Abstract: A method of laser-drilling a hole through a workpiece, such as an injector nozzle (40), into a cavity comprising drilling a hole (41) through the workpiece (40) with a laser (50), providing a fluid having laser-barrier properties in the cavity so that, when the hole (41) is open to the cavity, laserlight passing through the hole (41) is incident upon the fluid whereby the workpiece (40) across the cavity from the hole (41) is protected from the laserlight, and arranging that the fluid does not enter the laser-drillled hole (41) during the drilling process. Apparatus for performing the method is also described.

Abstract: A halogen generator which uses a material which absorbs commercially available halogen and, on being heated, releases the halogen in a very pure form, i.e. >99.7%. Such a generator can be used in a gas management system for an excimer laser in which the laser gas contains a halogen donor, an active rare gas and an inert gas diluent. Cleaners are provided to enable the removal from the laser gas mixture of contaminants which build up in operation of the laser and the halogen gas generator is provided to replace halogen lost in the contaminants and elsewhere. The generator can be operated even when the laser is in operation so that a desired partial pressure of the halogen can be maintained.

Abstract: A metal vapor laser which can produce two or more discrete outputs from a single vacuum chamber. This is achieved by using two or more different materials and by confining each material to its own area so that the materials do not mix one with the other and optimum lasing performance can be obtained from each material. All the lasing areas have a common optical axis. The lasing outputs can be produced separately or mixed together as required.

Abstract: A lasing device which uses as a lasing media a material which lases in the gas or vapor phase, and in which the discharge chamber includes a porous element which absorbs the lasing material when it condenses into the liquid or solid phase. The porous element, which can be a porous ceramic material, retains the liquid media and does not allow it to run along the discharge tube if this tube is moved or tilted. The laser is thus able to operate when being moved or tilted.