CONTINUOUS SURFACE DEFORMATION MEASUREMENT FIELD OF THE INVENTION The present invention relates to an apparatus, system and method for determining and/or measuring deformations in a surface. The present invention is particularly well suited to locating and measuring relatively small surface deformations in the exterior surface of aircraft, submarines and other similar structures that are subject to substantial pressure changes during operation. BACKGROUND OF THE INVENTION The presence of deformations in structures that are required to retain structural integrity whilst subject to substantial pressure changes during operation is problematic. Over time, as a structure is subjected to forces associated with exposure to substantial pressure changes, deformations in the structure may increase and ultimately lead to failure of the structure. As a result, it is important to measure and monitor the size and shape of deformations in structures such that any deformation exceeding a predetermined safe limit may be identified for repair or replacement prior to a potentially dangerous failure of a structural component. With reference to aircraft structures, there are various apparatus available to assist the detection and measurement of deformations or dimensional properties of component parts of a structure. For example, an optical micrometer is a visual inspection tool that may be used to determine dimensions of structural deformations that may be externally observed. This device relies upon an operator adjusting the tool to focus on different aspects of a structure and measuring the relative distance between settings of the device for which an aspect of the structure was in focus to the operator. By focusing on different aspects of a structure, the tool is able to provide to the operator an indication of the physical distance between the two aspects of the structure upon which the operator directed and focused the device. Although operation of optical micrometers is a relatively slow process, they are well accepted in the aircraft industry as being a relatively reliable and useful tool in specific circumstances. Another measurement device widely used in the aircraft industry uses the principle of eddy currents to determine the existence of deformations in locations that are not as readily accessible to a visual device. For example, in the case of a deformation residing within a wall of a borehole, insertion of an eddy current probe into the borehole and the establishment of eddy currents in the metallic material surrounding the probe, enables the detection of deformations that alter the flow of the eddy current. Whilst a device of this type may be used to determine the presence of an anomaly in a structure, it is not intended to be used to provide an absolute measurement or quantification of the size of the anomaly. Another device that is widely used relies upon the principle of transmission of ultrasonic energy to determine the physical distance between two points. In particular, such devices are useful for measuring the thickness of a substantially planar sheet of material. Whilst each of the above described devices have their particular uses for measuring and monitoring various aspects of structures, none of the devices lend themselves particularly well to the detection and measurement of surface deformations such as scratches. The existence of scratches in an external surface of a structure that is subject to substantial pressure changes can, if exceeding predetermined safe limits, lead to structural failure of that external surface component. Although the problem of measuring and monitoring the dimensional details of scratches to external surfaces is well recognised, there has yet to be developed an apparatus that provides a relatively quick and reliable measurement of the details of such deformations to external surfaces. Whilst attempts have been made to use the above mentioned devices for measuring dimensions of scratches to external surfaces, and in particular the depth of a scratch, they all have significant disadvantages. In particular, devices relying upon the principle of ultrasonic energy are extremely unreliable as they are insensitive to scratch depths below a certain threshold. Even if a surface deformation is of sufficient dimension to be detected by ultrasonic energy, the reliability of any measurements provided by such a device is low. Use of an eddy current probe to establish eddy currents in a metallic surface in which a scratch resides has also failed to provide reliable results. In this instance an eddy current probe is able to provide an indication of the width of a scratch and the volumetric displacement of material that has been removed or displaced during the process of scratching the surface. However, such a device cannot measure the depth of a scratch which is of primary importance to O

determining the potential for a scratch to lead to loss of structural integrity of the surface component. Of the three devices described, only the optical micrometer has provided useful and reliable results when measuring the depth of a scratch on an external surface. However, optical micrometers have significant disadvantages not the least of which is the requirement for a relatively highly skilled operator to operate the device to ensure correct use. Further, an optical micrometer is used to provide a measurement in a specific location and therefore to obtain measurements in a number of locations it is necessary to locate the device at each specific location of interest and perform a separate measurement. In the case of a relatively long scratch to a component, it is usually difficult to determine which locations on the surface may exhibit the greatest scratch depth and as such, it is necessary to select sample locations along the length of the scratch for establishing depth measurements. Of course, establishing sample locations may miss a location where the depth of the scratch is at its greatest. Other problems associated with using an optical micrometer for establishing the dimensions of a scratch to an external surface include the difficulty associated with using such an apparatus in awkward locations such as the under side of an aircraft fuselage and the substantial amount of time required to provide a series of measurements along the length of a scratch. When considering a scratch of one metre in length, to ensure sufficient sample points are measured in an attempt to locate the points of maximum scratch depth, it is estimated that it would require 40 minutes to operate the apparatus to obtain scratch depth measurements and a further 20 minutes to complete recordal of the various relative measurements to obtain an indication of the depth of the scratch at the sample points along the one metre length. Accordingly, using an optical micrometer to measure scratch depth, it is estimated that it would require approximately one hour for every one metre length of scratch analysed. In the instance of Boeing 737 and 747 aircraft it has been estimated that there is approximately 200 metres of the exterior surface of each aircraft that requires analysis for the identification and measurement of surface scratches to determine whether a scratch depth exceeds a safe level. The use of an optical micrometer for this purpose would require approximately 200 man hours for each aircraft which is considered prohibitive both in terms of the time and labour resource required. Furthermore, it is very difficult for an operator to quickly determine those scratches or deformations (or aspects of scratches or deformations) that are likely to exceed predetermined safe limits. If an operator were to treat every scratch or deformation as potentially failing the safety limit, the time required to fully inspect the surface of a structure such as an aircraft or sea going vessel would be prohibitive. However, without a relatively accurate guide, operators must select those scratches and/or deformations that appear to the operator as necessitating further detailed inspection. Accordingly, such determinations are a matter of judgement and hence reliant upon the skill and expertise of the operator and highly subject to the possibility of human error. Therefore, it is an object of this invention to provide an apparatus, system and method for determining and/or measuring deformations of surfaces that enables reliable detection, and measurement of the dimensional details of any such deformations that is less time consuming to effect the measurements as compared with an optical micrometer, it is a further object of the invention to provide an apparatus, system and method that is not subject to the limitation of detecting and/or measuring the dimensional details of deformations at sample points in order to provide an economically feasible solution. Any discussion of documents, devices, acts or knowledge in this specification is included to explain the context of the invention. It should not be taken as an admission that any of the material formed part of the prior art base or the common general knowledge in the relevant art on or before the priority date of the claims herein. SUMMARY OF THE INVENTION In one aspect, the invention provides a surface deformation measurement apparatus including: a light source generating a narrow curtain of light; an optical viewer; and a mounting arrangement; said light source being affixed to said mounting arrangement to project said narrow curtain of light onto the surface to be measured substantially perpendicular to the plane of the surface, said mounting arrangement also having said optical viewer affixed thereto and aligned such that the nominal viewing axis of the viewer substantially intersects said surface in a region illuminated by said light source, said narrow curtain of light thereby illuminating the surface to be measured and enabling the detail of any surface deformations to be viewed by the optical viewer; wherein the mounting arrangement is moveable along the surface to provide a continuous image of any. surface deformations. It is preferred that the light source is substantially monochromatic, such as that generated by a laser diode, and that the light emanating from the source is passed through a collimator and subsequently through a line generating optical arrangement such that a relatively narrow curtain of light is produced. The curtain of light generated by the light source is preferably narrow such that the footprint of the curtain of light as it impinges upon a surface has a width that is substantially smaller as compared with the length. Further, it is particularly preferred that the footprint of the light curtain as it is projected onto a surface display a relatively high level of contrast between the illuminated region as compared with non illuminated regions of the surface. The narrower the curtain of light and the greater the contrast distinction around the edges of the footprint of the light curtain, the more accurately measurement apparatus of the present invention is able to measure the dimensional details of surface deformations. In a particularly preferred embodiment, the relatively narrow curtain of light is projected onto the surface to be analysed in an orientation such that the length of the curtain of light is substantially perpendicular to the nominal viewing axis of the optical viewer. Further, the narrow curtain of light is preferably aligned such that in reflecting from the surface, it illuminates the depth profile of a scratch or deformation that the curtain of light impinges upon. In a preferred embodiment, the optical viewer is a bore scope. However, the viewer may also be a microscope. In any event, it is preferred that the optical viewer include a CCD camera to pass images presented to the optical viewer to a display means for displaying the images. A measurement grid which overlays the displayed images displayed on the display means may also be provided. The measurement grid preferably includes a plurality of equally spaced horizontal and vertical lines, with the distance between each horizontal and vertical line β o representing a known distance on the displayed image. An overlaid measurement grid thereby enables an operator to obtain a quick visual indication as to the physical distance between different portions of a reflected light pattern that is illuminating the profile of a scratch or other deformation. The images and overlying measurement grid may be stored for recall and analysis subsequent to locating the apparatus over a region of a surface and capturing the image of the region as illuminated by the light source. The captured images may be processed by a microprocessing device to thereby provide measurement of the dimensional details of surface deformation. In a particularly preferred embodiment, the distance between two points on a captured image selected by an operator may be measured by a microprocessing device determining the number of pixels between the two points and whether the distance measurement (converted from the pixel count) of the surface deformation exceeds a predefined limit. Whilst the nominal viewing axis of the optical viewer could be any angle as compared with the plane of the surface, it is preferred that the nominal viewing axis reside elevated at an angle of approximately 30 degrees from the plane of the surface being analysed. Whilst an apparatus according to the invention as described thus far provides for relatively reliable measurements of the dimensional details of a surface deformation at a specific point along a scratch without the relatively lengthy delays associated with the setup and operation of an optical micrometer, it is particularly preferred that the moveable mounting arrangement includes a replaceable plate-like member which has a lower surface conforming to the shape of the surface being measured such that the apparatus may be slid over the surface whilst the apparatus continuously displays an image of the detail of the surface of any surface deformations. Any displayed images may be stored and subsequently recalled for the purpose of analysing the illuminated deformations and measuring the dimensional details of same. In particular, images captured along a section of a surface may be analysed to determine the precise position of a maximum dimensional aspect of a deformation, such as scratch depth, and having selected the specific captured image detailing the maximum dimensional aspect, that dimensional aspect may be measured from the image. In an alternative embodiment, the mounting arrangement includes wheels such that the arrangement may be rolled over a surface whilst the apparatus continuously collects captured images of the details of surface deformations. In a particularly preferred embodiment, images processed by the optical viewer and the overlying measurement grid are stored and processed by a microprocessing device as a surface is inspected in order to provide a stored record of the surface as it is inspected along with the overlying measurement grid. An apparatus according to this embodiment is particularly advantageous in that the display and measurement grid provide an immediate indication to an operator of the dimensional details of surface deformations. The microprocessor may be used to process captured images and may be programmed to measure the dimensional details of surface deformations and to alert an operator when the dimensions of surface deformations either exceed a predefined safe limit or warrant closer inspection. In this regard, the operator would most likely initially utilise the measurement grid to provide an initial visual indication as to whether a surface deformation requires further investigation prior to utilising the microprocessor to measure the dimensional details of surface deformations. For regions of a surface where dimensions of surface deformations exceed a safe limit the apparatus may also provide a temporary surface marking such that an operator may pass the apparatus over a relatively long length of the surface allowing the apparatus to provide a temporary marking on the surface being analysed in those regions of particular interest where the dimensional details of surface deformations may exceed a predefined safe limit. Any such identified regions of interest may then be measured or investigated more carefully with an apparatus according to the present invention or with an alternate measuring means such as an optical micrometer. In another aspect, the present invention provides a method of measuring deformations in a surface including the following steps: illuminating the surface with a narrow curtain of light in a region where detection and/or measurement of a surface deformation is required; aligning an optical viewer such that the nominal viewing access of the viewer substantially intersects said surface in an illuminated region; and viewing the illuminated region of the surface to detect and/or measure the dimensions of a surface deformation; and sliding a mounting arrangement to which a light source for generating the narrow curtain of light and the optical viewer is fixed such that the sliding of the mounting arrangement along a surface enables continuous viewing of images of the surface as the mounting arrangement is moved. Preferably the method includes the step of projecting the narrow curtain of light onto the surface such that the narrow curtain of light is substantially perpendicular to the plane of the surface. Further, the optical viewer is preferably aligned such that the nominal viewing axis of the viewer resides substantially perpendicular to the dimension defining the length of the narrow curtain of light and also elevated at an angle of approximately 30° from the plane of the surface undergoing analysis. Although the nominal viewing axis of the viewer may be elevated from the plane of the surface at substantially any angle, it will be clearly recognised by persons skilled in the art that some angles will provide greater clarity with respect to viewing images of an illuminated region of the surface. In any event, it is preferable that an angle of elevation be selected and retained for the nominal viewing axis of the viewer so that any compensation required to be applied to measurements of surface deformations may take into account the angle of elevation of the optical viewer from the plane of the surface. Of course, if the angle of elevation is fixed with respect to the plane of the surface, the compensation to any measurements derived from images from the optical viewer may be applied consistently to successive viewed images. In the instance of the optical viewer including a device such as a CCD camera to process images, the method preferably includes the step of capturing and storing images as a mounting arrangement is moved over a surface. In a particularly preferred embodiment, the method includes the step of capturing images continuously as the mounting arrangement is moved over a surface and executing computer instruction code on a microprocessor to analyse the captured images for the purpose of detecting surface deformations and/or measuring the dimensional aspects of any surface deformations detected. The method may also include the step of comparing the measurements of any surface deformations with predefined and safe limits for the dimensions of surface deformations and the computer instruction code may provide an alert to an operator in the event that the dimension of a surface deformation exceeds a predefined safe limit. An apparatus, system or method according to the present invention enables surface deformations to be analysed and measured whilst requiring substantially less time and labour resource as compared with measurements conducted with an optical micrometer. Further, by providing a continuous image . of a surface under inspection, as the inspection process occurs, the present invention does not suffer the limitation of providing measurements of surface deformations at selected sample points or regions. Operation of an apparatus according to the present invention does not require the development of skills such as is required for the operation of an optical micrometer. Further benefits and advantages of a surface deformation measurement apparatus and method according to the present invention will, become apparent in the following description of a preferred embodiment of the invention. BRIEF DESCRIPTION OF THE DRAWINGS A preferred embodiment of the invention will now be described which should not be considered as limiting any of the statements in the previous section. The preferred embodiment will be described with reference to the following figures in which: Figure 1 is a diagrammatic representation of a section of material in which the surface has a deformation; Figure 2 is a side view of an apparatus according to an embodiment of the invention; Figure 3 is a partial front view of an embodiment of a light source for providing a narrow curtain of light; Figure 4 is a block diagram of the apparatus according to an embodiment of the invention; Figure 5 is a perspective view of a surface deformation that is analysed by an apparatus according to an embodiment of the invention; Figure 6 is side sectional views providing profiles of the deformation detailed in Figure 5 at the four separate planes identified as A, B, C and D; Figure 7 is another perspective view of the surface deformation detailed in Figure 5 identifying a temporary marking on the surface to indicate regions of the deformation that are of particular interest; Figures 8a - 8c illustrate the image displayed on the LCD display of the captured image and overlaying measurement grid as the apparatus scans across a surface deformation; Figure 9 is a perspective view of a skid member of the mounting member having a lower surface suitable to engage with a butt joint on an outer surface of the fuselage of an aircraft; Figure 10 is a perspective view of a skid member of the mounting arrangement having a lower surface suitable to engage with a lap joint on the outer surface of the fuselage of an aircraft; Figure 11 is a perspective view of a skid member of the mounting arrangement having a lower surface suitable for sliding over aircraft windows or any part of the aircraft fuselage where guiding of the apparatus is not required.. DESCRIPTION OF A PREFERRED EMBODIMENT With reference to Figure 1 , a diagrammatic representation of a section of material (5) is provided with the top surface of the material (9) having a surface deformation (7) in the form of a scratch. The diagrammatic representation of Figure 1 attempts to detail the deformation that would normally occur to a surface in the instance where the surface was scored or scratched with a relatively sharp object such as a screwdriver or the tip of a knife. In these instances, it is usual for the surface deformation to have a profile that includes a recess to the surface that conforms substantially with the profile of the tip of the sharp object that caused the scratch and for the edges of the scratch to exhibit a raised or swollen profile representing the material displaced at the time the void of the scratch was created. As detailed in Figure 1 , the scratch (7) in the surface of the material (9) has a maximum depth (22) at the tip of the scratch profile. Of course, along the length of the scratch (7) the maximum depth of the tip of the profile (22) may vary depending upon the force supplied to the sharp implement at the time of causing the scratch. In the instance that the section of material (5) is a section of material that is used for the outer surface of the fuselage of an aircraft, the presence of a scratch (7) is of particular concern as it could eventually lead to a crack developing along the line identified by item (17). In particular, as an aircraft is subjected to varying pressure changes, forces in the directions identified by item numbers (14) and (15) will occur and if the amount of material remaining between the maximum depth of a scratch (22) and the bottom surface of the material (11) falls below a predetermined safe limit, it is considered that a crack along the line identified, by item number (17) is likely to occur and as such, the section of the material where the scratch (7) resides should be repaired and/or replaced. Whilst the problem associated with surface deformations such as scratches in material is well recognised, the apparatus currently used to measure the dimensional aspects of such surface deformations is significantly limited with respect to reliability and the time and labour resource required. For example, to measure the maximum depth of a scratch (7), the current practice would be to use an optical micrometer. This device is an optical device that enables an operator to measure the relative distance between two points as a result of the difference in focal length of the device when focussed on those two points. In the example of Figure 1 , an optical micrometer could be used to focus upon a region (20) in the top surface (9) of the material to obtain a datum for comparison with other features of a deformation. An operator would usually annotate on a data sheet the precise micrometer reading according to the focal length of the optical arrangement that rendered the region (20) of the top surface (9) to be in focus. The operator would then shift the optical micrometer to a position directly above the scratch and attempt to focus the optical device on the region of the scratch corresponding to the maximum depth (22). At this point, the operator would once again annotate on a data sheet the precise micrometer reading according to the focal length of the optical device to bring the region of the material residing at the maximum depth of the scratch (22) into focus. A comparison of the micrometer readings according to the focal length of the optical device to focus upon region (20) and region (22) then enables the operator to determine the depth of the scratch as compared with the top surface of the material (9). Whilst an optical micrometer is recognised as providing relatively reliable results, it embodies significant disadvantages in that use of such a device requires a relatively highly skilled operator and operation of the device requires lengthy periods of time to obtain the required measurements. Further, an optical micrometer is restricted to only providing depth measurements at particular locations and in the event that it becomes necessary to measure the depth of a scratch along a significant length, it is necessary to sample the scratch at various locations in an attempt to determine that region of the scratch that would most likely represent the greatest depth. Generally, prior to using an optical micrometer, it is usual for an operator to use a magnifying glass in an attempt to determine the presence of scratches or surface deformations relatively quickly prior to operating the optical micrometer to obtain detailed measurement results. This additional step increases the time required to effect measurements with such a device. Attempts have been made to use alternative techniques to accurately measure the depth of a scratch to the surface of a portion of metallic material such as devices that rely upon the principle of eddy currents and ultrasonic sound waves. In the instance of a device that attempts to generate eddy currents in the surface of the material, it has been discovered that whilst an eddy current probe determines the presence of a surface deformation and can provide a reasonably good indication of the width (8) of a surface scratch, such a device is not able to determine the depth of a scratch (22). Further, devices relying upon the principle of ultrasonic sound waves have been successful in determining the thickness (25) of a section of material but such devices have been found to be ineffective with respect to measuring the precise dimensional aspects of the surface deformation. With reference to Figure 2, an embodiment of an apparatus (30) according to the present invention is detailed from a side view. The apparatus (30) includes a light source (34) for generating a relatively narrow light curtain (46) and an optical viewer (36) both of which are firmly affixed to the mounting arrangement (32). The mounting arrangement (32) preferably includes a plate-like member in the form of a skid member (110) which enables the apparatus (30) to be slid along the surface (33) that is subject to analysis for the detection and/or measurement of the surface deformations. Alternatively the mounting arrangement may include wheels (60) to enable the apparatus (30) to be rolled along the surface (33) under inspection for the detection and/or measurement of surface deformations. The optical viewer (36) includes an optical column (50) enabling the optical viewer (36) to focus upon the image of the surface in the region currently under analysis (51). The nominal viewing axis (52) of the optical viewer (36) is aligned to intersect with the surface (33) in the region (51) that will be illuminated by the narrow curtain of light (46). The light source (34) includes a laser diode (42) that generates monochromatic light. The light produced by the laser diode (42) is passed through a collimator (not shown) and subsequently through a line generating optical arrangement (44). In an embodiment of the invention the line generating optical arrangement (44) includes a prism. Emanating from the line generating optical arrangement (44) it is a relatively narrow curtain of light (46) that is preferably projected onto the surface (33) substantially at a right angle. The light source (34) is fixed to the mounting arrangement (32) by member (38) and the optical viewer (36) is affixed to the mounting arrangement (32) by lug (40). In the embodiment detailed in Figure 2, the optical viewer has its nominal viewing axis (52) elevated at an angle of 30° from the plane of the surface. Of course, the angle of elevation could vary although it is necessary to take into account the angle of elevation when viewing images from the optical viewer for the purpose of measuring dimensional aspects of surface deformations. As will also be noted in Figure 2, the curtain of light beam (46) generated by the light source (34) is relatively narrow (i.e. length of the footprint of light projected on to the surface (33) is substantially greater as compared to the width) and the curtain of light (46) is preferably projected onto the surface (33) with its length at an angle substantially perpendicular to the nominal viewing axis (52) of the optical viewer (36). The orientation of the curtain of light (46) substantially perpendicular to the nominal viewing axis (52) of the optical viewer (36) provides greater clarity with respect to the images viewed by the optical viewer (36). Effectively, the curtain of light (46) only illuminates a very narrow section of the surface which when projected onto a surface at a substantially right angle to the longitudinal axis of a deformation such as a scratch, and acts to provide a narrow beam of light that reflects from the surface, thus illuminating the profile of any deformation in the surface. Reflection of the curtain of light from the surface allows the profile of a surface deformation to be relatively easily detected. In essence, the present invention arises from the recognition that a narrow beam of light projected onto a surface provides a reflection pattern that conforms to the shape of the surface including the shape of any surface deformation and displaying a continuous image of the surface enables an operator to view the profile of a surface deformation as the apparatus is passed over the portion of the surface containing the deformation, effectively providing an instantaneous indication to an operator of the dimensions of a surface deformation. Viewing the reflection pattern thus enables information pertaining to the physical dimensions of the surface to be inferred. With reference to Figure 3, a front view of the light source (34) is provided detailing the laser diode (42), the line generating optical arrangement (44) and the curtain of light (46). In this particular view, it can be seen that the length (48) of the curtain of light (46) is substantially greater than the width of the light curtain as detailed in Figure 2. With reference to Figure 5, a perspective view of a surface deformation (60 is provided and upon noticing such a surface deformation, an apparatus according to the embodiment detailed in Figure 2 may be traversed along the longitudinal axis of the surface deformation (60) to determine the dimensions of the surface deformation (60). Of course, a significant advantage of the present invention is the ability to view images, and measure dimensions, along the entire length of a surface deformation. However, for purposes of illustration, captured images at four separate locations, namely, A, B, C and D are subsequently considered in Figure 6 for purposes of determining whether the surface deformation (60) represents a deformation that would require some form of intervention. The four section lines (62, 64, 66 and 68) corresponding to locations A, B, C and D respectively, identify the preferred orientation of the curtain of light that is projected onto the surface with respect to the surface deformation. With reference to Figure 6, the actual recorded profile at each location (A, B, C and D) is provided as it would be viewed by the optical viewer. The lines identified as items 70, 75, 80 and 85 represent the reflected light resulting from the projected narrow curtain of light onto the surface as would be processed by the optical viewer. Preferably, the optical viewer includes a CCD camera for processing images as the apparatus traverses a surface deformation such that the images may be concurrently or subsequently processed by a microprocessor executing appropriate computer instruction code. Lines 72, 77, 82 and 87 represent the maximum depth a surface deformation may reach before exceeding a predefined safe limit. In most instances, it is not expected that lines 72, 77, 82 and 87 would appear in a captured image. However, when considering the maximum safe limit to which a the depth of the surface deformation may extend, it can be seen from Figure 6 that the surface deformation viewed at locations A and D does not exceed the predefined maximum safe limit whereas the depth of the surface deformation at locations B and C exceed the safe limit. Figures 8a - 8e illustrate the image displayed on a LCD display (115) of the apparatus. In this regard, the LCD display may be mounted on the apparatus or attached via a connecting cable to the apparatus. Alternatively, an LCD display could be provided on the apparatus with an additional LCD display also provided at a remote location. The captured image has a measurement grid (120) which overlays the image to assist the operator in determining a visual indication as to the dimensions of a surface deformation as the apparatus traverses the surface. As can be seen in Figures 8a - 8e a reflected beam of light (100) conforms to the surface under consideration at the location where the beam of light is projected onto that surface. Accordingly, measurements of the extent to which the reflected beam of light varies and the distances associated with those variations corresponds directly to the physical dimensions of the surface deformation causing the reflected light pattern. As the beam of light (100) traverses a surface deformation (125) the reflected beam of light from the surface under consideration undergoes physical displacement as can be seen in Figures 8b - 8d. The greatest amount of variance in the reflected beam of light is shown in Figure 8c which is approximately the mid-point of the surface deformation (125). In order for the operator to be able to visually determine the dimensions of the surface deformation (125) at the point of greatest variance in the reflected beam of light (100) the operator must know the spacing between the horizontal lines (130) and the vertical lines (135) of the measurement grid (120). Accordingly, the apparatus must first be calibrated. As the width of the actual image displayed on the LCD display varies depending upon the magnification of the lens of the optical viewer it is necessary to determine the actual width of the displayed image at each focal length to calibrate the apparatus. In the first instance, the actual size of the image viewed on the LCD display must be known at a particular magnification. It is then determined as to how many pixels are displayed across the width of the display. This information can then be utilised to select a convenient spacing of the vertical grid lines (135) across the image such that the operator will know for example that between each grid line is 10,000th of an inch of actual surface. A similar approach is utilised in relation to the spacing between the horizontal lines of the measurement grid however the angle at which the optical viewer is located with respect to the surface must be taken into consideration. The same process is undertaken to determine the width of the image displayed at each level of magnification of setting of the lens. Whilst the measurement grid (120) is preferably displayed only on the image displayed on the remotely located LCD display, the LCD display mounted on the apparatus may also have the measurement grid (120) selectively displayed. Once completed this information is stored by the microprocessor and at each specific level of magnification of the optical viewer, an indication on the LCD display is provided to indicate to the operator the distance between each adjacent horizontal line of the measurement grid and each adjacent vertical line of the measurement grid. The operator, when viewing the LCD display of the reflected beam of light, will thereby be able to obtain a visual indication as to the depth of a surface deformation based upon the physical displacement of the reflected beam of light with respect to the measurement grid. Once the operator has determined a visual identification of a region where the depth of the surface deformation may be at its greatest, the operator can identify the points of maximum displacement of the reflected beam for measurement. In certain instances, the reflected light from the surface of a deformation may be diffused or scattered due to the irregularity of the surface or the presence of corrosion in a scratch. In these instances, it is preferable to allow a trained operator to assess a captured image and identify the two points in the stored image of a scratch profile (as illuminated by the laser) that represents the deepest point of the scratch and the nominal level of the surface from which the depth of the scratch should be measured. The two points identified by an operator will correspond to at least two pixels in the displayed image. In this regard, the microprocessor is able to measure the pixel distance between the two points selected by the operator and convert the pixel distance to a physical distance thereby providing the operator with the distance between the two points selected. In order for the microprocessor to determine the distance between points selected by the user on a selected captured image, the magnification level of the optical viewer must be known by the microprocessor. It is preferable to provide a signal from the optical lens to the microprocessor indicating the magnification of the image. With reference to Figures 9 - 11 there is shown various skid members of the mounting arrangement. The skid members each have a lower surface (140) which is suitably shaped to conform to various surfaces of the outer surface of the fuselage of an aircraft. The skid members are specifically shaped to suit a particular aircraft and are removably attached to the mounting arrangement such that the apparatus can be utilised on various shapes and sizes of aircraft. The skid member 110 shown in Figure 9 is utilised when the apparatus is used to examine butt joints on the aircraft fuselage. The lower surface 140 of the skid member 110 shown in Figure 9 has two protuberances (not shown) at each end which engage into a slot the goes around the circumference of the aircraft fuselage where sections of the fuselage are joined together. The engagement of the protuberances in the slots ensures that the apparatus remains suitably positioned and guided over the butt joint being examined. The skid member 110 shown in Figure 10 is utilised when the apparatus is used to examine lap joints on the aircraft fuselage. The lower surface 140 of the skid member 110 shown in Figure 10 has two raised sections 112 at each end which assist in guiding the apparatus along the lap joint such that the apparatus remains suitably positioned during examination of the lap joint. The skid member 110 shown in Figure 11 has a lower surface 140 which is suitable for sliding over the aircrafts windows or any part of the aircraft fuselage O

where guiding of the apparatus is not required. At each end of the skid member 110 depicted in Figure 11 is a series of upstanding members 117 which may be of any shape or form. In a particularly preferred embodiment, the processing of images occurs substantially simultaneously with the capture of images by the optical viewer. In this instance, by processing the collected pixel information from the image, and compensating for the angle of elevation of the nominal viewing axis of the optical viewer, it is possible to determine the depth of a surface deformation. Further, by suitable inclusion of the defined safe limit in the computer instruction code executed by the microprocessor that processes captured images, it is possible to provide an alert or indication at the time that the apparatus traverses a surface deformation that exceeds the maximum allowable depth. In a particularly preferred embodiment, the indication from the microprocessor activates a temporary marking device such that a temporary mark may be applied to the surface by the apparatus as it traverses the surface deformation in those regions where the apparatus measures the surface deformation as having a dimension that exceeds a predefined safe limit. With reference to Figure 7, it can be seen that a temporary marking (90) has been applied to the surface for those regions where the maximum depth of the surface deformation has exceeded a predefined safe level thus allowing an operator to quickly recognise those areas on the surface that require further investigation or repair. In an alternative embodiment, a temporary marking of any shape or form may be applied to the surface when the apparatus captures and/or stores an image. In operational use of the apparatus, the operator would initially slide the apparatus over the surface being examined with the magnification of the optical viewer selected such that a relatively large surface area will be displayed on the LCD display. If this initial scan identifies any areas which may require further investigation due to discontinuities of the reflected light beam, the operator would then proceed to adjust the magnification of the optical viewer to more closely inspect the location identified. If the location identified appears to be of a surface deformation such as a scratch having a depth approaching or exceeding safe limits, the operator would then align the apparatus with respect to the surface deformation being examined such that the beam of light is substantially perpendicular to the longitudinal length of the deformation. The operator would then traverse the apparatus along the deformation and proceed to record the images processed by the optical viewer including the overlaying measurement grid, for subsequent analysis. The apparatus of the present invention is suitable for using on metal, acrylic, glass and composite material surfaces. When using the apparatus on glass surfaces the gain control of the laser needs to be increased to initially locate surface imperfections due to the low level of reflectance. As increasing the gain of the laser increases the width of the curtain of light emitted measuring the dimensions of surface imperfections becomes difficult. Accordingly, once the surface imperfections have been located the gain control is decreased by the operator such that the curtain of light emitted by the laser is of a width suitable for performing measurements of the surface deformations. In a further embodiment of the present invention a small hand-held version of the apparatus is provided which has a plastic grid physically placed over the LCD display such that the operator is provided with a visual indication as to whether any markings on a surface being analysed are of particular interest due to the dimensional details of a surface deformation exceeding a predefined safe limit. In this regard, a series of plastic grids is provided with each corresponding to a specific magnification level of the optical viewer. Accordingly, if the magnification of the optical viewer is changed it is also necessary to change to a corresponding plastic grid which has been calibrated to the magnification selected. Whilst this form of the apparatus only provides an approximate indication of the depth of a surface deformation, it does provide a simple and cost-effective means of enabling early detection of surface deformations of interest. The apparatus of the present invention advantageously can operate on not only flat surfaces but also curved surfaces are varying degree of curvature and edge surfaces such as butt joints and lap joints. It will be appreciated by a person skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.