Linked Life Data

12928822

Source:http://linkedlifedata.com/resource/pubmed/id/12928822

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
2003-8-20
pubmed:abstractText
Uniform dosimetry is a prerequisite for reproducible laser applications in research and practice. The light-tissue interaction is dependent on the absorbed energy (J) per unit of time (tau) in the case of pulsed lasers, and on the absorbed power (W) per unit of volume (e.g. mm3) in the case of continuous-wave (cw) lasers, and thus directly dependent on the energy distribution within the laser beam. Consequently, precise knowledge of the spatial beam profile, and of the pulse duration and treatment time, is indispensable. The objective of this paper was a theoretical study of the impact of different mode profiles on energy distribution in the beam. Also examined was the question of the influence of changes in the laser parameters on the mode structure. Three erbium:YAG lasers (lambda=2.94 microm) were used for this purpose. The transversal mode structure of the lasers was observed by irradiating thermal paper and verified by means of calculations. The effect induced in the mode profile by changing the pulse energy and pulse repetition rate was investigated. The results of the tests show that changes in the laser parameters result in jumps in the transversal modes and associated energy distributions in the beam. The experiments confirm that simply changing the transversal modes has a substantial effect on the threshold energy required for the ablation of dental enamel (50 mJ with TEM00, 22.6 mJ with TEM31). In practice, inhomogeneity makes it impossible to determine the irradiated area in order to calculate the energy or power density. In addition, the energy distribution in the beam changes as a result of variation of the laser output energy and the pulse repetition rate. Consequently, simply measuring the beam diameter yields a totally incorrect result for the applied flux density when using a beam profile with a relatively high mode.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
0268-8921
pubmed:author
pubmed:issnType
Print
pubmed:volume
18
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
112-8
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2003
pubmed:articleTitle
Influence of the spatial beam profile on hard tissue ablation. Part I: Multimode emitting Er:YAG lasers.
pubmed:affiliation
Department of Conservative Dentistry, Periodontology and Preventive Dentistry, Aachen University, Germany. jmeister@ukaachen.de
pubmed:publicationType
Journal Article, In Vitro