Simultaneous measurement of shape and deformation using digital light-in-flight recording by holography

A method for direct simultaneous measurement of shape and deformation using short laser light pulses and digital holography with a CCD array is demons trated. This method can be used to study a rapid deformation cycle, to comb ine holographic interferometry with finite element analyze (FEA) modeling, and in other applications where information on both shape and displacement is of interest. Small displacements are measured with holographic interfero metry, and larger displacements by comparing the shapes before and after a displacement, An in-line setup for light-in-flight recording by holography is used, where the reference beam is retroreflected from a blazed reflectio n grating, i.e., a Littrow setup. By this a relatively large optical delay is created across the CCD array between the reference and the object beams even with a small object-reference angle, which is necessary due to the lim ited resolution of the CCD array. Theory and selected experimental results are presented for deformations evaluated with holographic interferometry. ( C) 2000 Society of Photo-Optical Instrumentation Engineers. [S0091-3286(00) 03301-8].