Search results for "laser"
showing 10 items of 3161 documents
Colonoscopic surveillance in inflammatory bowel disease: state of the art reduction of biopsies.
2011
Longstanding colitis in inflammatory bowel disease (IBD) is associated with an increased risk for intraepithelial neoplasia (IN). White light endoscopy (WLE) with 40–50 random biopsies has been promoted for surveillance but may miss a significant proportion of lesions. In addition, the yield of random biopsies to detect IN is low, and random biopsies are expensive, labor-intensive and distract from scrutinizing the colon. Chromoendoscopy with targeted biopsies has proven its superiority over WLE in multiple randomized trials. It has been incorporated into many national and international guidelines. Virtual chromoendoscopy techniques carry the potential to provide contrast enhancement withou…
Visual and optical performance with hybrid multifocal intraocular lenses
2010
During the past years, the wish to become independent of spectacles has been growing among cataract and presbyopic patients due to many factors, such as the increase in near visual demands, the aesthetic need for a spectacle-free image and ageing of refractive surgery patients, among others. This review assesses recently published studies that analyse visual and optical performance through different metrics of eyes implanted with multifocal intraocular lenses (IOLs), particularly hybrid IOL designs. The published evidence suggests that hybrid multifocal IOLs provide very good outcomes in a number of visual and optical performance parameters. Patients implanted with this type of IOL obtain a…
Intraocular pressure measurements during flap preparation using 2 femtosecond lasers and 1 microkeratome in human donor eyes
2012
Purpose To evaluate and compare intraocular pressures (IOPs) during flap preparations performed using 2 femtosecond lasers and a mechanical microkeratome in human donor globes. Setting University Medical Center Mainz, Mainz, and Euroeyes Clinic Stuttgart, Stuttgart, Germany. Design Experimental study. Methods A cannula was inserted through the optic nerve in human globes. The IOP was obtained continuously during flap preparation using the 60 kHz Intralase femtosecond laser, the 200 kHz Visumax femtosecond laser, or the Amadeus II microkeratome. For each experiment, a normal lamellar flap preparation (regular procedure) and a worst-case procedure (femtosecond laser interface was pressed agai…
New method for remote and repeatable monitoring of intraocular pressure variations
2014
We present initial steps toward a new measurement device enabling high-precision, noncontact remote and repeatable monitoring of intraocular pressure (IOP)-based on an innovative measurement principle. Using only a camera and a laser source, the device measures IOP by tracking the secondary speckle pattern trajectories produced by the reflection of an illuminating laser beam from the iris or the sclera. The device was tested on rabbit eyes using two different methods to modify IOP: via an infusion bag and via mechanical pressure. In both cases, the eyes were stimulated with increasing and decreasing ramps of the IOP. As IOP variations changed the speckle distributions reflected back from th…
Comparison of Intraocular Pressure During Corneal Flap Preparation Between a Femtosecond Laser and a Mechanical Microkeratome in Porcine Eyes
2011
To compare the increase in intraocular pressure (IOP) during corneal flap preparation in porcine eyes when using a femtosecond laser or a mechanical microkeratome.The present study was conducted at a university hospital and a private clinic.The vitreous IOP was directly measured with a cannula through the optic nerve in 24 porcine globes (n = 12 for each device). In the first procedure (worst-case procedure), the eye interface was lowered against the globe until abortion of the docking maneuver when using the IntraLase femtosecond laser (Abbott Medical Optics, Santa Ana, CA) or the suction ring was pressed very firmly against the globe when using the Amadeus microkeratome (Ziemer Ophthalmic…
The identification of autoionizing states of atomic chromium for the resonance ionization laser ion source of the ISOLDE radioactive ion beam facility
2017
Abstract This paper presents the results of an investigation into autoionizing states of atomic chromium, in the service of the resonance ionization laser ion source (RILIS): the principal ion source of the ISOLDE radioactive ion beam facility based at CERN. The multi-step resonance photo-ionization process enables element selective ionization which, in combination with mass separation, allows isotope specific selectivity in the production of radioactive ion beams at ISOLDE. The element selective nature of the process requires a multi-step “ionization scheme” to be developed for each element. Using the method of in-source resonance ionization spectroscopy, an optimal three-step, three-reson…
CRIS: A new method in isomeric beam production
2013
The Collinear Resonance Ionization Spectroscopy (CRIS) experiment at ISOLDE, CERN, uses laser radiation to stepwise excite and ionize an atomic beam for the purpose of ultra-sensitive detection of rare isotopes, and hyperfine-structure measurements. The technique also offers the ability to purify an ion beam that is heavily contaminated with radioactive isobars, including the ground state of an isotope from its isomer, allowing decay spectroscopy on nuclear isomeric states to be performed. The isomeric ion beam is selected by resonantly exciting one of its hyperfine structure levels, and subsequently ionizing it. This selectively ionized beam is deflected to a decay spectroscopy station (DS…
Towards high-resolution laser ionization spectroscopy of the heaviest elements in supersonic gas jet expansion
2017
Resonant laser ionization and spectroscopy are widely used techniques at radioactive ion beam facilities to produce pure beams of exotic nuclei and measure the shape, size, spin and electromagnetic multipole moments of these nuclei. However, in such measurements it is difficult to combine a high efficiency with a high spectral resolution. Here we demonstrate the on-line application of atomic laser ionization spectroscopy in a supersonic gas jet, a technique suited for high-precision studies of the ground- and isomeric-state properties of nuclei located at the extremes of stability. The technique is characterized in a measurement on actinium isotopes around the N=126 neutron shell closure. A…
Radium ionization scheme development: The first observed autoionizing states and optical pumping effects in the hot cavity environment
2018
© 2018 The Authors This paper reports on resonance ionization scheme development for the production of exotic radium ion beams with the Resonance Ionization Laser Ion Source (RILIS) of the CERN-ISOLDE radioactive ion beam facility. During the study, autoionizing states of atomic radium were observed for the first time. Three ionization schemes were identified, originating from the 7s2 1S0 atomic ground state. The optimal of the identified ionization schemes involves five atomic transitions, four of which are induced by three resonantly tuned lasers. This is the first hot cavity RILIS ionization scheme to employ optical pumping effects. The details of the spectroscopic studies are described …
Partial Laser Cooling and Saturation Spectroscopy on 9 MeV 7Li+ - Ions in a Storage Ring
1989
Publisher Summary Laser cooling and spectroscopy in traps have reached impressive perfections. This chapter discusses laser cooling and partially Doppler-suppressed spectroscopy on stored ions at 5.4% speed of light in the test storage ring (TSR) heavy ion storage ring in Heidelberg. It discusses the requirements for saturation spectroscpy with two counterpropagating collinear laser beams. In contrast to Penning and RF-traps, the ions in a storage ring move at a high longitudinal velocity with small transverse harmonic oscillations around the central orbit with just a few times the orbiting frequency in the case of strong focussing. However, the injection of the high velocity beam introduce…