Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 2 de 2
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Opt Lett ; 45(13): 3435-3438, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32630864

RESUMO

Measurements of the refractive indices and the full set of longitudinal acousto-optical figures of merit in an orthorhombic single-crystal indium iodide (InI) were carried out. The high acousto-optic characteristics (M2 up to 1100×10-15s3kg-1) and strong optical anisotropy (Δn=0.47) make it possible to design various types of high-performance acousto-optic devices of the middle and far-infrared spectral range. In combination with a wide transparency range (0.62-51µm), the obtained characteristics make the crystal extremely promising in comparison with most existing analogs.

2.
Methods Appl Fluoresc ; 8(2): 025006, 2020 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-32069443

RESUMO

Upconversion nanoparticles have attracted considerable attention as luminescent markers for bioimaging and sensing due to their capability to convert near-infrared (NIR) excitation into visible or NIR luminescence. However, the wavelength of about 970 nm is commonly used for the upconversion luminescence excitation, where the strong absorption of water is observed, which can lead to laser-induced overheating effects. One of the strategies for avoiding such laser-induced heating involves shifting the excitation into shorter wavelengths region. However, the influence of wavelength change on luminescent images quality has not been investigated yet. In this work, we compare wavelengths of 920, 940 and 970 nm for upconversion luminescence excitation in the thickness of biological tissues in terms of detected signal intensity and obtained image quality (contrast and signal-to-background ratio). Studies on biological tissue phantoms with various scattering and absorbing properties were performed to analyze the influence of optical parameters on the depth and contrast of the images obtained under 920-970 nm excitation. It was shown that at the same power the excitation wavelength shift reduces the detected signal intensity and the resulting image contrast. Visualization of biological tissue samples using shorter excitation wavelengths 920 and 940 nm also reduces signal-to-background ratio (S/B) of the obtained images. The S/B of the obtained images amounted to 2, 6 and 8 for 920, 940 and 970 nm, respectively. It was demonstrated that pulse-periodic excitation mode is preferable for obtaining high quality luminescent images of biological tissues deep layers and minimize overheating. Short pulse durations (duty cycle 20%) don't result in heating even for 1 W cm-2 pumping power density and allow obtaining high luminescence intensity, which provides good images quality.


Assuntos
Luminescência , Nanopartículas/química , Humanos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...