A catheter with many fiber optic pressure sensors. The sensor diaphragm is formed from a wafer with a thin silicon layer and a silicon substrate layer separated by a silicon dioxide layer. A method includes masking and etching channels through the silicon substrate layer in a pattern of concentric circles to form a concentric circular etched channels and cylindrical unetched portions of the silicon substrate layer between the channels, exposing the silicon dioxide in the etched regions, and dissolving the exposed silicon dioxide to expose the crystalline silicon layer in the etched regions. The unetched cylindrical portion of the silicon substrate forms the diaphragm support element and the thin silicon layer forms the diaphragm. After applying a reflective coating to the exposed thin silicon layer, the support element face is adhered to the end face of a tubular housing, and a fiber optic probe is inserted in the tubular housing.