Near-infrared bandpass filters from Si/SiO2 multilayer coatings

1999 ◽  
Vol 38 (2) ◽  
pp. 368 ◽  
Author(s):  
S. Ajith Kumar
Keyword(s):  
Near Infrared ◽  
Bandpass Filters ◽  
Multilayer Coatings

scholarly journals Dual-frequency-selective surfaces for near-infrared bandpass filters

2004 ◽  
Vol 43 (2) ◽  
pp. 95-98 ◽  
Author(s):  
S. Govindaswamy ◽  
J. East ◽  
F. Terry ◽  
E. Topsakal ◽  
J. L. Volakis ◽  
...  
Keyword(s):  
Near Infrared ◽  
Bandpass Filters ◽  
Frequency Selective Surfaces ◽  
Dual Frequency ◽  
Frequency Selective

scholarly journals Absolute calibration of the spectral responsivity of thermal detectors in the near-infrared (NIR) and mid-infrared (MIR) regions by using blackbody radiation

2021 ◽  
Vol 10 (1) ◽  
pp. 109-119
Author(s):  
Tobias Pohl ◽  
Peter Meindl ◽  
Lutz Werner ◽  
Uwe Johannsen ◽  
Dieter Taubert ◽  
...  
Keyword(s):  
Spectral Range ◽  
Near Infrared ◽  
Bandpass Filters ◽  
Blackbody Radiation ◽  
Absolute Calibration ◽  
Spectral Responsivity ◽  
Additional Measurement ◽  
Mid Infrared ◽  
Relative Standard ◽  
Measurement Approach

Abstract. The Physikalisch-Technische Bundesanstalt (PTB) has set up an additional measurement approach for the absolute calibration of the spectral responsivity of detectors in the near-infrared (NIR) and mid-infrared (MIR) spectral range. This alternative method uses the radiation of a blackbody operating at about 1200 K with a precision aperture. The blackbody radiation can be calculated by Planck's law and is additionally spectrally selected by accurately characterized optical bandpass filters. Thus, a calibration of the spectral responsivity of a detector with respect to irradiance can be achieved at the bandpass wavelength of the applied transmission filters. If the aperture of the detector is known, the spectral responsivity can also be calculated with respect to radiant power. Thermopile detectors with known aperture size were calibrated in terms of their spectral responsivity with several bandpass filters in the spectral range between 1.5 µm up to 14 µm with relative standard measurement uncertainties between 5 % and 19 %. The obtained results are consistent with previous calibrations at PTB's national primary detector standard. Therefore, this additional measurement approach is a further validation of the existing primary method which is based on a cryogenic radiometer and extends the usable wavelength range.

Multilayer Coatings and Optical Materials for Tuned Infrared Emittance and Thermal Control

1998 ◽  
Vol 555 ◽  
Author(s):  
P. M. Martin ◽  
J. W. Johnston ◽  
W. D. Bennett
Keyword(s):  
Thin Film ◽  
Near Infrared ◽  
Fiber Optic ◽  
Multilayer Coating ◽  
Thermal Control ◽  
Dielectric Materials ◽  
Base Layer ◽  
Multilayer Coatings ◽  
Wavelength Band ◽  
Absorption Bands

AbstractMany thermal control applications require thin film coatings that emit or absorb strongly at near infrared and infrared wavelengths. One of the primary applications for these coatings is thermal control for surfaces and structures of spacecraft, which are exposed to solar radiation during at least 60% of their orbit, causing wide temperature fluctuations. Another recent application for this type of coating is infrared emissive imaging employing a fiber optic infrared scene projector. While single layer coatings can provide high emissivity in a broad wavelength band, multilayer coatings can be used to obtain higher emissivities over a narrow wavelength band. This band can be tuned to a specific range of temperatures and wavelengths. Coatings developed for thermal control have a reflective base layer, either ZrN or a refractory metal boride or silicide. These materials have increased durability compared to metal layers. The multilayer coating deposited over the based layer consists of an A1203/SiO2 stack with high emittance at 300 K (9.8 μm), and solar reflectance near 0.6. Multilayer tuned infrared absorber/emitter coatings are applied to fiber optic infrared scene projectors. The coatings consists of a three layer Si3N4/Cr/Si3N4 absorber tuned at the 1.06 μtm laser wavelength, and a six layer Cr/dielectric/Cr/dielectric/Cr/dielectric coating which emits strongly in either the 3 - 5 jim or the 8 - 12 μm infrared wavelength bands. Absorption bands of the coatings are independently tunable. All coatings are deposited by reactive DC and RF magnetron sputtering onto 2.5-in fiber optic faceplates. Either Si3N4, Si, or ZnS thin film dielectric materials were used in the emitter coatings. With an input laser power of 15 W, the coatings emit at a black body temperature 529 K, which compared well with predicted performance.

scholarly journals Frequency-selective surface based bandpass filters in the near-infrared region

2004 ◽  
Vol 41 (4) ◽  
pp. 266-269 ◽  
Author(s):  
Srikanth Govindaswamy ◽  
Jack East ◽  
Fred Terry ◽  
Erdem Topsakal ◽  
John L. Volakis ◽  
...  
Keyword(s):  
Near Infrared ◽  
Frequency Selective Surface ◽  
Bandpass Filters ◽  
Infrared Region ◽  
Near Infrared Region ◽  
Frequency Selective

Construction of a near-infrared responsive upconversion nanoplatform against hypoxic tumors via NO-enhanced photodynamic therapy

Nanoscale ◽  
2020 ◽  
Vol 12 (14) ◽  
pp. 7875-7887 ◽  
Author(s):  
Ying Lan ◽  
Xiaohui Zhu ◽  
Ming Tang ◽  
Yihan Wu ◽  
Jing Zhang ◽  
...  
Keyword(s):  
Photodynamic Therapy ◽  
Near Infrared ◽  
Upconversion Nanoparticles

A near-infrared (NIR) activated theranostic nanoplatform based on upconversion nanoparticles (UCNPs) is developed in order to overcome the hypoxia-associated resistance in photodynamic therapy by photo-release of NO upon NIR illumination.

A nitroreductase-activatable near-infrared theranostic photosensitizer for photodynamic therapy under mild hypoxia

2020 ◽  
Vol 56 (43) ◽  
pp. 5819-5822
Author(s):  
Jing Zheng ◽  
Yongzhuo Liu ◽  
Fengling Song ◽  
Long Jiao ◽  
Yingnan Wu ◽  
...  
Keyword(s):  
Photodynamic Therapy ◽  
Triplet State ◽  
Near Infrared ◽  
Mild Hypoxia

In this study, a near-infrared (NIR) theranostic photosensitizer was developed based on a heptamethine aminocyanine dye with a long-lived triplet state.

Fluorescent proteins for in vivo imaging, where's the biliverdin?

2020 ◽  
Vol 48 (6) ◽  
pp. 2657-2667
Author(s):  
Felipe Montecinos-Franjola ◽  
John Y. Lin ◽  
Erik A. Rodriguez
Keyword(s):  
Hydrogen Peroxide ◽  
In Vivo Imaging ◽  
Near Infrared ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Fluorescent Imaging ◽  
Infrared Light ◽  
Red Fluorescent Protein ◽  
Color Palette

Noninvasive fluorescent imaging requires far-red and near-infrared fluorescent proteins for deeper imaging. Near-infrared light penetrates biological tissue with blood vessels due to low absorbance, scattering, and reflection of light and has a greater signal-to-noise due to less autofluorescence. Far-red and near-infrared fluorescent proteins absorb light >600 nm to expand the color palette for imaging multiple biosensors and noninvasive in vivo imaging. The ideal fluorescent proteins are bright, photobleach minimally, express well in the desired cells, do not oligomerize, and generate or incorporate exogenous fluorophores efficiently. Coral-derived red fluorescent proteins require oxygen for fluorophore formation and release two hydrogen peroxide molecules. New fluorescent proteins based on phytochrome and phycobiliproteins use biliverdin IXα as fluorophores, do not require oxygen for maturation to image anaerobic organisms and tumor core, and do not generate hydrogen peroxide. The small Ultra-Red Fluorescent Protein (smURFP) was evolved from a cyanobacterial phycobiliprotein to covalently attach biliverdin as an exogenous fluorophore. The small Ultra-Red Fluorescent Protein is biophysically as bright as the enhanced green fluorescent protein, is exceptionally photostable, used for biosensor development, and visible in living mice. Novel applications of smURFP include in vitro protein diagnostics with attomolar (10−18 M) sensitivity, encapsulation in viral particles, and fluorescent protein nanoparticles. However, the availability of biliverdin limits the fluorescence of biliverdin-attaching fluorescent proteins; hence, extra biliverdin is needed to enhance brightness. New methods for improved biliverdin bioavailability are necessary to develop improved bright far-red and near-infrared fluorescent proteins for noninvasive imaging in vivo.

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