LGYSB:Nd─High-Performance Lasing in the Near-Infrared Region

Three incongruent melting LawNdxGdyYzSc4-w-x-y-z(BO3)4 (LGYSB:Nd) crystals with different Y concentrations (z = 0.15, 0.05, and 0.025) have been grown by the Czochralski method for the first time. The LGYSB:Nd-type crystals exhibit an acentric structure similar to that of the natural mineral huntite CaMg3(CO3)4, with space group R32. The composition of the LGYSB:Nd_3 (z = 0.025) crystal grown from the starting melt composition La0.628Gd0.547Y0.025Nd0.05Sc2.75(BO3)4 was measured by inductively coupled plasma mass spectrometry method, and it was found to be La0.6794Gd0.4105Y0.0178Nd0.0381Sc2.8542(BO3)4. The transversal spatial distribution of the refractive index in the LGYSB:Nd_3 crystal was investigated. Third-order nonlinear optical susceptibility χ(3) of the LGYSB:Nd_3 crystal was determined from third-harmonic generation experiments with ultrashort (fs) laser pulses. The optical transmission spectrum was measured in the range of 200-2000 nm. The absorption cross-section at 808 nm in σ-polarization was determined to be 1.18 × 10-19 cm2 for the LGYSB:Nd_3 crystal. The 10K absorption spectra revealed that the Nd3+ ions occupy only La3+ cationic sites in the LGYSB host matrix. The emission cross-section at 1064 nm in σ-polarization was determined to be σem(σ) = 1.74 × 10-19 cm2 for the LGYSB:Nd_3 crystal. The fluorescence lifetime was found to be τ = 115 μs for all of the LGYSB:Nd crystals. The LGYSB:Nd_3 laser was operated at an emission wavelength of 1062 nm with very high slope efficiencies of ηsa = 0.74 and ηsa = 0.64 in quasi-cw and cw regimes, respectively.

RE3+-Doped Ca3(Nb,Ga)5O12 and Ca3(Li,Nb,Ga)5O12 Crystals (RE = Sm, Dy, and Pr): A Review of Current Achievements

Spectroscopic characteristics of RE³⁺ ions (RE = Sm, Dy, and Pr) doped in partially disordered Ca₃Nb_1.6875Ga_3.1875O₁₂-CNGG and Ca₃Li_0.275Nb_1.775Ga_2.95O₁₂-CLNGG crystals are reviewed in detail to assess their prospects as laser crystals with emission in the visible spectral domain. All investigated crystals were grown using the Czochralski crystal growth technique. High-resolution absorption and emission measurements at different temperatures, as well as emission dynamics measurements, were performed on the grown crystals. The spectroscopic and laser emission characteristics of the obtained crystals were determined based on the Judd-Ofelt parameters. The obtained results indicate that CNGG:RE³⁺ and CLNGG:RE³⁺ (RE = Sm, Dy, and Pr) crystals can be promising materials for lasers in the visible range.

Efficient 1 µm Laser Emission of Czochralski-Grown Nd:LGSB Single Crystal

A 5.0-at.% Nd-doped La_0.64Gd_0.41Sc_2.95(BO₃)₄ (Nd:LGSB) borate laser crystal was successfully grown by the Czochralski method, for the first time to our knowledge. The spectroscopic properties of the grown crystal are discussed and 1 µm laser emission, under end-pumping with a fiber-coupled diode laser at 807 nm, is reported. A c-cut Nd:LGSB medium yielded 1.35 W continuous-wave output power at 0.63 overall optical-to-optical efficiency, with respect to the absorbed pump power, together with the high 0.68 slope efficiency. With an a-cut Nd:LGSB sample, 0.81 W output power at 0.52 optical-to-optical efficiency was obtained. The laser emission performances under quasi-continuous wave pumping are presented as well, for both c-cut and a-cut crystals. Passive Q-switching was investigated with a semiconductor saturable absorber mirror (SESAM). Laser pulses with 2.2 µJ energy and 32.8 ns durations were recorded from a-cut Nd:LGSB. The average output power reached 0.36 W at 1.55 W absorbed pump power. Passive mode-locking with SESAM was achieved in a long Z-type resonator. Ultrashort pulses with 0.19 W average power, 1.63 nJ energy, and 1.43 ps pulse duration, at 118 MHz repetition rate, are demonstrated for the a-cut Nd:LGSB medium.

Upper and lower conjunctival fornix depth in healthy white caucasian eyes: a method of objective assessment

PurposeEvaluating anti-scarring therapies require objective assessment of scarring, and knowledge of normal fornix anatomy. Measurement of conjunctival scarring has focused on inferior fornix shortening, although the superior fornix is often overlooked. There are data on normal fornix depth (FD) in South Asians, but there are no studies investigating normal conjunctival FD in white Caucasians. We designed a fornix depth measurer (FDM) for objective measurement of upper and lower conjunctival FD. The purpose of this study was to evaluate intra- and inter-observer variability, and to establish a reference for normal conjunctival FD in an ethnically white Caucasian population.Patients and methodsProspective cross-sectional study evaluating conjunctival FD in 252 clinically normal white Caucasian participants aged 20-80. Paired observers evaluated inter- and intra-observer variability. Data was analyzed using Bland-Altman plots and analysis of variance.ResultsFor white Caucasian subjects, mean upper and lower conjunctival fornix depths were 15.6 mm (95% confidence interval (CI), 12.5-18.8) and 10.9 mm (95% CI, 8.0-13.7), respectively. Females have smaller FDs (upper FD 15.3 mm±1.6 females, 16.2 mm±1.4 males, P<0.001; lower FD 10.6 mm±1.3 females, 11.3 mm±1.4 males, P<0.001). There was a progressive decline in FD with age (upper fornix depth 16.3 mm±1.2 at age 20-29, and 15.0 mm±1.8 at age 80+ (P=0.04)). There was 94-100% intra-observer and inter-observer agreement for upper and lower fornix measurements.ConclusionsUsing a slightly different custom-designed FDM, central conjunctival fornix depth in white Caucasian eyes appears to be similar to data previously reported in South Asian eyes. Fornix depth measurements were repeatable and reproducible.

Efficient sensitization of Yb3+ emission by Nd3+ in Y2O3 transparent ceramics and the prospect for high-energy Yb lasers

Very efficient energy transfer from Nd3+ to Yb3+ in transparent Y2O3 ceramics in the temperature range 10-300 K is demonstrated. It is inferred that this shows potential for the construction of high-energy Yb3+ lasers under diode or flash-lamp excitation of Nd3+.

Patterns of ophthalmological complaints presenting to a dedicated ophthalmic Accident & Emergency department: inappropriate use and patients' perspective

OBJECTIVES

To investigate the appropriateness of patients attending an Accident & Emergency (A&E) department of an eye hospital, identify reasons for inappropriate use and propose recommendations in improving the provision of ophthalmic A&E care.

METHODS

A prospective questionnaire-based survey of consecutive patients who presented to the A&E department over a 7-day period was conducted. Patient demographic data, reason for attending from the patients' perspective, diagnosis, duration of symptom and management outcome were recorded. The diagnoses were grouped into acute and non-acute, and into those which were considered suitable to be seen in a primary care setting by specialist trained community general practitioners (GPs) or optometrists.

RESULTS

560 completed questionnaires were evaluated; 171 cases (30.6%) were considered as non-acute and 210 (37.5%) were considered suitable to be seen by specialist trained community GPs or optometrists. 352 patients (62.8%) had symptoms for 1-6 days, 144 (25.7%) had symptoms for 1-4 weeks and 64 (11.5%) had symptoms for >1 month before presentation; in the latter two groups, 52 of the 208 patients (25%) were diagnosed with non-acute conditions. "Great concern" was the most common reason for attending the casualty department. 350 patients (62.5%) were discharged on the day of presentation.

CONCLUSIONS

A significant number of patients who attend ophthalmic A&E departments have non-urgent conditions that could be managed satisfactorily in a primary care setting by specialist trained GPs or optometrists outside the hospital casualty department. Improvement in education of patients, the provision of specialist ophthalmic training for GPs and optometrists, and expansion of outpatient services are needed so that casualty remains a genuine emergency service.

["Repeating" the transference? The central relationship conflict topic of the 290th session--questions, problems, results]

The following text sums up the results of an examination of a therapeutic session in which a psychoanalyst treated a patient suffering from neurotic depression. We employed the CCRT method which was applied at various levels of abstraction and in two steps of evaluation. The standard evaluation procedure allows for both a more thorough evaluation of "self-relationship episodes" and episodes involving other objects. An integration of "tailor-made" formulations allowed us to analyse another set of "relationship-patterns": namely, those which, in contrast to those most often found in conflict themes, contain positive traits. These results were then discussed clinically to examine these in light of the therapeutic conception of depression. In this context, the question arose as to whether the classic CCRT method can be fruitfully applied in long-term analysis and if this notion should be modified in order to examine the analysis of depression more effectively. A first attempt at such a modification was undertaken in the hope it would allow us to evaluate both the relevance of meaning passages contained in the clinical data and the visible processes of change.

[Artistic dream reconstructions of the Wolf Man in the light of experimental findings]

The authors take the famous dream picture by the "wolf-man" as the starting-point for experimental research of their own and relate the one to the other. They see the significance of pictorial representations of dreams less in the supplementary information they convey about the "text" of dreams than in the fact that they give separate expression to motility-based "gesture-associated" memories and ideas. These need to be distinguished from "language-associated" memories as there are dissociated modes of encoding experience underlying verbal and pictorial representation. The splitting of these modes into different part-codes is an important component of repression. In addition, the pictorial representation of dreams enables the patient to re-associate part-codes and thus achieve a "deferred" reconstruction and complementation of significant experiences. In the authors view, pictorial representation is favorable to the discovery of repressed material; it is as yet however impossible to say exactly what relationship there is between verbalized and pictorial representation in the context of analysis.

["Mother" and "father" in psychoanalytic case vignettes. On some latent rules in the discourse of psychoanalysis]

Proceeding from the conviction that there is a collective gender-specific unconscious within the community of psychoanalysts which determines latent rules operative in psychoanalytic discourse, the authors have conducted a research project extending over a number of years and systematically examining case descriptions in psychoanalytic journals to see to what extent those latent gender-specific rules are in fact observed in such publications. The project examines the way in which male and female analysts employ the terms "mother" and "father" in these publications and also the frequency and connotations of concepts related to "mother" and "father". Significant differences between male and female analysts become apparent, substantiating the assumption of a collective gender-specific unconscious. The authors conclude that this unconscious finds its way into psychoanalytic therapy, leading to unconscious counter-transference reactions that are acted out rather than worked on.