Speckle photography can be used to monitor deformations of solid surfaces. Its measuring characteristics, such as range or lateral resolution, depend heavily on the optical recording and illumination setup. I show how, by the addition of two suitably perforated masks, the effective optical aperture of the system may vary from point to point of the surface, accordingly adapting the range and resolution to local requirements. Furthermore, by illuminating narrow areas, speckle size can be chosen independently from the optical aperture, thus lifting an important constraint on the choice of the latter. The technique, which I believe to be new, is described within the framework of digital defocused speckle photography under normal collimated illumination. Mutually limiting relations between the range of measurement and the spatial frequency resolution turn up both locally and when the whole surface under study is considered. They are deduced and discussed in detail. Finally, experimental results are presented.
© 2007 Optical Society of America
Coherence and Statistical Optics
Original Manuscript: April 12, 2007
Revised Manuscript: June 21, 2007
Manuscript Accepted: June 25, 2007
Published: August 14, 2007
Jose M. Diazdelacruz, "Adaptive aperture defocused digital speckle photography," Appl. Opt. 46, 6105-6112 (2007)