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Emerging applications of optical technologies are driving the development of miniaturised light sources, which in turn require the fabrication of matching micro-optical elements with sub-1 mm cross-sections and high optical quality. This is particularly challenging for spatially constrained biomedical applications where reduced dimensionality is required, such as endoscopy, optogenetics, or optical implants. Planarisation of a lens by the Fresnel lens approach was adapted for a conical lens (axicon) and was made by direct femtosecond 780 nm/100 fs laser writing in the SZ2080™ polymer with a photo-initiator. Optical characterisation of the positive and negative fraxicons is presented. Numerical modelling of fraxicon optical performance under illumination by incoherent and spatially extended light sources is compared with the ideal case of plane-wave illumination. Considering the potential for rapid replication in soft polymers and resists, this approach holds great promise for the most demanding technological applications.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC10856946 | PMC |
http://dx.doi.org/10.3390/nano14030287 | DOI Listing |
Nanomaterials (Basel)
January 2024
Optical Sciences Centre, ARC Training Centre in Surface Engineering for Advanced Materials (SEAM), Swinburne University of Technology, Hawthorn, VIC 3122, Australia.
Emerging applications of optical technologies are driving the development of miniaturised light sources, which in turn require the fabrication of matching micro-optical elements with sub-1 mm cross-sections and high optical quality. This is particularly challenging for spatially constrained biomedical applications where reduced dimensionality is required, such as endoscopy, optogenetics, or optical implants. Planarisation of a lens by the Fresnel lens approach was adapted for a conical lens (axicon) and was made by direct femtosecond 780 nm/100 fs laser writing in the SZ2080™ polymer with a photo-initiator.
View Article and Find Full Text PDFAppl Opt
January 2011
School of Advanced Technology, Algonquin College, Ottawa, Ontario K2G 1V8, Canada.
We design and manufacture a Fresnel axicon (fraxicon) that generates a quasi-diffraction-free/Bessel beam with a large depth of field. The novel optical element is characterized with both coherent and incoherent light, and its behavior is compared with that of a classical axicon. While the fraxicon exhibits a strong interference pattern in the on-axis intensity distribution, it can be smoothed out when using broadband light, partial spatial coherence light, or by period randomization.
View Article and Find Full Text PDFOpt Express
February 2009
Harbin Institute of Technology, Center of Ultra-Precision Optoelectronic Instrument, Harbin, China.
The focal performance of the micro-axicon and the Fresnel axicon (fraxicon) are investigated, for the first time, by the rigorous electromagnetic theory and boundary element method. The micro-axicon with different angle of apex and the fraxicon with various period and angle of apex are investigated. The dark segments of the fraxicon are explored numerically.
View Article and Find Full Text PDFA new optical element, a Fresnel axicon (fraxicon), is proposed. Similar to a Fresnel lens, this element consists of concentric prism-like grooves with an apex angle equal to that of a bulk axicon and whose action relies on refraction. The fraxicon is less chromatic and simpler to manufacture than holographic optical element-based diffractive axicons and, in comparison with regular refractive axicons, is more compact with less absorption loss in the material while allowing significant economy in mass production.
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