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Titolo:
Visible lesion threshold dependence on retinal spot size for femtosecond laser pulses
Autore:
Cain, CP; Toth, CA; Noojin, GD; Stolarski, DJ; Thomas, RJ; Cora, S; Rockwell, BA;
Indirizzi:
USAF, Res Lab, HEDO, Brooks AFB, TX 78235 USA USAF Brooks AFB TX USA 78235 SAF, Res Lab, HEDO, Brooks AFB, TX 78235 USA Litton TASC, San Antonio, TX 78212 USA Litton TASC San Antonio TX USA 78212 tton TASC, San Antonio, TX 78212 USA Duke Univ, Ctr Eye, Durham, NC 27710 USA Duke Univ Durham NC USA 27710Duke Univ, Ctr Eye, Durham, NC 27710 USA
Titolo Testata:
JOURNAL OF LASER APPLICATIONS
fascicolo: 3, volume: 13, anno: 2001,
pagine: 125 - 131
SICI:
1042-346X(200106)13:3<125:VLTDOR>2.0.ZU;2-C
Fonte:
ISI
Lingua:
ENG
Soggetto:
RHESUS-MONKEY; PRIMATE EYE; DAMAGE; MODEL; INJURY;
Keywords:
laser bioeffects; laser safety; retinal damage; ultrashort laser pulses;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Engineering, Computing & Technology
--discip_EC--
Citazioni:
25
Recensione:
Indirizzi per estratti:
Indirizzo: Rockwell, BA USAF, Res Lab, HEDO, 8111 18th St, Brooks AFB, TX 78235 USA USAF 8111 18th St Brooks AFB TX USA 78235 s AFB, TX 78235 USA
Citazione:
C.P. Cain et al., "Visible lesion threshold dependence on retinal spot size for femtosecond laser pulses", J LASER APP, 13(3), 2001, pp. 125-131

Abstract

National laser safety standards have only recently been specified for laser pulse widths below 1 ns, with the publication of the ANSI Z136.1-2000 American National Standard for Safe Use of Lasers. A number of in vivo retinalinjury studies using ultrashort laser pulses have been documented for pulse widths from nanoseconds to femtoseconds and having wavelengths from 1064 to 530 nm. These studies report data corresponding to the smallest retinal image diameters that can be achieved experimentally. The resulting data have been used to establish the exposure limits for small-source laser emitters. Data have shown that the thresholds decrease with pulse width and with wavelength for minimal retinal spot sizes. In this article we present measurements of the retinal lesion threshold as a function of retinal image size for 150 fs ultrashort laser pulses at 1060 nm. Retinal image size was varied from approximately 48 to 800 mum in diameter using external optics. Thresholds were determined using probit analysis of the data. The retinal spot sizes were calculated using the Gaussian beam propagation and multiple-lens formulas. The thresholds as a function of retinal image size were then compared to previously reported spot size studies. Results of our measurements show that as the retinal image diameter is increased from 48 to 800 mum, the threshold at 24 h postexposure increases from 1 to 54.1 muJ, corresponding to the fluence at the retina decreasing by a factor of five (from 56 to 11 mJ cm(-2)). Our results also show that as the retinal spot size increases, the radiant exposure necessary to cause a minimal visible lesion decreases, but not in proportion to the retinal image area. This decreasing radiantexposure for increasing retinal spot sizes at 150 fs follows the trends shown for previous studies with pulse duration from 30 ps to 10 s. Thus, extended sources for 150 fs and 1060 nm show no deviation from the trend of decreasing radiant exposure for increasing retinal image sizes. We conclude from our data that the current correction factors used in the laser safety standards also apply to femtosecond laser exposures between 400 and 1400 nm. (C) 2001 Laser Institute of America.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 18/01/20 alle ore 07:25:32