A fiber optic sensor head for detecting the shape or the distance of a test object has an optical fiber, in particular a glass fiber, for conducting and returning partial beams to and from the test object, and an injection/extraction lens on the test object side. For conducting partial beams, injected on the sensor head side and having an optical path length difference, to the test object and returning partial beams injected on the test object side without an optical path length difference, a Fizeau interferometer having a nondiscrete design is associated with the optical fiber and compensates for the optical path length difference between the partial beams.