Fiber-optic calorimeter with twin temperature sensor for high accurate measuring of laser power

Summary form only given. The fiber-optic sensors offer immunity from electromagnetic interference and capability for operation in hazardous high voltage environments, thus these sensors can be useful tools for power measurements of lasers operating at high voltage and high frequencies, such as CO/sub 2/ and excimer lasers. We describe a fiber-optic calorimeter with two temperature sensors based on a birefringent fiber Sagnac interferometer. One sensor measures a temperature of the calorimeter´s absorber that depends on the power of incident laser radiation, whereas the other is for monitoring of environmental temperature. The temperature sensing is based on the monitoring of temperature-induced changes in the fiber birefringence by a low-coherence interferometric technique. The basic element of the sensor´s optical arrangement is the Sagnac interferometer with /spl pi//2-twisted high-birefringent (HB) fiber. It is known that the interferomerer of this type is polarization independent that eliminates any polarization optics from the sensor arrangement and allows the use of an unpolarized light source.