| 摘要 |
A method for monitoring changes in a physical or chemical parameter, comprises constructing an optical fibre (35) having a colour-sensitive portion (37) comprising a core which is free from cladding or whose cladding is sufficiently thin or porous for a coloured fluid to be capable of absorbing light which may be passed through the sensitive portions (37) when the latter is immersed in the coloured fluid, immersing at least a part of the sensitive portion in a colourant-containing fluid, applying the parameter so as to vary the spectrum or amount of colour adjacent to the sensitive portion (37) of the fibre (35) with changes in the parameter, passing through the sensitive portion light having a wavelength or waveband which is absorbed at least in part by the colourant in amount which varies with the changes in parameter, and monitoring the absorption of the light which passes through the sensitive portion. The amount of colour in the fluid adjacent to the fibre can be varied by varying the intensity of the colour in the fluid, or the length of the sensitive fibre which is immersed in a coloured liquid. Variation in the spectrum can be monitored as variations in the wavelength of a peak absorption or as intensity variations at a predetermined wavelength. |
