High-power regenerative Nd:phosphate glass amplifier.
A compact high-power regenerative Nd:phosphate glass amplifier is described which incorporates spatial filtering and full image relay techniques. Output energies up to 1.2 J at a pulse duration of 140 ± 10 psec (FWHM) and 3 J at 900 ± 70 psec (FWHM) are achieved in a smooth nearly flattop beam intensity profile. Even with present-day technology, this system could be scaled into a terawatt regime.
Off-axis multipass amplifier as a large aperture driver stage for fusion lasers.
A multipass amplifier configuration is described which has potential as a large aperture, high gain driver stage for fusion laser systems. We avoid the present limitations of large aperture switches by using an off-angle geometry that does not require an optical switch. The saturated gain characteristics of this multipass amplifier are optimized numerically. Three potential problems are investigated experimentally, self-lasing, output beam quality, and amplified spontaneous emission output. The results indicate comparable cost for comparable performance to a linear chain, with some operational advantage for the multipass driver stage.
Tortuosity or aneurysm? The palaeopathology of some abnormalities of the vertebral artery
The anatomy of the vertebral artery (VA) and two pathological conditions which affect it—tortuosity and aneurysm—are described. The changes which these lesions produce in the cervical vertebrae are also described and we present two cases in which these changes have been found. One case is of a female aged at least 45 years at the time of death from a 15th century medieval cemetery site in Britain with what we consider to be tortuosity of the VA. The second case is of a male aged between 25 and 35 years at the time of death from a Coffin period site in Japan, dating to ca 1600 years BP. The changes in this skeleton are considered to be more in keeping with a diagnosis of aneurysm of the VA. Copyright © 2002 John Wiley & Sons, Ltd.