In this paper we present new results concerning the optical and morphologic properties of YVO4:Eu red nanophosphor
prepared by a precipitation method and subsequently annealed in air at various temperatures. We monitored the morphologic changes induced by the thermal treatments using the optical spectroscopy (reflectance and luminescence spectra), XRD and electron microscopy. The annealing leads to an increase of the particle size and improvement of the order of the crystalline lattice of YVO4. The annealing at 800°C produces the sample with the highest luminescence intensity.
Different accuracy enhancement devices have been and are being developed in order to improve the manipulation
accuracy of microsurgeons. The paper presents a one-degree-of-freedom proof of concept of a laser deflection system for
acousto-optic compensation of hand tremor. A recording of physiological tremor acquired in vivo during vitreoretinal
surgery in a rabbit model was used for the present experiment. When operating with a hand motion input tremor
amplitude of 4 microns rms, the average overall canceling error is 0.8 microns rms. The results obtained demonstrate the
general feasibility of the concept of tremor cancellation in laser surgery by using acousto-optic deflection.
Tissue ablation by mid-IR lasers is described using the linear mass loss model. The steady state equation, which relates the ablation depth to laser radiant exposure, can be transformed to characterize the dynamic crater formation. After the presentation of the steady state results obtained with the linear mass loss model,the basic equation is transformed into a time dependent equation. To calculate the focusability of laser beams, and hence the irradiance in the focal zone, the spot-size propagation for a Gaussian beam is taken into account. The model can be generalized for higher order modes by introducing the coefficient of beam quality (M2). The analytical solutions of the new equation gives valuable information on crater shape and dimensions on time evolution for crater formation and on time dependence of the ablation velocity. A comparison with experimental results proves usefulness of dynamic characterization of crater formation based on the time dependent linear mass loss model.
This paper presents a comprehensive review of the CO2 laser ablation of biological tissue. Based on energy balance for modeling laser ablation, the thermal relaxation time and the ablation threshold are determined. Laser ablation of biological tissue is related to the spatial coherence of laser beams, so that the propagation of laser beams, the beam quality and the focusability of laser beams are taken into consideration. To achieve the ablation threshold, the laser irradiance in the focal zone is computed as a function of laser parameters. The advantages of pulsed operation of the CO2 laser for minimum residual thermal damage of the tissue are stressed. The strengths and the weaknesses of the CO2 laser ablation are finally discussed.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.