Rectangular beam generating light source

DETAILED DESCRIPTION According to an aspect of the present invention, there is provided a light source comprising light generating means, and a reflector arranged to reflect light from the generating means into a directional light beam, wherein said beam is not uniform due to part of the reflector being obscured by the generating means, characterised by secondary reflection means arranged to direct part of the reflected beam so as to compensate for the obscured region.
Preferably, the secondary reflector consists of an annular reflector arranged to reflect peripheral light from the edge of a beam in a direction normal to the axis of propagation and a conical reflector centrally positioned so as to redirect said normal beam into the direction of propagation.
Another problem with known arc light sources is that, although they may operate at reasonable voltages during steady state operation, a very high voltage may be required to initiate discharge.
This creates problems in that additional equipment must be provided for generating the initial start up voltage and, furthermore, measures must be taken to protect other equipment from the effects of such a high voltage.
According to another aspect of the invention, there is provided a light source comprising an anode, a cathode and an electrical power source for creating an arc between said anode and cathode, characterised in that said anode and cathode are enclosed within a local atmosphere and a radio active source is introduced to ionise the enclosure, thereby reducing the level of an initial voltage required to initiate the arc.
A suitable radio active source may be included in or on the anode or the cathode.
Alternatively, a radio active source may be included in the material of an associated reflector if said reflector is enclosed within the arc source.
Other aspects of the invention will become apparent from the description of the embodiments, hereinafter described.