利用Kr F准分子激光器晶化非晶硅薄膜,研究了不同的激光能量密度和脉冲次数对非晶硅薄膜晶化效果的影响。利用X射线衍射(XRD)和扫描电子显微镜(SEM)对晶化前后的样品的物相结构和表面形貌进行了表征和分析。实验结果表明,在激光频率为1...利用Kr F准分子激光器晶化非晶硅薄膜,研究了不同的激光能量密度和脉冲次数对非晶硅薄膜晶化效果的影响。利用X射线衍射(XRD)和扫描电子显微镜(SEM)对晶化前后的样品的物相结构和表面形貌进行了表征和分析。实验结果表明,在激光频率为1 Hz的条件下,能量密度约为180 m J/cm2时,准分子激光退火处理实现了薄膜由非晶结构向多晶结构的转变;当大于晶化阈值180 m J/cm2小于能量密度230 m J/cm2时,随着激光能量密度增大,薄膜晶化效果越来越好;激光能量密度为230 m J/cm2时,晶化效果最好、晶粒尺寸最大,约60 nm,并且此时薄膜沿Si(111)面择优生长;脉冲次数50次以后对晶化的影响不大。展开更多
Background: Fundus autofluorescence (AF) is derived from the lipofuscin contained by the retinal pigment epithelial cells. Using a scanning laser ophthalmoscope, two- dimensional AF measurements of the ocular fundus c...Background: Fundus autofluorescence (AF) is derived from the lipofuscin contained by the retinal pigment epithelial cells. Using a scanning laser ophthalmoscope, two- dimensional AF measurements of the ocular fundus can be achieved. Directly after conventional photocoagulation and also after selective RPE laser treatment (SRT) with ophthalmoscopically non- visi- ble laser lesions, irradiated areas reveal reduced AF, indicating RPE damage. Since the green treatment laser beam could also be used for AF excitation, the aim of this study was to evaluate whether absolute measurements of AF can be performed, and also possible changes in AF detected, online during SRT. Methods: SRT was carried out by use of a frequency- doubled Nd:YLF laser (wavelength 527 nm, pulse duration 1.7 μ s, repetition rate 500 and 100 Hz, number of pulses 100 and 30, single pulse energy 50- 130 μ J) in vitro (porcine RPE; retinal spot size 160 μ m) and during patient treatment (retinal spot size 176 μ m). During irradiation, fluorescence light from the RPE was decoupled from the laser light inside the slit lamp and detected by a photomultiplier or photodiode at wavelengths above 550 nm. Additionally, temperature- dependent fluorescence intensity measurements of A2- E, the main fluorescent component of lipofuscin, were performed in a different in- vitro setup. Results: The intensity of AFdecreased over the number of applied pulses during laser irradiation, and this trend was more pronounced in porcine RPE samples than during human treatment. In vitro, the AF intensity decreased by about 22% ; however, only a weak signal was detected. When treating patients, the AF intensity was strong and the rate of decay of fluorescence intensity with number of pulses was greater when irradiating at 500 Hz than at the 100 Hz repetition rate. However, for both repetition rates the AF decay was merely up to 6- 8% over the number of pulses per laser spot. Fluorescence intensity of A2- E decreased linearly with increasing temperature at about 1% per 1° C and展开更多
文摘利用Kr F准分子激光器晶化非晶硅薄膜,研究了不同的激光能量密度和脉冲次数对非晶硅薄膜晶化效果的影响。利用X射线衍射(XRD)和扫描电子显微镜(SEM)对晶化前后的样品的物相结构和表面形貌进行了表征和分析。实验结果表明,在激光频率为1 Hz的条件下,能量密度约为180 m J/cm2时,准分子激光退火处理实现了薄膜由非晶结构向多晶结构的转变;当大于晶化阈值180 m J/cm2小于能量密度230 m J/cm2时,随着激光能量密度增大,薄膜晶化效果越来越好;激光能量密度为230 m J/cm2时,晶化效果最好、晶粒尺寸最大,约60 nm,并且此时薄膜沿Si(111)面择优生长;脉冲次数50次以后对晶化的影响不大。
文摘Background: Fundus autofluorescence (AF) is derived from the lipofuscin contained by the retinal pigment epithelial cells. Using a scanning laser ophthalmoscope, two- dimensional AF measurements of the ocular fundus can be achieved. Directly after conventional photocoagulation and also after selective RPE laser treatment (SRT) with ophthalmoscopically non- visi- ble laser lesions, irradiated areas reveal reduced AF, indicating RPE damage. Since the green treatment laser beam could also be used for AF excitation, the aim of this study was to evaluate whether absolute measurements of AF can be performed, and also possible changes in AF detected, online during SRT. Methods: SRT was carried out by use of a frequency- doubled Nd:YLF laser (wavelength 527 nm, pulse duration 1.7 μ s, repetition rate 500 and 100 Hz, number of pulses 100 and 30, single pulse energy 50- 130 μ J) in vitro (porcine RPE; retinal spot size 160 μ m) and during patient treatment (retinal spot size 176 μ m). During irradiation, fluorescence light from the RPE was decoupled from the laser light inside the slit lamp and detected by a photomultiplier or photodiode at wavelengths above 550 nm. Additionally, temperature- dependent fluorescence intensity measurements of A2- E, the main fluorescent component of lipofuscin, were performed in a different in- vitro setup. Results: The intensity of AFdecreased over the number of applied pulses during laser irradiation, and this trend was more pronounced in porcine RPE samples than during human treatment. In vitro, the AF intensity decreased by about 22% ; however, only a weak signal was detected. When treating patients, the AF intensity was strong and the rate of decay of fluorescence intensity with number of pulses was greater when irradiating at 500 Hz than at the 100 Hz repetition rate. However, for both repetition rates the AF decay was merely up to 6- 8% over the number of pulses per laser spot. Fluorescence intensity of A2- E decreased linearly with increasing temperature at about 1% per 1° C and
