Light-induced lens analysis in photorefractive crystals employing phase-shifting real-time holographic interferometry

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Refractive and geometric lens characterization through multi-wavelength digital speckle pattern interferometry

Physical parameters of different types of lenses were measured through digital speckle pattern interferometry (DSPI) using a multimode diode laser as light source. When such lasers emit two or more longitudinal modes simultaneously the speckle image of an object appears covered of contour fringes. By performing the quantitative fringe evaluation the radii of curvature as well as the refractive indexes of the lenses were determined. The fringe quantitative evaluation was carried out through the four- and the eight-stepping techniques and the branch-cut method was employed for phase unwrapping. With all these parameters the focal length was calculated. This whole-field multi-wavelength method does enable the characterization of spherical and aspherical lenses and of positive and negative ones as well. (C) 2007 Elsevier B.V. All rights reserved.

Time-resolved Z-scan and thermal lens measurements in Er+3 and Nd+3 doped fluoroindate glasses

In rare earth ion doped solids, a resonant non-linear refractive index, n2, appears when the laser pumps one of the ion excited states and the refractive index change is proportional to the excited state population. In these solids there are usually thermal and non-thermal lensing effects, where the non-thermal one is due to the polarizability difference, Δα, between excited and ground states of the ions. We have used the time resolved Z-scan and a mode-mismatched thermal lens technique with an Ar+ ion laser in Er+3 (20ZnF2-20SrF2-2NaF-16BaF2-6GaF3-(36 - x)InF3-xErF3, with x= 1, 2, 3 and 4 mol%) and Nd+3 (20SrF2-16BaF2-20ZnF2-2GdF3-2NaF-(40 - x)InF3-xNdF3, with x = 0.1, 0.25, 0.5-1 mol%) doped fluoroindate glasses. In both samples we found that the non-linear refraction is due to the thermal effect, while the non-thermal effect is negligible. This result indicates that in fluoride glasses Δα is very small (less than 10-26 cm3). We also measured the imaginary part of the non-linear refractive index (n″2) due to absorption saturation.

Effects of metaraminol bitartrate on intraocular pressure in dogs under halothane anesthesia

The effects of metaraminol bitartrate on intraocular pressure (IOP) were studied in dogs anesthetized with halothane. Forty-five healthy, adult, mixed-breed dogs, of both sexes, were divided into three groups of 15 dogs each (GI, GII and GIII) and maintained under general anesthesia with halothane after tranquilization with levomepromazine and induction with thiopental. Saline (0.9%) was administered intravenously (IV) to GI through continuous infusion, at a velocity of 0.125 mL kg -1 min -1. GII and GIII received metaraminol 0.004% IV, at a dose of 5 μg kg -1 min -1, at 0.125 mL kg -1 min -1 and at a dose of 2 μg kg -1 min -1, at 0.06 mL kg -1 min -1, respectively. IOP was measured by applanation tonometry (Tono-Pen) before and during anesthesia. Results showed that IOP decreased in GI, increased in GII, and remained at basal levels in GIII. Continuous infusion of metaraminol at 2 μg kg min -1 maintained IOP at pretest levels, while infusion at 5 μg kg -1 min -1 produced an elevation of IOP.

Evaluation of intraocular and partial CO2 pressure in dogs anesthetized with propofol

The effects of propofol on intraocular pressure (IOP) and end tidal CO2 (ETCO2) were studied because an elevation in the latter may alter IOP. Twenty dogs were divided into two groups (G1 and G2). G1 dogs were induced with 10 mg/kg (IV) of propofol followed by a 0.4 mg/kg/min continuous infusion of the same agent diluted in a 0.2% dextrose solution for 1 h. G(CAPS) 2 dogs served as the control group, where only dextrose solution was administered, under the same time intervals as in G1. Applanation tonometry (Tono-Pen) was used to determine IOP and ETCO2 as a method to determine partial CO2 pressure. Measurements were taken every 15 min for 1 h, with M1 occurring immediately before IV administration. IOP and ETCO2 were not statistically significant in either groups. Based on the results, it may be concluded that propofol does not alter IOP and ETCO2.

Two-wavelength whole-field interferometry setup for thermal lens study

In this paper we present a new approach for thermal lens analysis using a two-wavelength DSPI (Digital Speckle Pattern Interferometry) setup for wavefront sensing. The employed geometry enables the sensor to detect wavefronts with small phase differences and inherent aberrations found in induced lenses. The wavefronts was reconstructed by four-stepping fringe evaluation and branch-cut unwrapping from fringes formed onto a diffusive glass. Real-time single-exposure contour interferograms could be obtained in order to get discernible and low-spacial frequency contour fringes and obtain low-noise measurements. In our experiments we studied the thermal lens effect in a 4% Er-doped CaO-Al2O3 glass sample. The diode lasers were tuned to have a contour interval of around 120 μm. The incident pump power was longitudinally and collinearly oriented with the probe beams. Each interferogram described a spherical-like wavefront. Using the ABCD matrix formalism we obtained the induced lens dioptric power from the thermal effect for different values of absorbed pump power. © 2012 Copyright SPIE.

The value of intraocular pressure asymmetry in diagnosing glaucoma

PURPOSE

Progressive power lens measurement by low coherence speckle interferometry

This work proposes a method for dioptric power mapping of progressive lenses through dual wavelength, low-coherence digital speckle pattern interferometry. Lens characterization finds several applications and is extremely useful in the fields of ophthalmology and astronomy, among others. The optical setup employs two red diode lasers which are conveniently aligned and tuned in order to generate a synthetic wavelength. The resulting speckle image formed onto a diffusive glass plate positioned behind the test lens appears covered of contour interference fringes describing the deformation on the light wavefront due to the analyzed lens. By employing phase stepping and phase unwrapping methods the wavefront phase was retrieved and then expressed in terms of a Zernike series. From this series, expressions for the dioptric power and astigmatic power were derived as a function of the x- and y-coordinates of the lens aperture. One spherical and two progressive lenses were measured. The experimental results presented a good agreement with those obtained through a commercial lensometer, showing the potentialities of the method. © 2013 Elsevier Ltd.

Ultrassonografia oftálmica em cães com diferentes conformações cranianas

The aim of this study was to establish mean values for intraocular structures and analyse if the differences are present for different skull conformations in dogs. In this study, 30 dogs were selected and distributed into three groups according to skull conformation; thus, group 1 (G1) was composed of brachycephalic dogs, group 2 (G2) was composed of mesocephalic dogs and group 3 (G3) was composed of dolichocephalic dogs. A and B-mode ultrasound was performed simultaneously for obtainment of measurements relating to anterior chamber depth (D1); lens thickness (D2); vitreous chamber depth (D3); and the axial length of the eye (D4). No differences were observed when comparing left and right eyes of dogs within the same skull conformation group (p>0.05). Differences were observed when comparing D3 and D4 between groups G2 and G3 (p<0.05). Skull conformation of brachycephalic dogs did not influence intraocular measurement values when compared to dolicephalic and mesocephalic dogs. Skull conformation of dolichocephalic dogs had an influence in values of vitreous chamber and the complete length of the eye when compared to mesocephalic dogs.

Conjunctival flora, Schirmer's tear test, intraocular pressure, and conjunctival cytology in neotropical primates from Salvador, Brazil

Background: This study aimed to establish reference values for selected ophthalmic diagnostic tests in healthy neotropical primates from Salvador, Brazil. Methods: A total of 73 intact adults, including Callithrix jacchus (n = 31), Callithrix penicillata (n = 8), Cebus sp. (n = 22), and Cebus xanthosternos (n = 9) were used to evaluate the normal conjunctival bacterial flora. Cebus xanthosternos (n = 12) were used to evaluate tear production with Schirmer's tear test (STT), intraocular pressure (IOP), and conjunctival cytology. Results: For all animals evaluated, Gram-positive bacteria were predominant. Results of the diagnostic tests in Cebus xanthosternos were as follows: STT: 14.92 ± 5.46 mm/minutes, IOP: 19.62 ± 4.57 mmHg, and conjunctival cytology revealed intermediate squamous epithelial cells in great quantities. Conclusions: These ophthalmic reference values will be particularly useful to diagnose discrete or unusual pathological changes in the neotropical primates eye. © 2013 John Wiley & Sons A/S.

Luminescence quantum efficiency at 1.5 μm of Er3+-doped tellurite glass determined by thermal lens spectroscopy

Erbium doped tellurite glasses (TeO2 + Li2O + TiO2) were prepared by conventional melt-quenching method to study the influence of the Er3+ concentration on the luminescence quantum efficiency (η) at 1.5 μm. Absorption and luminescence data were used to characterize the samples, and the η parameter was measured using the well-known thermal lens spectroscopy. For low Er3+ concentration, the measured values are around 76%, and the concentration behavior of η shows Er-Er and Er-OH- interactions, which agreed with the measured lifetime values. © 2013 Elsevier B.V. All rights reserved.

Glaucoma secundário em cães e gatos

Glaucoma is a syndrome that affects animals of different species and in different moments of his life, having variables causes in function of this presentation. It is an ophthalmic emergency that may develop irreversible vision damage as well as the patient's aesthetic presentation. Increased intraocular pressure, presence of engorged episcleral vessels, conjunctival hyperemia, pain, anterior uveitis, lens luxation and buftalmia are commonly clinical signs presented by dogs while in cats, signs are less expressive, noting mydriasis, mild ciliary injection and progressive buftalmia. For diagnosis are carried out three basic procedures: tonometry, gonioscopy and ophthalmoscopy. The treatment can establish with medical therapy with or without surgical intervention, however, at some point it will be necessary to perform enucleation or evisceration of the eye bulb.

Ultrassonografia do bulbo do olho de cães, com diferentes conformações cranianas

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Micropartículas biodegradáveis para liberação prolongada intraocular de cetorolaco de trometamina obtidas po Spray Drying

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)