GB2158262A - Means for aiming a laser beam onto an optic fibre - Google Patents

Abstract

The invention relates to an aiming means (1) for aiming laser beam into an optic fibre (3), said means comprising: an adaptor (5) comprising a light passage (6) and a collimator lens (7), the end of the optic fibre and the lens being stably attached in conjunction with said light passage and the lens focussed on the end of the optic fibre; a frame body (8) likewise comprising a light passage (9) and intended to be stably attached to the laser source for conducting the laser beam into the optic fibre; at least one inclination adjusting member (10); wherein the adaptor (5) is supported by the frame body (8) with the aid of said inclination adjusting means so that the angle of inclination ( alpha , beta ) of the adaptor with reference to the direction of travel of the laser beam, and thus the focus of the lens in relation to the fibre end, is adjustable in two adjusting planes (p1, p2) substantially parallelling the beam. <IMAGE>

Description

SPECIFICATION Means for aiming a laser beam BACKGROUND OF THE INVENTION The invention concerns a means for aiming a laser beam, as defined in the premable part of claim 1.

Light power in the fractional kilowatt range, e.g. of the order of 0.1 to 100 watts can be transmitted by an optic fibre. For such transmision, the laser light is aimed into a fibre having a diameter on the order of 50 jbm, by focussing; focus diameter e.g. 40 clam.

In this case, when the diameter of the optic fibre and the focus of the laser light are approximately equal in order of magnitude, the aiming of the laser light into the optic fibre poses problems.

Accurate laser light collimators are comparatively expensive, yet not so stable in practice.

Inaccurate aiming of the laser light into the fibre, that is focussing the light outside (for instance the light hitting the cemented surface of the fibre) results in formation of cementing agent vapours, crusting of the fibre end, and finally fusing of the fibre end. Maintenance of the fibre gives rise to considerable extra costs, in addition to which the price of the fibre is rather high. In addition to the actual servicing and material costs, destruction of the fibre causes shutdown times in the use of the respective apparatus, e.g. an optic surgery laser, and this in turn entails inconvenience and extra costs.

The object of the present invention is to present a new type of laser beam aiming means by which the laser beam can be reliably and accurately centered and aimed to enter the fibre even if the laser beam should prior to the adjusting steps form a slight angle with the optic axis of the aiming means.

Furthermore, it is an object of the invention to provide a laser beam aiming means which is easier to service and to aim than any means of prior art.

SUMMARY OF THE INVENTION Regarding the features which are characteristic of the invention, reference is made to the claims section.

The invention is based on the fundamental idea that the adaptor to which the end of the optic fibre has been essentially immovably fixed and which comprises a collimating lens focussed on the end of the fibre in a substan tialiy stable manner has been connected to, and is supported by, a particular inclination adjusting member belonging to the frame member so that the angle of inclination, with reference to the direction of travel of the laser beam, of the adaptor with the optic fibre and lens, and therefore the position of the focal point of the lens in relation to the fibre end, is adjustable in two adjustment planes substantially parallell to the beam, the adjustment taking place substantially around the centre of the lens.It is thus understood that the adaptor with fibre end and with the lens focussed on the fibre end has been formed into one unitary, stable unit, whereby the alignment of the lens is adjustable by adjusting the inclination of the adaptor with reference to the direction of travel of the laser beam (before its arrival in the adaptor) with the aid of an inclination adjusting member. When using the means of the invention, the collimator lens and adaptor are adjusted to be in the centre of the laser beam. Alignment on the end of the optic fibre is acomplished with the aid of inclination adjusting members.

The frame body belonging to the means, against which the adaptor is supported with the aid of the inclination adjusting member, may belong to the laser light source as a part thereof. The frame body may thus consist e.g.

of the frame of the laser light source, of a part of the laser tube, of the mirror arm to which the laser light has been conducted from the laser tube, of a part of the mirror arm, etc. It is essential that the frame body is substantially stable in relation to the direction of travel of the laser beam before the entrance of the laser beam in the adaptor.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is described in the following in detail with the aid of embodiment examples, referring to the accompanying drawings, wherein Figure 1 presents schematically the principle design of a laser beam aiming means according to the invention, Figure 2 presents in elevational view another means according to the invention, partly sectioned, Figure 3 presents the means of Fig. 2, viewed in the direction of the arriving laser beam, and Figure 4 presents the connecting of the means of the invention with a certain laser unit.

DETAILED DESCRIPTION OF THE INVEN TION In Fig. 1, the laser beam emitted by the laser source 2 (not depicted in the figure, for simplifying and better illustrating the means) has been conducted through a light passage 9, i.e. an opening in the frame body 8 stably attached to the laser light source, into the light passage 6, that is, onto the collimator lens 7. The adaptor 5 comprises, in addition to the collimator lens 7, an optic fibre 3, on the end 4 of which the lens is stably focussed, i.e., the optic fibre has been substantially fixedly attached to the adaptor (in the figure, the optic fibre has been shown as if it were separate, for the purpose of illustrating the passage and adjusting of the laser beam).

In Fig. 1, the adaptor 5 has been supported against the frame body 8 with the aid of the inclination adjusting members 10, 10,, i.e.

the adjusting screws 11,, 112, so that the adaptor's angle of inclination a, ss with reference to the laser beam's direction of travel 1 is adjustable in two adjusting planes p1, p2 lying parallel to the beam. At the same time, as the said inclination of the adaptor is being adjusted, the focus f of the lens 7 with reference to the fibre end 4 is adjustable in said planes of adjustment p1, p2. These adjustment planes have been indicated in Fig. 1 adjacent to the adaptor by coordinate axes x and y. In the figure, the coordinates X and Y, respectively x and y are perpendicular to each other and to the direction of travel of the beam, 1.When the adaptor 5 is tilted in the plane p2 parallel to the Y axis and the laser beam 1 so that the angle a decreases, the optic fibre 3, stably attached to the adaptor,will turnalong with the adaptor in the same plane p2 into the position indicated with dotted lines 3'.The location of the focus f will then remain substantially stationary and, after the end of the optic fibre has moved upward in the plane p2, the focus can be adjusted to hit the end of the fibre 4, downwards in the same plane p2. When it is desired to adjust the focus in the direction of the x axis to one side, the adaptor 5 has to be tilted in the plane p1, parallell to the X axis so that the angle ss increases or decreases, as the case may be. Adjustment of the adaptor is in this case acomplished with the inclination adjust ing member 10, that is the fixing screw 1 1,.

When the adaptor 5 is being tilted in the planes parallel to the X and/or Y axis, the focus is not completely immovable in actual fact. As the lens 7 turns along with the adaptor substantially about the centre of the lens, the laser beam is displaced, owing to the thickness of the lens, somewhat in the direction in which the adaptor is turning, indicated in the figure with the reference numeral 1'.

This offset is however comparatively minor compared with the displacement of the fibre end and has no significance regarding alignment of the beam. Re-centering the lens and adaptor with reference to the laser beam, after the focus of the laser light has been adjusted to lie on the end of the optic fibre, enables the said offset to be eliminated.

In Fig. 1, the adaptor 5 has been connected to the frame body 8 by the aid of three fixing screws 11,, 112 and 113. Springs 121, 122, 123, for instance helical springs or cup springs, have been inserted in connection with the respective fixing screws.The fixing screws 11,, 112 and 113 have been arranged in a triangle in a plane which is substantially perpendicular to the direction of the beam 1; in the embodiment depicted, the triangle formed by the screws is rectangular, and the screws 111 and 113 located at the end points of the hypothenuse constitute the two inclination adjusting members 10 and 10, of the adaptor in the planes p, and p2 parallel to the axes X and Y respectively. The fixing screw 113 located at the apex of the rectangular triangle has been mounted substantially fixedly and it is not adjusted in connectionwith the laser beam aiming operation.

Figs. 2 and 3 reveal in detail the design of an aiming means according to another embodiment. Components equivalent to the components of the means depicted in Fig. 1 have in Figs. 2 and 3 been indicated with the same reference numerals. In Figs 2 and 3, the flange-like frame body 8 has been connected to the laser source 2 by the fixing screws 21.

The laser beam emitted by the laser source has been conducted through the light passage 9, that is an aperture in the frame body to the adaptor 5 attached to the frame body by the aid of a fixing plate 22 and fixing screws 111, 112 and 113. The adaptor 5 comprises a sleeve-like body part 24 attached by threads 23 to the fixing plate and through which passes a light passage 6. On the end of the body part adjacent to the light source has been mounted, with threads, a tubular seat 25 with the lens 7 fixed on its inside by means of a lock ring 26. On the end of the body part 24 opposite to the seat 25 has been attached a sleeve-like optic fibre fixing frame 27; in which the end of the optic fibre has been centered and fixed with the aid of a fixing ring 28 and a ferrule provided on the end of the fibre, by shoulder attachment 30.

The optic fibre 3 has in this way been stably attached to the fixing frame 27 by the fixing ring 28, this fixing ring being further attached with threads to the body part 24 of the adaptor. The collimator lens 7 has been substantially fixedly attached to the lens seat 25 with the aid of a locking ring 26, said seat being attached bythreads 31 to the adaptor's body part so that the lens can be focussed on the end 4 of the optic fibre 3 by revolving the seat in said threads 31. The sleeve-like aperture of the seat 25 will be placed in register with the laser beam and parallelling it, the lens perpendicular with reference to the laser beam. The end 4 of the optic fibre 3 will likewise assume a position parallel to the laser beam, at focussing distance from the lens 1.

The support of the fixing plate 22 by the frame body 28, and its fixing thereto, have been similarly carried out in the embodiment depicted in Figs. 2 and 3 as was done in Fig.

1, i.e., by three-point attachment with fixing screws 111, 112 and 113. The fixing screws have been placed in the configuration of a right-angled triangle, and the screws on the ends of the hypothenuse constitute the two inclination adjusting members 10, 1 O, of the adaptor. Between the fixing plate 22 and the body part 8 of the adaptor have been interposed cup springs 121, 122, 123 at the points where the fixing screws are located.

In Fig. 4, the optic fibre has been connected to the frame 2 of the laser unit by an aiming means as in Figs. 2 and 3. In this case no separate frame body 8 is included in the aiming means; it is constituted by the frame of the laser unit instead.

The embodiments of the invention are not confined to the embodiment examples presented and the invention may be modified and varied, as will be obvious to a person skilled in the art.

Claims (8)

1. A laser beam aiming means for aiming the laser beam emitted by a laser source into an optic fibre through the end thereof, said means comprising: an adaptor comprising a light passage and a collimator lens, the end of the optic fibre and the lens being stably atached in conjunction with said light passage and the lens focussed on the end of the optic fibre; and a frame body likewise comprising a light passage and intended to be stably attached to the laser source for conducting the laser beam through the light passage of the frame body into the light passage of the adaptor, and further to the lens and, collimated by this lens, into the optic fibre, characterised in that the means comprises at least one inclination adjusting member and that the adaptor is supported by the frame body with the aid of said inclination adjusting means so that the angle of inclination of the adaptor with reference to the direction of travel of the laser beam and thus the focus of the lens in relation to the fibre end, is adjustable in at least one adjusting plane substantially parallel to the beam.

2. Means according to claim 1, characterised in that the means comprises two inclination adjusting members, that the adaptor is supported by and adjusted with reference to the frame body in two planes substantially parallel to the beam with the aid of said adjusting elements.

3. Means according to claim 2, characterised in that the adjusting planes are perpendicular against each other.

4. Means according to claim 2, characterised in that the adaptor is attached to the frame body by the aid of three fixing screws, that between the adaptor and the frame body has been interposed at least one spring, and that at least two of the fixing screws are adjustable so that the adaptor is tiltable with reference to the fixing frame in two adjusting planes substantially parallel to the beam.

5. Means according to claim 4 characterised in that the fixing screws have been arranged in triangular configuration in a plane which is substantially perpendicular to the direction of the beam.

6. Means according to claim 4, characterised in that the fixing screws have been arranged in the configuration of a right-angled triangle in a plane which is substantially perpendicular to the direction of the beam and that the screws located in the ends of the hypotenuse constitute two inclination adjusting members.

7. Means according to claim 4, characterised in that the lens has been disposed in the adaptor so that the adjustment of the adaptor and the lens takes place substantially around the centre of the lens, i.e. the centre of the lens is substantially stationary throughout the adjustment.

8. An apparatus for adjusting the aim of a laser beam substantially as hereinbefore described in Figs. 1 to 4.