An optical system adapted to detect an object including a beam splitting and combing element, a catheter, a focusing element, a deformation detecting module, and an object detecting module is provided. The catheter sleeves outside an optical fiber, and the optical fiber has at least one fiber Bragg gratings. The deformation detecting module and the object detecting module are coupled to the beam splitting and combing element. A first light is reflected by the at least one fiber Bragg gratings and then transmitted to the deformation detecting module. A second light is transmitted to and reflected by the object, so as to be transmitted to the object detecting module. A first wavelength range of the first light is different from a second wavelength range of the second light.
