REMOTE OPTICAL THERMOMETER FOR SEVERE ENVIRONMENT

RESEARCH LEADING TO THE DEVELOPMENT OF A REMOTE OPTICAL THERMOMETER FOR SEVERE ENVIRONMENTS IS PROPOSED. THE TEMPERATURE SENSING ELEMENT CONSISTS OF A SMALL SAPPHIRE CRYSTAL TRANSDUCER WHICH IS COUPLED TO A REMOTE EXCITATION SOURCE AND READOUT UNIT BY OPTICAL FIBERS. THE BASIS FOR THE MEASUREMENT IS THE TEMPERATURE VARIATION OF BIREFRINGENCE WHICH OCCURS IN NATURALLY BIREFRINGENT CRYSTALS. RESPONSIVITY OF THE TEMPERATURE MEASUREMENT WOULD ONLY DEPEND ON THE TEMPERATURE DEPENDENT BIREFRINGENCE AND THE SIZE (LENGTH) OF THE CRYSTAL. THE FIRST PARAMETER IS STABLE AND INVARIANT FOR CRYSTALLINE MATERIALS AND THE SECOND, LENGTH, CAN BE CAREFULLY CONTROLLED. THEREFORE, LITTLE OR NO NEED FOR CALIBRATION CAN BE EXPECTED. THE CHOICE OF SAPPHIRE SHOULD MAKE OPERATION UP TO 2000 C ( ) FEASIBLE.