WO2000047950A1

WO2000047950A1 - Laser survey device

Info

Publication number: WO2000047950A1
Application number: PCT/IB2000/000106
Authority: WO
Inventors: Nigel Iivari Anderson
Original assignee: Nigel Iivari Anderson
Priority date: 1999-02-09
Filing date: 2000-02-02
Publication date: 2000-08-17
Also published as: ZA995175B; AU2124200A

Abstract

The invention concerns a laser survey device which can be used inter alia in setting out roads and splits in board-and-pillar mining practice. The device has a housing which can be mounted at a survey point in a mine working in a manner allowing the housing to be rotated about a vertical axis. In the housing are laser beam directing means in the housing for projecting from the housing first and second laser beams at predetermined angles to one another and transverse to the axis.

Description

LASER SURVEY DEVICE

BACKGROUND TO THE INVENTION

THIS invention relates to a laser survey device.

In certain types of mine, for instance coal mines, it is common practice to mine out material in a set pattern such that regular pillars of unmined material are left in position to support the overburden. This is shown in Figure 1 in which the pillars are indicated with the numeral 1. Normally, the supporting pillars are of square cross-section and are located in a regular rectangular grid pattern with material being mined out from between the pillars. To achieve the required rectangular grid pattern, a mine surveyor establishes survey stations 2 in forward-running tunnels 3, known as "roads" between two rows of pillars 1. The survey stations 2 are located at the intersections between the centrelines of the roads 3 and the centrelines of cross-tunnels 4 known as "splits".

The survey station itself comprises a brass spad which is attached to the roof or hanging wall of the mine working, at an accurately surveyed position and which serves as a datum location from which a series of survey points 5 can be established along the centreline of the previous split 4 at the intersections of the roads 3. Once established, the survey points 5 are used to set the positions of line pegs 6 along the roads 3. This is conventionally achieved with the use of an optical square which is suspended in turn from each survey point 5 with a suitable object such as a weighted string being suspended from an adjacent survey point.

An assistant located a short distance away from the optical square, in the

CO IRMATION COPY direction of development 7 of the road 3, then holds up a target in the form of a weighted string and the surveyor, sighting in conventional manner through the optical square, directs him to move the target to the right or left until the target lines up visually in the optical square with the string suspended from the adjacent survey point When the images sighted by the surveyor are coincident, a line peg in the form of a spad is attached to the roof directly above the target string There are now two spads attached to the roof in the direction of development 7 and these can be used to provide accurate guidance for further development

A disadvantage of the known procedure as described above is the fact that it is difficult and time-consuming to install the line pegs accurately in the required positions determined by use of the optical square

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided a laser survey device comprising a housing, means enabling the housing to be mounted at a survey point in a mine working in a manner allowing the housing to be rotated about a vertical axis transverse to the roof, and laser beam directing means in the housing for projecting from the housing first and second laser beams which are at a predetermined angle to one another and transverse to the vertical axis

The housing may be attachable to a laser unit which includes a laser projection module and which is suspendable from the roof of a mine working Typically the housing is attachable rotatably to the laser unit The housing may be attachable to the laser unit such that an incident laser beam produced by the laser projection module is directed into the housing, the housing including first and second laser beam exits at the predetermined angle to one another and the laser beam directing means being arranged to cause portions of the incident laser beam to be projected out of the housing through the respective laser beam exits Conveniently, the laser beam directing means comprises a beam splitter for reflecting a first portion of the incident beam laterally through the first laser beam exit and a mirror for reflecting a second portion of the incident beam which passes through the beam splitter laterally through the second laser beam

The invention includes a device in which the laser beam directing means comprises first and second laser modules in the housing which are oriented at the predetermined angle to one another to project first and second laser beams which are at that predetermined angle to one another It will be understood that in this aspect of the invention, the laser unit is incorporated as part of the survey device itself Specific embodiments may include beam fanning and beam directing features similar to those mentioned above

According to another aspect of the invention there is provided a laser survey device comprising means enabling the device to be mounted at a survey point in a mine working in a manner allowing the device to be rotated about a vertical axis, a laser unit including a laser module for projecting an incident laser beam and laser beam directing means onto which the incident laser beam is projected in use by the laser module and which is arranged to cause respective portions of the incident laser beam to be projected outwardly from the device at a predetermined angle to one another and transverse to the vertical axis

According to a further aspect of the invention there is provided a laser survey device comprising a housing having first and second laser beam exits therein oriented at a predetermined angle to one another, means enabling the housing to be mounted at a survey point in a mine working in a manner allowing the housing to be rotated about a vertical axis, and first and second laser modules in the housing which are arranged to project respective first and second laser beams outwardly from the housing through the laser beam exits in directions which are at the predetermined angle to one another and transverse to the vertical axis.

Yet another aspect of the invention, applicable to box-hole development in a mine, provides a laser survey device comprising:

a first housing which accommodates laser beam directing means;

a second housing accommodating a diode laser module, the second housing being attachable to the first housing with the axes of the housings coincident;

means enabling the attached housings to be mounted in a mine working with the axes of the housings vertical, whereby a diode laser of the diode laser module can project a laser beam vertically from the second housing into the first housing;

vertically spaced beam exits from the first housing through which the laser beam directing means will project respective portions of the laser beam projected into the first housing by the diode laser, such portions being at a predetermined angle to one another and transverse to the vertical axis with one of the beam portions being upwardly inclined relative to the horizontal for the purposes of box- hole guidance. BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which:

Figure 1 diagrammatically illustrates a section of an underground mine in horizontal cross-section;

Figure 2 at a larger scale, diagrammatically illustrates a portion of the mine with a laser survey laser device of the invention in use;

Figure 3 shows a diagrammatic cross-section at the line 3-3 in

Figure 2;

Figure 4 shows a diagrammatic cross-section at the line 4-4 in

Figure 2;

Figure 5 shows a vertical cross-sectional view of a device according to the invention with that part of the cross- section below the line 5-5 being at right angles to that part of the cross-section above this line;

Figure 6 shows a cross-section at the line 6-6 in Figure 5;

Figure 7 shows a cross-section at the line 7-7 in Figure 5;

Figure 8 diagrammatically illustrates another embodiment in which laser units are incorporated; Figure 9 shows a vertical cross-sectional view of another embodiment of the invention;

Figure 10 illustrates the housing of a further embodiment of the invention;

Figure 11 shows a cross-section at the line 11-11 in Figure 10;

Figure 12 shows a cross-sectional view of yet another embodiment;

Figure 13 shows a cross-sectional view of a part of another embodiment of the invention;

Figure 14 shows an exploded cross-sectional view of a further embodiment of the invention;

Figure 15 shows a partial cross-sectional view of another embodiment of the invention;

Figure 16 illustrates the use of the embodiments of Figures 14 and 15 in the development of a box-hole; and.

Figure 17 shows an enlarged diagramatic view of a portion of the embodiment of the invention shown in Figure 15. DETAILED DESCRIPTION OF THE DRAWINGS

As indicated above, Figure 1 diagrammatically illustrates a typical layout as found in an underground coal mine, with material mined out along roads 3 and splits 4, leaving square pillars 1 of unmined material to serve an overburden support function. Figure 2 shows a portion of Figure 1 , at an enlarged scale. In this Figure, it is assumed that line pegs 6.1 , 6.2 have already been installed in roads 3.1 , 3.2, that survey points 5.1 , 5.2, 5.3, .... have already been set out and installed, from a datum survey station 2 (not seen in Figure 2), in the split 4.2, and that it is required to set out and install a line peg in the road 3.3.

Reference is made to Figures 5 to 7 which illustrate a first embodiment of laser survey device 10 which can be used for this purpose. It is to be noted that in Figure 5 the lower part of the cross-section below the line 5-5 is shown in the same plane as the upper part above this line whereas, in reality and as indicated by Figures 6 and 7, it is at right angles thereto.

The device 10 has a housing 12 with a recess 14 at its upper end for rotational attachment to a laser unit 16 (Figures 3 and 4), typically the housing of a diode laser. A spring-loaded ball plunger 18 projects into the recess for location in a complemental groove in the laser unit (not shown). This locks the housing 12 axially relative to the laser unit but allows it to be rotated relative to the laser unit about the axis 20.

Located within the housing 12 is a support member 22 on which a beam splitter 24 is mounted at a 45° inclination adjacent a first cylindrical beam fanning lens 26. Beneath the support member 22 is a further support member 28 on which a mirror 30 is mounted at a 45° inclination adjacent a second cylindrical beam fanning lens 32. Angularly spaced adjustment screws 34 and 36 are provided for fine adjustment of the orientations of the beam splitter 24 and mirror 30 respectively.

In use, the laser unit 16 attached to the device 10 projects a laser beam vertically downwardly onto the beam splitter 24 which reflects a portion of the beam sideways onto the lens 26 which fans that portion of the beam in a vertical plane. The fanned beam exits the housing 12 through an exit opening 38. That portion of the incident laser beam which passes through the beam splitter 24 is reflected sideways by the mirror 30 onto the lens 32 which, once again, fans the beam portion in a vertical plane.

The fanned beam in this case exits the housing 12 through an exit opening 40. From what is said above about the orientation of the upper and lower parts of the cross-section in Figure 5, it will be understood that the exit openings 38 and 40 are at right angles to one another.

Referring to Figures 2 to 4 the surveyor attaches the device 10 to the laser unit 16 which is attached rigidly to a rigid suspension rod 42 suspended from a spad at the survey point 5.3. A reflective rod 44 is suspended vertically from the adjacent survey point 5.4. The surveyor rotates the device 10 on the laser unit 16 to a position in which the fanned laser beam 46 which is emitted through the exit opening 38 falls visibly on the reflective rod 44. The fanned laser beam 48 which is emitted through the exit opening 40, and which is accordingly at right angles to the beam 46, is then automatically projected along the road 3.3 in the development direction 7.

Referring in particular to Figures 3 and 4 it will be seen that the beams 46 and 48 are emitted by the device 10 in such a manner as to impinge on, and form lines of light extending along, the roof 50 of the mine working. In the case of Figure 4 that portion of the fanned laser beam 46 which bypasses the reflective rod 44 also impinges on the barrier pillar 52 at the side of the working while in the case of Figure 3, the beam 48 also impinges on the development face 54. The projected line of light in Figure 3 extends from a point 56 on the roof to a point 58 on the development face 54. It is now a relatively simple matter to install the required line peg 6.3 at any selected position along the length of this line from the point 56 to the point 60 at which the roof meets the development face. A feature of the device 10 is the fact that the lenses 26 and 32 are off-set, by distances 62 and 64 respectively, relative to the centre lines of the beam portions which are projected onto the lenses by the beam splitter 24 and the mirror 30. With this feature the beam portions are asymmetrically refracted by the lenses and are projected in selected angular segments only. This can be seen in Figures 3 and 4 where the fanned beams 46 and 48 are projected predominantly upwardly onto the roof, with small portions only of the beams being projected downwardly. The lines of light are accordingly projected preferentially onto the roof where, in the case of the beam 48, installation of the line peg 6.3 is to take place.

In the embodiment described above the device 10 is rotatably attached to the laser unit. In other embodiments, the housing could be connected non- rotatably to the laser unit with the laser unit itself being ratable relative to the suspension rod 42 or other suspension arrangement and itself forming a part of the laser projection device of the invention. In still other embodiments, the device 10 may be rotatably attached to the laser unit, with the laser unit possibly forming a part of the device and also being rotatable relative the spad suspension arrangement. Thus it will be understood that the invention includes versions in which the laser unit does not itself form part of the device as well as versions in which the laser unit, to which the housing may or may not be rotatably attached, does form such a part.

It will also be understood that the beam splitter and mirror of the embodiment shown in Figures 5 to 7 constitute beam directing means which receive the incident laser beam from the laser module and cause respective laser beam portions to be projected from the housing 12 at right angles to one another. It should however be understood that the invention also extends to survey devices in which the laser module is incorporated in the device For instance, the device of the invention may include both the apparatus illustrated in Figures 5 to 7 and the laser unit to which that apparatus is attached

Still further, the invention extends to embodiment such as that illustrated in Figure 8, where the laser beam directing means is provided by laser modules themselves The embodiment 68 illustrated in Figure 8 includes two diode laser modules 70 at right angles to one another, each serving to project one of the laser beams 46, 48 Beam fanning lenses 72, 74 are provided to fan the respective laser beams, and the device also incorporates batteries 76 to power the laser modules

The suspension arrangement in Figure 8 is similar to that described above for the device 10, with a recess 78 to receive the lower end of the suspension rod 42 in rotatable manner and with a spring-loaded ball plunger 80 locating in a groove 82 in the suspension rod to lock the device 68 axially with respect to the rod The upper end of the rod 42 has a hook 84 which engages the spad 86 at the survey point 5 3

The lenses 72 and 74 may also be off-set from the centre lines of the incident laser beams for the purpose described above It should however be noted that in either embodiment, one of the lenses could be omitted entirely In this arrangement, the unfanned laser beam projects a spot of light onto the reflective rod 41 while the other, fanned laser beam projects a line of light onto the roof of the mine working

The embodiments described above are set up to project the laser beams at right angles to one another Such an arrangement suits mine workings where the roads and splits are at right angles to one another

However, in some mine workings the layout may be such that the roads and splits are orientated relative to one another at angles other than a right angle, for instance 60° or 70°.

In such cases, the embodiments described above will be set up in the factory to project the laser beams at the appropriate, predetermined angle to one another.

Figure 9 illustrates another embodiment which has the facility for in situ adjustment of the angle between the projected laser beams. Components in this Figure corresponding to those in Figure 5 are indicated with the same reference numerals. The body 12 is composed of upper and lower parts 12.1 and 12.2 respectively which are rotatably with respect to one another about the vertical axis 20. The parts are held together by a spring- loaded ball plunger 90, carried by the lower part 12.2, which rides in a circumferential groove in the upper part 12.1. With this feature, the lower part, and with it the mirror 30, can be rotated to any predetermined angle relative to the upper part and in particular relative to the beam splitter 24 carried by the upper part. It is accordingly possible to vary the angle between the projected laser beams to any predetermined value.

To facilitate rotational setting of the parts 12.1 and 12.2 relative to one another to achieve the required angle between the projected laser beams, one of the parts may carry a graduated angular scale and the other part a pointer which will move over the scale to indicate the angular relationship of the parts as they are rotated relative to one another.

To facilitate rotational setting of the parts 12.1 and 12.2 to other specific angles which are sometimes found in mines, such as 60° or 70°, one of the parts may carry a spring-loaded detent, the other part then being formed with recesses at appropriate angular positions to receive and anchor the detent when the parts are at the correct rotational position relative to one another This feature may be provided alone or in addition to the angular scale mentioned above

It will be understood that the feature of relatively rotational housing parts could also be incorporated in the embodiment of Figure 8 Here the upper laser module will be housed in a part which is ratable relative to a part in which the lower laser module is housed

Figure 9 also shows a plane window or lens 92 through which the laser beam projected from the laser unit passes The lens 92 is very slightly inclined so that any component of the laser beam which it reflects is directed away from the laser unit, thereby avoiding possible damage to the laser unit This features may also be provided in the Figuire 5 embodiment Figure 9 also shows plane windows 94, 96 in the beam exits 38 and 40 to provide protection for the interior components Such windows may of course also be provided in the Figure 5 embodiment

Figures 10 and 11 illustrate the housing of another embodiment which is somewhat similar to that of Figure 9 Components corresponding to those in Figure 9 are indicated by the same reference numerals In this case, the parts 12 1 and 12 2 have cooperating flanges 100, 102 The upper flange 100 is formed with a passage 104 to receive a spring loaded ball plunger which can locate selectively in any one of a series of radial grooves 106 formed in the upper surface of the lower flange 102 The grooves are spaced apart at 20° intervals to provide for specific angular settings of the parts 12 1 , 12 2 relative to one another The parts are held together by screws 108, the tips of which locate in an annular groove in the part 12 1

In the embodiment of Figure 12 there are again relatively rotatable housing parts 12 1 and 12 2 To achieve a selected angular setting of the parts relative to one another a spring-loaded ball plunger 110 carried by the part 12.1 can locate in one of a series of angularly spaced, vertical grooves 112 in the part 12.2. As in Figures 9 and 10 a spring-loaded ball plunger 90 holds the housing parts 12.1 and 12.2 together.

A lower extension 1 14 of the housing part 12.2 accommodates a diode laser module 116 which is powered by batteries 118 beneath it. A knurled knob 120 serves as an ON/OFF switch for the laser module. Upper and lower set screws 122 are provided for precise setting of the orientation of the laser module. The module rocks about an O-ring 124 between the upper and lower set screws when the set screws are adjusted It will be understood that in this embodiment the laser module 116 projects a laser beam vertically upwardly.

In Figure 12 it will be noted that the upper housing part 12.1 is formed with a threaded socket 126 by means of which the housing can be connected to the lower end of a rotatable suspension rod 42 or other suspension means.

Figure 13 shows the laser module housing 128 of another embodiment of the invention. Here the upper part 128.1 of the laser module housing has a spigot 130 which is, in use, located in a corresponding socket at the bottom of the housing 12 (not illustrated). The spigot is formed with a circumferential groove 132 to receive the ends of screws which serve to keep the housings together.

The laser module housing 128 of the embodiment in Figure 13 can be mounted rotatably on a tripod in the mine working. In this situation, the tripod will be accurately sited over a spad or other survey mark in the floor or footwall of the mine working. Alternatively, as in previous embodiments, the upper housing can be suspended rotatably from a surveyed spad in the roof of the mine working. For the purposes of tripod mounting, the lower part 128.2 of the laser module housing has a threaded socket 134 at its lower end to receive the standard, upstanding, threaded tripod stud.

Because of the presence of the threaded socket 134 it is not possible to have the ON/OFF switch for the laser module situated at the bottom of the housing 128. For this reason, there is a transverse threaded shaft 136 which is transversely screwable in a threaded passage in the lower part 128.2 of the laser module housing. The transverse threaded shaft having located, along its length, spaced apart contacts 140. In a longitudinal position of the threaded shaft corresponding to an ON condition of the laser module, the contacts make electrical contact with the corresponding contacts at the lower end of the batteries. In other longitudinal positions, corresponding to an OFF condition of the laser module, battery contact is broken.

All of the above embodiments are designed for use in setting out lateral roads, splits and other developments in an underground mine, as described with reference to Figures 1 to 4. Another important survey function in underground mines, and particularly hard rock mines such as gold mines, is the development of box-holes or ore passes which extend from one level in a mine to a lower level for the purposes of conveying ore mined at the higher level to the lower level. A typical box-hole or ore pass extends at an angle of 55° to the horizontal between the respective levels.

A laser survey device according to this invention can be used to provide laser guidance for the development of a box-hole or ore pass. Different examples are illustrated in Figures 14 and 15 of the drawings. In these Figures, components corresponding to those described previously are indicated by the same reference numerals.

In the embodiment of Figure 14, the housing has upper and lower parts 12 1 , 12 2 which can be can be rotatably adjustable relative to one another, about a vertical axis, in the manner described for the embodiment of Figure 9 Alternatively, they may be fixed to one another at a selected orientation There is also a laser module housing 128 similar to that of Figure 13 The diode laser module 116 projects a laser beam vertically upwardly onto an inclined glass sheet 142, serving as a simple beam splitter, which reflects a portion 143 of the beam transversely through a laser beam exit opening 38 in the side of the housing 12 The inclination of the glass sheet is such that the portion of the beam which is reflected transversely through the opening 38 is inclined upwardly, typically at the angle of 55° mentioned above

The remaining, unreflected portion of the incident laser beam passes through the glass sheet 142 and is incident on an inclined mirror 144 which reflects it transversely through the other laser beam exit opening 40 in the side of the housing 12

Figure 15 shows a modified device for box-hole development in which the upwardly directed laser beam is incident on a beam splitter 160 which reflects a portion of the beam at right angles through the opening 38 The portion 143 of the beam which passes through the beam splitter is reflected transversely, at the required inclination to the horizontal, by a mirror 162

In a typical box-hole development application, the beam portion 143 which exits through the opening 40 will be in the form of a narrow, unfanned beam That portion exiting through the opening 38 will be fanned vertically In addition to a vertically fanned region the beam portion exiting through the opening 38 may also project a spot of light This is shown more clearly in Figure 17 which illustrates how the upwardly directed laser beam 164 is incident on the beam splitter 160 A portion 143 of the beam passes through the beam splitter Another portion 165 of the beam is reflected toward the lens 170 The beam splitter 160 and lens 170 are positioned so that a narrow beam 165.1 of the other beam portion 165 passes above the lens, and a fanned beam 165.2 of the other beam portion 165 is incident on the lens and is refracted to form a vertically fanned region. The effect of this arrangement is to project the narrow beam 165.1 and also the fanned beam 165.2 which respectively produce a spot 166 and line 167 on a surface. In practice, the device 10 will be set up at a lower level in the mine from which the box-hole is to be bored upwardly to a higher level, with the axis 20 vertical. Mounting may either be on a tripod or by suspension from a spad in the roof.

Reference is now made to Figure 16 which illustrates how a device according to Figure 14 or Figure 15 can be used in the development of a box-hole. As shown, the device 10 is suspended vertically from a surveyed spad 200 in the roof of a tunnel or other lateral mine working 201. The device is rotated as necessary for the fanned beam 202 which exits through the opening 40 to fall on a back marker or target 204 suspended vertically from a surveyed spad 206. The numerals 202.1 and 202.2 respectively indicate a spot of light and a fanned region of the fanned beam, as described above. The spot of light falls on the back marker and the fanned region on a side wall and the floor of the mine working 201. The numeral 208 indicates the narrow beam which is projected upwardly at the selected angle, typically 55°. This beam provides an illuminated spot on the roof of the mine working for the purposes of guiding the development of an inclined box-hole 210.

As box-hole development proceeds it is periodically necessary to reposition the device 10. The device 10 may be re-installed in the box hole at a new, elevated position, as indicated generally by the numeral 212. The device is suspended from a spad 214 in the inclined roof of the box-hole. In this case, the inclination of the box-hole prevents the use of a back marker or target like the back marker 204. Instead, the device is rotated for the fanned region 202.2 to intersect another surveyed spad 214 in the roof of the box-hole, thereby aligning the device correctly for the beam 208 to provide further guidance for continued development of the box-hole.

It will be understood that the relative rotatability of the parts 12.1 and 12.2 of the housing 12 will enable the angular spacing of the respective laser beam portions, measured in a horizontal plane, to be set, normally in the factory, to a required value. Also, the inclination of the upwardly directed beam portion can be set in the factory to a selected value, whether 55° or otherwise, to suit requirements. To facilitate the latter adjustment in Figure 14, the upper side edges of the glass sheet 142 are attached to nuts 150 (only one visible) each carried by an externally accessible screw 152. The lower edge of the glass sheet is set centrally into a recess in a block 154 carried by a similar screw 156. It will be understood that by adjustment of the screws 152, 156, it is possible to vary the inclination of the glass sheet in a vertical plane and also about its own central axis. Springs 158, 160 serve to maintain each screw setting.

In the embodiment of Figure 14 it is preferred that the laser module 1 16 is of a conventional type which produces a laser beam of elliptical cross- section. By rotating the laser module about a vertical axis it is accordingly possible to vary the orientation of the major and minor axes of the beam cross-section, i.e. the orientation of the beam about its own central axis. The optical characteristics of the glass sheet 142 is such that the respective intensities of the reflected and unreflected portions of the laser beam are dependent on the orientation of the laser beam and hence on the orientation of the laser module 1 16. By varying the orientation of the laser beam about its own vertical axis it is , for instance, possible to provide a relatively more intense box-hole development guidance beam and a relatively less intense reference beam, or vice versa. In most cases, the angular orientations of the various components relative to one another will be set in the factory. Sleeves of plastics or other materials may then be slipped snugly over the device 10 to prevent unauthorised tampering with the settings and also to provide the device with a measure of protection.

Claims

1 .

A laser survey device comprising a housing, means enabling the housing to be mounted at a survey point in a mine working in a manner allowing the housing to be rotated about a vertical axis, and laser beam directing means in the housing for projecting from the housing first and second laser beams which are at a predetermined angle to one another and transverse to the vertical axis.

2.

A laser survey device according to claim 1 wherein the housing is attachable to a laser unit which includes a laser projection module and which is suspendable from the roof of a mine working.

3.

A laser survey device according to claim 2 wherein the housing is attachable rotatably to the laser unit.

4.

A laser survey device according to claim 2 or claim 3 wherein the housing is attachable to the laser unit such that an incident laser beam produced in use by the laser projection module is directed vertically into the housing, the housing including first and second laser beam exits at the predetermined angle to one another and the laser beam directing means being arranged to cause portions of the incident laser beam to be projected out of the housing through the respective laser beam exits.

5.

A laser survey device according to claim 4 wherein the laser beam directing means comprises a beam splitter for reflecting a first portion of the incident beam laterally through the first laser beam exit and a mirror for reflecting a second portion of the incident beam which passes through the beam splitter laterally through the second laser beam exit.

6.

A laser survey device according to claim 4 or claim 5 comprising beam fanning means for vertically fanning one or both reflected laser beam portions.

7.

A laser survey device according to claim 6 wherein the beam fanning means comprises, for each reflected laser beam portion which is to be vertically fanned, a cylindrical lens which is off-set upwardly relative to the axis of the reflected beam portion, whereby the reflected beam portion is fanned in an angular segment which is predominantly upwardly directed.

A laser survey device comprising means enabling the device to be mounted at a survey point in a mine working in a manner allowing the device to be rotated about a vertical axis, a laser unit including a laser module for projecting an incident laser beam and laser beam directing means onto which the incident laser beam is projected in use by the laser module and which is arranged to cause respective portions of the incident laser beam to be projected outwardly from the device at a predetermined angle to one another and transverse to the vertical axis

9

A laser survey device according to claim 8 wherein the laser beam directing means is attached or attachable to the laser unit and the laser unit is attachable in rotatable manner to a suspension member extending from a survey point in the roof of the mine working

10

A laser survey device according to either one of claims 8 or 9 wherein the laser beam directing means is located in a housing which has first and second laser beam exits oriented at the predetermined angle to one another and the laser beam directing means is arranged to direct the respective laser beam portions through the exits

1 1

A laser survey device according to claim 10 wherein the laser beam directing means comprises a beam splitter for reflecting a first portion of the incident beam laterally through the first laser beam exit and a mirror for reflecting a second portion of the incident beam which passes through the beam splitter laterally through the second laser beam exit

12

A laser survey device according to claim 10 or claim 1 1 comprising beam fanning means for vertically fanning one or both laser beam portions 13

A laser survey device according to claim 12 wherein the beam fanning means comprises, for each reflected laser beam portion which is to be vertically fanned, a cylindrical lenses which is off-set upwardly relative to the axis of the reflected beam portion, whereby the beam portion is fanned in an angular segment which is predominantly upwardly directed

14

A laser survey device comprising a housing having first and second laser beam exits therein oriented at a predetermined angle to one another, means enabling the housing to be mounted at a survey point in a mine working in a manner allowing the housing to be rotated about a vertical axis, and first and second laser modules in the housing which are arranged to project respective first and second laser beams outwardly from the housing through the laser beam exits in directions which are at the predetermined angle to one another and transverse to the vertical axis

15

A laser survey device according to claim 14 comprising beam fanning means in the housing for vertically fanning one or both of the projected laser beams

16

A laser survey device according to claim 15 wherein the beam fanning means comprises, for each laser beam which is to be vertically fanned, a cylindrical lens which is off-set upwardly relative to the projection axes of the laser module which projects that laser beam, whereby the projected laser beam is fanned in an angular segment which is predominantly upwardly directed.

17.

A laser survey device according to claim 1 wherein the laser beam directing means comprises first and second laser modules in the housing which are oriented at the predetermined angle to one another to project first and second laser beams which are at the predetermined angle to one another.

18.

A laser survey device according to any one of the preceding claims wherein the housing has operatively upper and lower parts which are attached rotatably to one another.

19.

A laser survey device according to claim 5 or claim 1 1 wherein the beam splitter and first laser beam exit are located in an operatively upper housing part and the mirror and second laser beam exit are located in an operatively lower housing part, the upper and lower housing parts being rotatable relative to one another to enable the angle between the projected laser beams to be set to a predetermined value.

20.

A laser survey device according to claim 14 wherein the first laser module and the first laser beam exit are located in an operatively upper housing part and the second laser module and the second laser beam exit are located in an operatively lower housing part, the upper and lower housing parts being rotatable relative to one another to enable the angle between the projected laser beams to be set to a predetermined value.

21 .

A laser survey device according to claim 19 or claim 20 and comprising spring-loaded detent means to anchor the upper and lower housing parts relative to one another at one or more preselected angular positions relative to one another.

22.

A laser survey device comprising:

a first housing which accommodates laser beam directing means;

vertically spaced beam exits from the first housing through which the laser beam directing means will project respective portions of the laser beam projected into the first housing by the diode laser, such portions being at a predetermined angle to one another and transverse to the vertical axis with one of the beam portions being upwardly inclined relative to the horizontal for the purposes of box- hole guidance.

23.

A laser survey device according to claim 22 wherein another beam portion is projected substantially horizontally, the device including means for vertically fanning at least part of the other beam portion downwards relative to the horizontal.

24.

A laser survey device according to either one of claims 22 or 23 wherein the first housing is attachable to the top of the second housing and the bottom of the second housing is attachable to a tripod.

25.

A laser survey device according to claim 24 wherein the laser beam directing means comprises a beam splitter and a mirror above the beam splitter, the beam splitter being arranged to reflect a portion of the laser beam which is incident thereon at a orientation which is upwardly inclined relative to the horizontal.

26.

A laser survey device according to claim 24 wherein the laser beam directing means comprises a beam splitter and a mirror above the beam splitter, the mirror being arranged to reflect a portion of the laser beam which is incident thereon at a orientation which is upwardly inclined relative to the horizontal.

27.

A laser survey device substantially as herein described with reference to Figures 5 to 7, Figure 8, Figure 9, Figures 10 and 1 1 , Figure 12 or Figure 13, read with Figures 1 to 4, of the accompanying drawings.

28.

A laser survey device substantially as herein described with reference to

Figure 14 or Figure 15 of the accompanying drawings.