Biomedical subjects

Norman Heckenberg

Publications and source records attributed to Norman Heckenberg.

3 recordsLinked to original sources

PubMed2006

Coherent super-resolution microscopy via laterally structured illumination.

Theory describing a super-resolution microscopy experiment using temporally and spatially coherent structured illumination was developed, and used to derive a method for processing experimental data. Numerical simulations were performed to verify that the method can, in principle, produce super-resolved images that are exactly equivalent to an image processed by a system with a much larger aperture (that is, the correct weighting between different regions of the image spectrum is maintained). The process was then demonstrated experimentally, showing a factor of two improvement in resolution over a diffraction-limited, coherently illuminated, microscope.

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PubMed2005

Energy transfer dynamics of nanocrystal-polymer composites.

Steady-state and time-resolved photoluminescence spectroscopy are used to examine the photoluminescent properties of nanocrystal-polymer composites consisting of colloidal PbS nanocrystals blended with poly(2-methoxy-5(2-ethylhexyloxy)-p-phenylene vinylene). Quenching of the emission from the conjugated polymer due to the PbS nanocrystals is observed along with band edge emission from the ligand capped PbS nanocrystals. A decrease in the photoluminescence lifetime of MEH-PPV is also observed in the thin film nanocrystal-polymer composite materials. Photoluminescence excitation spectroscopy of the PbS nanocrystal emission from the composite shows features attributed to MEH-PPV providing evidence of a Förster transfer process.

Journal Article↗

PubMed2003

Mesostructured dye-doped titanium dioxide for micro-optoelectronic applications.

Optically transparent, mesostructured titanium dioxide thin films were fabricated using an amphiphilic poly(alkylene oxide) block copolymer template in combination with retarded hydrolysis of a titanium isopropoxide precursor. Prior to calcination, the films displayed a stable hexagonal mesophase and high refractive indices (1.5 to 1.6) relative to mesostructured silica (1.43). After calcination, the hexagonal mesophase was retained with surface areas > 300 m2 g-1. The dye Rhodamine 6G (commonly used as a laser dye) was incorporated into the copolymer micelle during the templating process. In this way, novel dye-doped mesostructured titanium dioxide films were synthesised. The copolymer not only directs the film structure, but also provides a solubilizing environment suitable for sustaining a high monomer-to-aggregate ratio at elevated dye concentrations. The dye-doped films displayed optical thresholdlike behaviour characteristic of amplified spontaneous emission. Soft lithography was successfully applied to micropattern the dye-doped films. These results pave the way for the fabrication and demonstration of novel microlaser structures and other active optical structures. This new, high-refractive index, mesostructured, dye-doped material could also find applications in areas such as optical coatings, displays and integrated photonic devices.

Journal Article↗