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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 17
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Book Description
The eyes of 38 anesthetized rhesus monkeys were exposed to near-infrared laser radiation from a repetitive pulse gallium arsenide laser. Pulse repetition frequencies of 40 pps and 1,000 pps were utilized with a 20 nsec. pulse width at the wavelength of 905 nm. Lesions for threshold determination were placed in the temporal paramacular area and could be produced only by varying exposure duration with fixed energy output. Therefore, the resultant 50% probability of damage values (ED-50) were expressed as total exposure duration rather than energy per pulse. The ED-50 value of 0.72 sec. for the 1, 000 pps exposure is significantly lower than the 22.3 sec. for the 40 pps exposure and demonstrates a cumulative effect.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 17
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Book Description
The eyes of 38 anesthetized rhesus monkeys were exposed to near-infrared laser radiation from a repetitive pulse gallium arsenide laser. Pulse repetition frequencies of 40 pps and 1,000 pps were utilized with a 20 nsec. pulse width at the wavelength of 905 nm. Lesions for threshold determination were placed in the temporal paramacular area and could be produced only by varying exposure duration with fixed energy output. Therefore, the resultant 50% probability of damage values (ED-50) were expressed as total exposure duration rather than energy per pulse. The ED-50 value of 0.72 sec. for the 1, 000 pps exposure is significantly lower than the 22.3 sec. for the 40 pps exposure and demonstrates a cumulative effect.
Author: Martino Grandolfo
Publisher: Springer Science & Business Media
ISBN: 1489906614
Category : Science
Languages : en
Pages : 420
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Book Description
This volume contains the formal record of the lectures presented at the 9th Course of the International School of Radiation Damage and Protection held at the "E . Majorana" International Centre for Scientific Culture in Erice (Italy) from May 9 to May 20, 1989. This course was the last of a series of 4 courses, started in 1981, that were dedicated to the assessment of risk hazard from non-ionizing radiation. The proceedings of these courses were all published by Plenum Press with the following headings: 1) M. Grandolfo, S. M. Michaelson and A. Rindi, Eds. : "Biological Effects and Dosimetry of Nonionizing Radiation; Radiofrequency and Microwave Energy", Plenum Press, New York, NATO ASI Series A Life Sciences, Vo1. 49 (1983); 2) M. Grandolfo, S. M. Michaelson and A. Rindi, Eds. : "Biological Effects and Dosimetry of Static and ELF Electromagnetic Fields", Plenum Press, New York, E. Majorana International Science Series, Life Sciences, Vol. 19 (1985) ; 3) M. H. Repacholi, M. Grandolfo and A. Rindi, Eds. : "Ultrasound; medical applications, biological effects and hazard potential", Plenum Press, New York (1987). We hope that all these volumes together may represent a complete textbook and a reference for the students and scientists interested in the physics, biology, measurement and dosimetry, health effects and standard setting, in short, the risk assessment of that wide field of radiation presently classified as non-ionizing radiation. We are indebted to the Associa?ione Italiana Protezione dalle Radiazioni (AIRP), The Internat:l.
Author: Edwin S. Beatrice
Publisher:
ISBN:
Category :
Languages : en
Pages : 11
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The retinas of rhesus monkeys were subjected to irradiation by a prototype gallium arsenide (GaAs) laser training device. The laser device operated at 1600 Hz (pulse repetition frequency mode) or 132 Hz (pulse code mode) with nominal peak pulse power of 1 watt and 10 watts. Exposure durations ranged from 1.0 sec to 90 sec. The tissue reaction at the exposure site was characterized by the development of a pale gray clouding within 10 seconds of initiation of the exposure. The nature of the retinal change could not be determined by ophthalmoscopic, histologic, or flourescein leakage techniques. (Author).
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Category : Aeronautics
Languages : en
Pages : 1102
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ISBN:
Category : Aeronautics
Languages : en
Pages : 890
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ISBN:
Category : Laser materials
Languages : en
Pages : 522
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Author:
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ISBN:
Category :
Languages : en
Pages : 24
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This study has examined the cumulative effects of multiple-pulse laser exposures in contributing to retinal damage via a thermal mechanism. Three sets of experiments have been conducted to determine the variation of multiple- pulse thresholds: With the interval between pulses; with the number of pulses in the pulse train when the interpulse interval is held constant; and with the retinal image size when both number of pulses and interpulse interval are invariant. In addition, thermal model calculations were carried out to compare model predictions with the experimental data. Conclusions from the experimental data are: (1) The threshold for a multiple-pulse train is related to that for an individual pulse in the train by a function of the number of pulses, but is independent of pulse-repetition frequency and pulse train length. This observation is in general accordance both with the thermal model predictions and with previously empirical models. (2) The additivity of multiple pulses is quantitatively similar for collimated and expanded laser beams incident at the eye. (3) The repair or recovery of laser-induced reversible retinal damage (i.e., sub-threshold with respect to the ophthalmoscopic lesion endpoint) is slow, having a time constant of the order of days. Thus, the cumulative nature of multiple-pulse or repeated exposures within a 24-hr period is relatively unaffected by the ongoing repair process; and only when repeated daily exposures are of concern does the repair process become a factor. Keywords: Laser damage; Retina.
Author:
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Category : Accidents
Languages : en
Pages : 604
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ISBN:
Category : High power lasers
Languages : en
Pages : 508
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Author:
Publisher:
ISBN:
Category : Lasers
Languages : en
Pages : 836
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