An all glass Fresnel lens (AGFL) was fabricated by glass molding with a vitreous carbon (VC) micro mold. In the glass molding process, a glass plate was heated up to its softening temperature and pressed against to the VC mold to replicate the Fresnel pattern. The VC molds having negative shape Fresnel profile were fabricated by carbonization of replicated Furan precursor using a diamond turning machined nickel master. During the carbonization process, the Furan precursor shrank due to the thermal decomposition, and this shrinkage must be compensated to obtain a precise AGFL. In this study, we examined the shrinkage ratio during the carbonization process using a preliminary experiment using the commercially available PMMA Fresnel lens as the master, and fabricated a nickel master with an enlarged Fresnel profile for shrinkage compensation. To verify the compensation method, the surface profiles of the fabricated VC mold and molded AGFL were measured and compared with the designed profile. The deviations between measured and designed profiles were less than 4 μm. In addition, the tip radii of the grooves and draft angle of the molded AGFL were within the acceptable tolerance for CPV applications.
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http://dx.doi.org/10.1364/OE.27.001553 | DOI Listing |
Polymers (Basel)
December 2024
Department of Chemical Engineering, Materials, Environment, Sapienza University of Rome, 00184 Rome, Italy.
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Nat Commun
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School of Materials Science and Engineering, Tsinghua University, Beijing, 100084, China.
As a medium to understand the nature of glass transition, ultrastable glasses have garnered increasing attention for their significance in fundamental science and technological applications. Most studies have produced ultrastable glasses through a surface-controlled process using physical vapor deposition. Here, we demonstrate an approach to accessing ultrastable glasses via the glass-to-glass transition, a bulk transformation that is inherently free from size constraints and anisotropy.
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Sree Chitra Tirunal Institute for Medical Sciences and Technology, Bioceramics Division, Biomedical Technology Wing, 695011, Thiruvananthapuram, INDIA.
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January 2025
Institute of Translational Medicine, Department of Health Sciences and Technology, ETH Zürich, 8092 Zürich, Switzerland.
Proteases, an important class of enzymes that cleave proteins and peptides, carry a wealth of potentially useful information. Devices to enable routine and cost effective measurement of their activity could find frequent use in clinical settings for medical diagnostics, as well as some industrial contexts such as detecting on-line biological contamination. In particular, devices that make use of readouts involving magnetic particles may offer distinct advantages for continuous sensing because material they release can be magnetically captured downstream and their readout is insensitive to optical properties of the sample.
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