Holographic profilometry with a rhodium-doped barium titanate crystal and a diode laser

We present a novel, whole-field, noncontact profilometer based on real-time, two-color contour holography. A single 30-mW laser diode was used to record a hologram in a BaTiO(3):Rh crystal, and the reconstructed image was interfered with the real-time object wave. Current modulation of the diode laser produced continuously tunable contour intervals. The resulting interferograms were processed by use of phase-shift interferometry algorithms to yield quantitative, three-dimensional measurements of the original object. We demonstrate submillimeter depth resolution and show how resolution and speed can be further improved.