A light generating system for use in a wellbore comprising a light generating transducer in the wellbore, the light generating transducer adapted to transform a physical state of a parameter in the wellbore to optical energy; recording equipment sensitive to optical energy to record a physical state;...http://www.google.es/patents/US7077200?utm_source=gb-gplus-sharePatente US7077200 - Downhole light system and methods of use
