Three-coordinate measurement of an object surface with a combined two-wavelength and two-source phase-shifting speckle interferometer

In a two-wavelength phase-shifting speckle interferometer for object contouring one usually obtains only the height co-ordinate of the object surface which is parallel to the viewing direction (here denoted as z- co-ordinate). In order to measure the lateral surface co-ordinates x and y by the same technique the light source is shifted in two directions (denoted as u and v) perpendicular to the optical axis. Two additional phase maps of parallel fringes are generated which are then used to assign the lateral co-ordinates x and y to the corresponding pixels of the camera. All the other advantages of two-wavelength interferometry remain unaffected.