Transformation optics (TO) is a new method to design metamaterials that can manipulate electromagnetic fields. Different from the traditional TO technique which is mostly based on the solid metamaterials with a limited range of tunability, a novel transformation optofluidics (TOF) method is proposed to manipulate the light path by changing the streamlines of the flow in a circular bounded domain. A dipole flow model was built for the first time to analytically calculate the streamlines of a liquid core/liquid cladding (L2) configuration inside the domain. Experiment show that the light paths agree well with the theoretical models and have a large range of tunability for any optical source-sink pair locations and flow rate ratio of two cladding fluids.
The surface roughness parameters encoded in a speckle pattern can be effectively extracted through correlation experiments. In the case of spectrally correlated speckle images, the degree of decorrelation arises from wavelength difference in the laser light irradiated on the surface. To obtain accurate results in such methodology, a proper design of experiments is important due to more than one parameter involved in the experiment. Here, experimental investigations and parametric studies of surface roughness measurements using spectral speckle correlation methodology are presented, considering the potential variables in the system. The sources of error and factors affecting the accuracy in measurement are identified and the experimental results obtained from standard calibration plate samples are presented.
In manufacturing engineering the surface finish of a machined component is of fundamental importance in order to ensure its performance. A non-contact and non-destructive device based on optical technique, is a promising alternative to stylus based device for carrying out measurement of surface quality. In addition to this, in situ monitoring of surface roughness on a workpiece is an important requirement in modern machining process, since it would increase on-line machining rate and consequently productivity. Here, measurement approaches and system configuration for surface roughness measurement using laser speckle intensity and contrast are discussed. The technique would allow full-field measurement over sample of interest having both rough and shiny surface properties. Measurement data on standard calibration plates is presented with details on the measurement accuracy and reliability.