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2D resolution improvement via 1D scanning Space-Time Digital Holography (STDH) in Optofluidics
Zhe Wang1,2, Vittorio Bianco1, Yutong Cui2, Melania Paturzo1, Pietro Ferraro1
1ISASI-CNR, Italy; 2College of Applied Sciences, Beijing University of Technology, China.
Space-Time Digital Holography (STDH) exploits the object motion to record the hologram in a hybrid space-time domain. This representation adds new capabilities to conventional DH, such as unlimited extension of the Field of View (FoV) and tunable phase shifting. Here we show that STDH is able to improve the spatial resolution as well. Differently from other super-resolution approaches, stitching between holograms or their spectra is no longer required. Moreover, we introduce a new STDH modality to record and process hybrid space-time representations. This allows improving resolution with one single object scan, paving the way to the use of STDH for superresolution imaging onboard Lab on a Chip devices.
Integration of Fluidic Channels and Total Internal Reflection Excitation with Supercritical Angle Fluorescence Detection
Kirsi Tappura, Aki Mäyrä, Markku Alamäki, Annukka Kokkonen, Sanna Aikio, Marianne Hiltunen
VTT Technical Research Centre of Finland Ltd., Finland
In many diagnostic applications, there is a growing demand for small cost effective portable devices that enable fast on-site analysis. For this target, we are developing an integrated approach of a previously reported surface-sensitive measurement system based on total internal reflection excitation and supercritical angle fluorescence detection. The integrated measurement platform includes a polystyrene substrate on which the fluidic channels for sample transport, waveguides for fluorescence excitation and the readout optics are fabricated. In addition, thin layers with dielectric properties differing from those of polystyrene may be needed on the fluidic channels for optimal sample transport or biomolecule immobilisation. Here, special attention is paid to the influence of the dielectric environment near the solid-liquid interface on the fluorescence distribution and to the design of the readout optics. The first version of the designed readout optics of the integrated measurement platform is presented.
Addressing the Fabrication Difficulties of Femtosecond Laser Written Surface Waveguides for Enhanced Evanescent Coupling
Vítor A. Amorim1,2, João M. Maia1,2, Duarte Viveiros1,2, P. V. S. Marques1,2
1Centre for Applied Photonics, INESC TEC, Rua do Campo Alegre 4150-179, Porto, Portugal; 2Department of Physics and Astronomy, Faculty of Sciences of University of Porto, Rua do Campo Alegre 4169-007, Porto, Portugal
In this work, the fabrication of optical waveguides embedded in fused silica(Suprasil1)and boro-aluminosilicate glass(Eagle2000)is demonstrated with femtosecond laser direct writing, as well as their suitability to be brought to the surface, through wet etching, for enhanced evanescent coupling with the external dielectric medium. Fused silica demonstrated to be inappropriate in this particular application, as the guiding region is at the bottom of the induced modification, creating a barrier between the guided mode and the substrate’s boundary. Furthermore, the existence of nanogratings meant that, upon contact of the top of the induced modification with the substrate’s boundary, the waveguide is quickly etched.Eagle2000 demonstrated to be superior to fused silica due to its characteristic modification cross-section and absence of nanogratings, which allowed the placement of the guiding region as close to the substrate’s surface as required. However, surface roughness arising from the creation of insoluble products in the HF solution was found. The addition of HCl to dissolve these products was implemented.