Retroreflective device

Abstract

To eliminate offset in a retroreflective device.SOLUTION: An arrangement of a corner cube prism 131 comprises a prizm assembly 130 configured so as to form one continuous ring column 137 by putting each adjacent side 136B of light transmission surfaces 133 into close contact with the adjacent side. Each corner cube prism 131 forming the ring column 137 is arranged in a state of directing the light transmission surface 133 at an outer side of a ring of the ring column 137, and, under a condition that incidence light of a direction vertical to a center axis C10 of the ring of the ring column 137 is made incident toward the corner cube prism 131, the corner cube prism 131 is arranged in a state of causing a relation in which two lengths of an optical passage length ranging up to a light emission position where retroreflective light transmits the light transmission surface 133 from a light incidence position where the incidence light transmits the light transmission surface 133 and a sum of the shortest distance from the light incidence position to the center axis C10, and the shortest distance from the center axis C10 to the light emission position are equal to establish.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to retroreflective devices. [Background technology]

[0002] Theodolites and total stations measure the direction of incidence of retroreflected light that is emitted from the position where they are set and is then retroreflected by a retroreflector, thereby obtaining data useful for surveying. Such retroreflectors may use corner cube prisms capable of retroreflection.

[0003] Regarding retroreflection devices, a technology has been publicly known that combines six corner cube prisms to retroreflect light from all around the circumference (see, for example, Patent Document 1). In the technology disclosed in Patent Document 1, the six corner cube prisms that make up the prism assembly are sandwiched between a pair of a first member and a second member, and this sandwiched state is maintained by a holding mechanism. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-204576 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the retroreflector disclosed in Patent Document 1, due to the influence of the refractive index of the corner cube prism, a deviation (offset) occurs between the position of the virtual reflection surface where retroreflection occurs in the corner cube prism and the position of the actual central axis of the retroreflector. In response to this, there has been a need to eliminate the offset in the retroreflector.

[0006] The present disclosure makes it possible to eliminate offset of a retroreflective device capable of retroreflecting light from the entire circumference in the circumferential direction. [Means for solving the problem]

[0007] In order to solve the above problems, the retroreflective device of the present disclosure takes the following measures.

[0008] First, the retroreflection device according to the first disclosure is a retroreflection device including a corner cube prism having three reflective surfaces each forming a plane perpendicular to one another, and a light-transmitting surface that transmits incident light that is incident toward the reflective surfaces and transmits retroreflected light that is the incident light reflected by the reflective surfaces, the light-transmitting surfaces being regular triangular surfaces with non-adjacent sides corresponding to the base and two adjacent sides corresponding to the two equal sides excluding the base, and a prism assembly including eight or more even number of the corner cube prisms arranged such that the adjacent sides of the light-transmitting surfaces are closely adjacent to each other to form a continuous ring array. each of the corner cube prisms constituting the ring array is arranged with its light-transmitting surface facing outward from the ring of the ring array; and under the condition that the incident light is incident toward the corner cube prism in a direction perpendicular to the central axis of the ring of the ring array, the corner cube prisms are arranged in a state in which two lengths, a first length which is the optical path length from an incident position where the incident light passes through the light-transmitting surface to an exit position where the retroreflected light passes through the light-transmitting surface, and a second length which is the sum of the shortest distance from the incident position to the central axis and the shortest distance from the central axis to the exit position, are equal to each other.

[0009] In this case, the term "surface forming an equilateral triangle" includes a surface formed by rounding the corners of an equilateral triangle and a surface formed by chamfering the corners to make them flat. Similarly, the "base" is the line segment that connects the vertices at both ends of the two equal sides of an equilateral triangle.

[0010] The term "incident position" refers to the position on the light-transmitting surface where the incident light incident on the reflecting surface passes through the light-transmitting surface. Similarly, the term "exit position" refers to the position on the light-transmitting surface where the retroreflected light that is reflected by the reflecting surface and returns passes through the light-transmitting surface.

[0011] According to the retroreflection device of the first disclosure, the three reflecting surfaces are planes perpendicular to each other, so that the incident light incident on the incident position of the light transmitting surface and the retroreflected light reflected at the exit position of the light transmitting surface are in a parallel relationship. In addition, the light transmitting surface of the corner cube prism of the prism assembly can retroreflect light over the entire circumference in the circumferential direction of the ring array. In addition, the prism assembly can adjust the deviation between the position of the virtual reflecting surface where retroreflection of the corner cube prism occurs and the position of the actual center axis of the retroreflection device. This makes it possible to eliminate the offset of the retroreflection device in a retroreflection device that can retroreflect light from the entire circumference in the circumferential direction.

[0012] Here, the retroreflection device according to the first disclosure may be the retroreflection device according to the second disclosure described below. In the retroreflection device according to the second disclosure, the prism assembly has a configuration in which eight of the corner cube prisms are arranged in a state in which the entire adjacent sides of the light transmitting surfaces are in close contact with each other.

[0013] In the first disclosure, the light-transmitting surfaces of the corner cube prisms are arranged in a continuous ring-shaped array with adjacent sides of the light-transmitting surfaces in close contact with each other, and the light is retroreflected around the entire circumference of the ring-shaped array. Therefore, in the case where the adjacent sides of the light-transmitting surfaces of the corner cube prisms are not in close contact with the adjacent sides of the adjacent light-transmitting surfaces of the corner cube prisms in the prism assembly, the retroreflection of light does not occur around the entire circumference at the non-close contact parts. In contrast, the retroreflection device according to the second disclosure has a configuration in which the non-close contact parts are eliminated from each corner cube prism, and it is possible to prevent the non-close contact parts from preventing the retroreflection of light around the entire circumference. This makes it possible to widen the effective range of the light-transmitting surface that retroreflects the incident light. In addition, when the prism assembly is made up of eight corner cube prisms, the size of the central axis in the radial direction can be set smaller in the entire retroreflection device than when the prism assembly is made up of an even number of corner cube prisms, 10 or more.

[0014] Here, the retroreflection device according to the first or second disclosure may be a retroreflection device according to the third disclosure, which will be described later. In the retroreflection device according to the third disclosure, the prism assembly includes a holding mechanism that holds the corner cube prisms in a holding state that allows the corner cube prisms to be individually attached and detached.

[0015] According to the retroreflection device of the third disclosure, when a corner cube prism in a prism assembly is damaged, it is possible to remove only the damaged corner cube prism and replace it with an undamaged corner cube prism.

[0016] Here, the retroreflection device according to the third disclosure may be the retroreflection device according to the fourth disclosure, which will be described later. In the retroreflection device according to the fourth disclosure, the holding mechanism includes a pair of main bodies that sandwich the corner cube prisms forming the annular array from both sides in the axial direction of the central axis, a hooking protrusion provided on each of the main bodies that hooks the non-adjacent sides of the corner cube prisms in the held state from the outside, and an engagement portion attached to each of the main bodies that engages with the corners between the adjacent sides of the corner cube prisms whose non-adjacent sides are hooked by the hooking protrusions from the outside, thereby realizing a retracted state in which the corner cube prisms in the held state can be individually attached and detached by removing the engagement portions.

[0017] According to the retroreflection device of the fourth disclosure, when attaching or detaching a corner cube prism in a held state, the hooking protrusion on one side of the main body can prevent the corner cube prism to be hung from falling off the holding mechanism. Also, when removing a corner cube prism in a retracted state, the corner cube prism can be removed by pulling the corner outward while it is hooked on the hooking protrusion.

[0018] Here, the retroreflection device according to the fourth disclosure may be a retroreflection device according to the fifth disclosure described below. In the retroreflection device according to the fifth disclosure, the holding mechanism includes a through hole drilled at a position and in a direction corresponding to the central axis, and a rod-shaped member is slidably inserted through the through hole, thereby enabling the prism assembly to slide along the extension direction of the rod-shaped member.

[0019] According to the retroreflection device of the fifth disclosure, the through hole provided in the holding mechanism of the prism assembly allows the rod-shaped member to slide along the extension direction of the rod-shaped member.

[0020] Here, the retroreflection device according to the third disclosure may be the retroreflection device according to the sixth disclosure described below. In the retroreflection device according to the sixth disclosure, the holding mechanism has a number of recesses corresponding to the number of the corner cube prisms arranged in the annular array, and each recess holds each of the corner cube prisms by receiving a corner portion where the three reflective surfaces of each of the corner cube prisms come together.

[0021] According to the retroreflection device of the sixth disclosure, by forming a prism assembly by mounting each corner cube prism in a respective recess of the holding mechanism, the workability of aligning each corner cube prism can be improved.

[0022] Here, the retroreflective device according to the fifth disclosure may be the retroreflective device according to the seventh disclosure described later. The retroreflective device according to the seventh disclosure includes an outer fitting member that is fitted onto the rod-shaped member, and an outer tube that is fitted onto the outer fitting member, the outer fitting member includes a protruding portion that protrudes outwardly from one side in the radial direction of the rod-shaped member when fitted onto the rod-shaped member, and a locking portion that locks onto one of the paired main bodies and prevents the main body from rotating in the circumferential direction, and the outer tube presses the outer fitting member against the rod-shaped member by tightening the protruding portion from the one side when fitted onto the outer fitting member.

[0023] According to the retroreflective device of the seventh disclosure, the outer fitting member is pressed against the rod-shaped member by tightening its protruding portion from one radially outward side of the rod-shaped member with the outer tube, making it difficult for the outer fitting member to shift position or rotate relative to the rod-shaped member. Also, the outer fitting member has a locking portion that locks onto one of the main body parts, preventing the main body part from rotating in the circumferential direction. As a result, the prism assembly can be positioned at a predetermined position in the circumferential direction relative to the rod-shaped member.

[0024] Here, the retroreflection device according to the seventh disclosure may be the retroreflection device according to the eighth disclosure described below. The retroreflection device according to the eighth disclosure has a horizontal detector attached to at least one of the pair of main bodies.

[0025] According to the retroreflector of the eighth disclosure, the horizontal detector can detect the inclination of the prism assembly relative to the horizontal direction, which improves the accuracy of horizontal alignment in the direction along which the rod-shaped member along which the prism assembly slides extends, thereby improving the accuracy of measurements using the retroreflector.

[0026] Here, the retroreflective device according to the third disclosure may be the retroreflective device according to the ninth disclosure described below. In the retroreflective device according to the ninth disclosure, the holding mechanism has an insertion hole formed at a position and in a direction corresponding to the central axis, and a support body that supports an external force applied to the holding mechanism is inserted into the insertion hole.

[0027] In the retroreflection device according to the ninth disclosure, the support members can reinforce the prism assembly in the direction along the central axis of the ring of the annular array of corner cube prisms without blocking light.

[0028] Here, the retroreflective device according to the ninth disclosure may be a retroreflective device according to a tenth disclosure described below. The retroreflective device according to the tenth disclosure is supported by the support body and includes an attachment part to which a target of a positioning system can be attached.

[0029] According to the retroreflective device of the tenth disclosure, by attaching a target of a positioning system to the support body of the holding mechanism, the position of this retroreflective device can be measured by both a total station and the positioning system. Effect of the Invention

[0030] By having the above-mentioned configurations, the present disclosure makes it possible to eliminate offset in a retroreflection device capable of retroreflecting light from the entire circumference in the circumferential direction. [Brief description of the drawings]

[0031] [Figure 1] FIG. 1 is an explanatory diagram showing a state in which the retroreflection device 100 according to the first embodiment is used. [Diagram 2] FIG. 1 is a perspective view of a retroreflection device 100 according to a first embodiment. [Diagram 3] FIG. 1 is a front view of a retroreflection device 100 according to a first embodiment. [Figure 4] FIG. 1 is a plan view of a retroreflection device 100 according to a first embodiment. [Diagram 5] 4 is a cross-sectional view taken along line VV in FIG. 3. [Figure 6] FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. [Figure 8] FIG. 1 is an exploded perspective view of a retroreflection device 100 according to a first embodiment. [Figure 9] 4 is an explanatory diagram of the state in which the holding mechanism 150 in FIG. 3 loosens its clamping force to disengage the engaging portion 210. FIG. [Figure 10] FIG. 6 is a front view of a retroreflection device 600 according to a second embodiment. [Figure 11] 11 is a cross-sectional view taken along line XI-XI of FIG. 10. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] <First embodiment> A retroreflection device 100 according to a first embodiment of the present disclosure is installed and fixed at a measurement point where a survey is to be performed, as shown in Fig. 1. The retroreflection device 100 is used to retroreflect laser light LR emitted by a total station 900 in a surveying operation performed using the total station 900.

[0033] <Configuration of the retroreflection device according to the first embodiment> As shown in FIG. 8, the retroreflection device 100 includes a prism assembly 130 (see FIG. 2) including eight or more even numbers (eight in this embodiment). As shown in FIG. 2, the prism assembly 130 is configured such that the corner cube prisms 131 are arranged to form a continuous annular array 137 by closely contacting adjacent sides 136B of the light-transmitting surfaces 133. Each of the corner cube prisms 131 forming the annular array 137 is arranged with its light-transmitting surface 133 facing the outside of the ring of the annular array 137. The prism assembly 130 also includes a holding mechanism 150 that holds the corner cube prisms 131 in a holding state that allows them to be individually attached and detached. The incident light referred to here is the laser light LR emitted by the total station 900 (see FIG. 1) and incident on the light-transmitting surface 133, as shown in FIGS. 5 and 6.

[0034] <Corner cube prism configuration> 8, corner cube prism 131 has a right-angled triangular pyramid shape having three reflective surfaces 132 that form mutually orthogonal planes, and one light-transmitting surface 133. In this right-angled triangular pyramid shape, the three reflective surfaces 132 come together at their right angles to form corner portion 132A.

[0035] The three reflecting surfaces 132 are surfaces that form a right-angled isosceles triangle shape. The light transmitting surface 133 is a surface that forms an equilateral triangle shape. Here, the above-mentioned "surfaces that form a right-angled isosceles triangle shape" is a concept that includes a surface in which the corners of the right-angled isosceles triangle shape are rounded or chamfered. The above-mentioned "surfaces that form an equilateral triangle shape" is a concept that includes a surface in which the corners of the equilateral triangle shape are rounded or chamfered. In this embodiment, the corner cube prism 131 is a right-angled pyramid shape in which all ridges and all corners (including the corner portion 132A) are chamfered. This chamfering is, for example, a light chamfering process that forms a surface with a width smaller than the beam diameter of the laser light LR.

[0036] The light transmitting surface 133 has a non-adjacent side 136A which is a side corresponding to the base of the equilateral triangle, and two adjacent sides 136B which are sides corresponding to the two equal sides excluding the base. Similarly, the light transmitting surface 133 has a corner 134 between each adjacent side 136B. That is, the side opposite the corner 134 on the light transmitting surface 133 becomes the non-adjacent side 136A.

[0037] The three reflecting surfaces 132 are provided with a reflecting material that reflects incident light. Furthermore, the light transmitting surface 133 transmits incident light that is incident on the three reflecting surfaces 132 and retroreflected light that is the incident light reflected by the three reflecting surfaces 132. This retroreflected light is parallel to the incident light and travels in the opposite direction to the incident light.

[0038] <Configuration of prism assembly> 8, the prism assembly 130 is configured by arranging eight of the above-mentioned corner cube prisms 131. That is, the prism assembly 130 has a configuration in which the eight corner cube prisms 131 are arranged in a state in which the entire adjacent sides 136B of their light-transmitting surfaces 133 are in close contact with each other. In other words, the corner cube prisms 131 constituting the prism assembly 130 are in a relationship in which both ends of the adjacent sides 136B of their light-transmitting surfaces 133 are adjacent to both ends of the adjacent sides 136B of the adjacent light-transmitting surfaces 133.

[0039] 2, the corner cube prisms 131 of the prism assembly 130 are arranged so that the orientations of their light transmitting surfaces 133 are staggered. In other words, the eight light transmitting surfaces 133 in the prism assembly 130 are arranged so as to have the same shape as the side surfaces of a square prism.

[0040] Moreover, the corner cube prism 131 is disposed in such a manner that a first length and a second length, which will be described later, are equal to each other.

[0041] Here, the first length is the optical path length from the incident position IP where the incident light passes through the light transmitting surface 133 to the exit position OP where the retroreflected light passes through the light transmitting surface 133 under the condition that the incident light is incident toward the corner cube prism 131 in a direction perpendicular to the central axis C10 of the ring array 137. Here, the "optical path length" is a value defined when light travels through a certain substance, and has a dimension of length. Here, when the refractive index of a substance can be considered to be homogeneous regardless of the part, the optical path length is given as the product of the sum of the lengths of the routes along which light travels through the substance and the refractive index of the substance.

[0042] In this embodiment, the corner cube prism 131 is adjusted so that its refractive index (hereinafter also referred to as "n") is uniform regardless of the location. In the corner cube prism 131, the incident light incident on the incident position IP first reaches the first reflection position RP1 and is reflected there, as shown in FIG. 5. This reflected light becomes retroreflected light when it reaches the first reflection position RP1 to the second reflection position RP2. This retroreflected light reaches the exit position OP and is exited from there. Therefore, the first length is given in the form of (L11+L12+L13)×n. Here, L11 is the length from the incident position IP to the first reflection position RP1. Also, L12 is the length from the first reflection position RP1 to the second reflection position RP2. Also, L13 is the length from the second reflection position RP2 to the exit position OP.

[0043] In addition, the second length is the sum of the shortest incident distance L21, which is the shortest distance from the incident position IP to the central axis C10, and the shortest exit distance L22, which is the shortest distance from the central axis C10 to the exit position OP, under the above conditions, as shown in Figure 6.

[0044] Moreover, the term "incident position IP" here refers to a position on the light transmitting surface 133 where the incident light incident on the reflecting surface 132 passes through the light transmitting surface 133. Similarly, the term "exit position OP" refers to a position on the light transmitting surface 133 where the retroreflected light, which is the incident light reflected by the reflecting surface 132 and then transmitted through the light transmitting surface 133.

[0045] <Configuration of retention mechanism> As shown in FIG. 2, the holding mechanism 150 holds each of the corner cube prisms 131 forming the ring array 137 with its light transmitting surface 133 facing the outside of the ring of the ring array 137. As shown in FIG. 8, the holding mechanism 150 includes a pair of main bodies 110, a shaft 140, a hooking protrusion 220, an engagement portion 210, and a through hole 103. The pair of main bodies 110 sandwiches and holds the eight corner cube prisms 131 forming the ring array 137 from both sides in the axial direction of the central axis C10. The shaft 140 aligns the corner cube prisms 131 at a predetermined position. The hooking protrusion 220 hooks the non-adjacent sides 136A of the corner cube prisms 131 from the outside of the ring of the ring array 137. The engaging portion 210 engages with the corner portion 134 of the corner cube prism 131 to which the hook protrusion 220 is hooked, from outside the ring of the annular array 137. The through hole 103 allows the rod-shaped member 60 to be slidably inserted therethrough, thereby enabling the prism assembly 130 to slide along the extension direction of the rod-shaped member 60 (see FIG. 5). The main body 110, the shaft portion 140, the hook protrusion 220, the engaging portion 210, and the through hole 103 will be described below.

[0046] <Main body configuration> The pair of main body parts 110 is a pair of one end side main body part A110 and the other end side main body part B110. Here, the one end side main body part A110 has an opposing part A111 which is a part facing the other end side main body part B110. The other end side main body part B110 has an opposing part B111 which is a part facing the one end side main body part A110. In this embodiment, the opposing part A111 and the opposing part B111 are each made of a metal plate having a black "spool of thread" design (a shape in which the four sides of a rounded square are curved inward). Each side of the opposing part A111, B111 is positioned so as to follow the arrangement of each non-adjacent side 136A in each of the corner cube prisms 131 constituting the prism assembly 130.

[0047] In the pair of main bodies 110, the opposing portion A111 of the one end side main body portion A110 and the opposing portion A111 of the other end side main body portion B110 have the same shape as shown in Fig. 8. For this reason, in the following, detailed explanations of the respective configurations of the opposing portions A111 and B111 will be given by representing them by explaining the shape of the opposing portion B111. The configuration of the opposing portion A111 will be corresponded by replacing the initial letter "B" in the symbols of the respective configurations of the opposing portion B111 with the initial letter "A", and detailed explanations thereof will be omitted.

[0048] The facing portion B111 is provided with two insertion holes B111F corresponding to each of the four sides curved inward. In this embodiment, the insertion holes B111F are elongated holes having a size that allows the hook pieces 221 (described later) to be inserted, and are formed so that the protrusions 221A (described later) protrude from the facing portion B111 when the hook pieces 221 are inserted. The insertion holes B111F are positioned so as to be aligned with the non-adjacent sides 136A of the corner cube prisms 131 sandwiched between the pair of main body parts 110 in the above-mentioned clamped state. The elongated holes of the insertion holes B111F are disposed so that their longitudinal direction is parallel to the non-adjacent sides 136A in the clamped state. The two insertion holes B111F are positioned so as to be spaced apart from each other and away from the corners 134.

[0049] As shown in FIG. 4, each of the four rounded corners in the facing portion B111 has an engagement hole B111A. In this embodiment, as shown in FIG. 9, the engagement hole B111A is a countersunk hole having a screw hole B111B and a countersunk B111C having an opening edge of the screw hole B111B as a cylindrical recessed surface. Here, the countersunk B111C is a recess into which the engagement portion 210 (described later) is attached and engaged by a "loose fit". The screw hole B111B is a hole drilled perpendicular to the bottom surface at the center of the bottom surface of the countersunk B111C. This hole is designed so that when the engagement portion 210 is attached to the engagement hole B111A, the shaft of the flat head screw 201A is deeper than the overhang length of the engagement portion 210. The engagement hole B111A is positioned so as to come into contact with the corner 134 of the corner cube prism 131 sandwiched between the pair of main body portions 110 in the above-mentioned sandwiched state.

[0050] As shown in FIG. 8, the facing portion B111 has a fitting hole B117 that fits with the end of the shaft portion 140 in the axial direction by a "loose fit". Here, a prepared hole B118A of a countersunk hole B118 penetrates the bottom of the fitting hole B117. The countersunk hole B118 is a screw hole for screwing the shaft portion 140 in a fitted state (described later) with a screw 81. The countersunk hole B118 is designed to accommodate the entire head 81B of the screw 81, and the depth of the prepared hole B118A is shorter than the shaft 81A of the screw 81. Also, the depth of a screw hole 142A (described later) of the shaft portion 140 is designed to be longer than the shaft 81A of the screw 81. That is, in the other end side main body portion B110, the support portion 240 (described later) is attached without interfering with the head 81B of the screw 81.

[0051] The countersunk hole A118 (see FIG. 5) of the one end side main body part A110 has the same configuration as the countersunk hole B118. A horizontal detector 320 (described below) is attached to the one end side main body part A110 without interfering with the head 81B of the screw 81.

[0052] The one-end main body portion A110 has a non-opposing portion A112 on the side opposite to the opposing portion A111. This non-opposing portion A112 is a base that forms a surface perpendicular to the central axis C10 of the ring of the ring train 137. The non-opposing portion A112 is provided with three screw holes A112A at positions that do not interfere with the countersunk hole A118.

[0053] 5, the other-end main body portion B110 has a non-opposing portion B112 on the side opposite to the opposing portion B111. The non-opposing portion B112 is provided with an inner tube portion 230 that forms an outer threaded tube and protrudes toward the other end. That is, the non-opposing portion B112 is provided with the inner tube portion 230 that forms a tube wall that extends outward so as to follow the outer periphery of the rod-shaped member 60 when the rod-shaped member 60 is slidably inserted into the other-end through-hole B113 (described later).

[0054] The inner tube portion 230 includes a male thread portion 231, a guide surface 233, and an engagement groove 234. The male thread portion 231 is a thread surface that is in a screw-fit state to be screwed into the female thread portion 241 of the support portion 240 (described later). The guide surface 233 is an inclined surface obtained by chamfering the inner peripheral edge of the tube of the inner tube portion 230. This guide surface 233 is a surface on which one end side inclined surface 73A (described later) of the eccentric positioning pin 70 slides when the eccentric positioning pin 70 (described later) is fitted on the rod-shaped member 60. The engagement groove 234 is a groove (notch) formed by cutting out a rectangular end of the tube of the inner tube portion 230 in the axial direction. This engagement groove 234 is of a size that allows the engagement portion 74 of the eccentric positioning pin 70 in the fitted state to be engaged.

[0055] <Shaft configuration> The shaft portion 140 is a cylinder having a shaft portion through hole 143 (described later). Both ends of the cylinder in the axial direction are fitted in the fitting holes A117 and B117 in a predetermined arrangement direction. In addition, screw holes 142A are provided at both ends of the shaft portion 140, which communicate with the countersunk hole A118 or the countersunk hole B118 when the shaft portion 140 is in the above-mentioned arrangement direction with respect to the fitting holes A117 and B117. Screws 81 inserted in the countersunk hole A118 or the countersunk hole B118 are screwed into these screw holes 142A. This configuration fixes the shaft portion 140 to the pair of main body portions 110. That is, when the shaft portion 140 is fixed in the fitted state (see FIG. 5), it realizes a clamping state between the pair of main body portions 110. Here, the shaft portion 140 is configured by integrally molding a frame 141 and a tube portion 142 by metal insert molding. The frame 141 is a jig that aligns each of the eight corner cube prisms 131 to the position that constitutes the prism assembly 130. The tube portion 142 is a tube that has a shaft portion through hole 143 and the above-mentioned screw hole 142A. The frame 141 and the tube portion 142 will be described below.

[0056] <Frame composition> The frame 141 of the shaft portion 140 has eight recesses 141A corresponding to the eight corner cube prisms 131 arranged to form the annular array 137. These eight recesses 141A are approximately triangular pyramid-shaped recesses provided at approximately equal intervals in the circumferential direction of the shaft portion 140. Each recess 141A holds each of the eight corner cube prisms 131 by mounting a corner portion 132A of each of the eight corner cube prisms 131 therein. At this time, each recess 141A is engaged with each reflecting surface 132 of each corner cube prism 131 from the inside of the ring of the annular array 137. In addition, each corner portion 132A of each corner cube prism 131 mounted in each recess 141A is positioned apart from each other in the circumferential direction of the annular array 137.

[0057] In this embodiment, each recess 141A is formed in a shape having a play S20 with respect to the corner portion 132A of the corner cube prism 131 to which it is to be attached, as shown in Fig. 9. The size of this play S20 is set to a size that can absorb any wobbling of the corner portion 132A when the corner portion 134 of the corner cube prism 131 is pulled outward from the ring of the annular array 137 (see the imaginary line in Fig. 9).

[0058] <Structure of the barrel> The tube portion 142 fixes the pair of main body portions 110 and reinforces the frame 141. Here, the tube portion 142 has a constriction 142B between both ends in the axial direction of the tube. In this embodiment, the constriction 142B has an hourglass shape in which a circular truncated cone is connected to both axial sides of a cylinder. A screw hole 142A corresponding to (communicating with) the pilot hole A118A of the countersunk hole A118 in the one end side main body portion A110 in the fitted state is provided at the end in the axial direction of the tube of the tube portion 142. Similarly, a screw hole 142A corresponding to (communicating with) the pilot hole B118A of the countersunk hole B118 in the other end side main body portion B110 in the fitted state is provided at the end opposite to the end in the axial direction of the tube of the tube portion 142. These screw holes 142A, when communicating with pilot holes A118A, B118A in the pair of main body 110, are positioned so that non-adjacent side 136A of corner cube prism 131 attached to recess 141A is engaged with hook protrusion 220. Note that screw hole 142A is set so that its depth is longer than shaft 81A of screw 81.

[0059] <Combination of the hook protrusion and the engagement portion> A hook projection 220 and an engagement portion 210 are provided on the facing portion B111 of the holding mechanism 150. The hook projection 220 and the engagement portion 210 will be described below.

[0060] <Configuration of the hook protrusion> 2, two hook protrusions 220 are provided on each of the facing portion A111 and the facing portion B111, corresponding to the four inwardly curved sides. These hook protrusions 220 are hooked to the non-adjacent side 136A of the corner cube prism 131 from the outside of the ring of the annular array 137. In this way, the hook protrusions 220 prevent the corner cube prism 131 from shifting out of position.

[0061] 8, each of the hook projections 220 is configured by inserting the hook piece 221 into an insertion hole (not shown) of the facing part A111 or the insertion hole B111F of the facing part B111. Here, the configuration for inserting the hook piece 221 into the insertion hole of the facing part A111 is the same as the configuration for inserting the hook piece 221 into the insertion hole B111F. Therefore, in the following, the configuration for inserting the hook piece 221 into the insertion hole of the facing part A111 or the insertion hole B111F will be representatively described by the configuration for inserting the hook piece 221 into the insertion hole B111F.

[0062] The hook piece 221 has bifurcated claws 221B that are wider on the side inserted into the insertion hole B111F, and these claws 221B engage with the side of the insertion hole B111F due to the force of spreading out. This fixes the hook piece 221 in a state inserted into the insertion hole B111F.

[0063] 9, when the hook piece 221 is inserted into the insertion hole B111F (see FIG. 8), the hook protrusion 220 has a protrusion 221A on the opposite side to the claw 221B (see FIG. 8) protruding from the facing portion B111, and this protrusion 221A hooks each non-adjacent side 136A. Here, the two protrusions 221A of the two hook protrusions 220 provided on each side of the facing portion B111 are positioned so as to follow the non-adjacent sides 136A of the corner cube prism 131 sandwiched between the pair of main body portions 110 in the clamped state.

[0064] <Configuration of engagement part> As shown in Fig. 8, the engagement portion 210 is attached to the four rounded corners (see Fig. 4) of the swollen thread spool in the facing portion A111 and the facing portion B111. The engagement portion 210 is engaged with each corner 134 of each corner cube prism 131 in the latched state (see Fig. 9) from the outside of the ring of the ring array 137. This prevents the corner cube prism 131 from shifting out of position. Here, the engagement portion 210 is attached to the engagement hole B111A via a countersunk screw 201A.

[0065] As shown in FIG. 9, the engagement portion 210 includes a hollow cylinder 211A that fits with the countersunk portion B111C of the engagement hole B111A in a "clearance fit" manner, and a contact portion 211F that protrudes from the bottom surface of the end in the longitudinal direction toward one end side in FIG. 9. The hollow cylinder 211A has a countersunk hole 211B that has approximately the same outer diameter as the countersunk portion B111C and is concentric with the countersunk portion B111C when the hollow cylinder 211A fits with the countersunk portion B111C in a "clearance fit" manner. Here, the countersunk portion 211C of the countersunk hole 211B is sized to fit with the head 201B of the countersunk screw 201A in a "clearance fit" manner. The pilot hole 211D of the countersunk hole 211B is designed to have a length shorter than the length of the shaft 201C of the countersunk screw 201A. The contact portion 211F is a support portion that faces the corner portion 134 of the corner cube prism 131 and comes into contact with the surface thereof when the hollow cylinder 211A forms a "clearance fit" with the countersink B111C. Here, the contact portion 211F has a flat inclined surface 211G that protrudes outward on one side in the cylindrical diameter direction of the hollow cylinder 211A (the left side in FIG. 9), and a flat notched surface 211H whose cross section, when cut inward in the cylindrical diameter direction of the hollow cylinder 211A, is elliptical.

[0066] 9, the engaging portion 210 is switched between the above-mentioned engaged state and a retracted state, which will be described later, by attaching and detaching the flat head screw 201A. In the retracted state, the engaging portion 210 and the flat head screw 201A are separated from the main body 110. As a result, the engaging portion 210 and the flat head screw 201A are retracted so as not to come into contact with the corner portion 134 of the corner cube prism 131, whose corner portion 132A is attached to the recess 141A.

[0067] 3, the engaging portion 210 includes a contact portion 211F that protrudes from the opposing portion B111 toward the opposing portion A111 (upward in FIG. 3). The protruding dimension of the contact portion 211F from the opposing portion B111 is set to be substantially the same as the protruding dimension of the protrusion 221A of the hook piece 221 from the opposing portion B111.

[0068] <Through hole configuration> As shown in FIG. 5, the through hole 103 is composed of a one-end through hole A113, an other-end through hole B113, and a shaft through hole 143. The one-end main body A110 has a one-end through hole A113 drilled at a position and in a direction corresponding to the central axis C10 of the pair of main bodies 110 in the clamped state. Similarly, the other-end main body B110 has a other-end through hole B113 drilled at a position and in a direction corresponding to the central axis C10 of the pair of main bodies 110 in the clamped state. In addition, the cylindrical portion 142 of the shaft 140 has a shaft through hole 143 drilled at a position and in a direction corresponding to the central axis C10 of the pair of main bodies 110 in the clamped state. The one-end through hole A113, the other-end through hole B113, and the shaft through hole 143 are concentric and form cylindrical shapes with the same diameter. A rod-shaped member 60 (see FIG. 1) is slidably inserted through the one-end through-hole A113, the other-end through-hole B113, and the shaft through-hole 143. This configuration enables the prism assembly 130 to slide along the extension direction of the rod-shaped member 60.

[0069] The one-end through-hole A113 is a circular hole having approximately the same outer diameter as the rod-shaped member 60 (see FIG. 1) and is provided so that the bottom surface penetrates vertically at the center of the bottom of the fitting hole A117. Similarly, the other-end through-hole B113 is a circular hole having approximately the same outer diameter as the rod-shaped member 60 and is provided so that the bottom surface penetrates vertically at the center of the bottom of the fitting hole B117.

[0070] The shaft through-hole 143 is a circular hole having substantially the same outer diameter as the rod-shaped member 60 (see FIG. 1), and is provided so as to penetrate the axial direction at the center of the end face of the tube portion 142 in the axial direction.

[0071] <Included configuration> 8, the retroreflection device 100 includes an eccentric positioning pin 70, a support portion 240, and a horizontal detector 320. These will be described below.

[0072] <Configuration of eccentric positioning pin> As shown in FIG. 7, the eccentric positioning pin 70 is a member that is fitted onto the outer circumferential surface of the rod-shaped member 60, and includes a protruding portion 71, a pair of gripping portions 72, a one-end side inclined surface 73A (see FIG. 5), a second-end side inclined surface 73B (see FIG. 5), and a locking portion 74. Here, the eccentric positioning pin 70 corresponds to the "fitting member" in this disclosure. In addition, in the description of this embodiment, the state in which the eccentric positioning pin 70 is fitted onto the outer circumferential surface of the rod-shaped member 60 is also referred to as the "fitting state". In this embodiment, the eccentric positioning pin 70 has a cylindrical shape with a slit S30 that extends in the axial direction (perpendicular to the paper surface in FIG. 7) formed at one location on the side surface. This slit S30 is a space that is sandwiched between the ends of the pair of gripping portions 72 in the circumferential direction of the cylinder.

[0073] <Configuration of the extension part> In the externally fitted state, the protruding portion 71 protrudes outwardly to one side in the radial direction of the rod-shaped member 60 (see FIG. 1). In this embodiment, the protruding portion 71 is configured such that a portion of the cylinder of the eccentric positioning pin 70 opposite to the portion on the slit S30 side is partially thickened.

[0074] <Grip configuration> The gripping portion 72 is a portion that constitutes the side surface of the cylindrical shape of the eccentric positioning pin 70. The gripping portion 72 extends outwardly from the protruding portion 71 in the fitted state so as to cover both circumferential ends of the rod-shaped member 60.

[0075] <Configuration of the slope on one end and the slope on the other end> As shown in FIG. 5, the one-end inclined surface 73A is an inclined surface provided on one end side of the gripping portion 72, which is inclined radially inwardly of the rod-shaped member 60 in the externally fitted state. The one-end inclined surface 73A is a surface facing a part of the guide surface 233 of the inner cylinder portion 230, and when the one-end inclined surface 73A slides on the guide surface 233, the gripping portion 72 (see FIG. 7) follows this sliding to hold the rod-shaped member 60. Similarly, the other-end inclined surface 73B is an inclined surface provided on the other end side of the gripping portion 72, which is inclined radially inwardly of the rod-shaped member 60 in the externally fitted state. The other-end inclined surface 73B is a surface facing a part of the guide surface 243 of the support portion 240, and when the other-end inclined surface 73B slides on the guide surface 243 of the support portion 240, the gripping portion 72 follows this sliding to hold the rod-shaped member 60. In this embodiment, the one-end inclined surface 73A is obtained by C-chamfering the outer edge of the end of the cylinder of the eccentric positioning pin 70 on the side of the other-end main body portion B110. Similarly, the other-end inclined surface 73B is obtained by C-chamfering the outer edge of the end of the cylinder of the eccentric positioning pin 70 opposite to the one-end inclined surface 73A.

[0076] <Configuration of the locking part> The locking portion 74 is a projection that extends from one end side of the overhanging portion 71 (see FIG. 7) in the extending direction of the rod-shaped member 60 in the externally fitted state. Here, the locking portion 74 extends so as to engage with the locking groove 234 when the one-end side inclined surface 73A faces a part of the guide surface 233 of the inner cylinder portion 230. The locking portion 74 is locked in the locking groove 234 of the other-end side main body part B110, thereby preventing the other-end side main body part B110 from rotating. In this embodiment, the locking portion 74 is an extension, toward the other end side main body portion B110, of the cylindrical wall of the eccentric positioning pin 70 on the opposite side to the slit S30. Specifically, the locking portion 74 has a rectangular parallelepiped shape.

[0077] <Support structure> The support portion 240 forms a tube (a socket with a set screw in this embodiment) that fits the eccentric positioning pin 70 from the outside in the radial direction of the rod-shaped member 60 in the externally fitted state. This support portion 240 corresponds to the "outer tube" in this disclosure. The support portion 240 includes a female thread portion 241, a guide surface 243, a sliding hole 244, and an accommodation space S10. The female thread portion 241 is a thread surface that is in a screw-fit state with the male thread portion 231 of the inner tube portion 230. The guide surface 243 is an inclined surface that spreads outward in the radial direction of the rod-shaped member 60. This guide surface 243 is a surface on which the other end side inclined surface 73B of the eccentric positioning pin 70 slides when the eccentric positioning pin 70 is in an externally fitted state with respect to the rod-shaped member 60. The sliding hole 244 is a hole that forms a "clearance fit" with the rod-shaped member 60, and is provided on the side of the tube of the support part 240 opposite the side of the female threaded portion 241. The accommodation space S10 is located between the female threaded portion 241 and the sliding hole 244 on the tube of the support part 240, and accommodates the eccentric positioning pin 70 with a "clearance fit" in the screwed state.

[0078] <Horizontal detector configuration> The level detector 320 includes a mounting plate 320A, three mounting holes 320B, an insertion hole 320C, and a vial 320D. The mounting plate 320A is a plate in the shape of a square with rounded corners, and its area is designed to be smaller than the area of ​​the non-opposing part A112. The mounting hole 320B is a hole provided in the mounting plate 320A that enables the mounting plate 320A to be attached to the non-opposing part A112 with a screw 81. The insertion hole 320C is a hole that forms a "loose fit" with the rod-shaped member 60, and is provided in the mounting plate 320A. The vial 320D is a transparent disk with a marked line (not shown) that contains liquid and bubbles, and is provided in a state of being fitted into a hole opened in the mounting plate 320A.

[0079] <Configuration of rod-shaped member> As shown in Fig. 1, the rod-shaped member 60 is a columnar body that has the prism assembly 130 attached to its outer periphery and supports the prism assembly 130. In this embodiment, the rod-shaped member 60 is a cylinder that is colored red and white in its length direction (the vertical direction in Fig. 1), and a ferrule (not shown) is attached to its lower end to be abutted against the ground GR at the measurement point. The rod-shaped member 60 is positioned so that the direction in which it extends overlaps with the central axis C10 of the ring of the annular array 137 (see Fig. 2) formed by the corner cube prisms 131 (see Fig. 2).

[0080] <Assembly procedure of the retroreflection device according to the first embodiment> A procedure for assembling the retroreflection device 100 according to the first embodiment described above will be described. When assembling the retroreflection device 100, an operator (not shown) first performs an installation operation of attaching eight engaging portions 210 to each of the one end side main body portion A110 and the other end side main body portion B110.

[0081] Next, the worker performs an integration operation in which the one-end body part A110 and the other-end body part B110 sandwich the shaft part 140 from both axial sides thereof and integrate them. In this integration operation, the worker brings the one-end body part A110 and the shaft part 140 into the fitted state described above, and screws them together with the four screws 81. The worker also brings the other-end body part B110 and the shaft part 140 into the fitted state described above, and screws them together with the four screws 81.

[0082] Next, the worker mounts one corner cube prism 131 in one of the recesses 141A in the shaft 140. This operation is also referred to as the "first mounting operation" below. In the first mounting operation, the worker, with the corner portion 132A of the corner cube prism 131 facing the recess 141A, latches one side (the side to be the non-adjacent side 136A) of the equilateral triangular light transmitting surface 133 on the inside of the latching protrusion 220 to achieve a latched state. Next, the worker presses the corner portion (the corner portion to be the corner portion 134) of the light transmitting surface 133 of the corner cube prism 131 in the latched state, which is the apex angle when the one side is taken as the base, toward the shaft 140. In this way, the worker engages each reflecting surface 132 of the corner cube prism 131 in the latched state with the recess 141A. Then, the worker engages the engaging portion 210 with the corner portion pressed toward the shaft portion 140, and screws the engaging portion 210 to the opposing portion B111 with one flat head screw 201A.

[0083] Next, the worker selects one of the recesses 141A in the shaft portion 140 that does not yet have a corner cube prism 131 attached thereto, the recess 141A being adjacent to the recess 141A to which a corner cube prism 131 has already been attached. The worker then performs the task of attaching one corner cube prism 131 to the selected recess 141A. This task is also referred to below as the "second attachment task." The worker repeats the second attachment task until the number of recesses 141A to which a corner cube prism 131 has not yet been attached is two (i.e., five times). The procedure for attaching the corner cube prism 131 in the second attachment task is the same as the procedure for attaching the corner cube prism 131 in the first attachment task, and therefore a detailed description thereof will be omitted.

[0084] Next, the worker mounts one corner cube prism 131 in each of the two recesses 141A in the shaft portion 140 that do not yet have a corner cube prism 131 mounted therein. This operation is also referred to below as the "third mounting operation." The procedure for mounting the corner cube prisms 131 in the third mounting operation is similar to that of the first mounting operation, except that two corner cube prisms 131 are mounted simultaneously in parallel, and therefore a detailed description thereof will be omitted.

[0085] Next, the worker performs an attachment operation to attach the level detector 320 to the non-opposing portion A112 of the one-end side main body portion A110. In this attachment operation, the worker fastens the mounting plate 320A of the level detector 320 to the non-opposing portion A112 with three screws 81.

[0086] Next, the worker performs an assembly operation to assemble the eccentric positioning pin 70 and the support portion 240 to the other-end side main body portion B110. This assembly operation completes the assembly of the retroreflection device 100. In the assembly operation, the worker engages the locking portion 74 of the eccentric positioning pin 70 with the locking groove 234 of the other-end side main body portion B110. The worker also accommodates the eccentric positioning pin 70 in the accommodation space S10 of the support portion 240. The worker then screws the female thread portion 241 of the support portion 240 into the male thread portion 231 of the other-end side main body portion B110.

[0087] <How to remove the corner cube prism> The procedure for removing the corner cube prism 131 from the retroreflection device 100 according to the first embodiment will be described with reference to FIG.

[0088] First, when removing corner cube prism 131 that is in a held state, an operator (not shown) removes engaging portion 210 that is engaged with corner portion 134 of corner cube prism 131 from main body portion 110 to set it in a retracted state. Here, each corner of the plate shaped like a "swollen spool" design on the opposing portion of paired main body portion 110 to which engaging portion 210 is attached is exposed without being covered or concealed by the opposing portion opposite to the opposing portion to which the corner belongs when viewed in the axial direction of central axis C10.

[0089] Next, when removing the retracted corner cube prism 131, an operator (not shown) pulls out the corner portion 134 of the corner cube prism 131 while it is still in the latched state outside the ring of the ring array 137 (see FIG. 2).

[0090] When removing the retracted corner cube prism 131, an operator (not shown) may loosen the screws 81 in the countersunk holes A118 and B118 (see FIG. 8) of the pair of main bodies 110 that are being held.

[0091] <Procedure for installing retroreflective devices> The procedure for installing the retroreflection device 100 according to the first embodiment described above will be described.

[0092] First, a surveyor (not shown) attaches the retroreflection device 100 to a rod-shaped member 60, and then butts the rod-shaped member 60 against the ground GR (see FIG. 1) at the measurement point and fixes it in place.

[0093] Next, the surveyor adjusts the inclination of the rod-shaped member 60 so that it faces vertically while checking the horizontal detector 320. This causes the central axis C10 of the prism assembly 130 to face vertically.

[0094] 5 and 6, the surveyor slides the prism assembly 130 along the direction in which the rod-shaped member 60 extends, and adjusts the height of the prism assembly 130. At this time, the surveyor temporarily loosens the screwed state between the support part 240 and the inner cylinder part 230, and allows the prism assembly 130 to slide.

[0095] Next, the surveyor screws the support part 240 and the inner cylinder part 230 of the other end side main body part B110 together as shown in Fig. 5. Then, the eccentric positioning pin 70 has its one end side inclined surface 73A sliding on the guide surface 233 and the other end side inclined surface 73B sliding on the guide surface 243. As a result, the support part 240 fits the eccentric positioning pin 70 from the outside, so that the protruding part 71 is fitted from one side and the grip part 72 strongly presses the rod-shaped member 60. In addition, the locking part 74 of the eccentric positioning pin 70 locks into the locking groove 234 of the inner cylinder part 230, so that the prism assembly 130 is prevented from shifting in position or rotating relative to the rod-shaped member 60.

[0096] <Actions and Effects> According to the above-mentioned retroreflection device 100, the three reflecting surfaces 132 are planes perpendicular to each other, so that the incident light incident on the incident position IP of the light transmitting surface 133 and the retroreflected light reflected at the exit position OP of the light transmitting surface 133 are in a parallel relationship. In addition, in the corner cube prism 131 of the prism assembly 130, the light transmitting surface 133 can retroreflect light over the entire circumference of the annular array 137 in the circumferential direction. In addition, the prism assembly 130 can adjust the deviation between the position of the virtual reflecting surface 132 where the retroreflection of the corner cube prism 131 is performed and the position of the actual central axis C10 of the retroreflection device 100. This makes it possible to eliminate the offset of the retroreflection device 100 in the retroreflection device 100 that can retroreflect light from the entire circumference in the circumferential direction.

[0097] According to the retroreflection device 100 described above, when viewed from one end side of the central axis C10, each corner of the facing part B111 (see FIG. 4) is exposed without being covered by the one-end side main body part A110 of the facing part A111 on one end side that faces the facing part B111 on the other end side to which the corner belongs. This allows the pair of main bodies 110 to set the corner cube prisms 131 constituting the prism assembly 130 so that the orientations of the light transmitting surfaces 133 are staggered. Furthermore, an operator can easily remove the countersunk screws 201A that attach the engagement parts 210 from each corner.

[0098] According to the above-mentioned retroreflection device 100, the adjacent sides 136B of the light-transmitting surfaces 133 of the corner cube prisms 131 are closely spaced to form a continuous ring array 137, and light is retroreflected around the entire circumference of the ring array 137. Therefore, in the prism assembly, when there is a non-close contact portion (not shown) where the adjacent sides of the light-transmitting surfaces of the corner cube prisms are not closely spaced from the adjacent sides of the adjacent light-transmitting surfaces, the non-close contact portion does not retroreflect light around the entire circumference. In contrast, according to the configuration of the retroreflection device 100, the non-close contact portion is eliminated from each corner cube prism 131, and it is possible to prevent the non-close contact portion from preventing retroreflection of light around the entire circumference. This makes it possible to widen the effective range ER of the light-transmitting surface 133 where the incident light is retroreflected. Furthermore, when the prism assembly 130 is constructed with eight corner cube prisms 131, the radial size of the central axis C10 can be set smaller throughout the entire retroreflection device than when the prism assembly is constructed with an even number of corner cube prisms 131, i.e., ten or more.

[0099] According to the above-described retroreflection device 100, the hooking projections 220 provided corresponding to each of the four sides in the facing portion B111 can hook each non-adjacent side 136A of the corner cube prism 131 in the held state from the outside of the ring of the ring array 137 in the clamped state. That is, the eight protrusions 221A in the clamped state can hook each non-adjacent side 136A of the corner cube prism 131 in the held state from the outside of the ring of the ring array 137.

[0100] According to the above-described retroreflection device 100, the four engagement portions 210 in the clamped state can engage with each corner 134 of each corner cube prism 131 whose non-adjacent side 136A is latched by the latching protrusion 220 from outside the ring of the annular train 137. In other words, the engagement portions 210 can engage with the respective corners 134 of the corner cube prism 131 at their contact portions 211F.

[0101] According to the above-described retroreflection device 100, when the corner cube prism 131 in the prism assembly 130 is damaged, it is possible to remove only the damaged corner cube prism 131 and replace it with an undamaged corner cube prism 131.

[0102] According to the retroreflection device 100 described above, when the corner cube prisms 131 in the held state are individually attached or detached, the hooking projection 220 provided on one side of the main body 110 can prevent the corner cube prism 131 to be hung from falling off the holding mechanism 150. Furthermore, when removing the corner cube prism 131 in the retracted state, the corner cube prism 131 can be removed by pulling the corner portion 134 outward from the ring of the ring array 137 while the corner cube prism 131 is still hooked to the hooking projection 220.

[0103] According to the retroreflection device 100 described above, when the corner cube prism 131 in the held state is to be removed, the corner cube prism 131 can be raised up by abutting its light transmitting surface 133 against the surface of the protrusion 221A.

[0104] According to the above-described retroreflection device 100, the rod-shaped member 60 slides through the one-end through-hole A113, the other-end through-hole B113, and the shaft through-hole 143 provided in the holding mechanism 150 of the prism assembly 130, so that the prism assembly 130 can slide along the extension direction of the rod-shaped member 60. That is, the rod-shaped member 60 is slidably inserted through the one-end through-hole A113, the other-end through-hole B113, and the shaft through-hole 143, so that the prism assembly 130 can slide along the extension direction of the rod-shaped member 60.

[0105] According to the above-described retroreflection device 100, by mounting each of the corner cube prisms 131 in each recess 141A of the holding mechanism 150 to form the prism assembly 130, the workability of aligning each of the corner cube prisms 131 can be improved.

[0106] According to the retroreflection device 100 described above, the play S20 that absorbs wobble of the corner portion 132A makes it easier to remove the retracted corner cube prism 131 while keeping the corner cube prism 131 in the latched state.

[0107] According to the retroreflection device 100 described above, the eccentric positioning pin 70 is pressed against the rod-shaped member 60 by the support 240 fastening its protruding portion 71 from one radially outward side of the rod-shaped member 60, thereby making it difficult for the eccentric positioning pin 70 to shift position or rotate relative to the rod-shaped member 60. Also, the eccentric positioning pin 70 has its locking portion 74 locked to the other end side main body B110, preventing the other end side main body B110 from rotating in the circumferential direction. As a result, the prism assembly 130 can be positioned at a predetermined position in the circumferential direction relative to the rod-shaped member 60.

[0108] According to the retroreflection device 100 described above, the protruding portion 71 is fastened from the one side by the support portion 240 and approaches the axis of the rod-shaped member 60 .

[0109] According to the retroreflection device 100 described above, in the screwed state, the eccentric positioning pin 70 is sandwiched between the inner tube portion 230 and the support portion 240, so that the one end side inclined surface 73A and the other end side inclined surface 73B each move in the radial direction inward of the rod-shaped member 60, and the gripping portion 72 strongly presses the rod-shaped member 60. As a result, when the support portion 240 is fitted onto the eccentric positioning pin 70, the overhanging portion 71 is tightened from the one side from which the overhanging portion 71 overhangs, so that the eccentric positioning pin 70 can be pressed onto the rod-shaped member 60. That is, the eccentric positioning pin 70 in the externally fitted state is sandwiched between the inner tube portion 230 and the support portion 240, so that the one end side inclined surface 73A and the other end side inclined surface 73B each move in the radial direction inward of the rod-shaped member 60. This allows the gripping portion 72 to hold down the rod-shaped member 60 by following the movements of the one end side inclined surface 73A and the other end side inclined surface 73B.

[0110] According to the retroreflective device 100 described above, when the protruding portion 71 of the eccentric positioning pin 70 in the externally fitted state is not fastened by the support portion 240, the gripping portion 72 holds the rod-shaped member 60. Furthermore, when the protruding portion 71 of the eccentric positioning pin 70 in the externally fitted state is fastened from the one side by the support portion 240, the gripping portion 72 holds the rod-shaped member 60 with a force stronger than the force with which the gripping portion 72 holds the rod-shaped member 60. Therefore, when the eccentric positioning pin 70 in the externally fitted state is fastened by the support portion 240, the force with which the gripping portion 72 holds the rod-shaped member 60 becomes stronger, and thus the eccentric positioning pin 70 is less likely to shift position or rotate relative to the rod-shaped member 60.

[0111] According to the above-described retroreflection device 100, the horizontal detector 320 can detect the inclination of the prism assembly 130 relative to the horizontal direction. This improves the accuracy of leveling in the direction along which the rod-shaped member 60 along which the prism assembly 130 slides extends, and improves the accuracy of measurements using the retroreflection device 100.

[0112] <Second embodiment> Next, the configuration of a retroreflection device 600 according to a second embodiment of the present disclosure will be described with reference to Figures 1, 10, and 11. The retroreflection device 600 according to the second embodiment is a modified version of the retroreflection device 100 according to the first embodiment. Therefore, for configurations common to the respective configurations of the retroreflection device 100 according to the above-mentioned first embodiment, a reference numeral obtained by adding "500" to the reference numerals given to the respective configurations of the retroreflection device 100 according to the first embodiment is given to correspond to the respective configurations, and detailed description thereof will be omitted.

[0113] <Configuration of the retroreflection device according to the second embodiment> A retroreflecting device 600 according to a second embodiment of the present disclosure is installed and fixed at a measurement point where surveying is to be performed, and is used to enable measurement of the distance from this measurement point to a total station 900, as shown in Fig. 1. A target 920 (see Fig. 10) of a positioning system (not shown) is also attached to the retroreflecting device 600. Here, the target 920 is attached to a holding mechanism 650 provided in a prism assembly 630 in the retroreflecting device 600. The holding mechanism 650 will be described below together with the target 920.

[0114] <Configuration of retention mechanism> As shown in FIG. 10, the holding mechanism 650 holds each of the corner cube prisms 631 forming an annular array (not shown) with its light transmitting surface 633 facing outward from the ring of the annular array. Here, the holding mechanism 650 includes a pair of main bodies 610, a shaft portion 640 (see FIG. 11), a hooking protrusion 720, an engagement portion 710, a through hole 603 (see FIG. 11), a one-end base A820, a support body 565 (see FIG. 11), and an other-end base B820. The pair of main bodies 610 sandwich the eight corner cube prisms 631 forming the annular array from both sides in the axial direction of the central axis C60 (see FIG. 11). The shaft portion 640 aligns the corner cube prisms 631 at a predetermined position. The hooking projection 720 hooks the non-adjacent side 636A of the corner cube prism 631 from the outside of the ring of the ring series. The engaging portion 710 engages the corner portion 634 of the corner cube prism 631 to which the hooking projection 720 is hooked from the outside of the ring of the ring series. The support body 565 is received in the through hole 603 so as to form a fit. The support body 565 supports an external force applied to the pair of main body portions 610. The one-end base A820 supports a target 920 of a positioning system (not shown), and the weight of the target 920 is applied to the support body 565. The support body 565 ensures that an external force applied to the one-end base A820 is applied to the other-end base B820. The other-end base B820 ensures that an external force applied to the support body 565 is applied to the rod-shaped member 560. The pair of main body portions 610, the through holes 603, the one end side base A820, the support pillars 565, and the other end side base B820 will be described below.

[0115] <Main body configuration> The pair of main body parts 610 is a pair of one end side main body part A610 and the other end side main body part B610. Here, the one end side main body part A610 has an opposing part A611 which is a part facing the other end side main body part B610. The other end side main body part B610 has an opposing part B611 which is a part facing the one end side main body part A610. In this embodiment, the opposing part A611 and the opposing part B611 are each formed of a metal plate shaped like a "swollen thread spool". Each side of the opposing part A611, B611 is positioned so as to follow the arrangement of each non-adjacent side 636A in each of the corner cube prisms 631 constituting the prism assembly 630.

[0116] In the paired main body 610, the one-end main body A610 is a modified embodiment of the one-end main body A110 according to the first embodiment. Therefore, for configurations common to the one-end main body A610 according to the first embodiment, the numerals added with "500" to the numerals attached to the configurations of the one-end main body A110 according to the first embodiment are used to correspond to the configurations, and detailed description thereof will be omitted.

[0117] The facing portion B611 is provided with two insertion holes (not shown) corresponding to each of the four sides curved inward. In this embodiment, the insertion holes are elongated holes large enough to insert the hook pieces 721, and are formed so that the protrusions 721A protrude from the facing portion B611 when the hook pieces 721 are inserted. The insertion holes are positioned so as to be aligned with the non-adjacent sides 636A of the corner cube prisms 631 sandwiched between the pair of main body portions 610 in the above-mentioned clamped state. The elongated holes of the insertion holes are disposed so that their longitudinal direction is parallel to the non-adjacent sides 636A in the clamped state. The two insertion holes are positioned so as to be spaced apart from each other and away from the corner portions 634.

[0118] As shown in FIG. 11, each of the four rounded corners in the facing portion B611 has an engagement hole B611A. In this embodiment, the engagement hole B611A is a countersunk hole having a screw hole B611B and a countersunk B611C having an opening edge of the screw hole B611B as a cylindrical recessed surface. Here, the countersunk B611C has a shape that allows the engagement portion 710 to be attached and engaged by a "loose fit". The screw hole B611B is a hole drilled perpendicular to the bottom surface at the center of the bottom surface of the countersunk B611C. This hole is designed so that when the engagement portion 710 is attached to the engagement hole B611A, the shaft of the flat head screw 701A is deeper than the overhang length of the engagement portion 710. The engagement hole B 611A is positioned so as to come into contact with the corner 634 of the corner cube prism 631 sandwiched between the pair of main body portions 610 in the above-mentioned sandwiched state.

[0119] The facing portion B611 has a fitting hole B617 that fits with the end of the shaft portion 640 in the axial direction by a "loose fit". Here, a pilot hole (not shown) of a countersunk hole (not shown) penetrates the bottom of the fitting hole B617. The countersunk hole is a screw hole for screwing the shaft portion 640 with a screw 581 in a fitted state in which the shaft portion 640 is fitted in the fitting hole B617 in a predetermined arrangement direction. Here, the countersunk hole is designed to accommodate the entire head 581B of the screw 581, and the depth of the pilot hole is shorter than the shaft 581A of the screw 581. Also, the depth of the screw hole 642A of the shaft portion 640 is designed to be longer than the shaft 581A of the screw 581. That is, in the other end side main body portion B610, the other end side base B820 is arranged without interfering with the head 581B of the screw 581.

[0120] The countersunk hole A618 of the one end side main body portion A610 has the same configuration as the above-mentioned countersunk hole, and the one end side base A820 is disposed without interfering with the head 581B of the screw 581.

[0121] The other end side main body portion B610 has a non-opposing portion B612 on the side opposite to the opposing portion B611. Here, the non-opposing portion B612 has a flat surface that comes into surface contact with the other end side base B820.

[0122] <Through hole configuration> The through hole 603 is composed of a one-end through hole A613, an other-end through hole B613, and a shaft through hole 643. The one-end main body A610 has a one-end through hole A613 drilled at a position and in a direction corresponding to the central axis C60 of the pair of main bodies 610 in the clamped state. Similarly, the other-end main body B610 has an other-end through hole B613 drilled at a position and in a direction corresponding to the central axis C60 of the pair of main bodies 610 in the clamped state. In addition, the cylindrical portion 642 of the shaft 640 has a shaft through hole 643 drilled at a position and in a direction corresponding to the central axis C60 of the pair of main bodies 610 in the clamped state. The one-end through hole A613, the other-end through hole B613, and the shaft through hole 643 are concentric and form cylindrical shapes with the same diameter. A support pillar 565 (see FIG. 11) is inserted with some play into the through-hole 603. This support pillar 565 is positioned so as to align with the central axis C60 of the ring of the annular train (not shown) of the corner cube prism 631.

[0123] The one-end through-hole A613 is a circular hole having approximately the same outer diameter as the support body 565, and is provided so that the bottom surface penetrates vertically at the center of the bottom of the fitting hole A617. Similarly, the other-end through-hole B613 is a circular hole having approximately the same outer diameter as the support body 565, and is provided so that the bottom surface penetrates vertically at the center of the bottom of the fitting hole B617.

[0124] The shaft portion through-hole 643 is a circular hole having substantially the same outer diameter as the support body 565, and is provided so as to penetrate the shaft direction at the center of the end face in the axial direction of the tube portion 642.

[0125] <Configuration of one end base> The one end base A820 includes a one end base A820A, an insertion hole A820B, a countersunk hole A820C, and a nipple A820D.

[0126] The one-end base A820A is a cylinder having an outer diameter smaller than the distance between two of the four inwardly curved sides at the facing portion A611. In this embodiment, the cylinder is a metal tube painted black and has the strength to support the target 920.

[0127] The insertion hole A820B is capable of a "loose fit" with the support body 565, and is a hole drilled in a position and direction corresponding to the central axis C70 of the cylinder of the one-end side base A820A. Therefore, in a state in which the support body 565 is inserted into the insertion hole A820B (hereinafter also referred to as the "one-end side insertion state"), the direction in which the support body 565 extends overlaps with the central axis C60. In other words, the insertion hole A820B is drilled in a position and direction corresponding to the central axis C60.

[0128] The countersunk hole A820C is a hole formed in the one-end base A820A so as to be concentric with the insertion hole A820B. The countersunk hole A820C communicates with the insertion hole A820B, thereby enabling the support body 565 to be screwed in place with the screw 592 when the support body 565 is in the one-end insertion state. In this embodiment, the countersunk hole A820C is formed so that the countersunk portion fits with the head of the screw 592 with a "clearance fit" and the pilot hole portion fits with the shaft of the screw 592 with a "clearance fit".

[0129] A nipple A820D extends from the opening edge of the countersunk portion of the countersunk hole A820C, protruding in the opposite direction to the insertion hole A820B in the one end base A820A. The nipple A820D is a cylinder whose inner circumferential surface is flush with the inner surface of the countersunk portion of the countersunk hole A820C. A male thread A820E that screws into a socket (described below, not shown) of the target 920 is provided on the outer surface of the nipple A820D. The nipple referred to here corresponds to the "mounting portion" in this disclosure.

[0130] <Structure of the support body> The support pillar 565 is a round bar that supports an external force applied to the holding mechanism 650 when the support pillar 565 is in the one-end-side insertion state and in the other-end-side insertion state (described later). Here, the support pillar 565 is a round bar that passes through the one-end-side through-hole A613, the other-end-side through-hole B613, and the shaft through-hole 643 in the holding mechanism 650 in the clamped state, and has screw holes 565A at both ends that can be screwed with the screws 592. The support pillar 565 is designed so that the support interval L31 is equal to or greater than the reinforced interval L32 when the support pillar 565 is in the one-end-side insertion state and in the other-end-side insertion state in the extending direction. Here, the support interval L31 is the interval between the hole bottom A820F of the insertion hole A820B in the one-end-side insertion state and the seat surface 592F of the head 592B of the screw 592 in the other-end-side base B820. The reinforced interval L32 is the interval between the hole bottom A820F of the insertion hole A820B in the one-end inserted state and the counterbore bottom B820G of the counterbore hole B820C in the other-end base B820.

[0131] <Configuration of the other end base> The other end side base B820 includes an other end side base B820A, an insertion hole B820B, a countersunk hole B820C, and a mounting hole B820E.

[0132] The other end side base B820A has an opposing portion B611 that is curved inwardly and has a cylindrical outer diameter smaller than the distance between two opposing sides of its four sides.

[0133] The insertion hole B820B is capable of a "loose fit" with the support body 565, and is a hole drilled in a position and direction corresponding to the central axis C80 of the cylinder of the other end side base B820A. Therefore, in a state in which the support body 565 is inserted into the insertion hole B820B (hereinafter also referred to as the "other end side insertion state"), the direction in which the support body 565 extends overlaps with the central axis C60. In other words, the insertion hole B820B is drilled in a position and direction corresponding to the central axis C60.

[0134] The countersunk hole B820C is a hole formed in the other end base B820A so as to be concentric with the insertion hole B820B. The countersunk hole B820C communicates with the insertion hole B820B, so that the support body 565 can be screwed in place with the screw 592 when the support body 565 is in the other end insertion state. In this embodiment, the countersunk hole B820C is formed so that the countersunk portion fits with the head of the screw 592 in a "clearance fit" and the pilot hole portion fits with the shaft of the screw 592 in a "clearance fit". The countersunk hole B820C in this embodiment is formed by forming a countersunk hole on the inner periphery of the washer B820D integrally molded with the other end base B820A.

[0135] The attachment hole B820E is provided at the end of the other end side base B820A opposite to the side of the insertion hole B820B, and is formed so as to form a "loose fit" with respect to the rod-shaped member 560.

[0136] <Target configuration> The target 920 includes a communication module (not shown) that supports services of a global navigation satellite system (hereinafter also referred to as "GNSS"). Here, an infrastructure (not shown) used for providing GNSS services has a satellite segment including at least four artificial satellites and a control segment that controls these artificial satellites. Note that a target that has been publicly known in the past can be used as the target 920. The shape of the target can be appropriately selected depending on the design. The target 920 of this embodiment has a socket (not shown) that can be screwed into the male screw A820E.

[0137] <Assembly procedure of the retroreflection device according to the second embodiment> A procedure for assembling the retroreflection device 600 according to the second embodiment described above will be described. When assembling the retroreflection device 600, an operator (not shown) first performs an installation operation of attaching eight engaging portions 710 to each of the one end side main body portion A610 and the other end side main body portion B610.

[0138] Next, the worker performs an integration operation in which the one end side main body part A610 and the other end side main body part B610 sandwich the shaft part 640 from both sides in the axial direction and integrate them. The specific procedure of this integration operation is similar to the specific procedure of the integration operation described above in the description of the first embodiment, so a detailed description thereof will be omitted.

[0139] Next, the worker mounts the corner cube prisms 631 in the eight recesses 641A of the shaft portion 640. This operation is the same as the "first mounting operation," "second mounting operation," and "third mounting operation" described above in the first embodiment, but in that order. Therefore, a detailed description of the specific steps of the above operations will be omitted.

[0140] Next, the worker performs a screwing operation to screw the one-end base A820 and the other-end base B820 together. This screwing operation completes the assembly of the retroreflection device 600. In the screwing operation, the worker inserts the support body 565 into the shaft through-hole 643, and then screws the one-end base A820 and the other-end base B820 into the screw holes 565A provided at both ends of the support body 565.

[0141] <Procedure for installing retroreflective devices> The following describes a procedure for installing the retroreflection device 600 according to the second embodiment. When installing the retroreflection device 600, a surveyor (not shown) first attaches the rod-shaped member 560 to the attachment hole B820E of the retroreflection device 600.

[0142] Next, the surveyor presses the rod member 560 against the ground GR at the measurement point and fixes it in place.

[0143] Next, the surveyor adjusts the inclination of the rod-shaped member 560 so that it faces vertically. At this time, if a target 920 is attached to the nipple A820D of the retroreflector 600, the surveyor may check information from a communication module (not shown) of the target 920.

[0144] <Actions and Effects> According to the above-described retroreflection device 600, when the countersunk hole B820C of the other-end base B820 engages with the head 592B of the screw 592, the one-end main body A610 moves following the other end, so that the force applied to the one-end base A820 is less likely to be applied to the non-facing portion A612. This allows the support body 565 to reinforce the prism assembly 630 in the direction along the central axis C60 of the ring of the annular train (not shown) of the corner cube prism 631.

[0145] According to the above-described retroreflection device 600, the support body 565 can reinforce the prism assembly 630 in the direction along the central axis C60 of the ring of the annular array (not shown) of the corner cube prisms 631 without blocking light.

[0146] According to the above-mentioned retroreflection device 600, it is possible to confirm the position information (not shown) of the retroreflection device 600 from the positioning information acquired by the target 920. This makes it possible to compare the position information (not shown) of the measurement point position acquired by the target 920 with the information of the distance from the position where the total station 900 is set to the retroreflection device 600.

[0147] According to the above-mentioned retroreflective device 600, by attaching a target 920 of a positioning system (not shown) to the support body 565 of the holding mechanism 650, the position of the retroreflective device 600 can be measured by both the total station 900 and the positioning system.

[0148] By having the above-mentioned configurations, the present disclosure can eliminate offset of a retroreflective device capable of retroreflecting light from the entire circumference in the circumferential direction.

[0149] <Other embodiments> The embodiment of the present invention has been described above. However, it will be appreciated that those skilled in the art will appreciate that various substitutions, modifications, and variations may be made without departing from the scope of the present invention. It is clear that the above-mentioned modifications are possible. That is, the embodiment for carrying out the object of the present invention is as follows: All substitutions, alterations, and modifications within the spirit and scope of the claims appended hereto. For example, the following various embodiments of the present invention may be used. The following form can be implemented.

[0150] In the retroreflection device according to the present disclosure, adjacent sides of each of the corner cube prisms may be butted together and fixed by a removable hook-and-loop fastener, allowing a prism assembly to be formed from multiple corner cube prisms without using a holding mechanism.

[0151] In the retroreflection device according to the present disclosure, the number of corner cube prisms constituting the prism assembly is not limited to eight. For example, the prism assembly may be constituted by ten corner cube prisms. In such a case, when viewed from the side, the prism assembly has the shape of an antipentagonal prism consisting of ten equilateral triangles and two regular pentagons. This allows the inclination angle of the light transmitting surface of the prism assembly relative to the central axis of the ring of the ring train to be set smaller.

[0152] In the retroreflection device according to the present disclosure, the protruding portion of the hooking piece of the hooking protrusion may have a surface facing the corner cube prism that is smoothly curved and convex toward the corner cube prism. In this case, when removing the hooked corner cube prism, the corner cube prism can be removed more smoothly by rotating the corner cube prism while abutting its light transmitting surface against the curved surface of the protruding portion.

[0153] In the retroreflective device according to the first embodiment of the present disclosure, an elastic body may be provided in the storage space of the support. As the additional configuration, the elastic body may be capable of storing an eccentric positioning pin in an externally fitted state in a natural state, and may be deformed radially inwardly of the rod-shaped member to a compressed state by being sandwiched between the support and the inner tube. As the additional configuration, the support may have an elastic body in a compressed state that externally fits the eccentric positioning pin in an externally fitted state. For example, a cylindrical rubber may be used as the elastic body. [Explanation of symbols]

[0154] 60 Rod-shaped member 70 Eccentric positioning pin 71 Overhang 72 Gripping part 73A One end slope 73B Other end slope 74 Locking part 81 Screw 81A Axis 81B head 100 Retroreflective device 103 Through hole 110 Main body 130 Prism Assembly 131 Corner cube prism 132 Reflective surface 132A Corner part 133 Light transmission surface 134 Corner 136A Non-adjacent edges 136B Adjacent side 137 Ring series 140 Shaft 141 Frames 141A Dent 142 Cylinder part 142A screw hole 142B Waist 142C flat surface 142D Slope 143 Shaft through hole 150 Retention mechanism 201A Flat head screw 201B head 201C axis 210 Engagement part 211A Hollow Cylinder 211B Counterbore 211C Countersink 211D Pilot hole 211F Contact part 211G Slope 211H Cutout surface 220 Latching protrusion 221 Latch piece 221A Protrusion 221B Claw 230 Inner cylinder 231 Male thread 233 Guide surface 234 Locking groove 240 Support part 241 Female thread 243 Guide surface 244 Sliding hole 320 Horizontal Detector 320A Mounting plate 320B Mounting hole 320C Insertion hole 320D Vial 560 Rod-shaped member 565 Post body 565A screw hole 581 Screw 581A axis 581B Head 592 Screw 592B head 592F seat 600 Retroreflective device 603 Through hole 610 Main body 630 Prism Assembly 631 Corner Cube Prism 632A Corner part 633 Light transmission surface 634 Corner 636A Non-adjacent edges 636B Adjacent side 640 Shaft 641 frames 641A Dent 642 Cylinder part 642A screw hole 643 Shaft through hole 650 Retention mechanism 701A Flat head screw 710 Engagement part 720 Latching protrusion 721 Latching piece 721A Protrusion 900 Total Station 910 Laser Light Source 920 Target A110 One end main body A111 Opposing part A112 Non-opposing part A112A screw hole A113 One end side through hole A117 Fitting hole A118 Counterbore A118A Pilot hole A610 One end main body A611 Opposing part A612 Non-opposing part A613 One end through hole A617 Fitting hole A618 Counterbore A618A Pilot hole A820 One end base A820A One end base A820B Insertion hole A820C Counterbore A820D Nipple A820E Male thread A820F hole bottom B110 Other end main body B111 Opposing part B111A Engagement hole B111B screw hole B111C Countersink B111F Insertion hole B112 Non-opposing part B113 Other end side through hole B117 Fitting hole B118 Counterbore B118A pilot hole B610 Other end main body B611 Opposing part B611A Engagement hole B611B screw hole B611C Countersink B612 Non-opposing part B613 Other end side through hole B617 Fitting hole B820 Other end base B820A Other end base B820B Insertion hole B820C Counterbore B820D Washer B820E Mounting hole B820G bottom C10 center axis C60 center axis C70 center axis C80 center axis ER Scope ERC area GR Daichi IP incidence position L11 Length L12 Length L13 Length L21 Minimum distance of incidence L22 Minimum emission distance L31 Support interval L32 Reinforced interval LR Laser Light OP output position RP1 First reflection position RP2 2nd reflection position S10 Storage space S20 Play S30 Slit

Claims

1. A retroreflection device comprising a corner cube prism having three reflecting surfaces each forming a plane perpendicular to each other, and a light transmitting surface that transmits incident light incident toward the reflecting surfaces and transmits retroreflected light that is reflected from the incident light by the reflecting surfaces, the light transmitting surface is a surface forming an equilateral triangle shape, and includes a non-adjacent side corresponding to a base of the triangle, and two adjacent sides corresponding to two equal sides excluding the base, a prism assembly including an even number (eight or more) of the corner cube prisms arranged in such a way that adjacent sides of the light transmitting surfaces of the corner cube prisms are closely adjacent to each other to form a continuous ring-shaped array; Each of the corner cube prisms in the annular array is arranged with the light transmitting surface facing the outside of the ring of the annular array, and Under the condition that the incident light is incident on the corner cube prism in a direction perpendicular to the central axis of the ring of the ring train, A first length is an optical path length from an incident position where the incident light passes through the light transmitting surface to an exit position where the retroreflected light passes through the light transmitting surface; and a second length that is the sum of the shortest distance from the incident position to the central axis and the shortest distance from the central axis to the exit position; The corner cube prism is disposed in such a manner that the two lengths are equal to each other. Retroreflective device.

2. 2. The retroreflective device according to claim 1, the prism assembly has a configuration in which eight of the corner cube prisms are arranged in a state in which the entire adjacent sides of the light transmitting surfaces are in close contact with each other, Retroreflective device.

3. The retroreflective device according to claim 1 or 2, The prism assembly includes a holding mechanism that holds the corner cube prism in a state in which the corner cube prism can be individually attached and detached. Retroreflective device.

4. The retroreflective device according to claim 3, The holding mechanism includes: a pair of main bodies sandwiching the corner cube prisms forming the annular array from both sides in the axial direction of the central axis; a locking protrusion provided on each of the main bodies for locking the non-adjacent sides of the corner cube prism in the held state from the outside; an engaging portion attached to each of the main bodies and engaged from the outside with a corner between each of the adjacent sides of the corner cube prism to which the engaging protrusion engages the non-adjacent side; a retracted state is realized in which the corner cube prisms in the held state can be individually attached and detached by removing the engagement portion; Retroreflective device.

5. The retroreflective device according to claim 4, The holding mechanism includes a through hole drilled at a position and in a direction corresponding to the central axis, a rod-shaped member is slidably inserted through the through hole, thereby allowing the prism assembly to slide along an extension direction of the rod-shaped member; Retroreflective device.

6. The retroreflective device according to claim 3, the holding mechanism has recesses the number of which corresponds to the number of the corner cube prisms arranged in the annular array, each of the recesses holds each of the corner cube prisms by receiving a corner portion where the three reflecting surfaces of the respective corner cube prisms meet; Retroreflective device.

7. The retroreflective device according to claim 5, an outer fitting member that is fitted onto the rod-shaped member; an outer cylinder fitted onto the outer fitting member; The outer fitting member is a protruding portion that protrudes outwardly to one side in a radial direction of the rod-shaped member when the rod-shaped member is fitted around the rod-shaped member; a locking portion that is locked to one of the pair of main body portions and prevents the main body portion from rotating in a circumferential direction, When the outer cylinder is fitted onto the outer fitting member, the protruding portion is tightened from the one side to press the outer fitting member against the rod-shaped member. Retroreflective device.

8. The retroreflective device according to claim 7, A horizontal detector is attached to at least one of the pair of body parts. Retroreflective device.

9. The retroreflective device according to claim 3, the holding mechanism includes an insertion hole formed at a position and in a direction corresponding to the central axis, A support body that supports an external force applied to the holding mechanism is inserted into the insertion hole. Retroreflective device.

10. 10. The retroreflective device according to claim 9, The support body is supported by the support body, and a mounting portion is provided to which a target of a positioning system can be attached. Retroreflective device.

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