SG188070A1

SG188070A1 - Surveying apparatus with height measurement capability

Info

Publication number: SG188070A1
Application number: SG2012063939A
Authority: SG
Inventors: Chikashige Kiyoshi; Zhong Ping Fang; Hui Jen Tang
Original assignee: Agency Science Tech & Res; Survey Instr Services Pte Ltd
Priority date: 2011-08-29
Filing date: 2012-08-28
Publication date: 2013-03-28
Also published as: CN102967298A

Abstract

23SURVEYING APPARATUS WITH HEIGHT MEASUREMENT CAPABILITYA surveying apparatus is provided comprising a light source configured to emit light along an optical axis for at least a distance measurement; and a height10 measurement module configured to manipulate a path of the light emitted from the light source for measuring a height of the surveying apparatus above a surface, wherein the height measurement module includes an extending member having thereon or integrated therewith an optical member, the extending member being configured to extend or be extendable at a predetermined angle to the optical axis to15 position the optical member at the optical axis for manipulating the path of the light towards the surface, wherein the predetermined angle is non-parallel to the optical axis.20 FIG. 1A

Description

SURVEYING APPARATUS WITH HEIGHT MEASUREMENT

CAPABILITY

FIELD OF INVENTION

The present invention relates to a surveying apparatus with height measurement capability, in particular, a surveying apparatus capable of measuring its height above a surface, e.g., above a reference point on the surface such as the plumb point. For example, the surveying apparatus can be a total station or a theodolite.

BACKGROUND

Conventional surveying apparatuses, such as total stations, are known in the art. A surveying apparatus is used for performing distance and/or angle survey measurements.

The surveying apparatus is typically mounted above the ground surface on a tripod or a base to perform survey measurements. Therefore, before using the surveying apparatus, it is necessary to determine the height of the surveying apparatus above the ground surface, such as above the plumb point on the ground surface. Conventionally, the height of the surveying apparatus is determined by a person using a measuring device manually, such a tape measure or a ruler. After reading the height indicated by the measuring device, the measured height value is manually entered into the surveying apparatus. However, a problem associated with such manual height measurements is that they are prone to human errors. For example, the height reading may not be performed accurately and the accuracy depends on the diligence of the person performing the measurement. Slight inaccuracy in the height measurement can significantly affect the accuracy of the survey measurements. In addition, such manual height measurements are cumbersome and time consuming.

There have been a number of attempts to remove manual height measurements.

However, such attempts in tum infroduce new problems and thus do not provide any practical solution to the above-mentioned problems. For example, it has been proposed to provide a separate height measurement device which can be mounted on the tripod for performing height measurement. Once the height measurement is completed, the height measurement device is disassembled from the tripod and the surveying apparatus is then reassembled on the tripod for performing survey measurements. This approach, whilst removing manual height measurements using a ruler or a tape measure, introduces new problems such as the need to carefully assemble/disassemble the height measurement device and carefully disassemble/reassemble the total station on the tripod {which is actually more time consuming than performing the height measurement using a ruler or measuring tape). Furthermore, instead of carrying a ruler or a measuring tape, it is necessary fo carry along a bulkier separate height measurement device. it is against this background that the present invention has been developed.

SUMMARY

156 The present invention seeks to overcome, or at least ameliorate, one or more of the deficiencies of the prior art mentioned above.

According fo a first aspect of the present invention, there is provided a surveying apparatus comprising: a light source configured to emit light along an optical axis for at least a distance measurement; and a height measurement module configured to manipulate a path of the light emitted from the light source for measuring a height of the surveying apparatus above a surface, wherein the height measurement module includes an extending member : having thereon or integrated therewith an optical member, the extending member being configured fo exiend or be extendable at a predetermined angle to the optical axis to position the optical member at the optical axis for manipulating the path of the light towards the surface, wherein the predetermined angle is non-parallel tc the optical axis.

Preferably, the surveying apparatus comprises a telescope having a housing within which the light source is located, and the height measurement module is located at an upper portion of the housing.

Preferably, the height measurement module is formed integrally with the upper portion of the housing.

Alternatively, the height measurement module is releasably attached to the upper portion of the housing.

Preferably, the extending member is movable between a stored state and an extended state, wherein at the extended state, the extending member is extended at the predetermined angle with respect to the optical axis and the optical member is positioned at the optical axis.

Preferably, at the stored state, the extending member is received within a slot of a housing of the height measurement module.

Preferably, the height measurement module comprises a guide member movable along the slot for guiding the extending member between the stored state and the . extended state.

Preferably, a rear portion of the extending member is pivotably attached to the guide member such that the extending member can pivot from an orientation at the stored state to the predetermined angle at the extended state, and vice versa.

Preferably, the height measurement module further includes a support member protruding from an end portion of the housing of the height measurement module adjacent and under an opening of the slot, the support member comprising an inclined surface adapted for the extending member to rest on in the extended state thereby supporting the extending member at the predetermined angle with respect to the opiical axis.

Preferably, the support member further comprises a positioning member on the inclined surface for holding the extending member in place.

The extending member may have a multistage sliding mechanism such that its length can be shortened at the stored state and lengthened at the extended state.

The height measurement module may further include a spring release mechanism for ejecting the extending member from the stored state within the slot to the extended state.

Preferably, the height measurement module includes a detachable member and a base member, the detachable member comprising the extending member, wherein the detachable member and the base member is releasably attachable to each other.

Preferably, the detachable member further includes a support member from which the extending member extends integrally at the predetermined angie, and wherein the support member and/or the base member comprise attachment means for releasably holding the support member in position on the base member.

Preferably, the predetermined angle is about 45°.

Preferably, the optical member is a reflective member.

Preferably, the optical member comprises a central portion and an outer portion, and wherein the central portion is a mirror and the outer portion is a diffuser.

According to a second aspect of the present invention, there is provided a height measurement module for attaching to a surveying apparatus to measure a height of the surveying apparatus above a surface, the surveying apparatus includes a light source configured to emit light along an optical axis for at least a distance measurement, the height measurement module comprising: an extending member having thereon or integrated therewith an optical member, the extending member being configured to extend or be extendable at a predetermined angle to the optical axis to position the optical member at the optical axis for manipulating the path of the light towards the surface, wherein the predetermined angle is non-parallel to the optical axis.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be better undersiood and readily apparent to one 5 of ordinary skill in the art from the following written description, by way of example only, and in conjunction with the drawings, in which:

Figures 1A to 1F depict various views of an exemplary surveying apparatus according to an embodiment of the present invention;

Figure 2 is a schematic diagram depicting various internal components of the exemplary surveying apparatus;

Figures 3A and 3B depict an optical member according to embodiments of the present invention; a

Figures 4A to 4C depict various perspective views of a height measurement module according fo a first embodiment of the present invention;

Figures 5A to 5C depict various perspective views of a height measurement module according fo a second embodiment of the present invention,

Figures 6A and 6B depict side cross-sectional views of a height measurement module in an extended and a stored state according to a third embodiment of the present invention, :

Figure BC depicts an exploded diagram of the height measurement module according to the third embodiment;

Figures 6D and 6E depict side views of the height measurement module in the extended and the stored state according to the third embodiment; and

Figure 6F depicts a front view of the height measurement module in the stored state according to the third embodiment.

DETAILED DESCRIPTION

Figures 1A to 1F illustrate an exemplary surveying apparatus 10 with height measurement capability according to an embodiment of the present invention. For example, the surveying apparatus 10 may be a total station or a theodolite. The surveying apparatus 10 is operable to perform distance and/or angle survey measurements in a manner known to a person skilled in the art. Therefore, the manner in which components of the surveying apparatus 10 operate to enable the distance and/or angle survey measurements will not be described herein for conciseness and clarity. Components of the surveying apparatus 10 for enabling the height measurement capability according to embodiments of the present invention will be described in detail herein.

Figure 2 depicts a schematic diagram showing exemplary internal components of the surveying apparatus 10. The surveying apparatus 10 comprises a light source 12 for emitting light along an optical axis 14, a photodetector 16 for receiving reflected light and sending a signal to a controller 18, the controller 18 processes the signal to determine a distance to a target from which the emitted light is reflected from, a memory module 20 for storing data/information (e.g., dala representing the determined distance and any user input data) and software / instructions for the controller 18. For example, the light source 12 can be a laser or infrared light source suitable for performing survey measurements known in the art. The memory module 20 may include a non-volatile memory such as Read-Only Memory (ROM) and/or a volatile memory such as Random Access Memory (RAM). The controller 18 may be a processor. The surveying apparatus 10 may further comprise a user interface 22 such as a keyboard for a user to input commands and communicate with the surveying apparatus 10, and a display 24 for displaying various information to the user (e.g., the determined distance and state/mode of the surveying apparatus 10).

It is apparent to a person skilled in the art that additional components can be added to the surveying apparatus 10 to provide further functionalities known in the art.

The surveying apparatus 10 has a base 30 configured so as to be mountable on a stand 32 (e.g. a tripod) above a surface (typically a ground surface) 34 as illustrated in Figure 1B (not to scale). The base 30 may be rotatable about a vertical axis 33 with respect to the stand 32. The height (H) of the surveying apparatus 10 mounted above the ground surface 34 (such as a reference point 35 on the ground surface 34 directly below the center of the surveying apparatus 10, also known as the plumb point) is usually different at each site. Therefore, when performing survey measurements, it is necessary to determine the height (H) of the surveying apparatus 10 above the ground surface 34 where it is positioned.

As described hereinbefore in the background, conventionally, the height of the surveying apparatus is determined by a person using a measuring device manually, such a tape measure or a ruler. After reading the height indicated by the measuring device, the measured height value is manually entered into the surveying apparatus.

However, a problem associated with such manual height measurements is that they are prone to human errors. For example, the height reading may be not performed accurately and the accuracy depends on the diligence of the person performing the measurement. Slight inaccuracy in the height measurement can significantly affect the accuracy of the survey measurements. In addition, such manual height measurements are cumbersome and time consuming.

To overcome the need for manual height measurement, the exemplary surveying apparatus 10 is integrated with height measurement capability. The exemplary surveying apparatus 10 comprises a light source 12 configured to emit light along an optical axis 14 for at least a distance measurement. For example, to measure a distance from the surveying apparatus 10 to a target (hot shown), light is emitted from the light source 12 towards the target and light reflected from the target is received by a photodetector 16 within the surveying apparatus 10. The controller 18 then automatically processes the signal output from the photodetector 16 in a manner known to a person skilled in the art (e.g., using modulation or phase measurement techniques) to determine the distance between the surveying apparatus 10 and the target. In the embodiment, the surveying apparatus 10 further comprises a height measurement module 36 for manipulating or bending a path of the light emitted from the light source 12 to measure the height (H) of the surveying apparatus 10 above the ground surface 34, preferably, a reference point 35 on the surface 34 such as the plumb point. The height measurement module 36 comprises an extending member 38 having thereon or integrated therewith the optical member 40, the extending member 38 being configured to extend or be extendable at a predetermined angle 42 (non-parallel) to the optical axis 14 to position the optical member 40 at the optical axis 14 for manipulating the path of the light towards the ground surface 34.

As illustrated in Figures 1A to 1D, the surveying apparatus 10 comprises a main body 37 and a telescope 39 rotatably supported by the main body 37 about a horizontal axis 41. For example, the main body 37 may have two side walls for supporting the telescope 39 therebetween. The telescope 39 has a housing 43 within which the light source 12 and the photodetector 16 are located. The telescope 39 has a lens 45 at a front side thereof through which both light emitted by the light source 12 and reflected light to be received by the photodetector 16 pass.

In a preferred embodiment as illustrated in Figure 1B, the predetermined angle 42 which the extending member 38 is configured to extend with respect to the optical axis 14 is about 45°. At this predetermined angle, light emitted from the light source 12 along the optical axis 14 will be incident on the optical member 40 and manipulated by the optical member 40 (i.e. reflected by the optical member 40) by about 90° fo travel downwards to the surface 34. In an embodiment, at this predetermined angle, in order for the light to travel to the reference point 35 on the surface 34, the telescope 39 is rotated about the horizontal axis 41 such that the light manipulated by the optical member 40 reaches the reference point 35 on the surface 34. Figures 1E and 1F illustrate an example whereby the telescope 39 is rotated by about 2.5° such that the light manipulated by the optical member 40 reaches the reference point 35 on the surface 34. Figure 1F is a close up view of

Figure 1E. It is apparent to a person skilled in the art that the degree of rotation is not limited to 2.5° and the telescope 39 can be rotated by more or less (e.g., in the range of 0° to 20° depending on various factors, such as the value of the predetermined angle 42 and the height of the surveying apparatus 10 above the surface 34. For example, at a certain predetermined angle 42 greater than 45°, light can be manipulated by the optical member 40 to reach the reference point 35 on the surface 34 without having to rotate the telescope 39 from its initial position where its optical axis is horizontal (i.e., degree of rotation is 0°).

For example, the optical member 40 may be a reflective member such as a mirror.

Similarly, light reflected from the surface 34, e.g., at the reference point 35 will be scattered and be incident back on the optical member 40 and manipulated by the optical member 40 to travel towards the photodetector 16 through the telescope lens 45. The photodetector 16 detects the reflected light and outputs a signal to the controller 18 for processing to determine the height of the surveying apparatus 10 above the ground surface 34.

Based on trigonometry principles known in the art, a person skilled in the art will be able to understand how the controller 18 can determine the height of the surveying apparatus 12. Therefore, it is not necessary to provide detailed description in this regard. However, as an example, the height of the surveying apparatus 12 can be calculated based on the formulas below:

B=90-a sin = b/H

H=b/sin where: “a” is the angle which the telescope 39 is rotated from its initial position where its optical axis 14 is horizontal (i.e., the angle between the optical axis 14 and the horizontal); “b” is the measured distance between the optical member 40 and the reference point 35 on the ground surface 34; and “C” is the determined height of the surveying apparatus 10 above the reference point 35

As known in the art, the angle “a” is automatically recorded or tracked by the surveying apparatus 10 when the telescope 39 is rotated about the horizontal axis 41. The distance “b” is computed by the surveying apparatus 10 based on the reflected light received by the photodetector 16 e.g., using modulation or phase measurement technigues known in the art. For example, referring to Figure 1F, the total distance (*a” and “b") will be measured by the surveying apparatus 10 based on the reflected light.

Since “a” {which is the distance between the light source 12 and the optical member 40) : is a known constant, the distance “db” can be computed by subiracting the total distance measured by the constant “a”.

Once the height of the surveying apparatus 10 is determined, height data/information representing the determined height of the surveying apparatus 10 can be stored in the memory module 20 and can be accessed by the controller 18 for various purposes such as when performing distance survey measurements.

Therefore, the height measurement module 36 eliminates the need for a person to measure the height manually using, for example, a measuring device, such a tape measure or a ruler. Furthermore, as will be apparent later, the height measurement module 36 can advantageously be deployed quickly and easily to manipulate the path of the light from the light source 12 towards the ground surface 34, such as the reference point 35, The surveying apparatus 10 is integrated with both height measurement and distance survey measurement capabilities, without having to assembie/disassemble a separate height measurement device for height measurement and disassemble/reassemble a separate surveying apparatus for survey measurements.

Another advaniage is that the same light source 12 in the surveying apparatus 10 is used for both distance measurement and height measurement. Therefore, additional components for implementing the height measurement capability are minimised.

The inventors have identified a problem whereby the reflected light may not be able to reach the photodiode 16 since it may be blocked by the light source 12 typically located at a central portion within the telescope 39. To address this problem, according fo an embodiment of the present invention, the optical member 40 comprises an inner or central portion 48 and an outer or peripheral portion 50 as illustrated in Figures 3A and 3B. The central portion 48 is a reflective member such as a mirror. In an embodiment, the central portion 48 is configured to have substantially the same cross-section as the incoming light beam from the light source 12 incident thereon. The outer portion 50 is a diffuser, such as a holography diffuser with suitably selected diffusing distribution towards the photodetector 16 or a diffractive grating diffuser with an appropriate diffusing angle toward the photodetector 16. Preferably, the central portion 48 has a circular cross-section for matching the cross-section of the incoming light beam from the light source 12. The outer portion 50 may have a circular or rectangular cross-section. oo

In an embodiment, the surveying apparatus 10 is manufactured having the height measurement module 36. In another embodiment, an existing survey apparatus is reconfigured or modified to incorporate the height measurement module 36 to manipulate or bend the light emitted from the light source 12 in the telescope 39 to the ground surface 34, preferably at the reference point 35. It is apparent to a person skilled in the art that software can be created or existing software for computing survey measurements can be modified to calculate the height of the surveying apparatus 100 in the manner as described hereinbefore (e.g., based on the formulas described hereinbefore)

Preferably, the height measurement module 36 is installed at an upper portion 54 of the telescope housing 43 above and adjacent the telescope lens 45. With this configuration, the extending member 38 of the height measurement module 36 can be extended at a predetermined angle 42 (preferably about 45°) to the optical axis 14 to position the optical member 40 at the optical axis 14 for manipulating the path of the light towards the surface 34, preferably at the reference point 35. As the height measurement module 36 is coupled to the telescope housing 43, the height measurement 36 will rotate with the telescope 43 when the telescope 39 is rotated about the horizontal axis 41 as for example illustrated in Figures 1E and 1F. As a result, the angle which the extending member 38 extends with respect to the optical axis 14 will advantageously be kept constant at the predetermined angle 42 even when the telescope 39 is rotated. The height measurement module 36 can be formed permanently (e.g., integrally) at the upper portion 54 of the telescope housing 43 or be a separate module releasably attachable with the upper portion 54 of the telescope housing 43. Although most preferable, it will be apparent to a person skilled in the art that the predetermined angle 42 is not limited to 45° and can be at other angles (such as in the range of 40° to 50° degrees and more preferably, in the range of 43° to 47°) as long as light from the light source 12 can be reflected to the ground surface 34, preferably at the reference point 35, without being obstructed by any part of the surveying apparatus 10 or the stand 32, with or without the telescope 39 being rotated about the horizontal axis 41.

By way of examples only, three specific types of height measurement modules 36 will now be described according to embodiments of the present invention. However, } it will be appreciated to a person skilled in the art that the present invention is not limited to the three specific types of height measurement modules 36 described in detail hereinafter and other types and various modifications are within the scope of the present invention so long as they comprise an extending member which extends or is extendable at a predetermined angle (non-parallel) to the optical axis to position the optical member at the optical axis for manipulating the path of the light from the light source towards the surface 34, preferably at the reference point 35, where the surveying apparatus is positioned.

Figures 4A to 4B depict an exemplary height measurement module 36a according to a first embodiment of the present invention. The height measurement module 36a comprises an extending member 38a having thereon or integrated therewith an optical member 40a, the extending member 38a being configured to be extendable at a predetermined angle 42a (non-parallel) to the oplical axis 14a to position the optical member 40a at the optical axis 14a for manipulating the path of the light towards a surface 34, preferably, a reference point 35 on the surface such as the plumb point. Similarly, the predetermined angle 42a which the extending member 38a is configured to extend with respect to the optical axis 14a is about 45°

However, it will be apparent to a person skilled in the art that the predetermined angle 42a is not limited to 45° and can be at other angles as explained hereinbefore.

The extending member 38a is movable or retractable between a stored state and an extended state. The height measurement module 36a comprises a housing 43a having a substantially horizontal slot 56 for receiving and storing the extending member 38a when the extending member 38a is in the siored state as shown in

Figure 4B. At the extended state, the extending member 38a is extended at the predetermined angle 42a to the optical axis 14a to position the optical member 40a at the optical axis 14a for manipulating the path of the light towards the surface 34.

Preferably, the housing 43a of the height measurement module 36a is formed integrally with the upper portion 54 of the telescope housing 43 of the surveying apparatus 10. Alternatively, the housing 43a of the height measurement module 36a and an upper portion 54 of the telescope housing 43 of the surveying apparatus 10 are configured to be releasably couplable with each other. For the latter, a surface of the upper portion 54 of the telescope housing 43 and a base of the height measurement module 36a may both have a substantially planar surface configured to be releasably couplable to each other so as to secure the height measurement module 36a in a substantially horizontal orientation.

The slot 56 of the height measurement module 36a has an opening 58 at an end portion 60 of the housing 43a for receiving the extending member 38a therein.

Preferably, the housing 43a supports the extending member 38a in a substantially horizontal orientation when the extending member 38a is received therein. The height measurement module 36a further comprises a support member 62 protruding from the end portion 60 of the housing 43a adjacent and under the opening 58 for supporting the extending member 38a at the predetermined angle 42a. The support member 62 comprises an inclined surface 65 on which the extending member 38a rests at the extended state for controlling the angle which the extending member 38a extends with respect to the optical axis 14a {(e.g., at the predetermined angle 42a).

In an embodiment, the extending member 38a has a multistage sliding mechanism such that its length can be shortened at the stored state and lengthened at the extended state. For example the extending member 38a may comprise a slidable body 64 and a storage slot 66. The slidable body 64 has the optical member 40a thereon and is receivable within and extendable from the storage slot 66. The extending member 38a is pivotably attached to a guide member (not shown) within the housing 43a at a rear portion 68 thereof (e.g., a rear portion 68 of the storage slot 66). The guide member is movable within the slot 56 of the housing 43a so as fo guide extending member 38a between the stored state and the extended state. With this configuration, the extending member 38a can pivot from a horizontal position (with respect to the optical axis 14a) at the stored state to the predetermined angle 42a at the extended state and vice versa.

The extending member 38a can be moved between the stored state and extended state by a person using their finger. For example, when in the stored state, a person can easily use their finger to pull the extending member 38a out from the slot 56 of the housing 43a at the opening 58. For ease of use, an end portion 70 of the extending member 38a may have a protrusion 72 adapted for a person's finger to pull on to extract the extending member 38a out of the slot 56. Once extracted, the extending member 38a can rest on the support member 62, thus automatically setting/holding the extending member 38a at the predetermined angle 42a with respect to the optical axis 14a. In an embodiment, the support member 62 comprises a positioning member 74 on the inclined surface 65 for holding or locking the extending member 38a in position in the extended state. For example, the positioning member 74 may be a magnetic member for holding the extending member 38a in place through magnetic force. It will be apparent to a person skilled in the art that other types of positioning member can be used for securing an object in place. When the extending member 38a is not in use, it can be easily pushed back by pushing the end portion 70 of the extending member 38a back within the slot 56 of the housing 43a.

Figures 5A to 5C depict an exemplary height measurement module 36b according to a second embodiment of the present invention. Similar to the first embodiment, the height measurement module 36b comprises an extending member 38b having thereon or integrated therewith an optical member 40b, the extending member 38b is configured to extend at a predetermined angle 42b (non-parallel) to the optical axis 14b to position the optical member 40b at the optical axis 14b for manipulating the path of the light towards a surface 34, preferably, a reference point 35 on the surface such as the plumb point. Similarly, the predetermined angle 42b which the extending member 38b extends with the optical axis 14b is about 45°. However, it will be apparent to a person skilled in the art that the predetermined angle 40b is not limited to 45° and can be at other angles as explained hereinbefore

The main difference between the height measurement module 36b according to the second embodiment and the height measurement module 36a according to the first embodiment is that instead of the extending member 38a being movable between a stored state inside the housing 43a and an extended state, there is provided a detachable member 76, comprising the extending member 38b, releasably attachable to a base member 78. The base member 78 may be formed integrally at the upper portion 54 of the telescope housing 43 or be releasably attachable to the upper portion 54 of the telescope housing 43.

The detachable member 76 comprises a support member 80 from which the extending member 38b extends integrally at the predetermined angle 42b. The support member 80 is releasably attachable to the base member 78. in particular, the support member 80 and/or the base member 78 comprise attachment means 82 for releasably holding/securing the support member 80 in position on the base member 78. By way of example only, the attachment means on the support member 80 may be one or more magnets 82 and the attachment means on the base member 78 may be corresponding one or more metal plate 82 (preferably steel), or vice versa. Therefore, the detachable member 76 can be mounted on the base member 78 through magnetic force. li is apparent to a person skilled in the art that the present invention is not limited to the use of magnetic force and various other types of attachments are possible.

When the detachable member 76 is mounted on the base member 78, the detachable member 76 is configured such that the support member 80 supports the extending member 38b at the predetermined angle 42b to the optical axis 14b to position the optical member 40b at the optical axis 14b. In an embodiment, in order to ensure the repeatability of positioning (i.e., the detachable member 76 can be repeatedly mounted on the base member 78 at the position and orientation), the detachable device is mounted using a kinematic support mechanism (not shown).

For example, the kinematic support mechanism may include protrusions on the bottom surface 84 of the support member 80 and corresponding grooves on the top surface 86 of the base member 78, or vice versa. The protrusions are configured to fit within the corresponding grooves such that when the detachable member 78 is mounted on the base member 78, the protrusions and the grooves function to guide the detachable member 76 to the same position on the base member 78, thus ensuring repeatability in positioning. When the height measurement is completed, the detachable member 76 can be removed from the base member 78, thereby no longer bending the light from the light source 12 towards the ground 34 and allowing : the surveying apparatus 10 to perform survey distance and/or angle measurements.

Figures BA to 6F depicts an exemplary height measurement module 36¢ according to a third embodiment of the present invention. The height measurement module 36¢ of the third embodiment is substantially the same as the height measurement module 36a of the first embodiment except that it includes a spring release mechanism 90 for ejecting the extending member 38¢ out of the height measurement module housing 43c when pressed instead of requiring a person to pull out the extending member 38a.

Figure 6A illustrates a side cross-sectional view of the height measurement module 36¢c when the extending member 38c is in the extended state and Figure 6B illustrates a side cross-sectional view of the height measurement module 36¢ when the extending member 38c is in the stored state. Figure 8C is an exploded diagram showing various exemplary components of the height measurement module 36c¢.

As illustrated in Figure 6A, the height measurement module 36¢ comprises an extending member 38c having thereon or integrated therewith an optical member 40c, the extending member 38¢c being configured to be extendable at a predetermined angle 42c (non-paraliel) to the optical axis 14c to position the optical member 40c at the opfical axis 14c for manipulating the path of the light towards a surface 34, preferably, a reference point 35 on the surface such as the plumb point.

Similarly, the predetermined angle 42¢ which the extending member 38c extends with respect to the optical axis 14c is about 45°. However, it will be apparent to a person skilled in the art that the predetermined angle 40c is not limited to 45° and can be at other angles as explained hereinbefore

The extending member 38c has a multistage sliding mechanism such that its length can be shortened when stored in the housing 43c. For example, the extending member 38c may comprise a slidable body 64c and a storage slot 66¢. The slidable body 84c¢ has the optical member 40c thereon and is receivable within and extendable from the storage slot 66¢c. The extending member 38c is pivotably attached, at a rear portion 68c thereof, to a guide member 92 in the housing 43c

(e.q., a rear portion 68c of the storage slot 66¢). The guide member 92 is movable within a slot 56c¢ of the housing 43c¢ so as to guide extending member 38c between the stored state and the extended state. With this configuration, the extending member 38c can pivot from a horizontal position (with respect to the optical axis 14c) at the stored state to the predetermined angle 42c¢ at the extended state and vice versa.

The spring release mechanism 90 comprises one or more first springs 94 and one or more second springs 96. The first springs 94 are located within the slot 56¢ between a rear end 98 of the siot 56c and a rear end 100 of the guide member 92,

The second springs 96 are located within the storage slot 66¢ between a rear end 102 of the storage slot 66c and a rear end 104 of the slidable body 64c. When the extending member 38c is in the stored state, both the first springs 94 and the second springs 96 are compressed by the guide member 92 and the slidable body 16 B4c, respectively. A latch or stopper 106 is provided to hold or retain the extending member 38c¢c in the stored state. The latch 106 is configured such that when the extending member is pressed inward (i.e., in the direction denoted by "A”), the latch 106 will unlatch thereby allowing the first and second springs 94, 96 to expand thereby respectively ejecting the guide member 92 and the slidable body 64c¢ out of the slot 56¢c. Due to the presence of the support member 62c adjacent and below the slot opening 58¢, and that the extending member 38c is pivotably attached to the guide member 92, the extending member 38c will rest on the inclined surface 65¢ of the support member 62c and extend at the predetermined angle 42¢ with respect to the optical axis 14c once ejected out of the slot 56¢.

In an embodiment, the support member 62c comprises a positioning member 74¢ on its inclined surface 65¢ for holding or locking the extending member 38c in place in the extended state. For example, the positioning member 74¢ may be a magnetic member for holding the extending member 38¢ in place through magnetic force. it will be apparent to a person skilled in the art that other types of positioning member can be used for securing an object in place. When the extending member 38c is not in use, it can be easily pushed back by pushing the end portion 70c of the extending member 38c back within the slot 56¢ of the housing 43c. As the extending member 38c is pushed back, the first springs 96 and the second springs 98 will be compressed until the latch 106 clicks in position thereby holding the extending member in the stored state.

In an embodiment as illustrated in Figures 6C to 6F, the height measurement module 36¢ further comprises a locking member 110 for locking and securing the height measurement module 36¢ to a body frame of the surveying apparatus 10 to hold the height measurement module at substantially horizontal position with respect to the optical axis 14c. co

The surveying apparatus 10 with height measurement capability described herein according to embodiments of the present invention includes one or more of the following advantages: 1. High efficiency — The laser measurement system (including the light source 12) of the surveying apparatus 10 is operable not only for distance measurement, but also for its height measurement. Accordingly, manual height measurement process can be abolished. 2. High measurement resolution and accuracy - Laser measurement has much higher measurement resolution and accuracy than a manual measurement using a ruler or a tape measure. 3. Fast measurement - The extending member of the height measurement module can be easily pulled out when height measurement is required and pushed back in for storage. Therefore, the height measurement process can be done in seconds. 4. Ease of use - No assembly and disassembly are required between height measurement and surveying measurements because the height measurement module is integrated into the surveying apparatus. 5. Light weight and suitable for outdoor use — The height measurement module is integrated into the surveying apparatus with minimum additional components.

Therefore, the surveying apparatus is integrated and light in weight (e.g., not necessary to carry separate devices for height measurements and surveying measurements) which is ideal for outdoor survey operations.

6. Effective reflection device - As the light source is typically located at the central portion of the telescope of the surveying apparatus, the reflected light to the center of optical system cannot reach the photodetector. In an embodiment, the optical member is designed with diffracting grating to diffract the reflected light to the photodetector. 7. Reliable and compact mechanical design - The extending member having the optical member thereon is moved out during the height measurement and is moved back in when height measurement is completed. Furthermore, there is positioning member for positioning and locking in the extending member so that consistency and accuracy in the positioning of the optical member at the optical axis can be achieved.

The extending member has a multistage sliding mechanism such that its length can be shortened when stored in the housing. 8. Ease of manufacture and at low cost - Only the housing of conventional surveying apparatus {in particular, the housing of the telescope) needs to be modified to incorporate the height measurement module. Conventional software for performing distance/angle measurements can be easily modified to also perform height measurements based on the reflected light by the height measurement module.

Other components of the surveying apparatus can remain the same as conventional surveying apparatus. Therefore, the increase in manufacturing cost is low.

It will be appreciated by those skilled in the art that modifications and variations to the present invention described herein will be apparent departing from the scope thereof.

The variations and modifications as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of the present invention as herein set forth.

Claims

1. A surveying apparatus comprising: a light source configured to emit light along an optical axis for at least a distance measurement; and a height measurement module configured to manipulate a path of the light emitted from the light source for measuring a height of the surveying apparatus above a surface, wherein the height measurement module includes an extending member having thereon or integrated therewith an optical member, the extending member being configured to extend or be extendable at a predetermined angle to the optical axis to position the optical member at the optical axis for manipulating the path of the light towards the surface, wherein the predetermined angle is non-parallel to the optical axis.

2. The surveying apparatus according to claim 1, wherein the surveying apparatus comprises a telescope having a housing within which the light source is located, and the height measurement module is located at an upper portion of the housing.

3. The surveying apparatus according to claim 2, wherein the height measurement module is formed integrally with the upper portion of the housing.

4. The surveying apparatus according to claim 2, wherein the height measurement module is releasably attached fo the upper portion of the housing.

5. The surveying apparatus according to claim 1, wherein the extending member is movable between a stored state and an extended state, wherein at the extended state, the extending member is extended at the predetermined angle with respect to the optical axis and the optical member is positioned at the optical axis.

6. The surveying apparatus according to claim 5, wherein at the stored state, the extending member is received within a slot of a housing of the height measurement module.

7. The surveying apparatus according to claim 6, wherein the height measurement module comprises a guide member movable along the slot for guiding the extending member between the stored state and the extended state.

8. The surveying apparatus according to claim 7, wherein a rear portion of the extending member is pivotably attached to the guide member such that the extending member can pivot from an orientation at the stored state to the predetermined angle at the extended state, and vice versa.

9. The surveying apparatus according to claim 6, wherein the height measurement module further includes a support member protruding from an end portion of the housing of the height measurement module adjacent and under an opening of the slot, the support member comprising an inclined surface adapted for the extending member to rest on in the extended state thereby supporting the extending member at the predetermined angle with respect to the optical axis.

10. The surveying apparatus according to claim 9, wherein the support member further comprises a positioning member on the inclined surface for holding the extending member in place.

11. The surveying apparatus according to claim 6, wherein the extending member has a multistage sliding mechanism such that its length can be shortened at the stored state and lengthened at the extended state.

12. The surveying apparatus according to claim 6, wherein the height measurement module further includes a spring release mechanism for gjecting the extending member from the stored state within the slot to the extended state.

13. The surveying apparatus according to claim 1, wherein the height measurement module includes a detachable member and a base member, the detachable member comprising the extending member, wherein the detachable member and the base member is releasably attachable to each other.

14. The surveying apparatus according to claim 13, wherein the detachable member further includes a support member from which the extending member extends integrally at the predetermined angle, and wherein the support member and/or the base member comprise attachment means for releasably holding the support member in position on the base member.

15. The surveying apparatus according to claim 1, wherein the predetermined angle is about 45°.

18. The surveying apparatus according to claim 1, wherein the optical member is a reflective member.

17. The surveying apparatus according to claim 16, wherein the optical member comprises a central portion and an outer portion, and wherein the central portion is a mirror and the outer portion is a diffuser.

18. A height measurement module for attaching to a surveying apparatus to measure a height of the surveying apparatus above a surface, the surveying apparatus includes a light source configured to emit light along an optical axis for at least a distance measurement, the height measurement module comprising: an extending member having thereon or integrated therewith an optical member, the extending member being configured to extend or be extendable at a " predetermined angle to the optical axis to position the optical member at the optical axis for manipulating the path of the light towards the surface, wherein the predetermined angie is non-parallel {o the optical axis.