Three-dimensional displacement gauge

A three-dimensional displacement gauge (10) comprises a housing (18) and a probe (12) rotatably and slidably mounted on the housing (18). The probe (12) is slidable along a first direction (z) and has a contact member (12b) attached at one end thereof. Two emitting members (13) are mounted on the probe (12) each for emitting a light beam (L1, L2). A two-dimensional measuring member (17), such as a position sensor, is fixed to the housing (18) for detecting the light beams (L1, L2). A biasing spring (16) is provided for biasing the probe (12) towards the contact member (12b). A limit switch (19) is attached to the housing (18) for detecting whether or not the probe (12) moves in the first direction (z). The two-dimensional measuring member (17) detects the light beams (L1, L2) struck thereon so as to measure a small displacement of the contact member (12b) of the probe (12) either in the first direction (z) or in a second direction (x) perpendicular to the first direction (z).