Abstract: The invention relates to a new method of using explosives.In the past it was the practice to use the shock wave front or the pressure pulse, or both, generated by a detonated explosive mass to directly affect a target or to deform and drive a solids element against the target.In the method proposed by the present invention the explosive mass (11) and a compressible focussing means (12) are supported in a liquid medium. The focussing means (12) lie between the explosive mass and the target (T) and is spaced therefrom by liquid medium. The compressible focussing means (12) may comprise a compressible solids material or a gas volume.When the explosive mass (11) is detonated the pressure pulse, and the liquid displaced by the gas bubble generated by the detonation, serve to collapse the focussing means (12), generating high pressure liquid flows directed towards the target (T).

Abstract: Explosive charges for blasting purposes are actuated by a system of optical fibres supplied with energy from a laser. The laser energy output is substantially in excess of that required for detonation and does not need to be preserved in coherent form, enabling transmission to be via optical fibres and connecting and/or distributing devices of quality or properties unsuitable for data transmission. Simple intermittently driven mechanical arrangements can be used for the sequential firing of a set of charges. Connection to detonators can be by expendable lengths of fibre fed from a main optical channel via simple, economic, plug-and-socket arrangements. The detonators, or components containing flashing composition coating the end of the expendable fibre, may be supplied with an attached fibre ready connected to an expendable optical plug.