A detailed experimental study of dispersion and anisotropy of thermo-optic coefficients dn/dT and thermal coefficients of the optical path W=dn/dT+(n-1)α is performed for tetragonal YVO(4) and GdVO(4) laser host crystals by a laser beam deviation method. It is supported by theoretical description of thermo-optic effects, taking into account the volumetric thermal expansion effect and the temperature dependence of electronic bandgap E(g). Linear thermal expansion coefficients α were also determined by a dilatometric technique. Thermo-optic dispersion formulas describing temperature variation of the refractive index and the thermal lens effect are derived for a wide spectral range of 0.4-2 μm. It allows us to estimate the values of E(g) and dE(g)/dT for the studied crystals. The influence of materials parameters and pumping conditions on thermal lens properties is discussed, revealing the significant impact of anisotropic and temperature-dependent thermal conductivity.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1364/AO.52.000698 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Biomarkers.
Alzheimers Dement
December 2024
Douglas Mental Health University Institute, Montreal, QC, Canada.
White matter hyperintensities (WMHs) are frequently observed in ageing individuals, and have a higher prevalence in neurodegenerative disorders such as Alzheimer's disease. Ex-vivo assessments of the microstructural alterations within WMHs have reported heterogeneous tissue alterations, with demyelination, axonal loss, and inflammation presenting with various degrees of severity. There is a crucial need to better assess the severity of WMH microstructural alterations in vivo, in particular with the emergence of anti-amyloid immunotherapies and the associated risk of Amyloid Related Imaging Abnormalities (ARIAs) in individuals with comorbid vascular disease.
View Article and Find Full Text PDFBackground: Dementia with Lewy bodies (DLB) frequently co-occurs with Alzheimer's disease (AD) pathologies, exacerbating disease progression. Biophysical models of diffusion imaging data, such as Neurite Orientation Dispersion and Density Imaging (NODDI), may reveal novel insights into the neurobiological substrates of AD on cortical and white matter microstructural injury.
Method: A cohort of 57 DLB patients on the DLB spectrum (33 clinically probable DLB and 14 prodromal DLB) and 57 cognitively unimpaired (CU) controls underwent NODDI and PET imaging with [F]-Flortaucipir and [C]-PiB (Table 1).
Biomarkers.
Alzheimers Dement
December 2024
Shandong Provincial Hospital affiliated to Shandong First Medical University, Jinan, China.
Background: Microstructural brain lesions have been linked to cognitive health. However, their combined effect and the role of the cognitive reserve (CR) remain unclear. We investigated the interplay of microstructural brain lesions and cognitive reserve in cognitive function in middle-aged and elderly adults.
View Article and Find Full Text PDFBiomarkers.
Alzheimers Dement
December 2024
Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, USA.
Background: In the context of pathological aging and Alzheimer's disease (AD), the overexpression of calcineurin has been identified as a factor linked to astrocyte reactivity, neuronal death, and inflammation. This suggests that inhibiting calcineurin or downstream nuclear factor of activated T cells (NFAT) signaling could be a promising strategy for preventing or slowing down AD pathophysiology.
Method: Baseline and annual MRI sessions including higher-order diffusion-weighted imaging was performed over four years on 43 dogs ranging from 5 to 8.
Background: Diffusion weighted imaging (DWI) of brain white matter is better at predicting future cognitive decline and medial temporal lobe atrophy than cerebrospinal fluid biomarkers in subjective cognitive decline (SCD). However, few studies have investigated gray matter DWI in SCD, despite the importance of regional gray matter changes as a biomarker for Alzheimer's Disease and related dementias.
Method: 316 cognitively normal participants from Cam-CAN (123 SCD) older than 55 were included in the analysis.
Want AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!