INTERFEROMETRIC NON-CONTACT OPTICAL PROBE AND MEASURING METHOD

A non-contact optical probe (10,32,36) utilizes an optical reference surface (18,34,38) that projects a curved test wavefront (T) toward the test surface (S) and detects it by creating curved interferometric fringes (16) localized in space in front of the reference surface. When a point to be measured on the test surface (S) intersects the location of the fringes, the condition is detected by the probe. Because the fringes (16) are localized at a known position in space with respect to a reference system, the precise coordinate of the surface point can be established. Such localized fringes are preferably produced by a spectrally controllable light source (12). The curvature of the fringes ensures a sufficiently large angle of acceptance for the probe to capture light reflected from points of high surface slope. The probe is particularly suitable for coordinate measurement machines.