Quantitative and automatic analysis of interferometric fringe data using carrier fringe and FFT techniques

Computerised analysis of optical fringe pattern is a rapidly developing approach to extract quantitative data from phase encoded intensity distribution. This thesis describes results of investigations of quantitative and automatic analysis of interference fringe data using carrier fringe and FFT techniques. Several automatic and semiautomatic fringe analysis algorithms that enable the reduction of fringe patterns to quantitative data have been reviewed and illustrated with some examples. A fresh holographic contouring approach by the movement of object beams through fibre optics is described. The use of fibre optics provides a simple method for obtaining contouring fringes in the holographic system. A carrier fringe technique for measuring surface deformation is described and verified by experiments. A theoretical analysis of the carrier fringe technique is given. The effects of carrier frequency on holographic fringe data has been investigated with computer generated holograms. In contrast to conventional holography and fringe analysis, this holographic system based on fibre optics and automatic spatial carrier fringe analysis technique. The FFT approach is used to process the interferograms. An excellent correlation between the theoretical deformation profile and that suggested by the technique is given. The accuracy of the measurement for a centrally loaded aluminum disk is 0.05pm. The design and construction of a computerised photoelastic stress measurement system is discussed. This full field, fully automated photoelastic stress measurement system is a new approach to photoelastic fringe analysis. Linear carrier fringes generated using quartz wedge are superimposed on fringes formed by the stressed model. The resultant fringes pattern is then captured using a CCD camera and stored in a digital frame buffer. A FFT method has been used to process the complete photoelastic fringe image over the whole surface of the model. The whole principal stress difference field has been calculated and plotted from one single video frame

Optical colour image encryption using spiral phase transform and chaotic pixel scrambling

10.1080/09500340.2019.1572807Journal of Modern Optics667776-78

Cryptoanalysis of the modified diffractive-imaging-based image encryption by deep learning attack

10.1080/09500340.2020.1862329Journal of Modern Optics67171398-140

Methods for enhancing photolithography patterning

US8450046Granted Paten

An experimental analysis of the real contact area between an electrical contact and a glass plane

The exact contact between two rough surfaces is usually estimated using statistical mathematics and surface analysis before and after contact has occurred. To date the majority of real contact and loaded surfaces has been theoretical or by numerical analyses. A method of analysing real contact area under various loads, by utilizing a con-contact laser surface profiler, allows direct measurement of contact area and deformation in terms of contact force and plane displacement between two surfaces. A laser performs a scan through a transparent flat side supported in a fixed position above the base. A test contact, mounted atop a spring and force sensor, and a screw support which moves into contact with the transparent surface. This paper presents the analysis of real contact area of various surfaces under various loads. The surfaces analysed are a pair of Au coated hemispherical contacts, one is a used Au to Au coated multi-walled carbon nanotubes surface, from a MEMS relay application, the other a new contact surface of the same configuration

Phase error correction for digital fringe projection profilometry

10.1016/j.phpro.2011.06.153Physics Procedia19227-23

A MEMS-based piezoelectric cantilever patterned with PZT thin film array for harvesting energy from low frequency vibrations

10.1016/j.phpro.2011.06.136Physics Procedia19129-13

Edge effects characterization of phase shift mask

10.1116/1.1865112Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures232417-424JVTB