title: Frequency-division multiplexing for multicomponent shearography.
abstract: A new method of multiplexing the speckle patterns needed in multicomponent digital shearography systems is presented. Frequency-division multiplexing (FDM) of the measurement channels is achieved by recording speckle patterns from objects illuminated by intensity-modulated sources. Each source is modulated at a discrete frequency, which is less than half of the camera frame rate, and a bank of images of the modulated speckle patterns is captured. This allows for pixel-by-pixel Fourier-based extraction of the individual speckle patterns from peaks in the power spectra. The approach is demonstrated with a two-component in-plane shearography instrument.
authors: Department of Engineering Photonics, School of Engineering, Cranfield University, Cranfield, Bedfordshire, UK.
authors: Ian A
authors: IA
authors: Bledowski
authors: Thomas O H
authors: TO
authors: Charrett
authors: Daniel
authors: D
authors: Francis
authors: Stephen W
authors: SW
authors: James
authors: Ralph P
authors: RP
authors: Tatam