Abstract: A GNSS data collection system includes a pole mounted GNSS receiver and inclination sensors. The range pole has an adjustable length and an integrated electronic measurement device to capture and provide length data. A data collection module provides a data collection graphical user interface (GUI) visible on a hand-held data collector computer. The data collector computer is communicably coupled to the GNSS receiver and/or the electronic measurement device and receives three-dimensional location data, the length data, and inclination data for the range pole in real-time. The inclination data and height of the range pole are used to calculate and display horizontal distance and direction to level the GNSS receiver.

Abstract: A surveying apparatus has a combined structure of a total station and a laser scanner. The surveying apparatus includes a point cloud data acquiring unit, an abnormal part detecting unit, an abnormal part position acquiring unit, and an automatic sighting controller. The point cloud data acquiring unit acquires first point cloud data and second point cloud data obtained by laser scanning that is performed on an object to be inspected at a time interval. The abnormal part detecting unit calculates a difference between the first and second point cloud data to detect a part of the object to be inspected, at which position information varies, as a detailed-inspection target part. The abnormal part position acquiring unit acquires a position of the detailed-inspection target part. The automatic sighting controller controls to make the total station sight the detailed-inspection target part, based on the position of the detailed-inspection target part.

Abstract: This unique and novel invention provides a telescoping level device used to effectively and efficiently measure the slope of objects and surfaces. The device comprises a telescoping arm, a ball joint, a level, and one or more contactors. The device allows the user to easily, accurately, and quickly verify the in-situ slope of pipes as well as a plurality of other objects and surfaces. The length and angle of the telescoping arm, relative to the level, are adjustable to prevent the user from unnecessarily stooping, kneeling, or climbing.

Abstract: One embodiment provides a device comprising at least one movable unit, at least one sensor, a printer, at least one processor, and a non-transitory processor-readable memory device storing instructions that when executed by the at least one processor causes the at least one processor to perform operations. The operations include receiving layout and design information, receiving, from the at least one sensor, contextual information indicative that the at least one movable unit is in direct contact with a surface, and triggering the printer to print one or more markings on the surface as the at least one movable unit moves along the surface based on the layout and design information.

Abstract: Disclosed is a method for monitoring ground settlement based on computer vision. Before monitoring starts, the first image frame is captured. For one measuring point, the area of the top LED lamp is defined as a tracking template, its pixel center is the reference point for settlement calculation, and a monitoring area is defined by an estimated range. After monitoring starts, the best matched of the lamp template is searched for in the monitoring area of a second image frame. When the best matched area is obtained, its pixel center is obtained as the new lamp position, and it is selected as the new template; the pixel displacement between two adjacent image frames can be obtained by comparison. The total pixel displacement of multiple points during the monitoring period is calculated through the accumulated displacement, and the actual settlement is calculated through a pixel-physical ratio.

Abstract: An augmented reality visualizer and measurement system for swimming pool components (e.g., liners and safety covers) is provided in some examples of the present disclosure. In one example, a system can receive images of physical markers positioned spatially around a perimeter of a swimming pool in real space. The system can identify the physical markers in the images by analyzing the images using one or more image processing techniques. The system can determine one or more characteristics of the swimming pool based on relationships between the physical markers. The system can then generate pool component information based on the determined one or more characteristics of the swimming pool, and output the pool component information.

Abstract: A stand-alone module for localizing a surveying device installed with a stand above a ground mark. The module has at least one housing attached between the stand and the surveying device, a measuring camera unit, which is arranged and designed in such a way that when the module is mounted on a stand the ground mark can be detected in the field of view of the measuring camera unit, a power supply, an inclination sensor and a communication unit.

Abstract: A GNSS data collection system includes a pole mounted GNSS receiver and inclination sensors. A data collection module provides a data collection graphical user interface (GUI) visible on a hand-held data collector computer. The data collector computer is communicably coupled to the GNSS receiver and receives three-dimensional location data and inclination data for the range pole in real-time. A virtual level component uses the inclination data to display on the GUI real-time tilt information in the form of a virtual bubble level indicator. The inclination data and height of the range pole are used to calculate and display horizontal distance and direction to level the GNSS receiver.

Abstract: A laser level including a control mechanism housing which houses a control mechanism, the control mechanism including at least a top surface and a bottom surface. A protective structure extends from the control mechanism housing configured to protect the control mechanism from impact and including an upper structure which extends from a top surface of the control mechanism housing and a lower structure which extends from a bottom surface of the control mechanism housing.

Abstract: In order to achieve the object described above, a communication management system includes: a surveying instrument including a survey unit, a GPS device, a control unit, and a communication unit; a management server capable of communicating with the surveying instrument; and a remote terminal capable of communicating with the management server, wherein the remote terminal sets a usable range of the surveying instrument, and sets determination on entrance and exit of the surveying instrument into and from the usable range, and an operation responsive to results of the determination, and makes the management server store these, the surveying instrument transmits own GPS information to the management server, and the management server compares entrance and exit of the surveying instrument into and from the usable range with the GPS information and executes the determination, and executes the operation based on results of the determination.

Abstract: Surveying device comprising a base defining a base axis (A), a support structure arranged to be rotatable around the base axis (A) and defining a rotation axis (B), a light emitting unit for emitting measuring signal and a light receiving unit comprising a detector for detecting reflected measuring signal. A rotation unit is mounted on the support structure for providing emission and reception of measuring light in defined directions, wherein the rotation unit comprises a rotation body which is mounted rotatable around the rotation axis (B) and the rotation body comprises a scanning mirror which is arranged tilted relative to the rotation axis (B). The device comprises at least one projector fixedly arranged with the support structure, defining a particular optical axis and configured to direct a light pattern at a scene, wherein position and shape of the pattern are controllable by the controlling and processing unit.

Abstract: A coordinate measuring and/or stake out device can be designed for being hand-held (one-handed), free carriage and movement by a user. A position giving means is for determination of an actual translational position of the device using an external position reference and an orientation giving means for determination of an actual rotational position of the device, such that the actual position of the device with respect to all six degrees of freedom of the device can be determined. A radiation source is for generation of a radiation beam as measuring and/or marking beam for measuring and/or visually marking of an object point. A beam steerer is for automatic steering of an alignment of the beam, whereby the beam which differ in the manner of automatic steering the beam alignment.

Abstract: Aspects of the present disclosure describe techniques for optical alignment using a reflective dove prism. For example, a system for optical alignment is described that includes an assembly having a housing with three separate, reflecting structures positioned to produce three reflections of one or more laser beams or one or more images, and a controller configured to control a rotation of the assembly about a pivot point to produce a tilt in orientation of the one or more lasers beams or the one or more images that is twice an angle of rotation of the assembly. Another system and a method for aligning laser beams using a housing with three separate, reflecting structures in a trapped ion quantum information processing (QIP) system are also described.

Abstract: The present disclosure relates to a laser level system. The laser level system includes a mount, a laser secured to the mount and a remove input device. The mount includes a rotating portion to which the laser level is secured. The remote input device controls rotation of the rotating portion. The laser level is secured to the rotating portion of the mount such that when the rotating portion rotates, the laser level rotates concurrently along with the rotating portion of the mount.

Abstract: There is provided a surveying instrument including a monopod which is installed on a reference point, a surveying instrument main body which is provided at a known distance from a lower end of the monopod and a known angle with respect to an axis of the monopod, two auxiliary legs which extend downward from a middle portion of the monopod at a predetermined angle, and a lower image pickup module which is provided at a known position with respect to the surveying instrument main body, wherein the surveying instrument main body comprises a measuring unit, a measuring direction image pickup module, and an arithmetic control module, wherein the surveying instrument main body is supported by three points by the monopod and the auxiliary legs, and a positional change or a rotational change of the surveying instrument main body is calculated based on a change of the lower image.

Abstract: A positioning device for arrangement of a basin false bottom in ocean engineering comprises a laser transmitting system, a rotating platform system, and a control and calculation system. The laser transmitting system comprises a laser transmitter used for providing laser beams. The rotating platform system comprises a two-degree-of-freedom rotating platform used for carrying the laser transmitter and making the laser beams have spatially arbitrary directivity. The control and calculation system is used for calculating, according to given coordinates, the angle by which the two-degree-of-freedom rotating platform needs to rotate, controlling rotation of the two-degree-of-freedom rotating platform, and making the laser beams transmitted by the laser transmitter accurately indicate the given coordinates at the basin false bottom.

Abstract: A surveying device including a base defining a base axis, a support structure rotatable around the base axis and defining a rotation axis, a light emitting unit emitting light and a light receiving unit for detecting reflected light. A rotation unit is mounted on the support structure for emitting and receiving light in defined directions, wherein the rotation unit comprises a rotation body rotatable around the rotation axis including a scanning mirror arranged tilted relative to the rotation axis. An imaging unit for capturing an image of a scanning region is provided. The imaging unit comprises a camera fixedly arranged on the support structure, the rotation body comprises at least one reflecting deflecting surface assigned to the camera. The imaging unit and the rotation body are arranged so that the field of view comprises a defined field angle around the rotation axis.

Abstract: A first surveying unit comprises a frame in a horizontally rotatable manner, a telescope unit in a vertically rotatable manner, a first angle measuring unit and a first distance measuring unit which measure a prism, wherein the second surveying unit comprises a scanning mirror which rotatably irradiates a laser beam and a second angle measuring unit which detects a rotation angle of the scanning mirror, wherein a target instrument comprises a pole installed at a measuring point, the prism has a known positional relationship with a lower end of the pole, and a target plate mounted on the pole, wherein an arithmetic control module scans a laser beam, calculates a measuring point direction vector based on point cloud data of the target plate, and calculates a three-dimensional coordinate of the measuring point based on an optical center of the prism, the measuring point direction vector, and the positional relationship.

Abstract: A target instrument has an illuminating lamp, wherein a total station has an optical axis deflector capable of deflecting a distance measuring optical axis, a projecting direction detecting module for performing an angle measurement of the distance measuring optical axis, an image pickup unit, and an arithmetic control module for controlling a deflecting action of the optical axis deflector and a distance measuring action of a distance measuring unit, wherein the arithmetic control module is configured to detect an illumination light from an image acquired by the image pickup unit, to acquire a direction of the illuminating lamp based on a detection result, to make the optical axis deflector to scan with a distance measuring light around the acquired direction and to perform a distance measurement and an angle measurement along a scanning path.

Abstract: A method for checking a rotating laser for cone errors using a laser receiver, where the rotating laser projects a laser beam which can rotate in a horizontal plane about an axis of rotation and the horizontal plane spans from a first horizontal axis to a second horizontal axis. The rotating laser is arranged in a horizontal position at a first location and at a second location between a first measurement surface and a second measurement surface. The rotating laser having, at the first location a first measurement distance, and having, at the second location a second measurement distance, to the second measurement surface.

Abstract: A system for vertical accuracy improvement includes a reference station, a rover, and a base station in communication with the reference station and the rover. The base station includes a GNSS antenna, an actuator coupled to the GNSS antenna, a wireless transceiver, a processor, and non-transitory computer readable media comprising instructions executable by the processor. The instructions may be executed to cause the base station to receive a first vertical error from the reference station. The base station may further be configured to determine a second vertical position at which the first vertical error is reduced, and adjust the GNSS antenna to be in the second vertical position. The base station may further be configured to generate correction data based at least in part on the phase of the carrier wave signal at the second vertical position, and transmit the correction data to the rover.

Abstract: One embodiment provides a device comprising at least one movable unit, at least one sensor, a printer, at least one processor, and a non-transitory processor-readable memory device storing instructions that when executed by the at least one processor causes the at least one processor to perform operations. The operations include receiving layout and design information, receiving, from the at least one sensor, contextual information indicative that the at least one movable unit is in direct contact with a surface, and triggering the printer to print one or more markings on the surface as the at least one movable unit moves along the surface based on the layout and design information.

Abstract: A method for checking and/or calibrating a vertical axis of a rotating laser which projects a first laser beam that can rotate about an axis of rotation and a second, stationary laser beam, using a laser receiver. The rotating laser is positioned at a measurement distance from the laser receiver, the rotating laser being oriented in a vertical position, and the laser receiver having a transverse arrangement.

Abstract: A method for checking and/or calibrating a first or a second horizontal axis of a rotating laser, which emits a laser beam rotating about an axis of rotation, with the aid of a laser receiver. The rotating laser is positioned at a measuring distance to the laser receiver, the rotating laser being aligned in the horizontal position and the laser receiver being aligned in a longitudinal arrangement.

Abstract: The invention provides a surveying instrument, which comprises a frame unit provided capable of rotating horizontally via a horizontal rotation shaft, a telescope unit provided capable of rotating vertically via a vertical rotation shaft in a recessed portion formed in the frame unit, a vertical rotation driving unit in which a vertical output shaft is connected to the vertical rotation shaft, and a whirl-stop unit provided on an outer side of a side plate of the frame unit along the side plate and connecting the vertical rotation driving unit and the frame unit to each other.

Abstract: A sensor comprises a detector defining a zone axis and adapted to receive a signal from within a zone around the zone axis and to generate an electrical signal, and a display module defining a display plane and adapted to display a pattern in the display plane based on the electrical signal, the display being oriented along an axis forming an angle with the zone axis such that the pattern is visible both from a direction parallel to the zone axis and from a direction perpendicular to the zone axis. In certain examples, the angle is about 45°, 40°-50°, 35°-55° or 25°-65°.

Abstract: Calibration device and calibration method for calibration of a laser beam horizontal trueness testing device whereby the calibration device comprises an elongated support body for support of an elongated laser housing with a longitudinal axis and a laser source, whereby a laser beam is emittable in a direction of the longitudinal axis. According to the calibration method, calibration parameters are determined based on at least three impinging positions of the laser beam of the laser housing for at least two different rotational positions of the laser housing in a first face and at least one position of the laser housing in a second opposing face.

Abstract: An angle square adapter including: a base, where base is attachable to a straight ruler; a series of holes over a top surface of the base; an alignment line between the holes; a laser assembly mountable on the base, where the laser assembly includes a circular measurement portion, a nose portion and a laser mounted on the nose portion; and a measurement scale along one edge of the base, where measurement scale assists in angle alignment. The series of holes preferably includes three holes aligned in a straight line. An angle scale is provided on the perimeter of the circular measurement portion. The angle square adapter may also include a plurality of magnets along one side of the base and a lanyard attached to the base.

Abstract: A calibration device to calibrate precise horizontality of a light emitting element includes a retaining rack, a microprocessor, a regulating member, two driven members, and two photo sensing members. The regulating member drives the light emitting element, the two driven members are on the retaining rack, and the microprocessor controls the driven members to move linearly. The photo sensing members detect light transmitted and data as to the vertical distance between two driven members, and vertical distance between the photo sensing member and the two driven members, is stored. The microprocessor calculates the moving distance of the photo sensing members carried by the driven members based on the signals of light detected, and further calculates declination of the light emitting element. The microprocessor can adjust the orientation of light emitting element.

Abstract: The invention provides a tilt detecting system comprising, a surveying instrument having a distance measuring function and a line laser projecting unit installed as horizontally rotatable for projecting a vertical line laser, and a photodetection device having at least two photodetection units provided at a known interval, a target with a retro-reflectivity and an arithmetic unit, wherein the line laser projecting unit is rotated, each of the photodetection units are made to scan the line laser and the arithmetic unit detects a tilting angle of the photodetection device based on a deviation between a photodetection time moment of each photodetection unit and the distance measurement result of the target of the surveying instrument.

Abstract: A survey instrument conveyance is disclosed. One embodiment includes a mobile platform having a set of wheels attached thereto. In addition, a mechanical coupling assembly is used to couple a survey instrument to the mobile platform. An adjustable position mechanism is coupled to the mechanical coupling assembly to raise and lower the survey instrument relative to the mobile platform.

Abstract: Layout equipment for locating a plurality of positions at a construction site is provided. The layout equipment includes a laser target rod, a self-leveling laser transmitter, and a remote control device. The rod has an elongated rod body including retroreflective material extending substantially the entire length of the body. The laser transmitter projects a beam of laser light, and receives laser light reflected from the rod. The laser transmitter includes a first wireless communication unit, and a transmitter control. The transmitter control is responsive to the first wireless communication unit. The remote control device includes a second wireless communication unit that communicates wirelessly with to the laser transmitter to cause the laser transmitter to project the beam of laser light toward a position at the construction site, and signals the user of the layout equipment when the rod has been placed at the position.

Abstract: Some embodiments of the invention relate to a rotation unit for a surveying device, in particular a laser scanner for optically scanning an environment and such a surveying device. The surveying device has a rotation unit having a rotation mirror, for deflecting an emission light beam and a reception light beam, and a rotation body implemented as a cylinder having a on a beveled, free end. The rotation body is implemented as a hollow cylinder having a cylinder bottom and a beveled cylinder wall on its free end. The hollow cylinder is connected coaxially with respect to its cylinder axis in a rotationally-fixed manner to a motor-driven shaft via the cylinder bottom. The rotation mirror is fastened in the region of its free end to the cylinder wall of the hollow cylinder so it is supported thereby.

Abstract: A spherically mounted retroreflector (SMR) having an embedded temperature sensor and a socket for attaching to an electrical connector.

Abstract: A construction laser system includes a rotating laser with self-leveling and a laser receiver. The system performs a self-leveling recalibration process by which-the self-leveling is checked automatically for quality and the related calibration data is updated automatically. A sequence of N calibration measurements is defined, where N is greater than or equal to three. The calibration measurements are obtained by the rotating laser and the laser receiver with a respective azimuthal alignment of the stand while the position of the laser receiver remains unchanged. As part of each calibration measurement, one output signal dependent on the laser beam impingement position is detected. The respective output signals or specified impingement positions are evaluated in pairs correlated with the respective I-th azimuthal alignments. The quality of the beam leveling functionality is thereby checked. If the requirements are not met, the previously stored calibration data can then be updated automatically.

Abstract: A geodetic device comprises three device components, two axes of rotation, and two angle sensors such that the device components are rotatable with respect to each other and their rotational positions are determinable, and an inclination sensor system. A method for determining a characteristic of the device comprises an alignment of the second device component with respect to the first device component into a plurality of different rotational positions, whereby in each rotational position of the plurality of rotational positions a measurement value is determined from the first angle sensor, a measurement value is determined from the second angle sensor, and a measurement value is determined for the orientation of the inclination sensor system.

Abstract: A method for a measuring instrument is disclosed, for separating the angular deviation of a rotational axis of an instrument body from a corresponding true rotational axis due to imperfections in at least one rolling-element bearing effectuating the rotational mounting of the instrument body into different parts corresponding to type of imperfection. The method comprises detecting rotary position of the at least one rolling-element bearing, and determining angular deviation of the rotational axis from the corresponding true rotational axis in a plurality of rotational positions of the instrument body, wherein the instrument body is rotated a plurality of successive full or partial revolutions about the rotational axis. There is also disclosed a measuring system and a measuring instrument to be used in such a measuring system.

Abstract: Some embodiments of the invention relate to a rotation unit for a surveying device, in particular a laser scanner for optically scanning an environment and such a surveying device. The surveying device has a rotation unit having a rotation mirror, for deflecting an emission light beam and a reception light beam, and a rotation body implemented as a cylinder having a on a beveled, free end. The rotation body is implemented as a hollow cylinder having a cylinder bottom and a beveled cylinder wall on its free end. The hollow cylinder is connected coaxially with respect to its cylinder axis in a rotationally-fixed manner to a motor-driven shaft via the cylinder bottom. The rotation mirror is fastened in the region of its free end to the cylinder wall of the hollow cylinder so it is supported thereby.

Abstract: A laser measurement system operates to measure portions of a vehicle, such as a vehicle frame. The measurements are used, for example, to determine if the portions of the vehicle are bent or damaged. The measurement system includes a laser scanner and at least one target assembly that can be connected to a point of the vehicle. The laser scanner emits a laser beam that is detected by the target. Time and laser position information detected by the target are used to determine the location of the target, as well as the location of the point of the vehicle. The location of the point is then compared to an original location of the point to determine if damage has occurred.

Abstract: Provided are examples of a hands-free level to quickly, accurately, and efficiency level and plumb a wide range of objects regardless of shape. The level includes a stationary component, an adjustable component, a level device attached to the stationary component/adjustable component, and a cord. The cord includes a J-shaped terminus that abuts the adjustable component. Advancing the cord urges the adjustable component towards the stationary component. Complementary locking teeth on the cord and stationary component lock the adjustable component in place and clamps the hands-free level to an object. This lets a user use two hands to hold and move the object while simultaneously checking the object for plumb and/or level.

Abstract: A surveying instrument includes a pedestal provided with a guide light irradiation unit provided with a light source to irradiate with guide light indicating a collimation direction of the surveying instrument to an operator, a tracking optical system which locks a target, a ranging optical system which ranges a distance to the target, and a control circuit which calculates surveying data by a ranging result of the ranging optical system, and a transmitting and receiving unit which receives survey setting point data regarding a survey setting operation and sends the surveying data obtained by the control circuit.

Abstract: A laser surveying device includes a rotatable and tiltable laser head in a housing to rotate about a rotational axis set in a certain direction and project a laser beam around and a tilt angle detector to detect a tilt angle of the laser head relative to the housing. The tilt angle detector includes a pattern plate on which a certain pattern is formed, provided in one of the laser head and the housing, light receiving elements arranged in the other of the laser head and the housing at different positions opposite to positions of the pattern plate to receive light beams reflected by the pattern plate, and a determiner to determine a direction and an amount of tilt of the laser head on the basis of a light receiving amount of each of the light receiving elements.

Abstract: The present invention relates to a light beam emission device for a measuring device for changing the optical properties of a light beam as well as to a corresponding method and to a measuring instrument which uses the light beam emission device, wherein the optical properties of the light beam can be changed automatically thereby from one state to another state.

Abstract: An electronic light detection circuit for detecting an intensity modulated light signal on a photosensitive element under backlight condition. The circuit comprises the photosensitive element, in particular as a light position detector for detecting a striking position of the light signal spot within a detection window, an amplifier with high input resistance connected to an output of the photosensitive element and a backlight suppression circuitry. The backlight suppression circuitry is connected to the output of the photosensitive element in parallel to the amplifier and comprises an electronic active resonator structure. The active resonator, structure is designed in such a way to provide a load impedance to an output of the photosensitive element with a low load impedance for low frequencies for suppression of natural and artificial backlight-saturation of the photosensitive element and a high load impedance at the frequency of the intensity modulated light signal.

Abstract: A survey setting point indicating device comprises a prism device 5 and a support member, and in the survey setting point indicating device, said prism device comprises a laser emitting device 16 for emitting a laser beam 17, an omnidirectional prism 9 having a cavity 14 in a center, a mirror 18 which is provided in said cavity, is rotatable about two axes crossing at right angles, and can deflect, in an arbitrary direction, said laser beam emitted from said laser emitting device, and a control unit 19 for controlling a posture or a rotation of said mirror, and said support member supports said prism device, and said laser beam is configured to attach (transfer) a position of a center of said prism device to a required surface.

Abstract: A process for installing electrical box, wiring, and receptacles or switch simultaneously that allows electricians to perform all 3 tasks at one time without the need to return to install receptacles or switch after wallboard is installed comprises: Housing with built-in laser guide and attached magnetic spacers for metal studs or wooden studs that allow for correct alignment of receptacle or switch for applicable wallboard thickness used.

Abstract: Some embodiments of the invention relate to a rotation laser and a method for operating a rotation laser. The rotation laser may be provided with a laser light source for generating a laser beam, a deflection means rotatable about a rotation axis and serving for the directional emission of the laser beam, and an optical system comprising one or more lenses for manipulating the laser beam. In some embodiments, at least one of the lenses is a lens which is deformable in a targeted manner by actuators. In some embodiments, a control unit is included for manipulating the at least one lens. In some embodiments, the at least one lens has at least four actuators which are drivable by the control unit and/or which are arranged in a manner distributed along a circumference of the lens.

Abstract: A rotary laser irradiating system, comprising a light emitting unit (41, 42) for emitting a laser beam, a rotator for forming a reference plane by projecting the laser beam by rotary irradiation, a tilt driving unit (21) for tilting the reference plane, a control unit (35) for controlling a light emission of the light emitting unit, and a tilted axis indicating means (35, 44) for turning off the laser beam so as to form a tilted reference axis indicating range in a tilt setting reference axis direction for setting a tilt.

Abstract: The invention provides a surveying instrument (1) which has a measuring unit comprises an operation control panel (4) rotatably mounted on the measuring unit with vertical axis as the center with respect to the measuring unit, and a relative angle detecting means for detecting a relative angle of the operation control panel and the measuring unit, wherein the operation control panel is so arranged that a command is issued to relatively rotate the measuring unit based on the relative angle detected by the relative angle detecting means.

Abstract: A survey setting point indicating device comprises a support member 3 which can be tilted with respect to a vertical direction, a connecting member which can be freely tilted with respect to the support member and hangs vertically downward by gravity, a laser pointer 7 which is provided at a lower end of the connecting member, is concentric with an axis of the connecting member and emits a laser beam vertically downward, and a reflector 5 provided such that the axis of the connecting member passes through a center of the reflector.