The measuring system can be easily adapted for a specific micro-sensor type simply by installing the appropriate optical excitation and detection filters. Data acquisition and the calibration and configuration of the instrument are controlled via an instrument micro-controller that interfaces to a PC, and special software has been developed for this purpose. It is suitable for both laboratory and field application, and a battery-operated version for field application has been successfully tested under harsh environmental conditions. A similar module has also been used to obtain the first field measurements of oxygen and carbon dioxide levels to be taken with fibre-optic micro-sensors in both shallow waters and deep sea. Currently, three units have been produced that can measure pH, carbon dioxide and oxygen with fibre-optic micro-sensors. Partners are sought for further research and development.