to generate a first double-reflected laser pulse. A second reflected laser pulse is received and reflected to generate a second double-reflected laser pulse. The first and second reflected laser pulses are generated by reflecting the initial laser pulse from respective first and second reflective surfaces of the laser receiver.

[0016] In one embodiment, an initial laser pulse is modulated by a laser transmitter with a plurality of modulated subcarriers to transmit a horizontal angle associated with the laser transmitter and additional data associated with the laser transmitter.

[0017] According to one embodiment, a laser measurement system is provided that includes a laser transmitter and a laser receiver. The laser transmitter includes one or more laser sources for projecting an initial laser pulse toward the laser receiver and a reflective surface. The laser receiver includes a first reflective surface for reflecting the initial laser pulse to provide a first reflected laser pulse, and a second reflective surface for reflecting the initial laser pulse to provide a second reflected laser pulse. The laser receiver also includes a photodetection unit for receiving: 1) a first double-reflected laser pulse generated by reflecting the first reflected laser pulse from the reflective surface of the laser transmitter, and 2) a second double-reflected laser pulse generated by reflecting the second reflected laser pulse from the reflective surface of the laser transmitter. The laser transmitter determines an azimuth angle associated with the laser receiver based on the first and second double-reflected laser pulses.

[0018] According to one embodiment, a system and method for operating a laser receiver and a laser transmitter to measure the position and / or orientation of the laser receiver is provided. An initial laser pulse is projected by the laser transmitter toward the laser receiver. The initial laser pulse is received and reflected by a first reflective surface of the laser receiver to produce a first reflected laser pulse. The first reflected laser pulse is received and reflected by a reflective surface of the laser transmitter to produce a first double-reflected laser pulse. The first double-reflected laser pulse is detected at a photoelectric detection unit of the laser receiver. The initial laser pulse is received and reflected by a second reflective surface of the laser receiver to produce a second reflected laser pulse. The second reflected laser pulse is received and reflected by a reflective surface of the laser transmitter to produce a second double-reflected laser pulse. The second double-reflected laser pulse is detected at the photoelectric detection unit of the laser receiver. Based on the first double-reflected laser pulse and the second double-reflected laser pulse, an azimuth angle associated with the laser receiver is determined.

[0019] These and other advantages of the present invention will become apparent to those skilled in the art upon reference to the following detailed description and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 An exemplary laser measurement system is shown;

[0021] Figure 2A An illustrative laser receiver having two reflective surfaces is shown;

[0022] Figure 2B An illustrative laser transmitter is shown;

[0023] Figure 3 A schematic diagram showing the emission and reflection of a laser beam between a laser transmitter and a laser receiver;

[0024] Figure 4 An explanatory diagram showing an N-type beam signal received by a laser receiver when a laser transmitter rotates two revolutions;

[0025] Figure 5 An explanatory diagram showing an N-type beam signal received by a laser receiver when a laser transmitter rotates one circle;

[0026] Figure 6 An illustrative diagram 600 showing a signal received by a laser receiver having one direct pulse and one double reflected pulse;

[0027] Figure 7A is a top view showing further details of the laser measurement system;

[0028] Figure 7B is a perspective view showing further details of the laser measurement system;

[0029] Figure 8 The following figure shows the workflow of horizontal angle demodulation:

[0030] Figure 9 Shown according to Figure 8 Summary of exemplary demodulation performed by a laser receiver;

[0031] Figure 10 An exemplary table summarizing demodulation with five subcarriers is shown;

[0032] Figure 11 An exemplary table summarizing demodulation with six subcarriers is shown;

[0033] Figure 12 An illustrative method of operation of a laser receiver for determining a position and / or orientation associated with the laser receiver is shown;

[0034] Figure 13 An illustrative method of operation of a laser transmitter for determining a position and / or orientation associated with a laser receiver is shown;

[0035] Figure 14 shows a high-level block diagram of an exemplary laser receiver; and

[0036] Figure 15 A high-level block diagram of an exemplary laser transmitter is shown. DETAILED DESCRIPTION

[0037] According to various embodiments of the present invention, a laser measurement system is provided for calculating a complete 3D position (i.e., vertical angle, horizontal angle, and distance) and / or a complete 3D orientation (i.e., azimuth and two tilt angles) associated with a laser receiver based on laser pulses received from a laser transmitter. In one embodiment, the laser transmitter includes a reflective surface offset from the center of a laser diode, and the laser receiver includes two reflective surfaces, each offset from the center of a photodiode. In this manner, an initial laser pulse projected by the laser transmitter will be reflected by the two offset reflective surfaces of the laser receiver to the laser transmitter as first and second reflected laser pulses, and then reflected by the offset reflective surfaces of the laser transmitter back to the laser receiver as first and second double-reflected laser pulses. By offsetting the reflective surfaces of the laser receiver, the laser receiver can easily distinguish between a direct initial laser pulse and the first and second double-reflected laser pulses by adding a time delay between the direct initial laser pulse and the first and second double-reflected laser pulses, thereby separating the signals in the time domain. By providing two reflective surfaces on the laser receiver on opposite sides of the photodiode, the laser receiver can determine its azimuth by comparing the phases of the first double-reflected laser pulse and the second double-reflected laser pulse. Advantageously, the laser receiver determines the azimuth angle and three-dimensional position (i.e., vertical angle, horizontal angle, and distance) associated with the laser receiver based on the transmitted and reflected signals. In one embodiment, the laser receiver may also be equipped with one or more sensors (e.g., a tilt sensor) to provide two additional orientation angles (i.e., roll angle and pitch angle), which, together with the azimuth angle (i.e., yaw angle), provide a complete three-dimensional orientation associated with the laser receiver. Laser measurement systems according to embodiments of the present invention can be used, for example, to perform construction and agricultural tasks.

[0038] Figure 1 FIG2 shows a laser measurement system 100 according to one or more embodiments. The laser measurement system 100 includes a laser transmitter 102 and a laser receiver 104. Figure 1 As shown, the laser receiver 104 is configured to be attached to a survey pole 106. However, it should be understood that various configurations of the laser receiver 104 are possible. For example, the laser receiver 104 can be configured to be attached to a construction machine (e.g., an excavator, a dump truck, a bulldozer, etc.) or can be a handheld device. Figure 2A and Figure 2B The laser receiver 104 and the laser transmitter 102 are described in more detail. It should be understood that the laser measurement system 100 may include any number of laser receivers for calculating position and orientation information for each laser receiver 104 based on the laser beam received from the laser transmitter 102.

[0039] The laser emitter 102 projects an N-shaped beam 108 in a rotating irradiation at a constant speed, for example, as described in U.S. Patent No. 7,196,302 issued on March 27, 2007, the entire disclosure of which is incorporated herein by reference. The laser emitter 102 can project an N-shaped beam 108 with modulation (e.g., phase or frequency). The N-shaped beam 108 includes a plurality of fan-shaped beams that are projected so that the cross-section of the light flux of the beam 108 forms an N shape. The N-shaped beam 108 is Figure 1 Illustratively shown are a vertical beam 110 -A, a vertical beam 110 -B, and a beam 110 -C that is tilted at an angle θ 112 on a diagonal line relative to the vertical beams 110 -A and 110 -B to form an N shape.

[0040] Figure 2A A detailed view of a laser receiver 200 is shown in accordance with one or more embodiments. In one embodiment, the laser receiver 200 is Figure 1 The laser receiver 200 includes a laser receiver for detecting or receiving a laser from a laser transmitter (e.g., Figure 1 102) of the laser emitter 102), and two reflective surfaces 204-A and 204-B (collectively referred to herein as reflective surfaces 204). The reflective surfaces 204 can be any reflective surface suitable for reflecting laser pulses. For example, the reflective surfaces 204 can be corner reflectors or prisms with multiple mirror edges, or can be flat surfaces of retro-reflectors. Each of the reflective surfaces 204 is positioned so that the center point of each reflective surface 204 is offset from the center point of the photodetector unit 202, and so that the center of the reflective surface 204 is located within the non-reflective area 206. In one embodiment, the center of the reflective surface 204 is located at a size (e.g., diameter) that is the size of the reflective surface of the laser emitter (e.g., Figure 2B 204-A and 204-B).

[0041] To prevent unwanted reflections from reflective objects behind the laser receiver 200, the front face 209 of the housing of the laser receiver 200 is at least a reflective surface for the laser emitter (e.g., Figure 2B In one embodiment, the laser receiver 200 has a non-reflective area 206 that is positioned (e.g., centered) around the photodetector unit 202 and has a non-reflective surface. Although for illustrative purposes, the laser receiver 200 is not shown in FIG. Figure 2A The non-reflective regions 206 are shown as overlapping portions of the reflective surface 204, but it should be understood that the reflective surface 204 is positioned above the non-reflective regions 206 and that these portions of the reflective surface 204 are not non-reflective. The non-reflective regions 206 may have any suitable dimensions and may have any suitable non-reflective surface, such as black paint. In one embodiment, the non-reflective regions 206 are at least the reflective surface of the laser emitter (e.g., Figure 2B twice the size (e.g., surface area) of the reflective surface 214 on the laser emitter 210 in FIG.

[0042] Figure 2B A detailed view of a laser emitter 210 is shown in accordance with one or more embodiments. In one embodiment, the laser emitter 210 is Figure 1 102 in the laser emitter 210. The laser emitter 210 includes a plurality of laser sources 212-A, 212-B, and 212-C (collectively referred to herein as laser sources 212), such as, for example, laser diodes, which are configured to project a fan-shaped beam in the form of rotating irradiation, thereby forming an N-shaped beam. The laser emitter 210 also includes a reflective surface 214, which can be any surface suitable for reflecting laser pulses (e.g., a corner reflector or a prism with multiple mirror edges, or a flat surface of a retro-reflector). The center point of the reflective surface 214 is positioned to be offset from the center point of the plurality of laser sources 212 and to be located within the non-reflective area 216. In one embodiment, the center of the reflective surface 214 is located at a size (e.g., diameter) that is the size of the reflective surface of the laser receiver (e.g., Figure 2A In one embodiment, the reflective surface 214 is within an area twice as large as the reflective surface 206 on the laser receiver 200. Figure 2A The reflecting surfaces 206 on the laser receivers 200 in FIG. 1 are of the same size (eg, diameter, surface area), but may be of different sizes.

[0043] To prevent unwanted reflections from reflective objects behind the laser transmitter 210, the front face 218 of the housing of the laser transmitter 210 is at least a reflective surface on the laser receiver (e.g., Figure 2AIn one embodiment, the laser emitter 210 has a non-reflective area 216 that is positioned (e.g., centered) around the plurality of laser sources 212 and has a non-reflective surface. Although for illustrative purposes, the non-reflective area 216 is not shown in FIG. Figure 2B The non-reflective regions 216 are shown as overlapping portions of the reflective surface 214, but it should be understood that the reflective surface 214 is positioned above the non-reflective regions 216 and that these portions of the reflective surface 214 are not non-reflective. The non-reflective regions 216 may have any suitable dimensions and may have any suitable non-reflective surface, such as black paint. In one embodiment, the non-reflective regions 216 are at least any reflective surface on the laser receiver (e.g., Figure 2A twice the size (e.g., surface area) of the reflective surface 204 on the laser receiver 200 in FIG.

[0044] Figure 3 A schematic diagram 300 illustrates the transmission and reflection of laser pulses between a laser transmitter 210 and a laser receiver 200 according to one or more embodiments. Figure 1 、 Figure 2A and Figure 2B To describe Figure 3 Diagram 300 illustrates the transmission and reflection of laser pulses between elements of a laser transmitter 210 and a laser receiver 200 , according to one embodiment, where events occur in time from top to bottom relative to a vertical axis.

[0045] The laser source 212 of the laser transmitter 210 projects an initial laser pulse 302 toward the laser receiver 200. Over time, the initial laser pulse 302 is continuously projected through the laser receiver 200 in a rotating pattern. Thus, the initial laser pulse 302 is continuously projected through the reflective surface 204-A, the photodetector unit 202, and the reflective surface 204-B of the laser receiver 200 at time points 312, 320, and 324, respectively. In one embodiment, the initial laser pulse 302 is an N-shaped beam (e.g., N-shaped beam 108) comprising three separate beams 110-A, 110-C, and 110-B projected by the laser sources 212-A, 212-B, and 212-C, respectively. In one embodiment, the initial laser pulse 302 is modulated using multiple modulated subcarriers to transmit a horizontal angle associated with the laser receiver 200 and additional data associated with the laser transmitter 210. The horizontal angle associated with the laser receiver 200 is provided by an encoder on the laser transmitter 210 and is transmitted to the laser receiver 200 via the modulated initial laser pulse 302 .

[0046] The initial laser pulse 302 projected by the laser source 212 of the laser transmitter 210 at time point 312 is received by the reflective surface 204-A of the laser receiver 200 at time point 314 and reflected toward the laser transmitter 210 as a first reflected laser pulse 304. The first reflected laser pulse is received by the reflective surface 214 of the laser transmitter 210 at time point 316 and reflected toward the laser receiver 200 as a first double-reflected laser pulse 306, wherein the first double-reflected laser pulse is detected by the photoelectric detection unit 202 of the laser receiver 200 at time point 318.

[0047] As the laser source 212 continues to irradiate through the laser receiver 200 in rotation, the initial laser pulse 302 projected by the laser source 212 at time 320 is detected by the photodetection unit 202 of the laser receiver 200 at time 322 .

[0048] As the laser source 212 continues to irradiate through the laser receiver 200 in rotation, the initial laser pulse 302 projected by the laser source 212 at time point 324 is received by the reflective surface 204-B of the laser receiver 200 at time point 326 and reflected toward the laser emitter 210 as a second reflected laser pulse 308, the second reflected laser pulse is received by the reflective surface 214 of the laser emitter 210 at time point 328 and reflected toward the laser receiver 200 as a second double-reflected laser pulse 310, wherein the second double-reflected laser pulse is detected by the photoelectric detection unit 202 of the laser receiver 200 at time point 330.

[0049] Due to the offset of reflective surfaces 204-A and 204-B on laser receiver 200, initial laser pulse 302 is received and reflected by first reflective surface 204-A (at time 314) before photodetection unit 202 detects initial laser pulse 302 (at time 322), and is received and reflected by second reflective surface 204-B (at time 326) after photodetection unit 202 detects initial laser pulse 302 (at time 322). The offset of reflective surfaces 204-A and 204-B enables laser receiver 200 to easily distinguish (in the time domain) between initial laser pulse 302 (received directly from laser transmitter 210) and first and second double-reflected laser pulses 306 and 310. Laser receiver 200 determines complete 3D positioning information (i.e., vertical angle, horizontal angle, and distance) and azimuth angle of laser receiver 200 based on the transmitted and reflected laser pulses.

[0050] Figure 4 According to one or more embodiments, a laser receiver (e.g., Figure 2A The laser receiver 200) is rotated twice from the laser transmitter (e.g. Figure 2B Graph 400 illustrates an N-beam signal received by a laser transmitter 210 (e.g., a laser transmitter 210). Graph 400 shows the laser receiver detecting: N-beam signal 402, which includes a first laser pulse 402-A projected by laser source 212-A, intermediate laser pulses 402-B projected by laser source 212-B, and a final laser pulse 402-C projected by laser source 212-C during a first rotation; and N-beam signal 404, which includes a first laser pulse 404-A projected by laser source 212-A, intermediate laser pulses 404-B projected by laser source 212-B, and a final laser pulse 404-C projected by laser source 212-C during a second rotation. The time between N-beam signal 402 and N-beam signal 404 represents one revolution of the laser transmitter (i.e., the transmitter head of the laser transmitter) rotating at 10 Hz. It should be understood that the laser receiver can detect double-reflected laser pulses of the N-type beam signals 402 and 404 which are not shown in diagram 400 .

[0051] Figure 5 An illustrative diagram 500 of an N-shaped beam signal received by a laser receiver (e.g., laser receiver 200 of FIG. 2 ) from a laser transmitter rotating in one revolution is shown in accordance with one or more embodiments. The laser receiver receives beams 502 , 504 , and 506 , which together form an N-shaped beam (e.g., Figure 1 Specifically, beam 502 corresponds to a vertical beam (e.g., vertical beam 110-A), beam 504 corresponds to an inclined beam (e.g., inclined beam 110-C), and beam 506 corresponds to a vertical beam (e.g., vertical beam 110-B).

[0052] Figure 6 An illustrative diagram 600 is shown of a signal having one direct pulse and one double-reflected pulse received by a laser receiver (eg, laser receiver 200 in FIG. 2 ) according to one or more embodiments. Figure 6 The depicted laser receiver includes a single reflective surface (eg, reflective surface 204 -B in FIG. 2 ). Thus, as shown in graph 600 , the laser receiver receives a direct initial laser pulse 602 and a double-reflected laser pulse 604 .

[0053] Figure 7A It is a top view. Figure 7B is a perspective view showing additional details of the laser measurement system 700 according to one or more embodiments. Figure 7A and Figure 7BIn the embodiment, the laser emitter 702 continuously projects an N-shaped beam 706 to the laser receiver 704 in a rotating irradiation manner. The laser emitter 702 and the laser receiver 704 include reflective surfaces 718 and 716, respectively. In one embodiment, the laser emitter 702 may be Figure 1 Laser emitter 102 or Figure 2B The laser transmitter 210, and the laser receiver 704 can be Figure 1 Laser receiver 104 or Figure 2A The laser receiver 200. It should be understood that Figure 7A and Figure 7B A high-level representation of the laser measurement system 700 is shown and the laser measurement system 700 may include additional components (eg, non-reflective regions).

[0054] The positioning of laser receiver 704 can be defined based on various parameters. In one embodiment, the positioning of laser receiver 704 can be represented by 3D coordinates and 3D orientation angles. The 3D coordinates of laser receiver 704 can be defined by a vertical angle 720, a horizontal angle 710, and a distance D 708. The 3D orientation angle of laser receiver 704 can be defined by an azimuth orientation angle 712 (i.e., yaw angle) and two tilt angles (i.e., pitch and roll angles). Vertical angle 720 is the angle at which laser receiver 704 is positioned relative to a transmitter reference horizontal plane 722. Horizontal angle 710 is the angle at which laser receiver 704 is positioned relative to a transmitter reference direction 714. Distance D 708 is the distance between laser transmitter 702 and laser receiver 704. Orientation angle 712 is the angle at which laser receiver 704 receives N-shaped beam 706 relative to a reference direction 724.

[0055] Parameters defining the 3D coordinates and 3D orientation angle of the laser receiver 704 can be determined based on the N-shaped beam 706 and its reflection. The vertical angle 720 associated with the laser receiver 704 can be calculated according to the following equation 1:

[0056]

[0057] Wherein, k is a coefficient based on the angle of laser tilt of the N-type beam 706 (i.e., based on Figure 1 112 of the tilted beam 110-C), and t1, t2, and t3 are the angles of each beam receiving the N-type beam 706 (e.g., Figure 1 The light beams 110-A, 110-C and 110-B in Figure 4 Pulse 402-A, 402-B, 402-C, or Figure 5 timestamps of the light beams 502, 504, 506).

[0058] The horizontal angle 710 associated with the laser receiver 704 can be demodulated from the N-shaped beam 706 according to Equation 2 as follows:

[0059] Horizontal angle H = P1 - P2 - P3 + P4 (Equation 2)

[0060] Where H is the rough horizontal angle, and P1, P2, P3, and P4 are the phases of the demodulated subcarriers of the N-shaped beam 706. For each direct pulse of the N-shaped beam 706 (e.g., for Figure 5 For each beam 502, 504, and 506 in the N-shaped beam 706, the horizontal angle can be individually demodulated. The physical angle between each direct pulse of the N-shaped beam 706 is used to compensate for the difference in horizontal angle between each pulse of the N-shaped beam 706 (e.g., the difference in the horizontal angles of the beams 502, 504, and 506). After compensation, the horizontal angles of each pulse of the N-shaped beam 706 can be averaged to reduce noise.

[0061] The distance D 708 between the laser transmitter 702 and the laser receiver 704 is determined by comparing the phase of the N-shaped beam 706 (i.e., the direct initial laser pulse) and one of the double-reflected laser pulses of the N-shaped beam 706 received by the laser receiver 704 (e.g., Figure 3 The first double-reflected laser pulse 306 or the second double-reflected laser pulse 310, or Figure 6 The phase of pulse 602 and pulse 604 is calculated according to Equation 3 as follows:

[0062]

[0063] Where c is the speed of light, is the phase (e.g., P1, P2, P3, or P4) of the reflected pulse (i.e., double-reflected pulse) of the N-shaped beam 706, in radians, is the phase of the N-shaped beam 706 (ie, the direct initial laser pulse), and f i is the effective frequency of the ith subcarrier. The distance can be calculated independently for all four subcarriers and then averaged. In one embodiment, the distance can be calculated independently for each direct pulse of the N-shaped beam 706 and the averaged.

[0064] The azimuth orientation angle 712 associated with the laser receiver 704 can be determined by comparing the first double-reflected laser pulse of the N-shaped beam 706 (e.g., Figure 4 The phase of the first double-reflected laser pulse 306 of the N-shaped beam 706 and the phase of the second double-reflected laser pulse of the N-shaped beam 706 (e.g., the second double-reflected laser pulse 310) are calculated according to Equation 4B as follows:

[0065] Azimuth = arcsin(c(P1-P2) / 4πLF) (Equation 4)

[0066] Wherein, c is the speed of light, P1 and P2 are the phases of the first double-reflected laser pulse and the second double-reflected laser pulse, respectively, and L is a reflective surface that reflects the first double-reflected laser pulse and the second double-reflected laser pulse (e.g., Figure 2A is the distance between the centers of the reflecting surfaces 204-A and 204-B), and F is the effective carrier frequency.

[0067] In one embodiment, the laser receiver 704 is configured with one or more sensors (not shown) to measure one or more additional orientation angles of the laser receiver 704, such as, for example, a roll angle and a pitch angle. The one or more sensors may be any suitable sensor for measuring the orientation of the laser receiver 200. For example, the one or more sensors may include a tilt sensor, such as, for example, an inertial measurement unit, an accelerometer, an inclinometer, etc.

[0068] Advantageously, according to one or more embodiments, full 3D positioning and 3D orientation are achieved for complete rigid body orientation in six dimensions. This full 3D positioning and 3D orientation is determined by the laser receiver 704 without communication from the laser receiver 704 to the laser emitter 702. Specifically, the laser receiver 704 determines all information about its position and orientation, while the laser emitter 702 propagates all required information and passively reflects laser pulses. Thus, the need for communication from the laser receiver 704 to the laser emitter 702 is eliminated.

[0069] According to one embodiment, reference Figure 1 , the laser transmitter 102 modulates an N-shaped light beam 108 using multiple subcarriers having the instantaneous rotation angle of the laser transmitter 102 and additional information 104 that may be useful to the laser receiver. In this way, upon receiving the modulated N-shaped light beam 108, the laser receiver 104 can additionally or alternatively estimate the horizontal angle associated with the laser receiver 104 by measuring the phase (or frequency) of the subcarriers of the carrier used in the modulation. It should be understood that although described herein in the context of a laser measurement system, modulation using multiple subcarriers can be applied to transmitting any type of signal, such as, for example, a radio frequency signal.

[0070] The plurality of subcarriers are sidebands of a carrier used to modulate the N-shaped light beam 108. The plurality of subcarriers may include any suitable number of subcarriers. In one embodiment, the plurality of subcarriers includes at least two subcarriers that utilize direct synthesis, wherein there is locked synchronization between the carrier frequency and the symbol frequency (i.e., one oscillator). In another embodiment, the plurality of subcarriers includes at least three subcarriers that do not utilize direct synthesis, wherein there is no synchronization between the carrier frequency and the symbol frequency (i.e., two independent oscillators).

[0071] Laser receiver 104 receives modulated N-shaped beam 108 and measures the phase of each of the multiple subcarriers. The phase of each subcarrier forms a vector in N-dimensional space, where N is the number of subcarriers. The vector is transformed into a transformation vector using a transformation matrix. The carrier phase, subcarrier phase, and head rotation (horizontal) angle of laser transmitter 102 can be independently extracted from the transformation vector.

[0072] The multiple subcarriers provide virtual channels through which the laser transmitter 102 can transmit data to the laser receiver 104 (and Figure 1 Other laser receivers not shown in FIG. ). Virtual channels are independently modulated signals, and the number of virtual channels corresponds to the number of subcarriers. By combining the subcarrier phase vectors (e.g., the subcarrier phase vectors {P1, P2, P3, P4} of four subcarriers) with the demodulation matrix (e.g., Figure 9 900) to extract the virtual channels. In one embodiment, one or more virtual channels can be used to transmit a rough estimate of the horizontal angle associated with the laser receiver 104 without introducing ambiguity. Different multiplications can be added to increase the accuracy of the estimate of the horizontal angle associated with the laser receiver 104. In another embodiment, one or more virtual channels can be used to propagate additional data such as, for example, a serial number of the laser transmitter 102, a transmitter channel, the location coordinates of the laser transmitter 102 (e.g., input by a user or calculated using other methods), calibration data (e.g., the precise angle of the N-shaped beam 108), or any other data that may be useful to the laser receiver 104.

[0073] refer to Figure 8 , continue to refer to Figure 1 , shows a workflow 800 for demodulating horizontal angle according to one or more embodiments. The workflow 800 may be performed by a laser receiver, such as, for example Figure 1 Laser receiver 104, Figure 2A or the laser receiver 704 of FIG. 7 .

[0074] The laser transmitter 102 can use four subcarriers to modulate the N-shaped light beam 108. The modulation signal (TxSignal) is expressed as follows in Formula 5, where A is the instantaneous head rotation angle of the laser transmitter 102 (from its encoder), C is the carrier phase, S is the subcarrier phase, and P1, P2, P3, and P4 are the phases of the modulated subcarrier signals.

[0075] TxSignal=sin(P1)+sin(P2)+sin(P3)+sin(P4) (Equation 5)

[0076] in, and Phases P1, P2, P3 and P4 are derived from the same phase S using integer multiplication and are therefore interlocked (ie, derived from the same oscillator and are not free running).

[0077] like Figure 8 As shown, the laser receiver 104 (e.g., a photodetection unit of the laser receiver 104) receives a modulated signal 802, which is sampled at an appropriate rate by an analog-to-digital converter (ADC) 804. The sampled signal is input to multipliers 806-A, 806-B, 806-C, and 806-D (collectively referred to herein as multipliers 806), which perform frequency shifting, and a pulse detector 812. The pulse detector 812 determines whether the sampled signal is a pulse by, for example, comparing the sampled signal with a threshold, and triggers sampling of the phase {P1, P2, P3, P4}. The multiplier 806 multiplies the sampled signal with the corresponding phase from the digital local oscillator 840, where the corresponding phase is determined as: carrier phase + N*subcarrier phase, where N is Figure 8 The output of multiplier 806 is a complex signal comprising in-phase (I) and quadrature (Q) components, which are low-pass filtered by respective low-pass filters 808-A, 808-B, 808-C, and 808-D (collectively referred to herein as low-pass filters 808).

[0078] The filtered signals from low-pass filter 808 are determined by corresponding phase converters 810-A, 810-B, 810-C, and 810-D (collectively referred to herein as phase converters 810) using: phase = arctan(Q / I). Multiplier 814 applies scalar multiplication to multiply phases P1, P2, P3, and P4 by the quadrature multiplier vector {+1, +1, +1, +1}, respectively. The outputs are combined by combiner 822 to extract carrier phase C with a 4x multiplication factor. Carrier phase C is input to carrier phase-locked loop 838, which outputs the phase to digital local oscillator 840. Multiplier 816 applies scalar multiplication to multiply phases P1, P2, P3, and P4 by the quadrature multiplier vector {+3, +1, -1, -3}, respectively. The outputs are combined by combiner 824 to extract the subcarrier phase S with a 20x multiplication factor. The subcarrier phase S is input into a subcarrier phase locked loop 836 which outputs the phase to a digital local oscillator 840.

[0079] Multiplier 818 applies scalar multiplication to multiply phases P1, P2, P3, and P4 by the quadrature multiplier vector {+1, -1, -1, +1}, respectively. The outputs are combined by combiner 826 to extract a coarse horizontal angle A 826 without ambiguity and with a 1x multiplication factor. Thus, an estimate of the horizontal angle A can be extracted according to Equation 6 as follows:

[0080]

[0081] Multiplier 820 applies scalar multiplication to multiply phases P1, P2, P3, and P4 by the quadrature multiplier vector {+1, -3, +3, -1}, respectively. The outputs are combined by combiner 828 to extract the precise horizontal angle A 832 with ambiguity and a 20x multiplication factor. The unambiguous coarse horizontal angle 830 and the ambiguous precise horizontal angle 832 are combined to determine the unambiguous precise horizontal angle 834.

[0082] Figure 9 Shows a summary Figure 8 The demodulated table 900 is shown in the workflow 800.

[0083] The vectors {+1, +1, +1, +1}, {+3, +1, -1, -3}, {+1, -1, -1, +1}, and {+1, -3, +3, -1} are orthogonal vectors in four dimensions. Since {+1, -1, -1, +1} and {+1, -3, +3, -1} are encoded using information about the same angle A, the noise estimation vector {+21, -23, -17, +19} can be extracted. Specifically, two of the four vectors are encoded using mutually dependent information (A / 4 and A), so the new independent vector can be expressed as a linear combination such as V' = (0.25) * {+1, -1, -1, +1} + {+1, -3, +3, -1} = {1.25, -3.25, 2.75, -0.75}. Multiplying by 4 to obtain integer coefficients results in V = {5, -13, 11, -3}. Therefore, all information about the rotation angle A is encoded along the basis {5, -13, 11, -3}. The orthogonal vector with integer coefficients {5, -13, 11, -3}, {1, 1, 1, 1}, and {+3, +1, -1, -3} is {+21, -23, -17, +19}. The signal extracted along this vector {+21, -23, -17, +19} does not carry any information about the carrier phase, subcarrier phase, or rotation angle A, so it is only noise. This amount of noise can be measured and used to estimate the accuracy of the rotation angle A.

[0084] Figure 10 Table 1000 summarizes demodulation for five subcarriers, where N subcarriers define an N-dimensional space. Two dimensions are used for carrier phase information and subcarrier phase information. The remaining three dimensions provide three virtual data channels (i.e., channel A, channel B, and channel C) for transmitting horizontal angle information and other data. In one embodiment, channel A, channel B, and channel C can be used to transmit horizontal angles with varying levels of accuracy. In another embodiment, only two of channels A, channel B, and channel C are used to transmit horizontal angles, while the third channel is used to broadcast supporting information to all receivers.

[0085] Figure 11 A table 1100 summarizing the demodulation with six subcarriers is shown. Four virtual data channels (ie, channel A, channel B, channel C, and channel D) are shared for transmission of horizontal angle information and other data.

[0086] Figure 12 A method 1200 of operating a laser receiver for determining a position and / or orientation associated with a laser receiver is shown in accordance with one or more embodiments. Figures 1 to 3 To describe method 1200. In one embodiment, the steps of method 1200 may be performed by Figure 1 Laser receiver 104, Figure 2A Laser receiver 200 or Figure 7A and Figure 7B The laser receiver 704 performs

[0087] At step 1202, an initial laser pulse 302 from the laser transmitter 210 is received and reflected by a first reflective surface (e.g., reflective surface 204-A) of the laser receiver 200 to generate a first reflected laser pulse 304. The initial laser pulse 302 may be an N-shaped beam 108 projected by the laser source 212 of the laser transmitter 210 through the laser receiver 200 in a rotating irradiation manner. In one embodiment, the initial laser pulse 302 is modulated with a plurality of modulated subcarriers to transmit horizontal angle information associated with the laser transmitter 210 and additional data associated with the laser transmitter 210 to the laser receiver 200.

[0088] At step 1204, a first double-reflected laser pulse 306 is detected at the photodetection unit 202 of the laser receiver 200. The first double-reflected laser pulse 306 is generated due to the first reflected laser pulse 304 being reflected from the reflective surface 214 of the laser emitter 210.

[0089] At step 1206 , the initial laser pulse 302 is detected at the photodetection unit 202 of the laser receiver 200 .

[0090] At step 1208, the initial laser pulse 302 is received and reflected by the second reflective surface (e.g., reflective surface 204-B) of the laser receiver 200 to generate a second reflected laser pulse 308. In one embodiment, the initial laser pulse 302 is received and reflected by the first reflective surface 204-A before the photodetection unit 202 detects the initial laser pulse 302, and is received and reflected by the second reflective surface 204 after the photodetection unit 202 detects the initial laser pulse 302.

[0091] At step 1210, a second double-reflected laser pulse 310 is detected at the photodetection unit 202 of the laser receiver 200. The second double-reflected laser pulse 310 is generated due to the second reflected laser pulse 308 being reflected from the reflective surface 214 of the laser emitter 210.

[0092] At step 1212, an orientation azimuth angle associated with the laser receiver 200 is determined based on the first double-reflected laser pulse 306 and the second double-reflected laser pulse 310. The orientation azimuth angle may be determined by determining a phase difference between the first double-reflected laser pulse 306 and the second double-reflected laser pulse 310. In one embodiment, the laser receiver 200 may include one or more sensors to determine one or more additional orientation angles.

[0093] At step 1214, a 3D position associated with the laser receiver 200 is determined. For example, the distance between the laser receiver 200 and the laser emitter 210 can be determined based on the difference between the phase of the initial laser pulse 302 and the phase of one or both of the first double-reflected laser pulse 306 or the second double-reflected laser pulse 310. The vertical angle associated with the laser receiver 200 can be determined based on the time difference ratio of the three beams of the N-shaped beam of the initial laser pulse 302. The horizontal angle associated with the laser receiver 200 can be determined by demodulating the horizontal angle from one or more modulation subcarriers of the modulated initial laser pulse 302.

[0094] Figure 13 A method 1300 of operating a laser transmitter according to one or more embodiments is shown. The method 1300 may be used in conjunction with Figure 12 The method 1200 for operating a laser receiver is used in conjunction with the method 1200 for operating a laser receiver to determine a location and / or orientation associated with the laser receiver. The method 1300 is passive in that it transmits and passively reflects laser pulses but does not calculate any location. Figures 1 to 3 To describe method 1300. In one embodiment, the steps of method 1300 may be performed by Figure 1 Laser transmitter 102, Figure 2B Laser emitter 210 or Figure 7A and Figure 7B The laser transmitter 702 performs

[0095] At step 1302, initial laser pulses 302 are continuously projected in a rotating irradiation pattern toward the laser receiver 200. The initial laser pulses 302 may be an N-shaped beam 108 projected in a rotating irradiation pattern by the laser source 212 of the laser transmitter 210. In one embodiment, the initial laser pulses 302 are modulated with a plurality of subcarriers to transmit horizontal angle information associated with the laser transmitter and additional data associated with the laser transmitter to the laser receiver.

[0096] At step 1304, the first reflected laser pulse 304 is received and reflected by the reflective surface 214 of the laser transmitter 210 to produce a first double-reflected laser pulse 306. The first reflected laser pulse 304 is generated by reflecting the initial laser pulse 302 from the first reflective surface (e.g., reflective surface 204-A) of the laser receiver 200.

[0097] At step 1306, the second reflected laser pulse 308 is received and reflected by the reflective surface 214 of the laser transmitter 210 to produce a second double-reflected laser pulse 310. The second reflected laser pulse 308 is produced by reflecting the initial laser pulse 302 from a second reflective surface (e.g., reflective surface 204-B) of the laser receiver 200.

[0098] Figure 14 A high-level block diagram of a laser receiver 1402 is shown in accordance with one or more embodiments. In one embodiment, the laser receiver 1402 may be Figure 1 Laser receiver 104, Figure 2A Laser receiver 200 or Figure 7A and Figure 7B Laser receiver 704. It should be understood that Figure 14 is a high-level representation of the laser receiver 1402 to generally illustrate the functional computing components of the laser receiver 1402 for illustrative purposes, and the laser receiver 1402 may be implemented with additional structures or functional components.

[0099] The laser receiver 1402 includes a laser module for detecting and receiving one or more laser pulses 1416 (e.g., Figure 1 The photodetection unit 1408 is configured to detect the laser receiver 1402 in the N-shaped beam 108. The photodetection unit 1408 may comprise, for example, one or more light detectors, photodiodes, or any other suitable device. Upon receipt of the laser pulse 1416, a light detection signal is provided as an input to a light detection signal processor 1406, wherein it is determined whether the laser receiver 1402 receives light. As will be appreciated, any required signal processing, such as analog to digital conversion, may be performed in a known manner, and any modulation data superimposed on the laser pulse 1416 is extracted and analyzed by the light detection signal processor 1406 in conjunction with the processor 1404. The power supply 1414 provides power to the laser receiver 1402 in a known manner. The power supply 1414 may be, for example, a rechargeable battery (e.g., NiMH) or an alkaline battery, or may be powered by an external power source, such as, for example, a construction machine associated with the laser receiver 1402. The memory 1412 stores computer program instructions (e.g., code) which, when executed by the processor 1404, perform various operations, such as, for example Figure 12Steps 1212 and 1214 of method 1200 or other operations of various embodiments described herein. Those skilled in the art will recognize that the implementation of the laser receiver 1402 may have other structures and may also include other components, and Figure 14 is a high-level representation of some components of such a laser receiver for illustration purposes.

[0100] Figure 15 A high-level block diagram of a laser transmitter 1502 is shown in accordance with one or more embodiments. In one embodiment, the laser transmitter 1502 may be Figure 1 Laser transmitter 102, Figure 2B Laser emitter 210 or Figure 7A and Figure 7B Laser emitter 702. It should be understood that Figure 15 is a high-level representation of the laser transmitter 1502 to generally illustrate the functional computing components of the laser transmitter 1502 for illustrative purposes, and the laser transmitter 1502 may be implemented with additional structural or functional components.

[0101] The laser emitter 1502 includes one or more laser sources 1506 for projecting one or more laser pulses 1514 (e.g., Figure 1 shaped beam 108 in the laser beam). The laser emitter 1502 can modulate data on the laser pulse 1514. The rotary encoder 1508 measures the instantaneous angle of the head of the laser emitter 1502. The power supply 1512 provides power to the laser emitter 1502 in a known manner. The power supply 1512 can be, for example, a rechargeable battery (e.g., NiMH) or an alkaline battery, or can be powered by an external power source, such as, for example, a construction machine associated with the laser emitter 1502. The memory 1510 stores computer program instructions (e.g., code) that, when executed by the processor 1504, perform various operations (e.g., modulation). Those skilled in the art will recognize that implementations of the laser emitter 1502 can have other structures and can also include other components, and Figure 15 is a high level representation of some of the components of such a laser transmitter for illustration purposes.

[0102] The systems, devices, and methods described herein can be implemented using digital circuits or using one or more computers that utilize known computer processors, memory units, storage devices, computer software, and other components. Typically, a computer includes a processor for executing instructions and one or more memories for storing instructions and data. A computer may also include or be coupled to one or more mass storage devices, such as one or more magnetic disks, internal hard disks and removable disks, magneto-optical disks, optical disks, and the like.

[0103] The systems, devices, and methods described herein can be implemented using computers operating in a client-server relationship. Typically, in such a system, the client computer is remotely located from the server computer and interacts via a network. The client-server relationship can be defined and controlled by computer programs running on the respective client and server computers.

[0104] The systems, devices, and methods described herein can be implemented within a network-based cloud computing system. In such a network-based cloud computing system, a server or another processor connected to the network communicates with one or more client computers via the network. For example, a client computer can communicate with a server via a web browser application that resides and operates on the client computer. The client computer can store data on the server and access the data via the network. The client computer can send a data request or an online service request to the server via the network. The server can perform the requested service and provide the data to the client computer. The server can also transmit data suitable for causing the client computer to perform a specified function, such as performing a calculation, displaying specified data on a screen, etc. For example, the server can send a request suitable for causing the client computer to perform one or more steps or functions of the methods and workflows described herein, including Figure 12 Certain steps or functions of the methods and workflows described herein include Figure 12 One or more steps or functions of the method and workflow described herein may be performed by a server or by another processor in a network-based cloud computing system. Figure 12 One or more steps of the method and workflow described herein may be performed by a client computer in a network-based cloud computing system. Figure 12 One or more steps of the process may be performed by a server and / or a client computer in a network-based cloud computing system in any combination.

[0105] The systems, apparatus, and methods described herein may be implemented using a computer program product tangibly embodied in an information carrier, for example, in a non-transitory machine-readable storage device, for execution by a programmable processor; and the method and workflow steps described herein, including Figure 12One or more of the steps or functions of a program may be implemented using one or more computer programs executable by such a processor. A computer program is a set of computer program instructions that can be used, directly or indirectly, in a computer to perform a certain activity or bring about a certain result. A computer program may be written in any form of programming language, including compiled or interpreted languages, and it may be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment.

[0106] Those skilled in the art will recognize that Figure 14 The laser receiver 1402 and Figure 15 Implementations of the laser emitter 1502 may have other structures and may include other components, and Figure 14 and Figure 15 is a high-level representation of some of the components of such a laser receiver and laser transmitter for illustrative purposes. For example, the laser receiver 1402 and the laser transmitter 1502 may also include one or more network interfaces for communicating with other devices via a network, and one or more input / output devices (e.g., a display, keyboard, mouse, speakers, buttons, etc.) that enable a user to interact with other computers or systems. Such input / output devices may include peripheral devices such as printers, scanners, display screens, etc. For example, the input / output devices may include: a display device such as a cathode ray tube (CRT) or liquid crystal display (LCD) monitor for displaying information to a user; a keyboard; and a pointing device such as a mouse or trackball through which a user can provide input.

[0107] Processors 1404 and 1504 may include general-purpose and specialized microprocessors and may be the sole processor or one of multiple processors. For example, processors 1404 and 1504 may include one or more central processing units (CPUs). Processors 1404 and 1504 and / or memories 1412 and 1510 may include, supplemented by, or incorporated into, one or more application-specific integrated circuits (ASICs) and / or one or more field-programmable gate arrays (FPGAs).

[0108] Memories 1412 and 1510 each include tangible, non-transitory computer-readable storage media, and may each include high-speed random access memory, such as dynamic random access memory (DRAM), static random access memory (SRAM), double data rate synchronous dynamic random access memory (DDRRAM), or other random access solid-state memory devices, and may include non-volatile memory, such as one or more magnetic disk storage devices such as internal hard disks and removable disks, magneto-optical disk storage devices, optical disk storage devices, flash memory devices, semiconductor storage devices, such as erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), compact disk read-only memory (CD-ROM), digital versatile disk read-only memory (DVD-ROM) disks, or other non-volatile solid-state storage devices.

[0109] The foregoing detailed description should be understood to be illustrative and explanatory in every respect, rather than restrictive, and the scope of the invention disclosed herein is determined not by the detailed description, but by the claims interpreted according to the full scope allowed by patent law. It should be understood that the embodiments shown and described herein are only illustrative of the principles of the present invention, and that various modifications may be made by those skilled in the art without departing from the scope and spirit of the present invention. Various other feature combinations may be implemented by those skilled in the art without departing from the scope and spirit of the present invention.

Claims

1. A method of operating a laser receiver, wherein: The method comprises: receiving and reflecting an initial laser pulse from a laser transmitter by a first reflective surface of the laser receiver to generate a first reflected laser pulse; detecting, at a photoelectric detection unit of the laser receiver, a first double-reflected laser pulse generated by reflecting the first reflected laser pulse from a reflective surface of the laser transmitter; receiving and reflecting the initial laser pulse by a second reflective surface of the laser receiver to generate a second reflected laser pulse; detecting, at the photodetection unit of the laser receiver, a second double-reflected laser pulse generated by reflecting the second reflected laser pulse from the reflective surface of the laser emitter; and An azimuth angle associated with the laser receiver is determined based on the first double-reflected laser pulse and the second double-reflected laser pulse.

2. The method according to claim 1, wherein Determining an azimuth angle associated with the laser receiver based on the first double-reflected laser pulse and the second double-reflected laser pulse includes: A phase difference between the first double-reflected laser pulse and the second double-reflected laser pulse is determined.

3. The method according to claim 1, wherein The method further comprises: The initial laser pulse is detected at the photoelectric detection unit of the laser receiver, wherein the initial laser pulse is received and reflected by the first reflection surface of the laser receiver before the photoelectric detection unit detects the initial laser pulse, and the initial laser pulse is received and reflected by the second reflection surface of the laser receiver after the photoelectric detection unit detects the initial laser pulse.

4. The method according to claim 1, wherein The initial laser pulse from the laser transmitter is modulated by the laser transmitter using a plurality of modulated subcarriers having interlocked phases to transmit a horizontal angle associated with the laser receiver.

5. The method according to claim 4, wherein The method further comprises: The modulated initial laser pulse is demodulated to extract the horizontal angle by multiplying the phases of the plurality of modulated subcarriers by an orthogonal vector.

6. The method according to claim 4, wherein: The initial laser pulse from the laser transmitter is modulated by the laser transmitter using the plurality of modulated subcarriers to transmit additional data associated with the laser transmitter.

7. The method according to claim 1, wherein The method further comprises: A tilt sensor is used to determine one or more orientation angles.

8. A method of operating a laser transmitter, wherein: The method comprises: projecting an initial laser pulse toward a laser receiver, the initial laser pulse being modulated by the instantaneous angle of rotation of the laser; receiving and reflecting a first reflected laser pulse by a reflective surface of the laser emitter to produce a first double-reflected laser pulse; and receiving and reflecting a second reflected laser pulse by the reflective surface of the laser emitter to produce a second double-reflected laser pulse, The first reflected laser pulse and the second reflected laser pulse are generated by reflecting the initial laser pulse from the corresponding first reflecting surface and second reflecting surface of the laser receiver.

9. The method according to claim 8, wherein Projecting the initial laser pulse toward the laser receiver includes: The initial laser pulse is modulated by the laser transmitter with a plurality of modulated subcarriers to transmit a horizontal angle associated with the laser transmitter.

10. The method according to claim 9, wherein: Modulating the initial laser pulse by the laser transmitter using the plurality of modulated subcarriers to transmit a horizontal angle associated with the laser transmitter includes: The initial laser pulse is modulated with the plurality of modulated subcarriers to transmit additional data associated with the laser transmitter.

11. The method according to claim 8, wherein The laser transmitter includes a non-reflective area positioned around one or more laser sources, the non-reflective area being at least twice the size of a reflective surface on the laser receiver.

12. A laser measurement system, wherein: The laser measurement system comprises: A laser transmitter, comprising: one or more laser sources for delivering the initial laser pulse, and reflective surfaces; and A laser receiver, comprising: a first reflective surface for reflecting the initial laser pulse toward the laser emitter to provide a first reflected laser pulse, a second reflective surface for reflecting the initial laser pulse toward the laser emitter to provide a second reflected laser pulse, a photoelectric detection unit for detecting: 1) a first double-reflected laser pulse generated due to reflection of the first reflected laser pulse from the reflective surface of the laser emitter, and 2) a second double-reflected laser pulse generated due to reflection of the second reflected laser pulse from the reflective surface of the laser emitter, processor, and a memory for storing computer program instructions that, when executed on the processor, cause the processor to perform operations comprising: An azimuth angle associated with the laser receiver is determined based on the first double-reflected laser pulse and the second double-reflected laser pulse.

13. A method of operating a laser transmitter and a laser receiver, wherein: The method comprises: Projecting an initial laser pulse from the laser transmitter toward the laser receiver; receiving and reflecting the initial laser pulse by a first reflective surface of the laser receiver to produce a first reflected laser pulse; receiving and reflecting the first reflected laser pulse by a reflective surface of the laser transmitter to produce a first double-reflected laser pulse; detecting the first double-reflected laser pulse at a photoelectric detection unit of the laser receiver; receiving and reflecting the initial laser pulse by a second reflective surface of the laser receiver to generate a second reflected laser pulse; receiving and reflecting the second reflected laser pulse by the reflective surface of the laser emitter to produce a second double-reflected laser pulse, detecting the second double-reflected laser pulse at the photodetection unit of the laser receiver; and An azimuth angle associated with the laser receiver is determined based on the first double-reflected laser pulse and the second double-reflected laser pulse.

14. The method according to claim 13, wherein Determining an azimuth angle associated with the laser receiver based on the first double-reflected laser pulse and the second double-reflected laser pulse includes: A phase difference between the first double-reflected laser pulse and the second double-reflected laser pulse is determined.

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