GB2186970A

GB2186970A - Safety system for iaser-utilising facility

Info

Publication number: GB2186970A
Application number: GB08604530A
Authority: GB
Inventors: Stanley Alfred Edwards; Arthur Frederick David Taylor
Original assignee: UK Atomic Energy Authority
Current assignee: UK Atomic Energy Authority
Priority date: 1986-02-24
Filing date: 1986-02-24
Publication date: 1987-08-26
Also published as: GB8604530D0; GB2186970B

Abstract

A laser beam-utilising facility is provided within a screening arrangement (22) which is opaque to infrared radiation but may be transparent to visible light. The screening arrangement is externally monitored by an infra-red sensor (18) which may be of a fixed or scanning type. In the event of an errant laser beam impinging on the screening arrangement, the hot spot that develops is detected by the sensor and appropriate remedial action is initiated. The screening arrangement (22) may be movable between an operative position and an inoperative position to facilitate access to the working area, such movement being coordinated with the laser so that the beam is disabled e.g. by isolator 14 when the arrangement is moved to the inoperative position. The screening arrangement may be in the form of a flexible curtain(s) or to be rigid. Suitable materials are sheet steel or polycarbonate-based plastics. <IMAGE>

Description

SPECIFICATION Safety system for laser-utilising facility This invention relates to a safety system for a laser-utilising facility.

For reasons of safety, standards and codes of practice have been adopted which require that multi Kilowatt lasers are operated only within enclosures which effectively safeguard personnel and equipment outside the designated operating area from the potential hazards of errant laser beams, which could occurunderpossible accident conditions.

During the past decade, this safety requirement has been met by providing a workstation enclosure having a specific structural burn through resistance relative to the power rating ofthe laser concerned.

This approach has proved adequate forthe relatively modest number and type of installations provisioned to date. However, when considered against the presenttrends of increasing industrial utilisation and the development and application of CW lasers rated up to powers of at least 20kW, the pressing requirementfora less expensive and more effective safety system has become increasingly evident.

Our prior Patent Application No 8602224 discloses a safety system intended to fulfill this need, the disclosed safety system being based on the use of infra red thermography implemented by means of an infra red-sensitive scanning unit for rapidly detecting the thermal energy radiated by any hot spot resulting from an errant laser beam impinging on inner surfaces of an enclosure, such as a room, in which the laser-utilising facility is installed. Forfurther details, Patent Application No 8602224 (the entire disclosure ofwhich is incorporated herein by reference) should be consulted.

The present invention is concerned with a further refinement of the invention disclosed in the prior Patent Application.

According to the present invention there is provided a safety system for a laser-utilising facility comprising screening means for location adjacent the laser working area to screen at least part of the environment from errant laser beams arising from the working area, the screening means being substantially opaque to infra red radiation, and infra red sensor means for externaily monitoring the screening means to detect the development of hot spots on the screening means.

The infra red sensor means may be constituted by at least onefixed infra red detector arranged so that at least the vulnerable area(s) ofthe screening means are within the field of view "seen" bythe detector(s).

Preferably however the sensor means forms part of a scanning arrangement such that field of view seen by the infra red sensitive detector is scanned overthe screening means, eg in a cyclicfashion. Where the sensor means forms part of a scanning arrangement, the latter may be constructed and arranged to operate in the manner disclosed in said prior PatentApplication.

The screening means of the present invention may be supplemental to the safety system disclosed in the prior Patent Application, ie as disclosed in the prior Application, the laser-utilising facility may be accommodated within an enclosure whose internal surfacesaremonitored byascanning arrangement, and the screening means may by located within the enclosure adjacent the laser working area to provide additional safeguards against the possibility of an errant laser beam. Thus, for example, by monitoring the screening means externally (ie monitoring those surfaces of the screening means which are external with respect to the laser working area), the existence of an errant laser beam may be detected before it burns through, and penetrates beyond, the screening means.

The sensor means associated with the screening means may be separate from the scanning arrange mentformonitoring the internal surfaces of the main enclosure or, if desired, the latter scanning arrangement may be arranged to execute a scan which encompasses the screening means as well as the main enclosure and, in this event, the screening means may be configured to facilitate external monitoring thereof by the scanning arrangement, eg the screening means may have sloping wallsto aid scanning if the scanning arrangement is mounted at ceiling level within the main enclosure.

The screening means will substantially opaque to infra red radiation but may, at least in part, be substantially transparent to visible light so that the laserworking area is open to inspection.

In general, the screening means will be of a disposable nature in the sense of having a relatively short specific burn-through time, the objective being primarily to afford early detection of an errant laser beam ratherthan attempt two contain itforany significant length oftime.

The screening means may be of substantially rigid construction or may alternatively be flexible and in the nature of,forexample, a hanging curtain or curtains which may be drawn around the laser working area prior to laser operation being initiated.

In some circumstances, the screening means may be arranged to operate in the manner of a conventional machine guard. For example, the screening means may be movable between an inoperative position to allow access to the laserworking area (but only while the laser beam is shut-off) and an operative position when the laser beam is present at the laser working area. Operation ofthe laser-utilising equipment and the screening means may be co-ordinated in such a way that the laser beam may only be made available within the working area when the screening means is in the operative position, ie in which the screening means to intercept any potential errant beams that mayarisefromtheworking area.

As disclosed in said prior Application, the sensor means associated with the screening means may be arranged to trigger laser-operation modifying means for shutting offthe laser beam from the working area, eg by way of a shutter device orthe like.

To aid further understanding of the invention, one embodiment ofthe invention will now be described by way of example only with reference to the accompanying drawing, the sole Figure of which is a schematic view of a laser-utilising facility within a safety enclosure.

As shown, a laser-working area 10 is provided with a laser beam via a flighttube system 12 connected to a laser source (not shown) and including a safety isolator 14to enablethe laser beam to be blocked from enteringtheworking area 10 when so desired. The laser-utilising facility is accommodated within a main enclosure 16 and an infra scanning unit 18 is mounted, eg at ceiling level, for repeatedly scanning internal surfaces of the enclosure 16 which may be vulnerable to penetration by an errant laser beam originating fromthe working area 10.The scanning unit 18 may be constructed and arranged to operate in the same manner as the unit specifically described in said prior PatentApplication, ie the scanning head 20 is continuously rotated about a vertical axis and the optical system ofthe unit may have a field of view of the order of 180" in a vertical plane and 1 in a horizontal plane.

The working area 10 is itself enclosed by a screening assembly 22 including sloping side walls 24 which are encompassed by the overall field of view seen by the scanning unit 18.The sidewalls22 are composed of a material substantially opaque to infra-red radiation, eg thin steel sheetorsuitable plastics material such as a poiycarbonate-based plastics material. It will be appreciated that in the event that an errant laser beam, originating attheworking area 10, impinges on the internal surfaces of the screening assembly a hot spot will develop as the laser beam burns through the material and will be detected by the scanning unit 18 thus enabling appropriate remedial action to be taken, egclosureofisolator 14.

If desired, one or both ofthe side walls 24 may be movable to allow access to the working area andfor this purpose they mayforexample be hinged at points 26, appropriate precautions being taken to ensure that the laser beam is shut offto working area 'IOwhen the side walls 24are open to permit such access.

Claims

1. A safety system for a laser-utilisingfacility comprising screening means for location adjacentthe laserworking area to screen at least part of the environmentfrom errant laser beams arising from the working area,the screening means being substantial lyopaqueto infra red radiation,and infra sensor means for externally monitoring the screening means to detectthe development of hot spots on the screening means.

2. A system as claimed in Claim 1 in which the infra red sensor means comprises at least one fixed infra red detectorarranged sothatat leastthe vulnerable area(s) of the screening means are within the field of view "seen" by the detector(s).

3. A system as claimed in Claim 1 in which the sensor means forms part of a scanning arrangement such thatthefieldofviewseen bythe infra red sensitive detector is scanned over the screening means,

4. A system as claimed in Claim 1, 2or3 in which the screening means is substantially opaque to infra red radiation.

5. A system as claimed in anyone of Claims 1 t J 3 in which the screening means, at leastin part, is substantially transpa rent to visible light so that the laserworking area is open to inspection.

6. A system as claimed in anyone of Claims 1 to 5 in which the screening means is flexible.

7. Asystem as claimed in Claim 6 in which the screening means comprises a hanging curtain or curtains.

8. A system as claimed in anyone of Claims 1-7 in which the screening means is movable between an inoperative position to allow access to the laser working area (but only while the laser beam is shut-off) and an operative position when the laser beam is presentatthe laserworking area.

9. A system as claimed in Claim 8 in which operation of the laser-utilising equipment and the screening means is co-ordinated in such a way that the laser beam may only be made availabie within the working area when the screening means is in the operative position.

10. Asystem as claimed in anyone of Claims 1-9 in which the sensor means associated with the screening means is arranged to trigger laser-operation modifying means for shutting offthe laser beam from the working area.

11. A safety system for a laser-utilising facility substantially as hereinbefore described with refer enceto, and as shown in, the accompanying drawings.