Optics: measuring and testing – Of light reflection
Patent
1998-08-10
2000-10-10
Font, Frank G.
Optics: measuring and testing
Of light reflection
356445, 356446, 356447, 356448, 250221, 2502221, 250205, 359589, 385126, 385127, G01N 2155
Patent
active
061307548
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to the transmission of a hazardous electromagnetic beam and the particular though certainly not exclusive application to the transmission of a hazardous laser beam, for example a non-eyesafe laser beam.
BACKGROUND ART
It is often necessary or desirable to transmit a continuous wave (CW) or pulsed laser beam through a space which, though not continuously occupied by humans, is used or traversed by humans. If the laser beam exceeds safe levels for human exposure, to the eye or other organs, then the transmission introduces a serious hazard to the space which may cause injury to any person who inadvertently crosses the path of the beam. Similar considerations apply to other objects, eg: animals for which the beam may be hazardous.
One approach to this problem in the past has been to avoid the hazard at source, that is by adopting eyesafe lasers for the specific application. This was achieved by maintaining energy/power output at safe levels, or through the use of eyesafe wavelengths, eg: 1.5 to 1.6 .mu.m. Where this approach was not satisfactory, it has been known to employ co-aligned radar systems which detect humans and other objects in the ray path and disable the transmission upon detection.
DISCLOSURE OF THE INVENTION
In many circumstances, it is not possible to use these techniques, and it is therefore an object of the invention to provide an alternative technique for the safe transmission of hazardous electromagnetic beams.
The present invention is based on the concept of providing a cladding or barrier beam of non-hazardous radiation which is employed to detect objects before they can penetrate to the hazardous beam. In a preferred arrangement, non-hazardous radiation wholly surrounds and clads the hazardous beam which then becomes a protected core within or at the centre of the cladding radiation.
The invention accordingly provides, in a first aspect, apparatus for transmitting a hazardous electromagnetic beam comprising a means to generate said hazardous beam and a non-hazardous electromatic beam; means to direct each of said beams along respective paths which are substantially parallel and either at least partially co-incident or in close proximity so that an object will traverse the path of the non-hazardous beam immediately before it is impinged by the hazardous beam; and means to detect disturbance of non-hazardous beam by an object and disable transmission of said hazardous beam in response to a predetermined disturbance of said non-hazardous beam so as to eliminate or substantially reduce the hazard posed by said hazardous beam.
In a further aspect, the invention provides a method of transmitting a hazardous electromagnetic beam comprising the steps of generating said hazardous beam and a non-hazardous electromagnetic beam; directing said beams along respective predetermined paths which are substantially parallel and either at least partially co-incident or in close proximity so that an object will traverse the path of the non-hazardous beam immediately before it is impinged by the hazardous beam; and detecting disturbance of the non-hazardous beam by an object, and in response to a predetermined disturbance of the non-hazardous beam disabling transmission of said hazardous beam.
In a particular application, the hazardous electromagnetic beam is a laser beam, eg: a continuous wave or pulsed laser beam. The non-hazardous electromagnetic beam is then preferably also a laser beam, most preferably a pulsed laser beam.
In one embodiment, the path of the non-hazardous beam includes a segment which in cross-section is adjacent to the path of the hazardous beam. In a particularly preferred embodiment, this segment wholly surrounds and thereby clads the path of the hazardous beam. In this arrangement, the path of the hazardous beam is effectively a core coaxial with or within the path of the non-hazardous beam.
In another embodiment, the paths of the hazardous and non-hazardous beam are at least partially coincident but the hazardous beam is pulsed s
REFERENCES:
patent: 5091627 (1992-02-01), Kimura
patent: 5837996 (1998-11-01), Keydar
Electro Optic Systems Pty. Limited
Flores Ruiz Delma R.
Font Frank G.
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