Comparative analysis of two optical biometry devices: high wavelength swept source OCT versus partial coherence interferometry

Purpose To study the reproducibility of measurements performed with a recently developed multimodal high resolution swept source optical coherence tomography (SSOCT) and to make comparisons with a partial coherence interferometry (PCI) biometer. Methods One hundred and fifty-two eyes of 152 subjects were involved in this study with a mean age of 65.71 ± 13.86 years (26–85 years). Anterior surface keratometry (K), anterior chamber depth (ACD), white-to-white (WTW) and axial length (AL) values were recorded by the SSOCT (ANTERION, Heidelberg Engineering Ltd, Germany) and PCI (IOLMaster 500, version 5.5, Carl Zeiss Meditec, Germany). Intraocular lens (IOL) power was calculated based on ANTERION and IOLMaster keratometry values by using five traditional vergence formulas. Results Anterior surface simulated keratometry values did not differ significantly between the IOLMaster and ANTERION (P > 0.05). AL measurements were successful in 95% of the cases both with the SSOCT and PCI. No significant difference was disclosed between the two instruments (P = 0.229). For WTW measurements, a significant difference was observed between the two optical biometers (P < 0.0001). The difference between PCI and SSOCT in IOL powers was statistically significant for SRK/T, Hoffer and Holladay formulas (P < 0.001). Conclusion Our results implicated an overall good reproducibility of anterior keratometry, AL, ACD and WTW measurements for IOLMaster and ANTERION. The discrepancies between their measurements resulted in significant difference in the calculated IOL power for SRK/T, Hoffer and Holladay formulas, but not for Haigis formula.

Synthesis and Properties of Polyimide Silica Nanocomposite Film with High Transparent and Radiation Resistance

In order to prepare flexible glass cover sheet materials suitable for space solar cells, fluorinated diamine 2,2’-bistrifluoromethyl benzidine (TFDB) and fluorinated dianhydride 4,4’ (hexafluoroisopropyl) diphthalic dianhydride (6FDA) as the monomer, polyimide (PI)/SiO2 composite film was synthesized by in situ polymerization, and the influence of coupling agent and SiO2 nanoparticle content on the film structure and properties was studied. The results show that PI synthesized from fluorine-containing monomers has better light transmittance, and the highest transmittance can reach 91.4%. The average visible light transmittance of the composite film decreases with the increase of SiO2 content, and the transmittance of the film decreases less in the high-wavelength region and greatly decreases in the low-wavelength region. The tensile strength and elastic modulus of PI/SiO2 composite film increase with the increase of SiO2 content, first increase and then decrease, reaching the maximum when the content is 10%; while the elongation at break of the composite film gradually increases with the increase of SiO2 content reduce. The thermal stability of PI/SiO2 composite film increases with the increase of SiO2 content. The doping of nano-SiO2 significantly suppresses the influence of irradiation on the mechanical properties of the film.

Core–shell NaErF4@NaYF4 upconversion nanoparticles qualify as a NIR speckle wavemeter for a visible CCD

This work demonstrated a NIR speckle wavemeter using a visible CCD assisted by prepared NaErF4@NaYF4 upconversion nanoparticles. High wavelength precision was achieved through a designed neural network and cylindrical random scattering waveguide.

Frame overlap Bragg edge imaging

Neutron Bragg edge imaging enables spatially resolved studies of crystalline features through the exploitation and analysis of Bragg edges in the transmission spectra recorded in each pixel of an imaging detector. Studies with high spectral resolutions, as is required e.g. for high-resolution strain mapping, and with large wavelength ranges have been largely reserved to pulsed neutron sources. This is due to the fact, that the efficiency for high wavelength resolution measurements is significantly higher at short pulse sources. At continuous sources a large fraction of the available neutrons must be sacrificed in order to achieve high wavelength resolution for a relevant bandwidth e.g. through a chopper system. Here we introduce a pulse overlap transmission imaging technique, which is suited to increase the available flux of high wavelength resolution time-of-flight neutron Bragg edge imaging at continuous neutron sources about an order of magnitude. Proof-of-principle measurements utilizing a chopper with a fourfold repeated random slit distribution of eight slits were performed at a thermal neutron beamline. It is demonstrated, that disentanglement of the overlapping pulses is achieved with the correlation theorem for signal processing. Thus, the Bragg edge pattern can be reconstructed from the strongly overlapping Bragg edge spectra recorded and the results demonstrate the feasibility of the technique.

Thermal Radiation Effect on Entropy in Hydromagnetic Peristaltic Flow of a Jeffrey Nanofluid Through an Unsymmetrical Channel

The present work focuses on the thermal radiation effect in Hydro Magnetic peristaltic pumping of Jeffrey nano fluid in an unsymmetrical channel. The present work looks at the radiation effect, magnetic field, Brownian motion, thermophoresis, and buoyancy forces. Well established high wavelength and tiny Reynolds number assumptions are invoked. The exact solution for the velocity, concentration, temperature has been evaluated. It has been observed that temperature is reducing with increasing of Radiation parameter