Measuring device

Abstract

To provide a survey instrument which offers reduced errors in ranging results by making a ranging light beam profile uniform.SOLUTION: A survey instrument is provided, comprising a ranging light emission unit having a light-emitting unit for emitting ranging light toward a survey target object and a one-dimensional diffusion optical element for diffusing the ranging light in a one-dimensional direction, a ranging light receiving unit having a light receiving element for receiving reflected ranging light from the survey target object, and an arithmetic control unit 17 configured to control the light-emitting unit and compute the distance to the survey target object based on a result of reception of the reflected ranging light by the light receiving element. The light-emitting unit has at least two light-emitting elements that are stacked in one direction, and the one-dimensional diffusion optical element is configured to diffuse the ranging light in the lamination direction of the light-emitting elements.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a surveying instrument capable of acquiring three-dimensional coordinates of a measurement object. [Background technology]

[0002] Surveying instruments such as laser scanners and total stations have optical distance measuring devices that detect the distance to an object to be measured using prism distance measurement, which uses a retroreflective prism as the object to be measured, or non-prism distance measurement, which does not use a reflective prism.

[0003] Some surveying instruments use a multi-stack laser as a light source, in which multiple light-emitting elements, such as laser diodes, are stacked and emit light simultaneously. A multi-stack laser increases the amount of light from the multiple light-emitting elements to measure distances, thereby increasing the distance that can be measured.

[0004] However, even if each light-emitting element is controlled to emit light simultaneously, there may be a difference in the timing of light emission due to manufacturing errors, etc. Furthermore, this difference may cause a difference in the distance measurement value of, for example, about ±10 mm for each light-emitting element.

[0005] On the other hand, in the case of prism distance measurement in which a retroreflective prism or the like is used as the measurement object, the distance measurement light is reflected while maintaining the beam profile (intensity distribution) of the distance measurement light. Therefore, when performing prism measurement using a multi-stack laser as the light source, there is a risk of errors in the distance measurement results depending on which part of the distance measurement light is reflected, i.e., which light-emitting element's light is reflected. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2021-25993 [Patent Document 2] Japanese Patent Application Publication No. 2018-91764 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention provides a surveying instrument that makes the beam profile of distance measurement light uniform and reduces errors in distance measurement results. [Means for solving the problem]

[0008] The present invention relates to a surveying instrument comprising an emitting unit that emits distance measuring light to an object to be measured, a distance measuring light emitting unit having a one-dimensional diffusion optical element that diffuses the distance measuring light in one direction, a distance measuring light receiving unit having a light receiving element that receives the reflected distance measuring light from the object to be measured, and an arithmetic control unit that controls the emitting unit and calculates the distance to the object to be measured based on the reception result of the reflected distance measuring light at the light receiving element, wherein the emitting unit has at least two light emitting elements stacked in one direction, and the one-dimensional diffusion optical element is configured to diffuse the distance measuring light in the stacking direction of the light emitting elements.

[0009] The present invention also relates to a surveying device in which the object to be measured is a corner cube having retroreflective properties, and the distance measurement light diffused by the one-dimensional diffusion optical element forms an overlapping portion where all the light emitted from each light-emitting element overlaps, and the distance to the corner cube is measured at the overlapping portion.

[0010] The present invention also relates to a surveying instrument that further comprises a base frame that rotates horizontally around a horizontal rotation axis by a horizontal rotation motor, a scanning mirror that is attached to the base frame and rotates vertically around a vertical rotation axis by a vertical rotation motor, irradiating the corner cube with the distance measuring light and receiving the reflected distance measuring light from the corner cube, a horizontal angle encoder that detects the horizontal angle of the base frame, and a vertical angle encoder that detects the vertical angle of the scanning mirror, and the calculation control unit is configured to calculate the position of the center of gravity of the corner cube based on the amount of reflected distance measuring light received and the horizontal and vertical angles when the corner cube is scanned with the distance measuring light, and to measure the angle of the corner cube based on the position of the center of gravity.

[0011] The present invention also relates to a surveying instrument in which the calculation control unit determines whether the corner cube has been measured at the overlapping portion based on the amount of light received from the reflected distance measuring light, and discards the distance measurement results that are determined to have not been measured at the overlapping portion.

[0012] The present invention also relates to a surveying device in which the calculation control unit calculates the center of gravity position of the corner cube based on the light intensity distribution obtained when the corner cube is scanned with the distance measurement light, determines whether the corner cube has been measured at the overlapping portion based on whether it is located within a predetermined threshold range from the center of gravity position, and discards distance measurement results that are determined to not have been measured at the overlapping portion.

[0013] The present invention also relates to a surveying instrument in which the distance measurement light emitting unit further comprises a drive mechanism, and the drive mechanism is configured to insert and remove the one-dimensional diffusion optical element into and from the optical axis of the distance measurement light.

[0014] Furthermore, the present invention relates to a surveying instrument in which the distance measuring light receiving section further comprises a light receiving prism that causes the reflected distance measuring light to be internally reflected a plurality of times and then received by the light receiving element. [Effects of the Invention]

[0015] According to the present invention, the device comprises an emitting unit that emits distance measurement light to the object to be measured, a distance measurement light emitting unit having a one-dimensional diffusion optical element that diffuses the distance measurement light in a one-dimensional direction, a distance measurement light receiving unit having a light receiving element that receives the reflected distance measurement light from the object to be measured, and an arithmetic control unit that controls the emitting unit and calculates the distance to the object to be measured based on the reception result of the reflected distance measurement light at the light receiving element, and the emitting unit has at least two light-emitting elements stacked in one direction, and the one-dimensional diffusion optical element is configured to diffuse the distance measurement light in the stacking direction of the light-emitting elements, so that the distance measurement light can be superimposed on each other and the beam profile of the distance measurement light can be made uniform, thereby providing the excellent effect of obtaining uniform distance measurement results regardless of the number of light-emitting elements stacked. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a front cross-sectional view showing a surveying instrument according to an embodiment of the present invention. [Figure 2] 1A and 1B are diagrams showing the configuration of a distance measurement unit according to an embodiment of the present invention. [Figure 3] (A) is the beam profile of the distance measurement light when a one-dimensional diffusing optical element is not used, (B) is the beam profile of the distance measurement light when a one-dimensional diffusing optical element is used, and (C) is the cross-sectional intensity of the profile of each distance measurement light at line A. [Figure 4] (A) is an explanatory diagram showing the relationship between the distance measurement light and the corner cube when a one-dimensional diffusing optical element is not used, and (B) is an explanatory diagram showing the relationship between the distance measurement light and the corner cube when a one-dimensional diffusing optical element is used. [Figure 5] (A) is an explanatory diagram showing the case where a corner cube is scanned with distance measurement light without using a one-dimensional diffusion optical element, and (B) is a distribution diagram showing the relationship between the angle and the amount of received light in this case. [Figure 6] (A) is an explanatory diagram showing the case where a corner cube is scanned with distance measurement light when a one-dimensional diffusing optical element is used, and (B) is a distribution diagram showing the relationship between the angle and the amount of received light in this case. [Figure 7] FIG. 10 is a configuration diagram showing a distance measurement unit according to a modified example of the embodiment of the present invention. [Figure 8] 10 shows the cross-sectional intensity of a profile of each distance measuring light beam according to a modified example of the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0018] First, referring to FIG. 1, a surveying instrument according to a first embodiment of the present invention will be described.

[0019] The surveying instrument 1 is, for example, a laser scanner, and is composed of a leveling unit 2 attached to a tripod (not shown), and a surveying instrument main body 3 attached to the leveling unit 2.

[0020] The leveling unit 2 has a leveling screw 10, and the leveling screw 10 is used to level the surveying device main body 3.

[0021] The surveying instrument main body 3 comprises a fixed section 4, a base section 5, a horizontal rotation shaft 6, a horizontal rotation bearing 7, a horizontal rotation motor 8 as a horizontal rotation drive section, a horizontal angle encoder 9 as a horizontal angle detector, a vertical rotation shaft 11, a vertical rotation bearing 12, a vertical rotation motor 13 as a vertical rotation drive section, a vertical angle encoder 14 as a vertical angle detector, a scanning mirror 15 as a vertical rotation section, an operation panel 16 that serves both as an operation section and a display section, a calculation control section 17, a memory section 18, a distance measurement section 19, etc. A CPU specialized for this instrument or a general-purpose CPU is used as the calculation control section 17.

[0022] The horizontal rotation bearing 7 is fixed to the fixed part 4. The horizontal rotation shaft 6 has a vertical axis 6a, and the horizontal rotation shaft 6 is rotatably supported by the horizontal rotation bearing 7. In addition, the base frame part 5 is supported by the horizontal rotation shaft 6, and the base frame part 5 rotates integrally with the horizontal rotation shaft 6 in the horizontal direction.

[0023] The horizontal rotation motor 8 is provided between the horizontal rotation bearing 7 and the base frame 5, and the horizontal rotation motor 8 is controlled by the arithmetic and control unit 17. The arithmetic and control unit 17 causes the horizontal rotation motor 8 to rotate the base frame 5 about the axis 6a.

[0024] The relative rotation angle of the base unit 5 with respect to the fixed unit 4 is detected by the horizontal angle encoder 9. A detection signal from the horizontal angle encoder 9 is input to the arithmetic and control unit 17, which calculates horizontal angle data. The arithmetic and control unit 17 performs feedback control on the horizontal rotation motor 8 based on the horizontal angle data.

[0025] The base part 5 is provided with the vertical rotation shaft 11 having a horizontal axis 11a. The vertical rotation shaft 11 is rotatable via the vertical rotation bearing 12. The intersection of the axis 6a and the axis 11a is the emission position of the distance measuring light, and is the origin of the coordinate system of the surveying device main body 3.

[0026] A recess 22 is formed in the base frame portion 5. One end of the vertical rotation shaft 11 extends into the recess 22, and the scanning mirror 15 is fixed to the one end, and the scanning mirror 15 is housed in the recess 22. The vertical angle encoder 14 is provided on the other end of the vertical rotation shaft 11.

[0027] The vertical rotation motor 13 is provided on the vertical rotation shaft 11, and the vertical rotation motor 13 is controlled by the arithmetic and control unit 17. The arithmetic and control unit 17 rotates the vertical rotation shaft 11 using the vertical rotation motor 13, and the scanning mirror 15 rotates around the axis 11a.

[0028] The rotation angle of the scanning mirror 15 is detected by the vertical angle encoder 14, and the detection signal is input to the arithmetic and control unit 17. The arithmetic and control unit 17 calculates vertical angle data of the scanning mirror 15 based on the detection signal, and performs feedback control on the vertical rotation motor 13 based on the vertical angle data.

[0029] The horizontal angle data, vertical angle data, and measurement results calculated by the calculation control unit 17 are stored in the storage unit 18. Various storage means can be used for the storage unit 18, such as a hard disk drive (HDD) as a magnetic storage device, a CD or DVD as an optical storage device, a memory card as a semiconductor storage device, a USB memory, etc. The storage unit 18 may be detachable from the base unit 5, or may be capable of transmitting data to an external storage device or external data processing device via a communication means (not shown).

[0030] The storage unit 18 stores various programs such as a control program for controlling the driving of light-emitting elements of the light-emitting unit described below, a sequence program for controlling distance measurement operation, a calculation program for calculating distance through distance measurement operation, a calculation program for calculating angle based on horizontal angle data and vertical angle data, a program for calculating three-dimensional coordinates of a desired measurement point based on distance and angle, a calculation program for calculating the center of gravity of a measurement object based on measurement results, and a control program for discarding distance measurement results containing errors based on the amount of received reflected distance measurement light. Also, various processes are performed by the calculation control unit 17 executing various programs.

[0031] The operation panel 16 is, for example, a touch panel, and serves as both an operation section for issuing distance measurement instructions and changing measurement conditions, such as the measurement point interval, and a display section for displaying distance measurement results, images, and the like.

[0032] Next, the distance measurement unit 19 will be described with reference to FIGS. 2(A) and 2(B).

[0033] The distance measurement unit 19 has a distance measurement light emitting unit 23 and a distance measurement light receiving unit 24. The distance measurement light emitting unit 23 and the distance measurement light receiving unit 24 constitute a distance measurement unit.

[0034] The distance measurement light emitting unit 23 has a distance measurement optical axis 38. The distance measurement light emitting unit 23 also has a light emitting unit 25 provided on the distance measurement optical axis 38, a collimator lens 26, the beam shaping optical element 27, a one-dimensional diffusion optical element 28 provided on the reflected optical axis of the beam shaping optical element 27, a reflecting prism 29 as a deflecting member, and a fixing member 31 for fixing the reflecting prism 29. The scanning mirror 15 is provided on the distance measurement optical axis 38 reflected by the reflecting prism 29. The fixing member 31 is made of a transparent material such as a glass plate. A window 32 made of a transparent material and rotating integrally with the scanning mirror 15 is provided on the reflected optical axis of the scanning mirror 15.

[0035] The collimator lens 26, the beam shaping optical element 27, the one-dimensional diffusion optical element 28, the reflecting prism 29, etc. constitute a light projection optical system 33. In this embodiment, the distance measurement optical axis 38, the distance measurement optical axis 38 reflected by the beam shaping optical element 27, and the distance measurement optical axis 38 reflected by the reflecting prism 29 are collectively referred to as the distance measurement optical axis 38.

[0036] The distance measurement light receiving unit 24 has a light receiving optical axis 39. The distance measurement light receiving unit 24 has a light receiving element 34 and a light receiving prism 35 arranged on the light receiving optical axis 39, and also has a light receiving lens 36 having a predetermined NA arranged on the axis of the light receiving optical axis 39 reflected by the light receiving prism 35. The light receiving prism 35 and the light receiving lens 36 constitute a light receiving optical system 37. In this embodiment, the light receiving optical axis 39 and the axis of the light reflected by the light receiving prism 35 are collectively referred to as the light receiving optical axis 39.

[0037] The light-emitting unit 25 is a multi-stack laser light source in which a plurality of light-emitting elements, for example, laser diodes (LDs), are stacked. The light-emitting unit 25 is composed of, for example, three stacked light-emitting elements, and is controlled so that each light-emitting element simultaneously emits a pulse of laser beam, and the synthesized pulsed light is emitted as distance-measuring light 41 (described later). By simultaneously emitting light from the three light-emitting elements and emitting the synthesized distance-measuring light 41, the amount of light emitted from the light-emitting unit 25 is ensured, enabling long-distance measurement by the surveying device 1.

[0038] The number of light emitting elements constituting the light emitting unit 25 may be two, four, or five. Number of is set appropriately according to the expected distance to the object to be measured.

[0039] The beam shaping optical element 27 is, for example, a reflective or transmissive anamorphic prism. The distance measuring light 41 emitted from the light emitting unit 25 and collimated by the collimator lens 26 has an elliptical beam shape, and the beam shaping optical element 27 is configured to correct the elliptical distance measuring light to a circular beam and deflect it at a right angle.

[0040] The one-dimensional diffusion optical element 28 is configured to diffuse in a predetermined direction (one-dimensional direction) the distance measurement light 41 deflected by the beam shaping optical element 27. In this embodiment, the direction in which the distance measurement light 41 is diffused by the one-dimensional diffusion optical element 28 is the stacking direction of the light emitting elements of the light emitting unit 25.

[0041] Note that various lenses and optical elements can be used as the one-dimensional diffusing optical element 28, such as a cylindrical lens, a lenticular lens, a micro-cylindrical lens array, an elliptical diffusion film, a binary optical element, and a diffractive optical element. A micro-cylindrical lens array is an array of minute cylindrical lenses. In the following description, any of an elliptical diffusion film, a binary optical element, and a diffractive optical element will be used as the one-dimensional diffusing optical element 28.

[0042] The distance measurement unit 19 is controlled by the arithmetic and control unit 17. When the pulsed distance measurement light 41 is emitted from the light emitting unit 25 onto the distance measurement optical axis 38, the distance measurement light 41 is collimated by the collimator lens 26 and deflected at a right angle by the beam shaping optical element 27 while its beam shape is corrected. The distance measurement light 41 reflected by the beam shaping optical element 27 is diffused in one dimension by the one-dimensional diffusion optical element 28 and reflected at a right angle by the reflecting prism 29. The distance measurement optical axis 38 of the distance measurement light 41 emitted from the reflecting prism 29 via the fixed member 31 coincides with the axis center 11a, and the distance measurement light 41 is deflected at a right angle by the scanning mirror 15 and irradiated onto the measurement object via the window 32. As the scanning mirror 15 rotates around the axis 11a, the distance measuring light 41 rotates (scans) within a plane that is perpendicular to the axis 11a and includes the axis 11a.

[0043] The window 32 is inclined at a predetermined angle with respect to the optical axis of the distance measurement optical axis 38 so that the distance measurement light 41 reflected by the window 32 does not enter the light receiving element 34 .

[0044] The distance measuring light 41 reflected by the object to be measured (hereinafter referred to as reflected distance measuring light 42) is reflected at a right angle by the scanning mirror 15, passes through the light receiving optical system 37 and is received by the light receiving element 34. The light receiving element 34 is, for example, an avalanche photodiode (APD) or an equivalent photoelectric conversion element.

[0045] The arithmetic and control unit 17 measures distance for each pulse of the distance measuring light 41 based on the time difference between the light emission timing of the light emitting unit 25 and the light reception timing of the light receiving element 34 (i.e., the round trip time of the pulsed light) and the speed of light (Time Of Flight). The light emission timing of the light emitting unit 25, i.e., the pulse interval, can be changed via the operation panel 16.

[0046] In addition, the distance measurement unit 19 is provided with an internal reference light optical system (described later), and distance measurement is performed based on the time difference between the reception timing of the internal reference light (described later) received from the internal reference light optical system and the reflected distance measurement light and the speed of light, making it possible to measure distance with higher accuracy.

[0047] The base frame 5 and the scanning mirror 15 each rotate at a constant speed, and the vertical rotation of the scanning mirror 15 and the horizontal rotation of the base frame 5 cooperate to perform two-dimensional scanning with the distance measuring light 41. Furthermore, by detecting the vertical angle and horizontal angle for each pulse of light using the vertical angle encoder 14 and the horizontal angle encoder 9, vertical angle data and horizontal angle data can be obtained. From the vertical angle data, horizontal angle data and distance measuring data, the three-dimensional coordinates of the measurement object and three-dimensional point cloud data corresponding to the measurement object can be obtained.

[0048] Next, we will explain the light receiving optical system 37. Note that in Figures 2(A) and 2(B), only the chief ray of the distance measuring light 41 (the distance measuring optical axis 38) and the chief ray of the reflected distance measuring light 42 (the light receiving optical axis 39) are shown.

[0049] The light-receiving prism 35 is a quadrangular prism having a predetermined refractive index, and has a first surface 35a onto which the reflected distance-measuring light 42 passing through the light-receiving lens 36 is incident, a second surface 35b from which the reflected distance-measuring light 42 passing through the surface of the first surface 35a is reflected, a third surface 35c onto which the reflected distance-measuring light 42 reflected by the second surface 35b and the first surface 35a is incident, and a fourth surface 35d as a transmitting surface through which the reflected distance-measuring light 42 reflected by the third surface 35c passes. The reflected distance-measuring light 42 passing through the fourth surface 35d is incident on the light-receiving element 34.

[0050] In addition, a reference prism 43 having retroreflectivity is provided below the scanning mirror 15. In the process of rotating and irradiating the distance measurement light 41 via the scanning mirror 15, a part of the distance measurement light 41 is incident on the reference prism 43. The distance measurement light 41 retroreflected by the reference prism 43 is incident on the light receiving optical system 37 via the scanning mirror 15 and is received by the light receiving element 34.

[0051] Here, the optical path length from the light emitting unit 25 to the reference prism 43 and the optical path length from the reference prism 43 to the light receiving element 34 are known. Therefore, the distance measuring light 41 reflected by the reference prism 43 can be used as internal reference light 44. The scanning mirror 15 and the reference prism 43 form an internal reference light optical system 45.

[0052] Next, a case where measurement is performed by the surveying instrument 1 having the distance measurement unit 19 will be described with reference to Figures 3 to 6. Various operations of the distance measurement unit 19 are performed by the arithmetic control unit 17 executing various programs. Note that the following describes a case where prism measurement is performed.

[0053] The distance measurement light 41 emitted from each light-emitting element of the light-emitting unit 25 is irradiated onto a measurement object, for example, a corner cube 46, via the collimator lens 26, the beam shaping optical element 27, the one-dimensional diffusion optical element 28, the reflecting prism 29, the fixed member 31, and the scanning mirror 15. The reflected distance measurement light 42 is reflected by the corner cube 46 and enters the light-receiving optical system 37 via the scanning mirror 15, and is refracted while passing through the light-receiving lens 36 and the first surface 35a. Furthermore, the reflected distance measurement light 42 is reflected successively by the second surface 35b, the first surface 35a, and the third surface 35c inside the light-receiving prism 35, passes through the fourth surface 35d, and is received by the light-receiving element 34.

[0054] The calculation control unit 17 calculates the three-dimensional coordinates of the corner cube 46 based on the distance measurement result of the distance measurement unit 19 and the detection results of the horizontal angle encoder 9 and the vertical angle encoder 14 .

[0055] The corner cube 46 may be measured by scanning the entire circumference or the periphery of the corner cube 46 with the distance measuring light 41 and measuring the position where the reflected distance measuring light 42 is received as the position of the corner cube 46 .

[0056] Here, Fig. 3(A) shows the beam profile of the distance measurement light 41 when the one-dimensional diffusing optical element 28 is not used, and Fig. 3(B) shows the beam profile of the distance measurement light 41 when the one-dimensional diffusing optical element 28 is used. Also, Fig. 3(C) compares the cross-sectional intensity of the beam profile of each distance measurement light 41 at the position of line A, where the solid line shows the case when the one-dimensional diffusing optical element 28 is used and the dashed line shows the case when the one-dimensional diffusing optical element 28 is not used.

[0057] 3(A) to 3(C), when the one-dimensional diffusion optical element 28 is not used, the distance measurement light 41 from each light-emitting element is emitted independently while maintaining its shape. Furthermore, the cross-sectional intensity of the beam profile at this time is also detected independently for the distance measurement light 41 from each light-emitting element, so the beam intensity of the beam cross section of the distance measurement light 41 varies greatly.

[0058] On the other hand, when the one-dimensional diffusion optical element 28 is used, the distance measurement light 41 of each light-emitting element is expanded in one dimension, for example, in the stacking direction of the light-emitting elements, and the distance measurement light 41 of each light-emitting element is overlapped and averaged before being emitted. Moreover, the profile cross-sectional intensity at this time is also detected in a state in which the distance measurement light 41 of each light-emitting element is overlapped and averaged, so the beam intensity of the beam cross section of the distance measurement light 41 is approximately constant.

[0059] 4(A) and 4(B) show the relationship between the beam profile of the distance measurement light 41 and the position of the corner cube 46 when the one-dimensional diffusion optical element 28 is used and when it is not used. In FIGS. 4(A) and 4(B), reference numeral 47 indicates the light receiving range of the light receiving element 34.

[0060] 4A, the distance measurement light 41 is composed of distance measurement light 41a to 41c pulsed from three light emitting elements. However, due to an error in the light emission timing of each light emitting element caused by manufacturing errors, etc., an error occurs in the distance measurement result based on the distance measurement light 41a to 41c.

[0061] Therefore, when the corner cube 46 reflects the distance measurement light 41a (corner cube 46a) and when the corner cube 46 reflects the distance measurement light 41c (corner cube 46c), an error of approximately ±5 mm occurs compared to when the corner cube 46 reflects the distance measurement light 41b (corner cube 46b).

[0062] 4(B), the distance measurement light beams 41a to 41c diffused only in the stacking direction (one direction) of the light emitting elements by the one-dimensional diffusing optical element 28 are overlapped with each other, synthesized, and homogenized. Also, the overlapping portion 41d where all the distance measurement light beams 41a to 41c overlap each other is received within the light receiving range 47.

[0063] If the distance measurement light 41 is reflected from the overlapping portion 41d, no matter which position of the corner cube 46 (corner cubes 46d to 46i) it is reflected from, the beam profile of the distance measurement light 41 is approximately uniform, as shown in Figure 3(C), so no error will occur in the distance measurement result.

[0064] On the other hand, when the corner cube 46 is measured while scanning the distance measuring light 41 through cooperation of the support section 5 and the scanning mirror 15, the corner cube 46 may reflect the distance measuring light 41 at the portion where any one of the distance measuring lights 41a to 41c or any two of the distance measuring lights 41a to 41c overlap, as in corner cubes 46k and 46j.

[0065] In this case, an error occurs in the distance measurement result compared to when the corner cube 46 reflects the distance measurement light 41 from the overlapping portion 46d. Meanwhile, a difference occurs in the amount of light received by the light-receiving element 34 when the reflected distance measurement light 42 is received. Therefore, the arithmetic and control unit 17 can determine whether the distance measurement light 41 from the overlapping portion 41d was reflected by the corner cube 46 based on the difference in the amount of light received of the reflected distance measurement light 42. Furthermore, the arithmetic and control unit 17 can discard, as an erroneous distance measurement result, any distance measurement result determined to have been performed using the distance measurement light 41 other than the overlapping portion 41d.

[0066] Alternatively, it may be determined whether the corner cube 46 has been measured by the distance measurement light 41 in the overlapping portion 41d based on the light intensity distribution when the corner cube 46 is scanned with the distance measurement light 41. In this case, the horizontal and vertical angles of the center of gravity of the corner cube 46 are calculated based on the horizontal and vertical angles of each point at which the light intensity distribution is obtained, and it can be determined whether the corner cube 46 has been measured by the distance measurement light 41 in the overlapping portion 41d based on whether the center of gravity is located within a predetermined angle range (within a preset threshold range) from the center of gravity.

[0067] The calculation control unit 17 calculates the center of gravity position of the corner cube 46 based on the horizontal and vertical angles of each point where the light intensity distribution is obtained, and determines whether each distance measurement result is located within a threshold range from the center of gravity position of the corner cube 46 based on a preset angle threshold, and can discard distance measurement results determined to be outside the threshold range as incorrect distance measurement results.

[0068] 5(A) and 5(B) are graphs showing the relationship between the horizontal angle of the base unit 5, the vertical angle of the scanning mirror 15, and the amount of received reflected distance-measuring light 42 when measuring the corner cube 46 while scanning the distance-measuring light 41 without using the one-dimensional diffusion optical element 28. Also, FIGS. 6(A) and 6(B) are graphs showing the relationship between the horizontal angle of the base unit 5, the vertical angle of the scanning mirror 15, and the amount of received reflected distance-measuring light 42 when measuring the corner cube 46 while scanning the distance-measuring light 41 with the one-dimensional diffusion optical element 28 provided.

[0069] In Figures 5(B) and 6(B), the triangular plot 48 indicates the amount of light received in the V-axis direction (vertical direction), and the cross plot 49 indicates the amount of light received in the H-axis direction (horizontal direction).

[0070] 5(B), when the one-dimensional diffusing optical element 28 is not provided, discrete sampling of the received light signal results in a continuous distribution of the amount of received light in the H-axis direction, but a discontinuous distribution of the amount of received light in the V-axis direction, i.e., the amount of received light in the stacking direction of the light-emitting elements. This results in a large error when calculating the center of gravity of the corner cube 46, which in turn results in an error in the angle measurement results of the corner cube 46.

[0071] 6(B), when the one-dimensional diffusion optical element 28 is provided, the amount of received light in both the V-axis and H-axis directions becomes a continuous distribution when the received light signal is discretely sampled. This prevents errors in calculating the center of gravity of the corner cube 46, and also prevents errors in the angle measurement results of the corner cube 46.

[0072] As described above, in this embodiment, a multi-stack laser light source is used as the light-emitting unit 25, in which multiple light-emitting elements are stacked in one direction and each light-emitting element emits light simultaneously. Therefore, by adding up the light-receiving signals when the reflected distance-measuring light 42 emitted from each light-emitting element and received by the light-receiving element 34, the amount of received light can be increased substantially by approximately the number of light-emitting elements. This makes it possible to extend the reach of the distance-measuring light 41 and increase the distance that can be measured.

[0073] Furthermore, since the projection optical system 33 uses the one-dimensional diffusion optical element 28 that diffuses the distance measurement light 41 only in the stacking direction (one direction) of the light-emitting elements, the distance measurement light 41a to 41c emitted from each light-emitting element is all overlapped, forming the overlapping portion 46d with a uniform beam profile.

[0074] Therefore, as long as the distance measurement light 41 is from the overlapping portion 46d, uniform distance measurement results can be obtained regardless of which portion of the corner cube 46 is measured, regardless of the number of light-emitting elements stacked, thereby improving distance measurement accuracy.

[0075] Furthermore, even when measuring the corner cube 46 by scanning the distance measurement light 41, a continuous distribution of the amount of received light can be obtained in both the V-axis and H-axis directions, making it possible to calculate the accurate center of gravity position of the corner cube 46 and improve the angle measurement accuracy of the corner cube 46. Thus, the one-dimensional diffusing optical element 28 can improve distance measurement accuracy and angle measurement accuracy, thereby improving the measurement accuracy of the surveying device 1.

[0076] Furthermore, when the corner cube 46 is measured using the distance measuring light 41 other than the overlapping portion 46d, a difference occurs in the amount of light received from the reflected distance measuring light 42 compared to when the corner cube 46 is measured using the distance measuring light 41 in the overlapping portion 46d.

[0077] Therefore, by discarding the measurement results of the corner cube 46 measured with the distance measuring light 41 other than the overlapping portion 46d based on the difference in the amount of light received by the reflected distance measuring light 42, it is possible to eliminate measurement results containing errors and improve measurement accuracy.

[0078] Furthermore, the one-dimensional diffusion optical element 28 is a one-dimensional diffusion optical element that diffuses the distance measurement light 41 in only one direction, and can make the beam diameter of the distance measurement light 41 smaller than that of a two-dimensional diffusion optical element that diffuses the distance measurement light 41 in two directions.

[0079] Therefore, the amount of the reflected distance measuring light 42 received can be increased, and the distance that can be measured can be extended.

[0080] Furthermore, the light-receiving prism 35 is used as the light-receiving optical system 37, and the reflected distance-measuring light 42 is internally reflected multiple times within the light-receiving prism 35. This bends the optical path of the reflected distance-measuring light 42, ensuring an optical path length equivalent to the focal length of the light-receiving lens 36.

[0081] Therefore, the length of the light receiving optical system 37 in the optical axis direction can be shortened, which makes it possible to reduce the size of the optical system of the distance measuring unit 19 and the size of the entire surveying device.

[0082] In this embodiment, a multi-stack laser light source in which three light-emitting elements are stacked is used as the light-emitting unit 25. On the other hand, the light-emitting unit 25 may be a multi-stack laser light source in which two light-emitting elements are stacked, or a multi-stack laser light source in which four or five light-emitting elements are stacked.

[0083] Furthermore, in this embodiment, the one-dimensional diffusing optical element 28 is provided on the distance measurement optical axis 38, but the one-dimensional diffusing optical element 28 may be made insertable and detachable relative to the distance measurement optical axis 38 by a drive mechanism such as a solenoid. By making the one-dimensional diffusing optical element 28 insertable and detachable, the one-dimensional diffusing optical element 28 can be inserted onto the distance measurement optical axis 38 when performing prism measurement, and the one-dimensional diffusing optical element 28 can be removed from the distance measurement optical axis 38 when performing non-prism measurement, and the distance measurement light 41 can be used differently depending on the object to be measured, thereby improving operability.

[0084] In addition, in this embodiment, the surveying instrument 1 is a laser scanner, but it goes without saying that the configuration of this embodiment can also be applied to a total station.

[0085] In this embodiment, the one-dimensional diffusing optical element 28 is disposed between the beam shaping optical element 27 and the reflecting prism 29, but the one-dimensional diffusing optical element 28 may be disposed at another position. For example, as shown in Fig. 7, the one-dimensional diffusing optical element 28 may be disposed between the collimator lens 26 and the beam shaping optical element 27.

[0086] Furthermore, if the use of the surveying instrument 1 is limited to prism measurement only, that is, if the one-dimensional diffusing optical element 28 is fixed with respect to the distance measurement optical axis 38, the one-dimensional diffusing optical element 28 may be disposed between the fixed member 31 and the scanning mirror 15, or may be disposed between the scanning mirror 15 and the window portion 32. Furthermore, instead of the one-dimensional diffusing optical element 28, a thin film having an optical effect of diffusing light in a one-dimensional direction may be formed on the reflecting prism 29, the fixed member 31, the scanning mirror 15, and the window portion 32.

[0087] In addition, in this embodiment, an elliptical diffusion film, a binary optical element, or a diffractive optical element is used as the one-dimensional diffusion optical element 28, but a cylindrical lens, a lenticular lens, or a microcylindrical lens array may also be used as the one-dimensional diffusion optical element 28.

[0088] When a cylindrical lens, a lenticular lens, or a micro-cylindrical lens array is used and further optimized by making them aspherical, the beam profile of the distance measuring light 41 can be made uniform over the entire area, as shown in the profile cross-sectional intensity of each distance measuring light in Figure 8, thereby further improving measurement accuracy. [Explanation of symbols]

[0089] 1 Surveying equipment 3 Surveying device body 5 Tray section 8 Horizontal rotation motor 9 Horizontal angle encoder 13 Vertical rotation motor 14 Vertical angle encoder 15 Scanning mirror 17 Calculation control unit 19 Distance measurement unit 23 Distance measurement light emission part 24 Distance measurement light receiver 25 Light-emitting part 28 One-dimensional diffusing optical element 41 Ranging light 42 Reflected ranging light 46 Corner Cube

Claims

1. A surveying device comprising: a light-emitting unit that emits distance-measuring light onto a retroreflective corner cube; a distance-measuring light emitting unit having a one-dimensional diffusion optical element that diffuses the distance-measuring light in one direction; a distance-measuring light receiving unit having a light-receiving element that receives the reflected distance-measuring light from the corner cube; and a calculation control unit that controls the light-emitting unit and calculates the distance to the corner cube based on the reception result of the reflected distance-measuring light at the light-receiving element, wherein the light-emitting unit has at least two light-emitting elements stacked in one direction, and the one-dimensional diffusion optical element is configured to diffuse the distance-measuring light in the stacking direction of the light-emitting elements, and the distance-measuring light diffused by the one-dimensional diffusion optical element forms an overlapping portion where all of the light emitted from each light-emitting element overlaps, and the surveying device is configured to measure the distance to the corner cube at the overlapping portion.

2. 2. The surveying instrument according to claim 1, further comprising: a base unit that rotates horizontally around a horizontal rotation axis by a horizontal rotation motor; a scanning mirror that is provided on the base unit and rotates vertically around a vertical rotation axis by a vertical rotation motor, irradiating the corner cube with the distance measurement light and receiving the reflected distance measurement light from the corner cube; a horizontal angle encoder that detects the horizontal angle of the base unit; and a vertical angle encoder that detects the vertical angle of the scanning mirror, wherein the calculation and control unit is configured to calculate the position of the center of gravity of the corner cube based on the amount of received reflected distance measurement light, the horizontal angle, and the vertical angle when the corner cube is scanned with the distance measurement light, and to measure the angle of the corner cube based on the position of the center of gravity.

3. The surveying device according to claim 1 or claim 2, wherein the calculation control unit is configured to determine whether the corner cube has been measured at the overlapping portion based on the amount of light received from the reflected distance measuring light, and to discard distance measurement results determined to have not been measured at the overlapping portion.

4. The surveying device described in claim 2, wherein the calculation control unit calculates the center of gravity position of the corner cube based on the light intensity distribution obtained when the corner cube is scanned with the distance measurement light, determines whether the corner cube has been measured at the overlapping portion based on whether it is located within a predetermined threshold range from the center of gravity position, and discards distance measurement results determined to have not been measured at the overlapping portion.

5. A surveying device as described in any one of claims 1 to 4, wherein the distance measurement light emission unit further comprises a drive mechanism, and the drive mechanism is configured to insert and remove the one-dimensional diffusion optical element relative to the optical axis of the distance measurement light.

6. A surveying instrument as described in any one of claims 1 to 5, wherein the distance measuring light receiving unit further has a light receiving prism that causes the reflected distance measuring light to be internally reflected multiple times and then received by the light receiving element.

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