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Abstract Traditional deep fluorescence imaging has primarily focused on red‐shifting imaging wavelengths into the near‐infrared (NIR) windows or implementation of multi‐photon excitation approaches. Here, the advantages of NIR and multiphoton imaging are combined by developing a dual‐infrared two‐photon microscope that enables high‐resolution deep imaging in biological tissues. This study first computationally identifies that photon absorption, as opposed to scattering, is the primary contributor to signal attenuation. A NIR two‐photon microscope is constructed next with a 1640 nm femtosecond pulsed laser and a NIR PMT detector to image biological tissues labeled with fluorescent single‐walled carbon nanotubes (SWNTs). Spatial imaging resolutions are achieved close to the Abbe resolution limit and eliminate blur and background autofluorescence of biomolecules, 300 µm deep into brain slices and through the full 120 µm thickness of aNicotiana benthamianaleaf. NIR‐II two‐photon microscopy can also measure tissue heterogeneity by quantifying how much the fluorescence power law function varies across tissues, a feature this study exploits to distinguish Huntington's Disease afflicted mouse brain tissues from wildtype. These results suggest dual‐infrared two‐photon microscopy can accomplish in‐tissue structural imaging and biochemical sensing with a minimal background, and with high spatial resolution, in optically opaque or highly autofluorescent biological tissues.
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Is Backside the New Backdoor in Modern SoCs?
Modern integrated circuits (ICs) possess several countermeasures to safeguard sensitive data and information stored in the device. In recent years, semi-invasive physical attacks based on optical debugging techniques have proven to be capable of easily bypassing these security measures implemented in the chip. Optical attacks can reveal the data stored in memory, cache and register through various methods such as photon emission analysis, laser fault injection, laser voltage probing, and thermal laser stimulation. The above-mentioned methods, which employ laser scanning microscopy and photon emission microscopy, are effective because the silicon substrate is transparent to near-infrared (NIR) photons. Therefore, the most vulnerable part of an IC to optical attacks is the backside, where the chip's transistors can be accessed and probed with a NIR laser beam. Although different optical attack detection and …
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- Award ID(s):
- 1821780
- PAR ID:
- 10156770
- Date Published:
- Journal Name:
- 2019 IEEE International Test Conference (ITC)
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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