One major advantage of using gold nanoparticles is the possibility of tuning their absorption peak by modifying their surface plasma resonance. They are proven to be a promising multi-functional platform that can be used for many imaging and therapeutic applications. As a true multi-modality imaging technique, Photo-Magnetic Imaging (PMI) has a great potential to monitor the distribution of gold nanoparticles non-invasively with MR resolution. With a simple addon of a continuous wave laser to an MRI system, PMI uses the laser induced temperature increase, measured by MR Thermometry (MRT), to provide tissue optical absorption maps at MR resolution. PMI utilizes a Finite Element Method (FEM) based algorithm to solve the combined diffusion and bio-heat equations. This system of combined equations models the photon distribution in the tissue and heat generation due to the absorption of the light and consequent heat diffusion. The key characteristic of PMI is that its spatial resolution is preserved at any depth as long as the temperature change within the imaged medium is detectable by MRT. Agar phantoms containing gold nanoparticles are used to validate the ability of PMI in monitoring their distribution. To make PMI suitable for diagnostic purposes, the laser powers has been kept under the American National Standard Institute maximum skin exposure limits in this study.
This study defines measurements of three-dimensional rigid-body shapes by using a fiber optic Lloyd’s mirror.
A fiber optic Lloyd's mirror assembly is basically a technique to create an optical interference pattern using real light
point sources and their images. The generated fringe pattern thanks to this technique is deformed when projected on an
object's surface. The deformed fringe pattern containing information of the object's surface profile is captured by a digital
CCD camera. The two-dimensional Fourier transformation is applied to the image, which is digitized with a frame
grabber card. After applying a band-pass filter to this transformed data in its spatial frequency domain, the twodimensional
inverse Fourier transform is applied. Using the complex data obtained by the inverse Fourier transform, the
phase information is determined. A phase unwrapping algorithm is applied to eliminate discontinuities in the phase
information and to make the phase data continuous. Finally, the continuous data determines the depth information and
the surface topography of the object. It is illustrated for the first time that the use of such a fiber optic Lloyd's system
increases the compactness and the stability of the fringe projection system. Such a fiber optic Lloyd’s system which
provides an accurate non-contact measurement without contaminating and harming the object surface has a wide range
of applications from laser interference lithography (LIL) in nano-scale to macro-scale interferometers.