Wavelength and pulselength dependence of laser conditioning and bulk damage in doubler-cut KH2PO4

An experimental technique has been utilized to measure the variation of bulk damage scatter with damaging fluence in plates of KH{sub 2}PO{sub 4} (KDP) crystals. Bulk damage in unconditioned and laser-conditioned doubler-cut KDP crystals has been studied using 527 nm (2{omega}) light at pulselengths of 0.3-10 ns. It is found that there is less scatter due to damage at fixed fluence for longer pulselengths. In particular, there is {approx}4X increase in fluence for equivalent scatter for damage at 2{omega}, 10 ns as compared to 0.30 ns in unconditioned KDP. The results for the unconditioned and conditioned KDP show that for all the pulselengths the scatter due to the bulk damage is a strong function of the damaging fluence ({phi}{sup -5}). It is determined that the 2{omega} fluence pulselength-scaling for equivalent bulk damage scatter in unconditioned KDP varies as {tau}{sup 0.30{+-}0.11} and in 3{omega}, 3ns ramp-conditioned KDP varies as {tau}{sup 0.27{+-}0.14}. The effectiveness of 2{omega} and 3{omega} laser conditioning at pulselengths in the range of 0.30-23 ns for damage induced 2{omega}, 3 ns is analyzed in terms of scatter. For the protocols tested (i.e. peak conditioning irradiance, etc.), the 3{omega}, 300 ps conditioning to a peak fluence of 3 J/cm{sup 2} had the best performance under 2{omega}, 3 ns testing. The general trend in the performance of the conditioning protocols was shorter wavelength and shorter pulselength appear to produce better conditioning for testing at 2{omega}, 3 ns

Ventricular Geometry From Non-contrast Non-ECG-gated CT Scans:An Imaging Marker of Cardiopulmonary Disease in Smokers

Cardiovascular disease is a major cause of morbidity in smokers, and as much as 50% of the estimated 24 million patients in the United States with chronic obstructive pulmonary disease (COPD) die of cardiovascular causes (1,2). Although echocardiography and cardiac magnetic resonance imaging (MRI) are often used to study cardiac structure and function in COPD (3), these are not routinely deployed in all smokers. Computed tomographic (CT) imaging of the chest is broadly used in clinical care and is increasingly used for lung cancer screening in high-risk smokers (4). Assessment of cardiac structure on those CT scans may help identify patients with COPD at greater risk of developing cardiac dysfunction. Rapid, noninvasive assessments of cardiac morphology and a better understanding of the functional interdependence of heart and lung may improve healthcare outcomes through early detection and initiation of treatment

Wavelength and pulselength dependence of laser conditioning and bulk damage in doubler-cut KH2PO4 Wavelength and pulselength dependence of laser conditioning and bulk damage in doubler-cut KH 2 PO 4

ABSTRACT An experimental technique has been utilized to measure the variation of bulk damage scatter with damaging fluence in plates of KH 2 PO 4 (KDP) crystals. Bulk damage in unconditioned and laser-conditioned doubler-cut KDP crystals has been studied using 527 nm (2ω) light at pulselengths of 0.3 -10 ns. It is found that there is less scatter due to damage at fixed fluence for longer pulselengths. In particular, there is~4X increase in fluence for equivalent scatter for damage at 2ω, 10 ns as compared to 0.30 ns in unconditioned KDP. The results for the unconditioned and conditioned KDP show that for all the pulselengths the scatter due to the bulk damage is a strong function of the damaging fluence (φ~5). It is determined that the 2ω fluence pulselength-scaling for equivalent bulk damage scatter in unconditioned KDP varies as τ 0.30±0.11 and in 3ω, 3ns ramp-conditioned KDP varies as τ 0.27±0.14 . The effectiveness of 2ω and 3ω laser conditioning at pulselengths in the range of 0.30-23 ns for damage induced 2ω, 3 ns is analyzed in terms of scatter. For the protocols tested (i.e. peak conditioning irradiance, etc.), the 3ω, 300 ps conditioning to a peak fluence of 3 J/cm 2 had the best performance under 2ω, 3 ns testing. The general trend in the performance of the conditioning protocols was shorter wavelength and shorter pulselength appear to produce better conditioning for testing at 2ω, 3 ns