GB2033649A - Laser device - Google Patents

Abstract

A laser beam produced by a light source 13 is conducted by a light conductor 11 to an irradiation point for use in a surgical operation or the cutting, drilling or welding of a material, for example. The conductor 11 comprises a section 14 formed by two telescopically engaged tubular parts 14a, 14b which can be expanded and contracted, a bend section 15 including a mirror M which reflects the laser beam through a predetermined angle, a flexible section 18 whose internal surface is reflective, and a beam focussing section 12. The expandability and contractability of the section 14 combined with the flexibility of the section 18 give the device good manoeuverability, which can be further improved by making a flange connection 16 between the sections 14 and 15 and/or a flange connection 17 between the sections 15 and 18 rotatable to enable swivelling movement to be effected between those sections. <IMAGE>

Description

SPECIFICATION Laser device This invention relates to a laser device such as may used to perform surgical operations on the human body and cutting, drilling and welding of metal, cloth or synthetic resin using high power laser beams, for example.

Avariety of laser devices using high power laser beams have been proposed an put to practical use.

With such laser devices, it is necessary to apply the laser beam at a particular desired point (henceforth referred to as the "irradiation point"), such as on a material under manufacture, and accordingly it is necessary to transmit the laser beam through a flexible light conducterto the irradiation point. The light conductor must have a low laser beam transmission loss, preferably less than 1 dB/m, and the transmission loss must not be greatly affected by temperature and humidity. Moreover, the light conductor must have excellent manoeuverability, high durability and excellent safety properties.

Figure 1 of the accompanying drawings shows a so-called multi-articulation mirror type of light con ductorwhich has hitherto been employed. Such a conductor comprises a pipe 1 having a plurality of bend sections each of which contains a mirror 2 to reflect the laser beam from a light source 3 through a predetermined angle. At its end remote from the light source 3, the light conductor terminates in a beam focussing section 4 which includes a lens 5 for focussing the laser beam at the irradiation point.

Various sections of the pipe 1 are joined together by means of stationary (fixed) flange connections 6 and by rotary flange connections 7, the latter permitting articulation of the conductor as a whole.

The operation and manipulation of such a laser device is rather difficult, however, because movement of the focussing section 4 from which the laser beam is emitted to a desired position or in a desired direction must be effected through an intricate articulation mechanism utilizing rotation of a number of rotary flange connections 7. Moreover in order that the focussing section 4 can be moved readily in three-dimensional space, it is necessary to provide at least five articulated joints which in turn requires at least five bend sections and mirrors 2. The transmission loss resulting from the reflection of the laser beams by such a large number of mirrors is great, which is one of the drawbacks of this type of conventional laser device.

Furthermore, the tolerance which can be permitted in angular variations of the mirrors 2 from their set positions is quite severe, being of the order of minutes to seconds. Any slight vibration or impact imparted to a portion of the pipe 1 or the flange connections 6 or 7 will cause a bending stress which deflects the mirrors beyond their permitted angular tolerances, as a result of which the laser beam will not be entirely transmitted through the light conductor. Hence, the transmission loss is greatly increased resulting in a decrease in the energy density of the beam emitted from the focussing section 4, and it therefore becomes difficult to cut a desired material, for instance. In addition, the laser beam may strike the walls of the pipe 1 and heat the latter, thereby lowering the safety of the laser device.

As is clear from the above description conventional laser devices which utilize a multi-articulation mirror system are disadvantageous in the following respects. It is difficult to apply the laser beam to a desired point on a material, and especially it is difficult to move the light conductor in a desired direction at high speed because of the Irge number of articulated joints: therefore the manoeuverability of the device is relatively low. Since the laser beam is reflected many times by the mirrors, the transmission loss is relatively high. The optical axis of the device is susceptible to deformation thereby lowering the safety of the device. In addition, whenever the installation position of the device is moved, it is necessary to perform fine adjustments to ensure proper alignment of the optical axis, which procedure may typically take half a day.

It is an object of the present invention to obviate or mitigate the above-described problems and disadvantages.

Accordingly,the present invention provides a laser device acomprising a laser light source and light conducting means arranged to conduct a laser beam from the light source to an irradiation point, the light conducting means being composed of at least one light-transmitting section which is linearly expandable in the direction of travel of the laser beam therethrough a hollow light-transmitting section which is disposed at an end of the light conducting means remote from the light source and whose internal surface is reflective to said laser beam, the extendable and hollow sections being arranged in succession along the light conducting means with each pair of successive sections being interconnected by a light-transmitting bend section arranged to deflect the laser beam through a predetermined angle.

In a preferred arrangement, the laser device comprises a laser light source and light conducting means arranged to conduct a laser beam from the light source to an irradiation point, the light conducting means being composed of a light-transmitting section which is linearly extendable in the direction of travel of the laser beam therethrough and which has one end thereof disposed adjacent the light source, a light-transmitting bend section having one end thereof connected to an end of the expandable section remote from the light source and arranged to deflect the laser beam through a predetermined angle, a light-transmitting flexible section having one end thereof connected to an end of the bend section remote from the extendable section, the flexible section being hollow and having an internal surface which is reflective to the laser beam, and a beam focussing section connected to an end of the flexible section remote from the bend section and arranged to focus the laser beam on said irradiation point.

Desirably, the extendable section comprises a pair of tubular parts which are telescopically engaged, the internal surfaces of these parts preferably being reflective to the laser beam.

Conveniently, each pair of adjacent sections are joined together by means of flanges on their adjacent ends. The connection between the extendable section and the bend section and/orthe connection between the bend section and the flexible section can be so arranged as to permit swivelling movement between those sections.

An embodiment of the present invention will now be described, by way of example, with reference to the remainder of the accompanying drawings, in which: Figure 2 is a schematic sectional view of a laser device according to the present invention; and Figure 3 is an enlargement of part of Figure 2.

The laser device illustrated in Figure 2 and 3 comprises a light source 13 which emits a laser beam and a light conductor 11 which conducts the laser beam from the source 13 to an irradiation point. The source 13 is, for example, a C02 laser or a YAG laser.

The light conductor 11 comprises an expandable section 14 having one end thereof disposed adjacent the source 13, a bend section 15 which is joined to an end of the expandable section 14 remote from the source 13 by means of a flange connection 16, a flexible section 18 which is joined to an end of the bend section 15 remote from the expandable section 14 by means of a flange connection 17, and a beam focussing section 12 which is connected to an end of the flexible section 18 remote from the bend section 15. The expandable section 14 is in the form of an insertion-type extendable hollowwareguide and is composed of two tubular parts 14a and 146 which are telescopically engaged, thereby permitting the section 14 to be expanded and contracted in the direction of travel of the laser beam therethrough.

The parts 14a and 14b can be rigid or flexible. The internal surfaces of the tubular parts 14a and 14b have a coating ill of a material which is reflective to the laser beam, for example gold or silver. The coating 1 1r is applied by any suitable technique, such as by plating or vacuum evaporation.

The bend section 15 is arranged to deflect the laser beam through a predetermined angle, and to this end is provided with a plane reflection plate M (Figure 3) at its bend. The section 15 is in the general form of a pipe bent at a suitable angle and having flanges at its ends, and its internal surface has a reflective coating 1 1r similar to that on the internal surfaces of the parts 14a and 14b. Each of the flange connections 16 and 17 by means of which the section 15 is respectively joined to the sections 14 and 18 can be either fixed (stationary) or rotary.

The flexible section 18 is in the form of a pipe made of, for example, organic macromolecular resin and has a reflective coating 1 lron its internal surface similar to the reflective coatings on the sections 14 and 15. The beam focussing section 12 is joined to the flexible section 18 by means of a flange connection, and is constructed as a hollow body whose interior is of frustoconical shape or which otherwise tapers inwardly away from the section 18 such that the internal diameter at its output end is less than the internal diameter at its input end, the latter being substantially equal to the internal dia meter of the remainder of the light conductor 11. TheliThe internal surface of the section 12 also has a reflective coating which is similar to that applied to the sections 14, 15 and 18.A lens 12a is provided at a selected position in the section 12 for focussing the laser beam as a spot onto, for example, a material under manufacture (not shown).

As described above, the section 14 can be expanded and contracted by sliding the parts 14a and 14b relative to one another. This enables the beam focussing section 12 to be readily moved linearly in a predetermined plane, giving the laser device a much improved manoeuverability as compared with conventional devices employing a multi-articulation system. If the flexible section 18 is joined to the bend section 15 by way of a rotary flange connection, the beam focussing section 12 can then readily be moved in three-dimensional space. In such a case, the laser beam is reflected only once (i.e. by the bend section 15) giving a reduced transmission loss compared with conventional laser devices which are movable in three-dimensional space.

It is of course possible to increase the range of operation of the laser device by making it extendable in three different directions. In this case, the light conductor would comprise three extendable sections connected in series with each successive pair interconnected by a bend section, and a flexible section joined to the final extendable section through a further bend section. The maximum number of bend sections in such a device would be four, as compared with more than five bends in a multi-articulation type of device. Since the number of bends (and thus reflections) is reduced, the transmission loss is less than that of conventional laser devices employing a multi-articulation system.

Furthermore, the range of movement of the laser device of the present invention can be further increased by mounting the part in which the light conductor is incorporated on a rotatable or extendable support.

As described above, the internal surface of the light conductor 11 has a coating which is reflective to the laser beam. Therefore even when the optical axis of the light conductor is deflected by the bend section or sections, almost all of the laser beam is transmitted to the beam focussing section. In Figure 2 one example of such a laser beam propagation path is shown. Even if a bending stress is exerted on a portion of the flexible section 18, the lightconductor 11 will still transmit the laser beam emitted by the source 13 to the irradiation point through substan- tially complete reflection, so that an increase in transmission loss is prevented. Accordingly, the laser device of the present invention can fully utilize the merits of a manupuiator-type light conductor, i.e.

the beam focussing section 12 can be moved to a desired position in three-dimensional space which is defined by the dimensions of the extendible section 14, the bend section 15 and the flexible section 18 irrespective of the deflection of the optical axis.

Accordingly, high speed operation of the laser device is attained, and even if its installation position is changed it is unnecessary to affect fine adjustment of the optical axis.

The laser beam transmitted through the light conductor 11 is focussed by the lens 12a and thereby forms a spot outside the beam focussing section 12.

As described previously, the beam focussing section 12 has a reflective coating on its internal surface, and therefore the laser beam is not absorbed thereby to a great extent: accordingly, the beam focussing section 12 is not excessively heated. Moreover, the spot into which the laser beam is focussed is sharp.

In the case where the material of the reflective coating ill on the internal surfaces of the extendable section 14, the bend section 15, the flexible section 18 and the beam focussing section 12 is gold or solver of high purity and the laser beam is in the infrared region of the spectrum, about 99% of the laser beam energy will be reflected.

As is apparent from the above description, a laser beam is transmitted through a light conductor which comprises a series connection of at least one expandable section, at least one bend section and a flexible section, each pair of successive sections being joined by means of a stationary or a rotary flange connection. Accordingly, the amount of transmission of laser beam and the safety of laser beam transmission are maintained satisfactorily. Moreover, the laser device can be operated at a high speed as desired, and adjustment of the optical axis of the light conductor is unnecessary. In addition, the effort required for changing the installation position of the laser device is considerably simplified as compared with conventional laser devices.

Claims (15)

1. A laser device comprising a laser light source and light conducting means arranged to conduct a laser beam from the light source to an irradiation point, the light conducting means being composed of at least one light-transmitting section which is linearly expandable in the direction of travel of the laser beam therethrough and a hollow lighttransmitting section which is disposed at an end of the light conducting means remote from the light source and whose internal surface is reflective to said laser beam, the extendable and hollow sections being arranged in succession along the light conducting means with each pair of successive sections being interconnected by a light-transmitting bend section arranged to deflect the laser beam through a predetermined angle.

2. A laser device as claimed in claim 1, wherein at least some of the connections between the or each bend section and the adjacent extendable or hollow sections are such as to permit swivelling movement therebetween.

3. A laser device as claimed in claim 1 or 2, wherein adjacent sections are connected together by means of respective flanges thereon.

4. A laser device as claimed in claim 1,2 or 3 wherein the or each extendable section comprises a pair of tubular parts which are telescopically engaged.

5. A laser device as claimed in any preceding claim, wherein the or each extendable section is hollow and its internal surface is reflective to the laser beam.

6. A laser device as claimed in any preceding claim, further comprising a beam focussing section at an end of the hollow section remote from the adjacent bend section for focussing the laser beam on said irradiation point.

7. A laser device as claimed in claim 6, wherein the focussing section tapers inwardly away from the hollow section.

8. A laser device as claimed in any preceding claim, wherein the hollow section is flexible.

9. A laser device comprising a laser light source and a light conducting means arranged to conduct a laser beam from the light source to an irradiation point, the light conducting means being composed of a light-transmitting section which is linearly extendable in the direction of travel of the laser beam therethrough and which has one end thereof disposed adjacent the light source, a lighttransmitting bend section having one end thereof connected to an end of the extendable section remote from the light source and arranged to deflect the laser beam through a predetermined angle, a light-transmitting flexible section having one end thereof connected to an end of the bend section remote from the extendable section, the flexible section being hollow and having an internal surface which is reflective to the laser beam, and a beam focussing section connected to an end of the flexible section remote from the bend section and arranged to focus the laser beam on said irradiation point.

10. A laser device as claimed in claim 9, wherein the extendable section comprises a pair of tubular parts which are telescopically engaged.

11. A laser device as claimed in claim 10, wherein the internal surfaces of the tubular parts are reflective to the laser beam.

12. A laser device as claimed in claim 9, 10 or 11, wherein each pair of adjacent sections are joined together by means of flanges on their adjacent ends.

13. A laser device as claimed in any one of claims 9 to 12, wherein the connection between the extendable section and the bend section and/or the connection between the bend section and the flexible section permits swivellng movement between said sections.

14. A laser-type manufacturing device having a light source and a light conducting path adapted to transmit a laser beam from the light source to an irradiation point, the light conducting path comprising a first portion having an internal surface which is reflecting to the laser beam, a second portion in the form of an insertion-type hollow waveguide which can be extended and retracted, a mirror bend, and juncture flanges operatively coupled upon both sides of the mirror bend.

15. A laser device substantially as hereinbefore described with reference to Figures 2 and 3 of the accompanying drawings.