scholarly journals Eye Safety Related to Near Infrared Radiation Exposure to Biometric Devices

2011 ◽  
Vol 11 ◽  
pp. 520-528 ◽  
Author(s):  
Nikolaos Kourkoumelis ◽  
Margaret Tzaphlidou
Keyword(s):  
Infrared Radiation ◽  
Near Infrared ◽  
Biological Effects ◽  
Infrared Region ◽  
Infrared Light ◽  
Near Infrared Radiation ◽  
Potential Threat ◽  
Incoherent Light ◽  
Light Emitting ◽  
Living Tissues

Biometrics has become an emerging field of technology due to its intrinsic security features concerning the identification of individuals by means of measurable biological characteristics. Two of the most promising biometric modalities are iris and retina recognition, which primarily use nonionizing radiation in the infrared region. Illumination of the eye is achieved by infrared light emitting diodes (LEDs). Even if few LED sources are capable of causing direct eye damage as they emit incoherent light, there is a growing concern about the possible use of LED arrays that might pose a potential threat. Exposure to intense coherent infrared radiation has been proven to have significant effects on living tissues. The purpose of this study is to explore the biological effects arising from exposing the eye to near infrared radiation with reference to international legislation.

scholarly journals Stimulated emission of near-infrared radiation in silicon fin light-emitting diode

2011 ◽  
Vol 98 (26) ◽  
pp. 261104 ◽  
Author(s):  
S. Saito ◽  
T. Takahama ◽  
K. Tani ◽  
M. Takahashi ◽  
T. Mine ◽  
...  
Keyword(s):  
Infrared Radiation ◽  
Near Infrared ◽  
Light Emitting Diode ◽  
Stimulated Emission ◽  
Near Infrared Radiation ◽  
Light Emitting

Near infrared radiation shielding using CsxWO3 nanoparticles for infrared mini light-emitting diodes

2020 ◽  
Vol 260 ◽  
pp. 126961 ◽  
Author(s):  
Chi-Ping Li ◽  
Chieh-Yu Kang ◽  
Shu-Ling Huang ◽  
Po-Tsung Lee ◽  
Hao-Chung Kuo ◽  
...  
Keyword(s):  
Infrared Radiation ◽  
Near Infrared ◽  
Light Emitting Diodes ◽  
Radiation Shielding ◽  
Near Infrared Radiation ◽  
Light Emitting

Quantitative Seasonal Changes in Gross Turfgrass Morphometry

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 456e-456
Author(s):  
Steven C. Wiest
Keyword(s):  
Leaf Area ◽  
Infrared Radiation ◽  
Near Infrared ◽  
Cell Structure ◽  
Warm Season ◽  
Infrared Light ◽  
Canopy Reflectance ◽  
Near Infrared Radiation ◽  
Visible Radiation ◽  
Quantitative Changes

Photographs of turfgrass canopies were taken throughout Spring, Summer, and Fall 1997 at a height of 1.3 m using a 28-mm lens and film sensitive to either visible or infrared light. The species evaluated were warm-season Bermudagrass, buffalograss, zoysiagrass, and cool-season tall fescue. Color spectra of digitized photographs were obtained by first separating the hue, saturation, and intensity components of the color photo into separate 8-bit (256 gray levels) files. Calculations were then made on the basis of those color components. The infrared photos were scanned as 8-bit files without conversion. Greenup was indicated by a decrease in the frequency of hues between 0 and 50° (reds, browns, and yellows) and an increase in the frequency of hues between 50 and 100° (green and yellow-green). It is well-known that canopy reflectance in the green wavelengths is primarily a function of chlorophyll density, whereas reflectance of near-infrared radiation is indicative more of cell structure. More near-infrared radiation is reflected from leaf surfaces than is green radiation, and less infrared is absorbed by internal leaf structures than is visible radiation. Thus, it is possible to approximate canopy leaf area ratios by using both visible and near-infrared photographic measurements. Quantitative changes in visible and near-infrared canopy reflectances, leaf area ratios, and other morphometric parameters will be presented as a function of time of the year and species. The results demonstrate the utility of using this relatively inexpensive procedure to obtain quantitative measurements as a substitute for, or in conjunction with, subjective visual ratings of turfgrass plots.

Catalyst Halogenation Enables Rapid and Efficient Polymerizations with Visible to Near-Infrared Light

2020 ◽  
Author(s):  
Alex Stafford ◽  
Dowon Ahn ◽  
Emily Raulerson ◽  
Kun-You Chung ◽  
Kaihong Sun ◽  
...  
Keyword(s):  
Near Infrared ◽  
Transient Absorption ◽  
Reaction Times ◽  
Infrared Light ◽  
Structure Property ◽  
Light Emitting ◽  
Structure Property Relationships ◽  
Nir Light ◽  
Light Intensities ◽  
Emission Quenching

Driving rapid polymerizations with visible to near-infrared (NIR) light will enable nascent technologies in the emerging fields of bio- and composite-printing. However, current photopolymerization strategies are limited by long reaction times, high light intensities, and/or large catalyst loadings. Improving efficiency remains elusive without a comprehensive, mechanistic evaluation of photocatalysis to better understand how composition relates to polymerization metrics. With this objective in mind, a series of methine- and aza-bridged boron dipyrromethene (BODIPY) derivatives were synthesized and systematically characterized to elucidate key structure-property relationships that facilitate efficient photopolymerization driven by visible to NIR light. For both BODIPY scaffolds, halogenation was shown as a general method to increase polymerization rate, quantitatively characterized using a custom real-time infrared spectroscopy setup. Furthermore, a combination of steady-state emission quenching experiments, electronic structure calculations, and ultrafast transient absorption revealed that efficient intersystem crossing to the lowest excited triplet state upon halogenation was a key mechanistic step to achieving rapid photopolymerization reactions. Unprecedented polymerization rates were achieved with extremely low light intensities (< 1 mW/cm<sup>2</sup>) and catalyst loadings (< 50 μM), exemplified by reaction completion within 60 seconds of irradiation using green, red, and NIR light-emitting diodes.

scholarly journals Hyperthermia by near infrared radiation induced immune cells activation and infiltration in breast tumor

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Wan Fatin Amira Wan Mohd Zawawi ◽  
M. H. Hibma ◽  
M. I. Salim ◽  
K. Jemon
Keyword(s):  
Breast Cancer ◽  
T Cells ◽  
Side Effects ◽  
Immune Cells ◽  
Infrared Radiation ◽  
Near Infrared ◽  
Tumor Regression ◽  
Immunohistochemical Analysis ◽  
Therapeutic Effects ◽  
Near Infrared Radiation

AbstractBreast cancer is the most common cancer that causes death in women. Conventional therapies, including surgery and chemotherapy, have different therapeutic effects and are commonly associated with risks and side effects. Near infrared radiation is a technique with few side effects that is used for local hyperthermia, typically as an adjuvant to other cancer therapies. The understanding of the use of near NIR as a monotherapy, and its effects on the immune cells activation and infiltration, are limited. In this study, we investigate the effects of HT treatment using NIR on tumor regression and on the immune cells and molecules in breast tumors. Results from this study demonstrated that local HT by NIR at 43 °C reduced tumor progression and significantly increased the median survival of tumor-bearing mice. Immunohistochemical analysis revealed a significant reduction in cells proliferation in treated tumor, which was accompanied by an abundance of heat shock protein 70 (Hsp70). Increased numbers of activated dendritic cells were observed in the draining lymph nodes of the mice, along with infiltration of T cells, NK cells and B cells into the tumor. In contrast, tumor-infiltrated regulatory T cells were largely diminished from the tumor. In addition, higher IFN-γ and IL-2 secretion was observed in tumor of treated mice. Overall, results from this present study extends the understanding of using local HT by NIR to stimulate a favourable immune response against breast cancer.

scholarly journals Two-dimensional perovskites with alternating cations in the interlayer space for stable light-emitting diodes

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Yiyue Zhang ◽  
Masoumeh Keshavarz ◽  
Elke Debroye ◽  
Eduard Fron ◽  
Miriam Candelaria Rodríguez González ◽  
...  
Keyword(s):  
Thin Films ◽  
Near Infrared ◽  
Light Emitting Diodes ◽  
Interlayer Space ◽  
High Current Density ◽  
Operational Stability ◽  
Infrared Light ◽  
Two Dimensional ◽  
Commercial Development ◽  
Light Emitting

Abstract Lead halide perovskites have attracted tremendous attention in photovoltaics due to their impressive optoelectronic properties. However, the poor stability of perovskite-based devices remains a bottleneck for further commercial development. Two-dimensional perovskites have great potential in optoelectronic devices, as they are much more stable than their three-dimensional counterparts and rapidly catching up in performance. Herein, we demonstrate high-quality two-dimensional novel perovskite thin films with alternating cations in the interlayer space. This innovative perovskite provides highly stable semiconductor thin films for efficient near-infrared light-emitting diodes (LEDs). Highly efficient LEDs with tunable emission wavelengths from 680 to 770 nm along with excellent operational stability are demonstrated by varying the thickness of the interlayer spacer cation. Furthermore, the best-performing device exhibits an external quantum efficiency of 3.4% at a high current density (J) of 249 mA/cm2 and remains above 2.5% for a J up to 720 mA cm−2, leading to a high radiance of 77.5 W/Sr m2 when driven at 6 V. The same device also shows impressive operational stability, retaining almost 80% of its initial performance after operating at 20 mA/cm2 for 350 min. This work provides fundamental evidence that this novel alternating interlayer cation 2D perovskite can be a promising and stable photonic emitter.

Heat-resistant reflectors for enhanced 850-nm near infrared light-emitting diode efficiency

2021 ◽  
pp. 103879
Author(s):  
Hyung-Joo Lee ◽  
Gwang-Hoon Park ◽  
Jin-Su So ◽  
Choong-Hun Lee ◽  
Jae-Hoon Kim ◽  
...  
Keyword(s):  
Near Infrared ◽  
Light Emitting Diode ◽  
Infrared Light ◽  
Near Infrared Light ◽  
Light Emitting ◽  
Heat Resistant
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