Abstract: A force sensor assembly for use in the field of cardiac ablation, for the ablation-based treatment of atrial fibrillation and other cardiac arrhythmias. Various embodiments of the disclosure are directed to a catheter distal force sensor for measuring catheter tip-to-endocardial wall force by measuring displacement of irradiation patterns sensed with a two-dimensional imaging sensor. The disclosed devices sense an array of irradiation pattern characteristics, including changes in size and location of irradiation shapes of the irradiation pattern. In some embodiments, multiple irradiation spots are tracked with the two-dimensional imaging sensor to infer the components of a reaction force vector acting the force sensor assembly. The disclosed force is designed to accommodate typical catheter tip dimensions, the outer diameter of these usually being less than or equal to 9 French (3 mm).