GB2102147A

GB2102147A - Blocking laser beam for safety

Info

Publication number: GB2102147A
Application number: GB08217398A
Authority: GB
Inventors: Jack Armstrong
Original assignee: ROBERTS AND ARMSTRONG
Current assignee: ROBERTS AND ARMSTRONG
Priority date: 1981-06-16
Filing date: 1982-06-16
Publication date: 1983-01-26
Also published as: GB2102147B

Abstract

Apparatus for examination of the cut end of an optical fibre with a laser beam comprises a casing, enclosing the beam generator, specimen holder and screen, which has an access aperture (11) for the specimen holder e.g. on the top (2) and side (3) walls of the casing closable by an optionally L- shaped cover (12). A hinged flap (15) may include two arms (17) and (18). When the cover is open the arm (17) blocks the beam as a safety measure. As the cover is closed it engages the arm (18) rotating the flap to move the arm (17) clear of the beam. <IMAGE>

Description

SPECIFICATION Apparatus employing laser beams This invention relates to apparatus in which a laser beam is directed onto a specimen for examination or treatment of the specimen.

To ensure safety in operation it is important that the beam emission is interrupted while a specimen is inserted in or removed from the apparatus, and it is desirable that such interruption should take place automatically so that there is no danger that the operator will inadvertently be abie to obtain access to the specimen while the beam is directed on to it.

According to the invention, apparatus for directing a laser beam onto a specimen includes casing which surrounds a support or holder for the specimen, an access aperture within a wall of the casing and a cover member normally closing the aperture and which, when moved to open the aperture, introduces a barrier to interrupt the beam between the source and the specimen.

Exemplary of the apparatus to which the invention relates is apparatus for examining the break angle at the tip or end of an optical fibre. In such apparatus, a specimen optical fibre is supported in a V-block mounted on a rotatable carrier, and a laser beam is directed into the end face of the fibre from which it is reflected onto a screen. The movement of the image of the reflected beam thrown onto the screen as the specimen is rotated gives a measurement of the break angle of the optical fibre.

For a clearer understanding of the invention, an embodiment thereof applied to such an apparatus will now be described with reference to the accompanying drawings.

In the drawings, Figure 1 shows a plan view of apparatus according to invention, Figure 2 shows a side elevation of a part of the apparatus on an enlarged scale, Figure 3 is a diagrammatic elevation of the specimen holder, and Figures 4, 5 and 6 show end views of modified forms of the holder.

The apparatus shown in Figs 1 and 2 comprises a generally rectangular casing 1 having a top wall 2 and a side wall 3 and enclosing a laser generator 4 which produces a laser beam 5. The beam is rotated through 900 and focussed by a prism/lens element 6 on to the tip of an optical fibre specimen 7 which is mounted in 9 rotatable holder 8. From the specimen tip the beam is reflected onto a viewing screen 9 in an end wall 10 of the casing. As the specimen is rotated about its axis, any error in the angle of cut of the fibre tip causes a movement of the beam image seen on the screen.

In order to provide access to the holder for insertion and removal of a specimen, an aperture 11 is provided in the top and side walls which is closed during operation of the beam by an Lshaped cover member 12 which is hinged along one edge 13 to the top wall. The edge of the cover remote from the hinge has a flange 14 by means of which it can be raised or lowered.

Associated with the cover is a cranked flap 1 5 mounted on a hinge 1 6 beneath the top wall.

When the cover is open one arm 1 7 of the flap lies in the path of the beam and the other arm 18 includes a portion 1 9 which projects through the part of the aperture in the top wall and at an acute angle slightly less than 900 to the top wall. Thus with the cover open the beam is blocked by the arm 17 and the operator can safely insert or remove a specimen. When the cover is closed its underside engages the portion 19 so swinging the flap about its pivot and moves the arm 1 7 clear of the beam.

The specimen holder, as shown in Figure 3 and 4, comprises a rigid rotatable shaft 20 mounted on bearings 21 and 22 so that the shaft end 23 overhangs the bearing 21. A quadrant section portion is cut away from the overhanging part 23 of the shaft to provide a V-groove 24 (Figure 4) having faces mutually at an angle of 600C and intersecting so that a fibre lies parallel to the shaft axis. Since the shaft forms a one piece holder for the specimen, the specimen is supported more rigidly than is the case with known holders formed by blocks which are movable and detachably securable by bolts or other means to a rotatable support device.

In the alternative constructions shown.in Figures 5 and 6, respectively, the V-groove is formed in a rigid block 25 welded to the end of the shaft 20 or by flat plates 26 arranged at angles to each other and also welded to the shaft end.

The shaft has a knurled knob at its other end by means of which it can be manually rotated.

1. Apparatus for directing a laser beam onto a specimen including a casing which surrounds a holder for the specimen, an access aperture in a part of the casing, and a cover member normally closing the casing aperture and which, when moved to open the aperture, introduces a barrier to interrupt the beam between the source and the specimen.

2. Apparatus according to claim 1 wherein the barrier is formed by a hinged cranked flap having two arms one of which projects through the aperture when the cover is opened and the other intercepts the beam path, the flap being rotated about its hinge by engagement of the said one arm with the cover as the cover is closed so as to withdraw the said other arm from the beam path.

3. Apparatus according to claim 1 or 2 wherein the aperture extends through adjacent parts of a top wall and side wall of the casing, and the cover is an L-shaped member hinged to the top wall.

4. Apparatus according to any of claims 1-3 wherein the specimen holder comprises a Vshaped support arranged at one end of a rotatable shaft so that a cylindrical specimen within the angle of the V lies parallel to the shaft axis.

5. Apparatus according to claim 4 wherein the V-shaped support is a block at the end of the

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Apparatus employing laser beams This invention relates to apparatus in which a laser beam is directed onto a specimen for examination or treatment of the specimen. To ensure safety in operation it is important that the beam emission is interrupted while a specimen is inserted in or removed from the apparatus, and it is desirable that such interruption should take place automatically so that there is no danger that the operator will inadvertently be abie to obtain access to the specimen while the beam is directed on to it. According to the invention, apparatus for directing a laser beam onto a specimen includes casing which surrounds a support or holder for the specimen, an access aperture within a wall of the casing and a cover member normally closing the aperture and which, when moved to open the aperture, introduces a barrier to interrupt the beam between the source and the specimen. Exemplary of the apparatus to which the invention relates is apparatus for examining the break angle at the tip or end of an optical fibre. In such apparatus, a specimen optical fibre is supported in a V-block mounted on a rotatable carrier, and a laser beam is directed into the end face of the fibre from which it is reflected onto a screen. The movement of the image of the reflected beam thrown onto the screen as the specimen is rotated gives a measurement of the break angle of the optical fibre. For a clearer understanding of the invention, an embodiment thereof applied to such an apparatus will now be described with reference to the accompanying drawings. In the drawings, Figure 1 shows a plan view of apparatus according to invention, Figure 2 shows a side elevation of a part of the apparatus on an enlarged scale, Figure 3 is a diagrammatic elevation of the specimen holder, and Figures 4, 5 and 6 show end views of modified forms of the holder. The apparatus shown in Figs 1 and 2 comprises a generally rectangular casing 1 having a top wall 2 and a side wall 3 and enclosing a laser generator 4 which produces a laser beam 5. The beam is rotated through 900 and focussed by a prism/lens element 6 on to the tip of an optical fibre specimen 7 which is mounted in 9 rotatable holder 8. From the specimen tip the beam is reflected onto a viewing screen 9 in an end wall 10 of the casing. As the specimen is rotated about its axis, any error in the angle of cut of the fibre tip causes a movement of the beam image seen on the screen. In order to provide access to the holder for insertion and removal of a specimen, an aperture 11 is provided in the top and side walls which is closed during operation of the beam by an Lshaped cover member 12 which is hinged along one edge 13 to the top wall. The edge of the cover remote from the hinge has a flange 14 by means of which it can be raised or lowered. Associated with the cover is a cranked flap 1 5 mounted on a hinge 1 6 beneath the top wall. When the cover is open one arm 1 7 of the flap lies in the path of the beam and the other arm 18 includes a portion 1 9 which projects through the part of the aperture in the top wall and at an acute angle slightly less than 900 to the top wall. Thus with the cover open the beam is blocked by the arm 17 and the operator can safely insert or remove a specimen. When the cover is closed its underside engages the portion 19 so swinging the flap about its pivot and moves the arm 1 7 clear of the beam. The specimen holder, as shown in Figure 3 and 4, comprises a rigid rotatable shaft 20 mounted on bearings 21 and 22 so that the shaft end 23 overhangs the bearing 21. A quadrant section portion is cut away from the overhanging part 23 of the shaft to provide a V-groove 24 (Figure 4) having faces mutually at an angle of 600C and intersecting so that a fibre lies parallel to the shaft axis. Since the shaft forms a one piece holder for the specimen, the specimen is supported more rigidly than is the case with known holders formed by blocks which are movable and detachably securable by bolts or other means to a rotatable support device. In the alternative constructions shown.in Figures 5 and 6, respectively, the V-groove is formed in a rigid block 25 welded to the end of the shaft 20 or by flat plates 26 arranged at angles to each other and also welded to the shaft end. The shaft has a knurled knob at its other end by means of which it can be manually rotated. CLAIMS

5. Apparatus according to claim 4 wherein the V-shaped support is a block at the end of the shaft.

6. Apparatus according to claim 5 wherein the block is formed by cutting away a portion of the shaft end.

7. Apparatus for directing a laser beam onto a specimen comprising a casing housing a laser generator to project a laser beam onto a screen in one wall of the casing, a holder for supporting a rod-shaped specimen with one end thereof in the beam path, and an aperture in the casing for providing access to the holder for insertion or removal of a specimen with a cover member wherein the holder comprises a V-shaped support to receive the specimen rigidly arranged at one end of a rotatable shaft so that the specimen is parallel to the shaft axis.

8. Apparatus for directing a laser beam onto a specimen constructed and arranged substantially as hereinbefore described and shown in the accompanying drawings.