MODULATION OF LASER-DIODE PARAMETERS FOR SPECIAL PERFORMANCE ELECTRONIC SPECKLE PATTERN INTERFEROMETRY (ESPI)

Sophisticated optical metrology Like 3-D electronic speckle pattern in terferometry (ESPI) benefits from the possibility to modulate diode la ser sources. Modulation of light intensity is utilized to select branc hes of the optical setup designed for different sensitivity vectors. P hase shifting can be simplified by employing the tunability of the las er wavelength. The wavelength characteristic within a laser pulse can be suitably tailored by adjusting the time dependence of the injection current signal. All features enter into the design of a powerful metr ological tool for displacement studies under industrial or even out-of -doors environments like in the monitoring of deterioration processes in historical monuments. (C) 1997 Elsevier Science B.V.