An ablation catheter Has a spring assembly residing between an ablation head and a proximal catheter body. Three optical fibers extend through a lumen in the catheter body. Three mirrors supported by the ablation head face proximally but are spaced distally from the optical fibers. The mirrors are provided with a pattern of reflectance that varies along a radius from a central area of reflectance. Light of a respective defined power shines from each of the optical fibers to a corresponding one of the mirrors with a reflected percentage of the respective defined light power being reflected back to the optical fiber. A percentage of the reflected percentage of the respective defined light power is captured by and travels along each optical fiber to a dedicated light wave detector connected to a controller. From the percentage of the reflected percentage of the light of the respective defined power received by each detector, the controller is programmed to calculate whether an axial or lateral force is imparted to the ablation head and, if so, the magnitude and vector of those forces.