A laser device

Abstract

A laser device includes a laser unit 12 for producing a laser beam and an optics module 16. The optics module has an optical axis O connected to the laser unit. The laser beam is received and focused onto a focal plane along this axis. The optics module increases the laser beam’s cross-sectional size from a first, incident, cross-section 40 to a second, pre-determined, cross-section 42. The second, pre-determined cross-section is located at the focal plane of the optics module.The first and second cross-sections may each have a width dimension W1,W2 respectively and a height dimension H1,H2 respectively and the optics module may vary these properties so that W2 > W1 and / or H2 ≤ H1. The ratio of W2 to H2 may be at least 1000 or at least 2000. The first cross-section may be a different shape to the second cross-section which may be an elongate shape such as an ellipse, rectangle or line. The optics module may include a lens 61 with a width axis WD perpendicular to the optical axis and a height axis HD perpendicular to both the optical axis and the width axis, refracting the laser beam to produce the second cross-section.

Description

This invention relates to a laser device. More particularly, but not exclusively, the invention relates to a laser device for treating and / or modifying an object. The present invention seeks to provide a laser device that may address issues and / or disadvantages of prior art laser devices in relation to treating and / or modifying an object. BRIEF DESCRIPTION OF THE INVENTION According to an aspect of the present invention we provide a laser device including: a laser unit for producing a laser beam; an optics module having an optical axis (O) connected to the laser unit for receiving the laser beam therethrough and focusing the laser beam onto a focal plane; wherein the optics module increases the size of the cross-section of the laser beam from a first, incident, cross-section to a second, pre-determined, crosssection located at the focal plane of the optics module. Optionally or preferably the first cross-section has a width dimension Wi and a height dimension Hi, and the second cross-section has a width dimension W2 and a height dimension H2, and wherein the optics module is configured such that W2 is larger than W1, optionally or preferably H2 is equal to or less than Hi. Optionally or preferably wherein the first cross section has a width dimension W1 and a height dimension Hi, and the second cross-section has a width W2 and a height H2, wherein the optics module is configured such that W2 is equal to W1 and H2 is smaller than Hi. Optionally or preferably wherein the ratio of W2 to H2 is at least 1000, optionally or preferably the ratio is at least 2000. Optionally or preferably wherein the first cross-section is a first shape and the second cross-section is a second shape; and wherein the second shape is different to the first shape. Optionally or preferably wherein the second cross-section is an elongate shape, optionally or preferably the elongate shape is one of: an ellipse; a rectangle; or a line. Optionally or preferably wherein the optics module includes a lens including: a width axis perpendicular to the optical axis (O); and a height axis perpendicular to the optical axis (O) and to the width axis, wherein the lens is configured to refract the laser beam along the width axis and / or the height axis to produce the second cross-section at the focal plane. Optionally or preferably wherein the optics module includes a first said lens and a second said lens spaced apart along the optical axis (O); wherein the first lens is configured to diverge the laser beam along its width axis and not alter the laser beam along its height axis; and wherein the second lens is configured to converge the laser beam along its height axis and not alter the laser beam along its width axis. Optionally or preferably wherein the optics module includes a first said lens and a second said lens spaced apart along the optical axis (O); wherein the first lens is configured to converge the laser beam along its height axis and not alter the laser beam along its width axis; and wherein the second lens is configured to diverge the laser beam along its width axis and not alter the laser beam along its height axis. Optionally or preferably wherein the optics module includes a plurality of lenses, wherein: one or more of the plurality of lenses refract, e.g. diverge, the laser beam along their respective width axes only; one or more of the plurality of lenses refract, e.g. converge, the laser beam along their respective height axes only; and / or one or more of the plurality of lenses refract the laser beam along their width axis and height axes. Optionally or preferably wherein the optics module includes a first and second said lens spaced apart along the optical axis (O) wherein the optics module is configured such that: the first lens converges the laser beam along its width axis, wherein the focal point of the first lens is located between the first lens and second lens so that the width of the laser beam is diverging as it reaches the second lens; optionally or preferably the first lens does not alter the laser beam along its height axis; and the second lens collimates the laser beam along its width axis and converges the laser beam along its height axis, to produce the second cross-section at the focal plane. Optionally or preferably wherein the optics module includes a first, second and third said lens spaced apart along the optical axis (O) wherein the optics module is configured such that: the first lens converges the laser beam along its width axis and its height axis; the second lens collimates the laser beam along its width axis and its height axis; and the third lens converges the laser beam along its height axis and does not alter the laser beam along its width axis, to produce the second cross-section at the focal plane. Optionally or preferably wherein the optics module includes a first, second and third said lens spaced apart along the optical axis (0) wherein the optics module is configured such that: the first lens diverges the laser beam along its width axis and its height axis; the second lens collimates the laser beam along its width axis and its height axis; and the third lens converges the laser beam along its height axis and does not alter the laser beam along its width axis, to produce the second cross-section at the focal plane. Optionally or preferably wherein the optics module includes a first, second, third, fourth and fifth said lens spaced apart along the optical axis (O) wherein the optics module is configured so that: the first lens converges the laser beam along its width axis; the second lens converges the laser beam along its height axis; the focal point of the second lens is located between the second lens and third lens so that the width of the laser beam is diverging as it reaches the third lens; the third lens collimates the laser beam along its width axis; the fourth lens collimates the laser beam along its height axis; and the fifth lens converges the laser beam along its width axis, to produce the second cross-section at the focal plane. Optionally or preferably wherein the optics module includes one or more asymmetric lenses, optionally or preferably wherein one or more of the first, second, third, fourth and fifth said lenses are asymmetric micro lens arrays. Optionally or preferably wherein the optics module includes one or more cylindrical lenses, optionally or preferably wherein one or more of the first, second, third, fourth and fifth said lenses are cylindrical lenses. Optionally or preferably wherein the optics module includes one or more diffractive optical elements for changing the shape of the laser beam; optionally or preferably wherein one or more of the first, second, third, fourth and fifth said lenses include one or more diffractive optical elements. Optionally or preferably wherein the optics module is releasably connectable to the laser unit. According to another aspect of the present invention we provide a laser device system including: the laser device according to any preceding aspect wherein the optics module includes a first part, optionally or preferably the first part includes one or more of the said lenses, and a second part, optionally or preferably the second part includes one or more of the said lenses, and wherein the second part is releasably connectable to the first part; and a plurality of second parts; wherein the laser device is configured such that the second part can be interchanged with one of the plurality of second parts, wherein each of the plurality of second parts, when connected to the first part causes the optics module to have a different second cross-section, and / or a different focal plane. Optionally or preferably wherein one or more of the plurality of second parts is an elongate shape which is relatively long compared to the first part, optionally or preferably the elongate second part is at least 50cm long. According to another aspect of the present invention we provide a laser device system including: the laser device according to any preceding aspect; and a plurality of said optics modules; wherein the laser device is configured such that the optics module can be interchanged with any one of the plurality of optics modules; wherein each of the plurality of optics modules, when connected to the laser unit, produce one or both of: a different second cross-section, and / or a different focal plane. Optionally or preferably wherein the optics module is directly adjacent the laser unit so that the laser beam travels directly into optics module, during use. Optionally or preferably wherein the laser device and optics module are configured such that the optics module does not move or any of its components do not move during operation of the laser device. Optionally or preferably wherein the laser device includes a housing, including: a first portion for a user to grip the laser device during use; a second portion which extends transversely away from the first portion, wherein the second portion houses or supports the optics module. Optionally or preferably wherein the first portion includes a pistol grip, optionally or preferably the pistol grip includes a trigger for switching the laser unit on. Optionally or preferably wherein the housing contains one or more of: the laser unit; the optics module; and / or a power supply for the laser unit. Optionally or preferably wherein at least a part of the laser device is contained in a handheld part, optionally or preferably the whole of the laser device is handheld. Optionally or preferably wherein the laser unit and optics module are contained within the handheld part. Optionally or preferably wherein the housing includes an elongate part in which the optics module is contained. Optionally or preferably wherein the laser unit includes a fibre laser, optionally or preferably the fibre laser is connected to the handheld part via an optical fibre cable. Optionally or preferably wherein the laser unit includes a direct diode laser to generate the laser beam, optionally or preferably the laser unit includes a plurality of direct diode lasers used in combination to generate the laser beam. Optionally or preferably wherein the laser device is configured to remove an unwanted material from a target object, and wherein the fluence of the laser beam at the focal plane is greater than the ablation threshold of the unwanted material, so that, in use, the laser beam is directed at the unwanted material to remove it from the target object, optionally or preferably the unwanted material is one of a surface oxide or organic contaminant. Optionally or preferably wherein the fluence of the laser beam at the focal plane is less than the ablation threshold of the target object, so that, in use, the laser beam removes the unwanted material from the target object without removing any of the material of the target object. Optionally or preferably wherein the laser unit includes first and second lasers which have different wavelengths, wherein the first and second lasers are selectable by the user to provide laser beams with different properties. Optionally or preferably wherein the laser beam is in the visible portion of the light spectrum, optionally or preferably the laser is one of either: a blue laser having a wavelength of approximately 455nm: or a green laser having a wavelength of approximately 520nm. Optionally or preferably wherein the laser beam has a height axis beam quality factor, M2, of less than 1.3, optionally or preferably less than 1.2, optionally or preferably less than 1.1. Optionally or preferably wherein the laser beam has a power of less than or equal to 100W, optionally or preferably less than or equal to 60W, optionally or preferably less than or equal to 30W. Optionally or preferably wherein the fluence of the laser beam at the focal plane is at least 0.5J / cm2, optionally or preferably the fluence is at least 1 J / cm2. Optionally or preferably wherein the fluence of the laser beam has a maximum value of 5J / cm2, optionally or preferably the maximum fluence is 3J / cm2. Optionally or preferably wherein the laser unit is directly modulated to produce a pulsed output, optionally or preferably the pulses are in the order of nanoseconds. According to another aspect of the present invention we provide a kit of according to any preceding aspect BRIEF DESCRIPTION OF THE FIGURES In order that the present disclosure may be more readily understood, preferable embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1a is a side cross-section view of a laser device embodying one or more aspects of the present disclosure; Figure 1b is an exploded perspective view of the laser device shown in figure 1a; Figure 2 is a schematic side view of the laser device of figure 1a being used on a target object; Figure 3a is a front view of a first cross-section of a laser beam produced by the laser device shown in figure 1a; Figure 3b is a front view of a second cross-section of the laser beam shown in figure 3a; Figure 4 is a front view of a lens of the laser device of figure 1; Figure 5 is a schematic side view of a laser device embodying one or more aspects of the present disclosure; Figure 6 is an image of a sample object having been treated by a laser device embodying one or more aspects of the disclosure; Figures 7a and 7b are side and plan views respectively of certain components of a laser device in a first configuration embodying one or more aspects of the disclosure; Figures 8a and 8b are side and plan views respectively of certain components of a laser device in a second configuration embodying one or more aspects of the disclosure; Figures 9a and 9b are side and plan views respectively of certain components of a laser device in a third configuration embodying one or more aspects of the disclosure; Figures 10a and 10b are side and plan views respectively of certain components of a laser device in a fourth configuration embodying one or more aspects of the disclosure; Figures 11a and 11 b are side and plan views respectively of certain components of a laser device in a fourth configuration embodying one or more aspects of the disclosure; Figure 12 is a schematic side view of a laser device embodying one or more aspects of the disclosure; Figure 13 is a schematic side view of a laser device embodying one or more aspects of the disclosure; and Figure 14 is a schematic side view of a laser device embodying one or more aspects of the disclosure. DETAILED DESCRIPTION OF THE DISCLOSURE With reference to figures 1a to 3b and figures 7a and 7b, a laser device 10 in accordance with embodiments of the present disclosure is shown. The laser device 10 is suitable for treating and / or modifying an object in accordance with embodiments of the present disclosure. The laser device 10 includes a laser unit 12 for producing a laser beam 14, and an optics module 16 having an optical axis (O) connected to the laser unit 12 for receiving the laser beam 14 therethrough and focusing the laser beam 14 onto a focal plane F. The optics module 16 increases the size of the cross-section of the laser beam 14 from a first, incident, cross-section 40 to a second, predetermined, cross-section 42 located at the focal plane F of the optics module 16. The term “incident” in relation to the first cross-section 40 denotes the cross-section of the laser beam 14 at the point it is incident on the optics module 16, e.g. a lens within the optics module 16. In examples, the optics module 16 may include a lens (not shown in figures 1a to 3b) including a width axis perpendicular to the optical axis (O), and a height axis perpendicular to the optical axis (0) and to the width axis. The lens may be configured to refract the laser beam 14 along the width axis and / or the height axis to produce the second cross-section 42 at the focal plane F. The optics module 16 contains asymmetric optics, e.g. one or more lenses, to form the second cross-section 42. The size of each ofthe first 40 and second 42 cross-sections may be defined by the largest dimension of the shape of the cross-section. For example, the major axis of an ellipse. Alternatively, the size may be defined by the area of each cross-section. The focal plane F is defined as a plane that is perpendicular to the optical axis (0) of the laser beam 14 on which the laser beam 14 is focused by the optics module 16. The laser device 10 may be directed at a target object 34 to treat or modify the target object 34. The term “treat” denotes that the laser beam 14 alters a surface of the target object 34. For example, treating may include applying heat to the surface to change properties of the surface 35, remove or ablate the surface, surface oxide(s) at the surface, or peening the surface. By “modify” it is meant to denote that the laser beam 14 removes an unwanted material 36 from the target object 34 which may include, but is not limited to removing dirt, a coating on an object (e.g. a coating such as paint on a substrate), or rust or other surface oxides. In examples, the laser device 10 may be operated in different modes to switch between treating and modifying the target object 34. The parameters of the laser beam may be varied according to the different types of desired treatment or modification of the target object 34, e.g. changing the properties of the laser source producing the laser beam such as power or frequency. Referring to figures 1a and 1b, the laser device 10 includes a handheld part 25. The main components of the laser device 10, e.g. the laser unit 12 and optics module 16 may be contained within the handheld part 25. The handheld part 25 may be connected to a power source by a power cable (not shown) or may be battery powered. The laser device 10 may include a housing 20 which defines an internal space which contains the laser unit 12, optics module 16 and power supply for connection to the power source. The housing 20 may include a first portion 22 for a user to grip the laser device 10 during use, and a second portion 24 connected to an upper end of the first portion 22. The second portion 24 extends transversely away from the upper end of the first portion 22. The second portion 24 is generally cylindrical shaped in this example but may be other shapes in examples, e.g. rectangular cuboid. The second portion 24 may house or support the optics module 16, the laser unit 12 and power supply. The first portion 22 may include a pistol grip 26 and may include a trigger 28 for switching the laser unit 12 on and off. The optics module 16 and laser unit 12 are spaced along a common axis, e.g. a central axis of the second portion 24, with the laser unit 12 being positioned to the rear of the optics module 16 so that the laser beam travels directly from the laser unit 12 to the optics module 16. The optics module 16 includes an enclosure 17 which defines a space in which components, e.g. one or more lenses, of the optics module 16 are enclosed. In this example, the enclosure is generally cylindrical but may be other shapes in examples. The optics module 16 may include an incident face 18, onto which the laser beam 14 is incident, and an exit face 19 from which the laser beam 14 exits the optics module 16. The exit face 19 may include an aperture 21 for the laser beam 14 to exit the optics module 16. The aperture 21 may be an opening in the exit face 19 and may contain a material which is transparent or translucent to the laser beam 14 such as N-BK7 glass (optical borosilicatecrown glass) or fused silica. Typically, the aperture 21 does not have any refractive effect on the laser beam 14. A protective cover 21a including an outlet aperture 21a’ is positioned adjacent the front or distal end of the optics module 16. The outlet aperture 21a’ is aligned to the aperture 21 and has no effect on the shape, size or geometry of the laser beam 14. In this example, the cover 21a is supported or connected at the distal or front end of the housing 20, e.g. at the end of the second part 24 and is generally conical shaped. In examples, there may be no protective cover 21a, and instead the outlet aperture 21a’ is formed directly at the exit face of the optics module 16. The optics module 16 is connected to the laser unit 12. The optics module 16 may be directly adjacent the laser unit 12 so that the laser beam 14 travels directly into the optics module 16, during use. Any standard connection method may be used to connect the optics module 16 to the laser unit 12 including, but not limited to, fasteners, interlocking parts or magnets. The laser unit 12 contains at least one laser, which may be any type of suitable laser. In this example, the laser unit 12 may include an asymmetric laser source, e.g. a direct diode laser, to generate the laser beam 14. The laser unit 12 may include a plurality of direct diode lasers used in combination to generate the laser beam 14. The laser unit 12 may include first and second laser beams which have different wavelengths, e.g. the laser source may be a tunable laser that can be adjusted to change the wavelength to generate the first and second laser beams or separate laser sources to produce the respective laser beams. The first and second laser beams may be selectable by the user to have different properties. The first and second laser beams may be used for different applications. For example, the first laser beam may be used to remove a first unwanted material 36 or treat the surface of the target object 34 in a first manner and the second laser beam may be used to remove a second unwanted material 36 or treat the surface of the target object 34 in a second manner. The laser unit 12 may be directly modulated to produce a pulsed output. This is beneficial as a pulsed output can provide a laser with a higher fluence than an equivalent continuous wave laser. The pulses may be in the order of microseconds or nanoseconds long, which in combination with the fluence values of the laser beam, may be sufficient to remove the unwanted material 36 from the target object 34, or provide the necessary surface treatment. The laser device 10 may be configured to remove the unwanted material 36 from the target object 34. In such configurations, the laser device 10 is configured so that the fluence of the laser beam 14 at the focal plane F is greater than the ablation threshold of the unwanted material 36, so that, in use, when the laser beam 14 is directed at the unwanted material 36, the laser beam 14 removes the material from the target object 34. The unwanted material 36 may be a surface oxide or organic contaminant. For example, the unwanted material may be rust or paint. The fluence of the laser beam 14 at the focal plane may be less than the ablation threshold of the target object 34, so that, in use, the laser beam 14 removes the unwanted material 36 from the target object 34 without removing any of the material of the target object 34, or substrate on which the unwanted material 36 is present. The laser beam 14 has a first fluence at the laser unit 12 and the optics module 16 refracts the laser beam 14 such that the laser beam 14 has a second fluence at the focal plane F. The second fluence may be larger than the first fluence. Referring to figures 7a and 7b, these are respective side and plan schematic drawings showing a laser unit 12 and optics module 16 according to aspects of the present disclosure. In this example, the laser beam 14 is produced by an asymmetric laser source, e.g. a direct diode laser but it need not be in other examples. The laser beam 14 has a slow axis and a fast axis. The slow axis refers to the axis along which the laser beam 14 diverges the least and the fast axis refers to the axis along which the laser beam 14 diverges the most. The optics module 16 includes a lens 61 and has an optical axis (O). The lens 61 is an asymmetric lens in this example, e.g. a cylindrical lens. Referring to figure 4, the lens 61 has a width axis Wd which is perpendicular to the optical axis (O) and a height axis Hd which is perpendicular to optical axis (O) and perpendicular to the width axis Wd. In other words, the optical axis (O) is orthogonal to the lens 61. The height axis Hd and width axis Wd may correspond to the slow axis 14a and the fast axis 14b respectively of the laser beam 14. The lens 61 has a focal point Fp which sets the focal plane F. The first cross-section 40 is the cross-section of the laser beam 14 as incident on the lens 61. In this example, the first cross-section 40 is generally elliptical in shape due to the natural asymmetry of the laser beam 14 produced by the direct diode laser. The first cross-section 40 corresponds to the cross-section shown in figure 3a and has a height Hi, width Wi (also denoted in respective figures 7a, 7b) and a shape Si. The laser beam 14 diverges from the laser unit 12 at an angle 02 (see figure 7b) along the width axis and at an angle 01 along the height axis (see figure 7a). In this example, angle 9i is approximately 30 degrees and angle 02 is approximately 10 degrees. The optics module 16 is configured such that the lens 61 converges the laser beam 14 along its height axis Hd and does not alter the laser beam 14 along its width axis Wd to produce the second cross-section 42 at the focal plane F. The second cross-section 42 has the elongated shaped shown in figure 3b and approximates to a relatively long thin line in comparison to the original cross-section 40 incident on the lens 61, i.e. the size of the cross-section has increased. This makes the laser beam 14 suitable for treating a relatively larger surface area of the target object 34. In this example, the natural asymmetry of the laser beam 14 caused by the direct diode laser provides an advantageously approximate line beam. Use of the laser device 10 will now be described with reference to the laser unit 12 and optics module 16 shown in figures 7a and 7b. Firstly, the user may select the desired properties of the laser device 10 through a control interface (not shown). The properties may include characteristics of the laser beam, e.g. type of laser source, wavelength, power etc., the type of desired operation, e.g. treating an object 34 or modifying the object 34. The user may then grasp the first portion 22 to handle the handheld part 25 and direct the laser device 10 towards the target object 34. The laser device 10 may include a display or other information indicating to the user the distance at which the laser device 10 should be held relative to the target object 34 to treat or modify the object 34 effectively. This distance will correspond to the distance at which the focal plane lies. The user will then place the handheld part 25 accordingly relative to the object 34 and direct the aperture 21a’ to the relative portion of the surface of the target object 34. The user then presses the trigger 28 to cause the laser unit 12 to generate the laser beam 14 and directs the laser beam 14 into the optics module 16. The laser beam 14 has a first crosssection 40 incident on the optics module 16 at the lens 61 which is defined by the laser unit 12, e.g. the geometry of the diode laser. The optics module 16 then acts on the laser beam 14 in the manner described above in relation to figures 7a and 7b such that the size of the laser beam 14 is increased so that the second cross-section 42 at the focal plane F is larger than the first cross-section 40. In particular, the shape of the laser beam 14 at the focal plane F approximates a relatively long and thin line, i.e. a line beam. The laser beam 14 acts on the target object 34 to treat the surface, or modify the surface, e.g. remove material, according to the settings selected by the user. The user may then move the handheld part 25 so that the laser beam 14 sweeps an area of the target object 34 which the user wishes to treat or modify. Due to the laser beam 14 having a relatively larger cross-section where the laser beam 14 is incident on the target object 34, a relatively larger area of the target object 34 can be treated or modified in a convenient way. In examples, the laser device 10 may be arranged so that the outlet aperture 21a’ is positioned at the focal plane F of the optics module 16. As such, the user may place the outlet aperture 21a’ directly adjacent to the surface being treated so that the laser beam has the second pre-determined cross-section 42 positioned at the surface being treated. In this way, the user can reliably know that the laser device 10 is correctly positioned for optimised treatment. In examples, the laser device 10 may have any form of mechanical device, e.g. a fixed length body connected to the device 10 which rests on the surface being treated to space the outlet aperture 21 a’ a pre-determined distance away therefrom, to ensure the laser device 10 is held at the correct distance away from the surface of the target object 34, i.e. that the focal plane F is located at the surface of the target object. In examples, the optics module 16 may include the outlet aperture 21a’ and have no protective cover 21a and in such cases the outlet aperture 21a’ is at the focal plane F and the user simply handles the laser device 10 so that the end of the optics module 16 defining the outlet aperture 21a’ rests on the surface being treated. In this way, the laser beam 14 reaches the surface at the focal plane F of the optics module 16 for optimised treatment The laser device 10 and optics module 16 may be configured such that the optics module 16 does not move or such that any of its components do not move during operation or movement of the laser device 10. The laser device 10 is accordingly more robust and less likely to fail. It also reduces cost, size and weight, as well as avoids the need for thermal management systems that may otherwise be required to remove the heat generated by any moving components / actuators. The laser unit 12 may produce a laser beam 14 that is in the visible portion of the light spectrum. For the purposes of this disclosure, the definition of visible light shall be taken to include light with a wavelength of between 400nm to 700nm . In this example, the laser beam 14 is one of either a blue laser having a wavelength of approximately 455nm or a green laser having a wavelength of approximately 520nm. By way of example, the laser device 10 may be configured to create a laser beam 14, and first / second cross-sections, having the properties set out in Table 1 below Table 1 Inputs Wavelength 445 nm Power 23 W Frequency 1 kHz Height axis Hd beam quality factor, M2 1.1 Height axis Hd beam width (1 / e2) before lens 1 mm Effective focal length of lens 50 mm Truncation factor 1.273 Outputs Pulse energy 23.00 mJ Height axis Hd beam parameter product 0.16 mm mRad Height axis Hd divergence of input (full angle) 0.62 mRad Height axis Hd beam size at focus 31.16 pm Height axis Hd divergence of focussed beam (full angle) 20.00 mRad Height axis Hd Rayleigh range (depth of field) 1.56 mm Target beam properties Target fluence 1 J / cm2 Allowable width 73.81 mm Figure 6 shows a sample which has been modified using a laser device 10. The sample is a sheet of anodised aluminium 33 which has been exposed to a laser beam 14 that has the properties listed above in Table 1 at a test frequency repetition of 1kHz. In this case, the sheet of aluminium 33 is the target object 34 and the surface oxide is the unwanted material 36. The laser beam was tested at different distances from the target object 34 and at different laser powers as set out in the Table 2 below. Table 2 Reference numeral Power (%) Distance to target object 34 (mm) 57a 50 90 57b 75 90 57c 100 90 58c 100 91 59b 75 91 59c 100 93 The test resulted in various levels of the removal of the unwanted material 36. This demonstrates that a laser beam 14 with properties according to the present disclosure is suitable for removing an unwanted material 36 from a target object 34. Various examples embodying aspect(s) of the present disclosure may be employed. In examples, such as that shown in figure 5, the laser unit 12 may be separate from the rest of the laser device 10, e.g. separate from the handheld part 25, and be provided as a separate unit. The laser unit 12 may include the laser source, e.g. cavity laser, and be connected to the handheld part 25 by an optical fibre / fibre cable 49 to provide the laser beam to the optics module 16. In such examples, the laser unit 12 is a fibre laser. An advantage of such systems compared to the prior art is that a focused laser beam cross-section area can be achieved having a certain desired shape, e.g. circular / elliptical I elongate size, without having to use moving parts to move the laser beam, e.g. using galvos, to form a similar shape which would otherwise be required. In examples, various properties of the laser beam 14 may be adopted for use with the laser device 10 according to the desired application of the laser device 10. The laser device 10 may be configured to permit a user to select between the different properties accordingly. The laser beam may have a slow 14a axis beam quality factor, M2, of less than 1.3, optionally or preferably less than 1.2, optionally or preferably less than 1.1. The laser beam 14 may have a power of less than or equal to 100W, optionally or preferably less than or equal to 60W, optionally or preferably less than or equal to 30W. Due to the configurations disclosed herein, the laser device 10 permits the use of lower power laser beams 14 to treat or modify an object than is possible in the prior art which brings advantages which include, but are not limited to, lower power consumption and / or a safer device. In examples, the laser device 10 may be configured such that the fluence of the laser beam 14 at the focal plane F may be at least 0.5J / cm2. In examples, the fluence may be at least 1J / cm2. In examples, the fluence of the laser beam 14 may be selected by the suer, e.g. by changing the power of the laser beam 14 or by changing the final lens. The fluence of the laser beam 14 may have a maximum value of 5J / cm2, optionally or preferably the maximum fluence is 3J / cm2. In examples, the laser unit 12 may produce a laser beam 14 that is in the visible portion of the light spectrum. For the purposes of this disclosure, the definition of visible light shall be taken to include light with a wavelength of between 400nm to 700nm. In this example, the laser beam 14 is one of either a blue laser having a wavelength of approximately 455nm or a green laser having a wavelength of approximately 520nm. Blue or green lasers have a relatively shorter wavelength and therefore a small focus, as well as using relatively lower power when compared with other lasers, such as infrared lasers. This allows the second cross section 42 to be more easily changed from a shape Si to a smaller shape S2, and therefore means an second cross-section 42 which is smaller can be achieved using a relatively lower power laser compared to infrared lasers. The optics module 16 may be configured in various ways without departing from the scope of the present disclosure. For example, the optics module 16 may be configured such that W2is larger than W1. Alternatively, the optics module 16 may be configured such that W2 is equal to W1 and H2 is smaller than Hi Additionally, H2 may be equal to or less than Hi. W1 and Hi may be approximately 1mm. W2 may be approximately 70mm and H2 may be approximately 31pm, The ratio of W2 to H2 may be at least 1000 and may be at least 2000. The optics module 16 may include a plurality of lenses which are spaced apart along the optical axis (0). One or more of the plurality of lenses may refract, e.g. diverge, the laser beam along their respective width axes only. One or more of the plurality of lenses may refract, e.g. converge, the laser beam along their respective height axes only. Furthermore, one or more of the plurality of lenses may refract the laser beam along their width axis and height axes. In examples, one or more lenses of the optics module 16 may be an asymmetric lens. In examples, the laser unit 12 and optics module 16 may be configured such that the first crosssection 40 is a first shape Si and the second cross-section 42 is a second shape S2. In examples, the second shape S2 may be a different shape to the first shape Si. In examples, the second shape S2 may be the same shape as the first shape Si, and only differ in size. The second cross-section 42 may be an elongate shape as shown in figure 3b. In examples, the second cross-section may be an ellipse, a rectangle or a line. Other shapes are possible, depending on the shape produced by the laser unit 12 and the configuration of the optics module 16. In examples, one or more lenses of the optics module 16 may be an asymmetric lens, e.g. asymmetric micro lens arrays or graded index lens. Alternatively, or in addition, the optics module 16 may include one or more cylindrical lenses. In examples, the optics module 16 may include one or more diffractive optical elements for changing the shape of the laser beam 14 and which elements may be part of the lens or lenses of the optics module 16. For example, a diffractive optical element may be used to change the shape of the laser beam 14 from an elliptical shape at the first cross-section 40 to a generally rectangular shape at the second cross-section 42. The one or more diffractive optical elements may be part of a lens of the optics module 16, or they may be a separate part. In general, laser beam fluence is larger in the centre of the laser beam cross-section and gradually reduces to a lower fluence value at the perimeter of the cross-section. The use of a diffractive optical element may allow for a more consistent fluence across a larger portion of the centre of the second cross-section 42 of the laser beam 14 which is advantageous. The optics module 16 may include lenses which are configured in various ways without departing from the scope of the present disclosure. It will be appreciated that these configurations are examples, and other configurations are possible without departing from the scope of the disclosure. For example, the optics module 16 may include a first lens and a second lens spaced apart along the optical axis (O). The first lens may be configured to diverge the laser beam 14 along its width axis Wd and not alter the laser beam 14 along its height axis Hd. The second lens may be configured to converge the laser beam 14 along its height axis Hd and not alter the laser beam 14 along its width axis Wd. Alternatively, the first lens may be configured to converge the laser beam 14 along its height axis Hd and not alter the laser beam 14 along its width axis Wd and the second lens may be configured to diverge the laser beam 14 along its width axis Wd and not alter the laser beam 14 along its height axis Hd. Referring to figures 8a and 8b, these are schematic drawings similar to figures 7a and 7b showing a further example with common features denoted by the same reference numerals. The optics module 16 includes first and second lenses 71, 72 spaced apart along the optical axis (O). Referring to figure 8b, the optics module 16 is configured such that the first lens 71 converges the laser beam 14 along its width axis Wd. The first lens 71 has a focal point Fp located between the first lens 71 and second lens 72 so that the laser beam 14 is diverging as it reaches the second lens 72. In other words, between the first lens 71 and second lens 72, the laser beam 14 converges to the focal point Fp of the first lens 71 and then starts to diverge after the focal point Fp of the first lens 71 so that the cross-section of the laser beam 14 incident on the second lens 72 is larger in the width dimension compared to the first cross-section 40. The second lens 72 collimates the laser beam 14 along its width axis Wd and converges the laser beam 14 along its height axis Hd of the second lens 72 to produce the second cross-section 42 at the focal plane F. First lens 71 is a cylindrical lens and second lens 72 is a positive lens. Collimating the laser beam 14 along the width axis Wd may include an advantage that it allows more control over the size of the width axis Wd of the laser beam 14 Referring to figures 9a and 9b, these are schematic drawings similar to figures 7a and 7b showing a further example with common features denoted by the same reference numerals. The optics module 16 includes first, second and third lenses 81,82, 83 spaced apart along the optical axis (O). The optics module 16 is configured such that the first lens 81 converges the laser beam 14 along its width axis Wd and its height axis Hoto respective focal points Fp between the first lens 81 and second lens 82 such that the width and height of the cross-section of the laser beam 14 incident on the second lens 82 are larger than those of the first cross-section 40. The second lens 82 collimates the laser beam 14 along the width axis Wd and its height axis Hd and the third lens 83 converges the laser beam 14 along its height axis Hd and does not alter the laser beam 14 along its width axis Wd, to produce the second cross-section 42 at the focal plane F. First lens 81 and second lens 82 together form a Keplerian expander. The third lens 83 is a cylindrical focusing lens. This is advantageous as the laser beam 14 is collimated in both the width axis Wd and height axis Hd after travelling through the first lens 81 and second lens 82. This allows the distance between the second lens 82 and third lens 83 to be changed without affecting the cross-section 42 of the laser beam 14 at the focal plane F. Referring to figures 10a and 10b, these are schematic drawings similar to figures 7a and 7b showing a further example with common features denoted by the same reference numerals. The optics module 16 includes first, second and third lenses 91,92, 93 spaced apart along the optical axis (O). The second and third lenses 92, 93 are spaced relatively close together compared to the distance between the first lens 91 and the second lens 92. The optics module 16 is configured such that the first lens 91 diverges the laser beam 14 along its width axis Wd and its height axis Hd such that the cross-section of the laser beam 14 incident on the second lens 92 is larger in both dimensions compared to the first cross-section 40. The second lens 92 collimates the laser beam 14 along its width axis Wd and its height axis Hd and the third lens 93 converges the laser beam 14 along its height axis Hd and does not alter the laser beam 14 along its width axis Wd, to produce the second cross-section 42 at the focal plane F. First lens 91 is a Galilean expander or collimator, second lens 92 is a positive lens and third lens 93 is a cylindrical focusing lens. The use of a Galilean expander or collimator allows for a more compact optics module 16 compared with that of optical configuration 80. Referring to figures 11aand11b, these are schematic drawings similar to figures 7a and 7b showing a further example with common features denoted by the same reference numerals. The optics module 16 includes a first, second, third, fourth and fifth lenses 101, 102, 103, 104, 105 spaced apart along the optical axis (O). The first and second lenses 101, 102 are positioned relatively close together as a pair of lenses, and the third, fourth and fifth lenses 103, 104, 105 are positioned relatively close together to form a group of lenses which are spaced relatively far away from the second lens 102. The optics module 16 is configured so that the first lens 101 converges the laser beam 14 along its width axis Wd without altering the height dimension of the laser beam 14. The second lens 102 converges the laser beam 14 along its height axis Hd and width axis Wd to a focal point Fp which is positioned closer to the second lens 102 than the third lens 103. The laser beam 14 diverges along its width and height so that these dimensions of the cross-section are larger compared to the first cross-section 40. The third lens 103 collimates the laser beam 14 along its width axis Wd of the third lens 103 without altering the height dimension of laser beam 14. The fourth lens 104 collimates the laser beam 14 along its height axis Hd and width axis Wd without altering the height dimension of the laser beam 14. The fifth lens 105 converges the laser beam 14 along its height axis Hd, to produce the second cross-section 42 at the focal plane F without altering the width dimension of the laser beam 14. First lens 101, second lens 102, third lens 103, fourth lens 104 and fifth lens 105 are all cylindrical lenses. This arrangement gives precise control over the cross-section of the laser beam 14 in both the width axis Wd and height axis Hd and produces a collimated beam before the fifth, final, lens 105. This allows the distance between the second lens 102 and third lens 103 to be changed without affecting the cross-section 42 of the laser beam 14 at the focal plane F. Different lens configurations may be better suited to different applications. It is beneficial for the user to be able to use different lens configurations depending on various factors such as the distance to the target object 34, the properties of the unwanted material 36, the shape of the target object 34. Referring to figures 12 to 14, the laser device 10 may be part of a laser device system 108 which includes the laser device 10 as previously described. The laser device system 108 includes a plurality of optics modules 16 which may be interchanged by the user according to the desired application. For example, they may be interchanged to change one or both of the second crosssection and / or focal plane. For example, they may be interchanged to form one or more of the configurations shown in figures 7a to 11b. Referring to figure 12, one or more of the optics modules 16 may configured as a two-part module having a first part 113 and a second part 114. The second part 114 may be releasably connectable to the first part 113. In this example, there may be a plurality of second parts 114 which can be interchanged and connected to the first part 113 to change the second cross-sections and / or focal plane F of the optics module 16. The first part 113 may have a fixed lens arrangement whilst the interchangeable second parts 114 may each have different lens configurations to change the crosssection and / or focal plane of the optics module 16 when connected to the first part 113. For example, in reference to the fifth optical configuration 100 shown in figures 11a and 11b, the second part 114 may contain the third lens 103, fourth lens 104 and fifth lens 105 with the remaining lenses, first lens 101 and second lens 102 in the first part 113. It will be understood that other configurations with a different number and / type of lenses being contained within the releasable part 114 are possible. The first part 113 and the second part 114 may perform different functions within the optics module 16. For example, the first part 113 may diverge the laser beam and the second part 114 may converge the laser beam along the optical axis (0). Alternatively, the first part 113 may converge and the second part 114 may diverge the laser beam 14 along the optical axis (0). Referring to figure 13, the entire optics module 16 may be replaced by another optics module 16 to change the second cross-section and / or focal plane. The different optics modules 16 may have different lens configurations to cause the change in cross-section and / or focal plane. Referring to figure 14, one of the plurality of optics modules 16 thereof may be an elongate shape as shown in figure 14. Alternatively, the optics module 16 may include first and second parts 113, 114 for which the second part 114 is an elongate shape. The elongate shape is relatively long compared to the rest of the laser device 10. It may be at least 50cm long. This may be beneficial for applications of the laser device 10 where the user is standing up and the target object is at a distance away from the user, for example on the floor. One such application is for the removal of weeds, from a patio, for example. Advantageously, as the laser device 10 is handheld and the laser unit 12 and optics module 16 are contained within the housing 20, the laser device 10 is portable and can be used on any target object 34. The laser device 10 does not require any programming and can simply be pointed at a target object 34 and switched on, therefore little or no training is required to use the laser device 10. The user may switch the optics module 16 and / or releasable part 114 to provide a laser beam 14 with different properties, thereby providing a flexible tool for the removal of unwanted material 36. According to an aspect of the present disclosure, there is provided a kit of parts. The kit may include an optics module 16 such as that as described previously. The kit of parts may include an optics module 16 having first and second parts 113, 114 such as that as described previously. When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components. The invention may also broadly consist in the parts, elements, steps, examples and / or features referred to or indicated in the specification individually or collectively in any and all combinations of two or more said parts, elements, steps, examples and / or features. In particular, one or more features in any of the embodiments described herein may be combined with one or more features from any other embodiment(s) described herein. Protection may be sought for any features disclosed in any one or more published documents referenced herein in combination with the present disclosure. Although certain example embodiments of the invention have been described, the scope of the appended claims is not intended to be limited solely to these embodiments. The claims are to be construed literally, purposively, and / or to encompass equivalents.

Claims

1. A laser device including:a laser unit for producing a laser beam;an optics module having an optical axis (O) connected to the laser unit for receiving the laser beam therethrough and focusing the laser beam onto a focal plane;wherein the optics module increases the size of the cross-section of the laser beam from a first, incident, cross-section to a second, pre-determined, crosssection located at the focal plane of the optics module.

2. A laser device according to claim 1 wherein the first cross-section has a width dimension Wi and a height dimension Hi, and the second cross-section has a width dimension W2 and a height dimension H2, andwherein the optics module is configured such that W2 is larger than W1, optionally or preferably H2 is equal to or less than Hi.

3. A laser device according to claim 1 wherein the first cross section has a width dimension W1 and a height dimension H1, and the second cross-section has a width W2 and a height H2, wherein the optics module is configured such that W2 is equal to W1 and H2 is smaller than Hi.

4. A laser device according to claim 2 or 3 wherein the ratio of W2 to H2 is at least 1000, optionally or preferably the ratio is at least 2000.

5. A laser device according to any preceding claim wherein the first cross-section is a first shape and the second cross-section is a second shape; andwherein the second shape is different to the first shape.

6. A laser device according to any preceding claim wherein the second cross-section is an elongate shape, optionally or preferably the elongate shape is one of:an ellipse;a rectangle; or a line.

7. A laser device according to any preceding claim wherein the optics module includes a lens including:a width axis perpendicular to the optical axis (O); anda height axis perpendicular to the optical axis (O) and to the width axis,wherein the lens is configured to refract the laser beam along the width axis and / or the height axis to produce the second cross-section at the focal plane.

8. A laser device according to claim 7 wherein the optics module includes a first said lens and a second said lens spaced apart along the optical axis (O);wherein the first lens is configured to diverge the laser beam along its width axis and not alter the laser beam along its height axis; andwherein the second lens is configured to converge the laser beam along its height axis and not alter the laser beam along its width axis.

9. A laser device according to claim 7 wherein the optics module includes a first said lens and a second said lens spaced apart along the optical axis (O);wherein the first lens is configured to converge the laser beam along its height axis and not alter the laser beam along its width axis; andwherein the second lens is configured to diverge the laser beam along its width axis and not alter the laser beam along its height axis.

10. A laser device according to claim 7 wherein the optics module includes a plurality of lenses, wherein:one or more of the plurality of lenses refract, e.g. diverge, the laser beam along their respective width axes only;one or more of the plurality of lenses refract, e.g. converge, the laser beam along their respective height axes only; and / orone or more of the plurality of lenses refract the laser beam along their width axis and height axes.

11. A laser device according to any preceding claim wherein the optics module includes one or more asymmetric lenses, and / or wherein the optics module includes one or more cylindrical lenses,optionally or preferably wherein one or more of the first, second, third, fourth and fifth said lenses are asymmetric lenses and / or cylindrical lenses.

12. A laser device according to any preceding claim wherein the optics module includes one or more diffractive optical elements for changing the shape of the laser beam; optionally or preferably wherein one or more of the first, second, third, fourth and fifth said lenses include one or more diffractive optical elements.

13. A laser device according to any preceding claim wherein the optics module is releasably connectable to the laser unit.

14. A laser device system including:the laser device of claims 1 to 13 wherein the optics module includes a first part, optionally or preferably the first part includes one or more of the said lenses, and a second part, optionally or preferably the second part includes one or more of the said lenses, and wherein the second part is releasably connectable to the first part; anda plurality of second parts;wherein the laser device is configured such that the second part can be interchanged with one of the plurality of second parts,wherein each of the plurality of second parts, when connected to the first part causes the optics module to have a different second cross-section, and / or a different focal plane.

15. A laser device system according to claim 14 wherein one or more of the plurality of second parts is an elongate shape which is relatively long compared to the first part, optionally or preferably the elongate second part is at least 50cm long.

16. A laser device system including:the laser device of any preceding claim; anda plurality of said optics modules;wherein the laser device is configured such that the optics module can be interchanged with any one of the plurality of optics modules;wherein each of the plurality of optics modules, when connected to the laser unit, produce one or both of:a different second cross-section, and / ora different focal plane.

17. A laser device according to any preceding claim wherein the laser device and optics module are configured such that the optics module does not move or any of its components do not move during operation of the laser device.

18. A laser device according to any preceding claim wherein at least a part of the laser device is contained in a handheld part, optionally or preferably the whole of the laser device is handheld, optionally or preferably the laser unit and optics module are contained within the handheld part.

19. A laser device according to any preceding claim wherein the laser unit includes a direct diode laser to generate the laser beam, optionally or preferably the laser unit includes a plurality of direct diode lasers used in combination to generate the laser beam.

20. A laser device according to any preceding claim wherein the laser device is configured to remove an unwanted material from a target object, andwherein the fluence of the laser beam at the focal plane is greater than the ablation threshold of the unwanted material, so that, in use, the laser beam is directed at the unwanted material to remove it from the target object,optionally or preferably the unwanted material is one of a surface oxide or organic contaminant.

21. A laser device according to claim 20 wherein the fluence of the laser beam at the focal plane is less than the ablation threshold of the target object, so that, in use, the laser beam removes the unwanted material from the target object without removing any of the material of the target object.

22. A laser device according to any preceding claim wherein the laser beam is in the visible portion of the light spectrum, optionally or preferably the laser is one of either:a blue laser having a wavelength of approximately 455nm; ora green laser having a wavelength of approximately 520nm.

23. A laser device according to any preceding claim wherein the laser beam has one or more of the following properties:a height axis beam quality factor, M2, of less than 1.3, optionally or preferably less than 1.2, optionally or preferably less than 1.1;a power of less than or equal to 100W, optionally or preferably less than or equal to 60W, optionally or preferably less than or equal to 30W;a fluence at the focal plane of at least 0.5J / cm2, optionally or preferably the fluence is at least 1J / cm2.

24. A kit of parts including:an optics module for connection to a laser unit and for receiving a laser beam therethrough and focusing the laser beam onto a focal plane;wherein the optics module increases the size of the cross-section of the laser beam from a first, incident, cross-section to a second, pre-determined, crosssection located at the focal plane of the optics module.

25. A kit of parts according to claim 24 wherein the optics module is releasably connectable to the laser unit;wherein the kit of parts includes:a first said optics module;a second said optics module;wherein the second optics module, when connected to the laser unit, produces one or both of:a second cross-section that is different to the second cross-section of the first optics module, when connected to the laser unit, and / or5 has a focal plane that is different to the focal plane of the laser beam of thefirst optics module, when connected to the laser unit.10

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