Abstract: A method of calibrating pressure sensitive paint is provided comprising the steps of: illuminating the paint under a range of pressures and temperatures; measuring the intensity of light emitted by the paint following each illumination thereby measuring decay curves; and performing a curve fit of the decay curves to determine characteristic constants. These constants can then be used to generate a model of decay curves and a polynomial relating pressures and temperatures for ratios of intensities over gated areas of the model decay curves can be calculated. Pressure determination at the calibrated paint can then be performed by illuminating the paint, measuring the intensity of light emitted by the paint over two of the gated areas, determining the ratio of the gated area intensities and finally determining the pressure and/or temperature from the polynomial using the determined ratio of the gated area intensities.

Abstract: Apparatus for controlling the composition of a laser gas or gas mixture includes a cryogenic gas-processor (2) connectible to a gas laser (1) selectively to receive gas or a gas mixture therefrom, remove impurities from the gas or gas mixture and selectively return the purified gas or gas mixture to the laser (1). A high temperature gas-purifier (3) is provided in gas flow connection with the processor (2) and with the laser (1) selectively to receive gas or a gas mixture therefrom, remove halogen and/or impurities from the gas or gas mixture and selectively return the dehalogenated or purified gas or gas mixture to the laser (1). Gas analysis means (4) is provided for receiving gas or gas mixture from the laser (1) to analyze it and produce output signals indicative of the actual composition of the laser gas or gas mixture.