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Investigation of Pico-second Laser Heating Process of Polymer-Film through Thermo-Modulation Spectroscopy

通过热调制光谱研究聚合物薄膜的皮秒激光加热过程

基本信息

批准号：
08650253
负责人：
HANAMURA Katsunori
金额：
$ 1.6万
依托单位：
Gifu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

项目摘要

Thermo-modulation spectroscopy is applied for the investigation of the relaxation process in nano-seconds laser heating of a polystirene-film. A thin polystirene-film of a 1 micron thickness is pasted on a polished copper surface. The film is heated by a pulse beam of CO_2 laser (wavelength of 10.6 microns) ; where a CW laser beam is modulated by a chopper which is made of a stainless disc of 120 mm diameter and 0.2 mm thickness and is rotated by synchronous motor with 24000 rpm. Since there are180 slits on the circumference of the disc, when the width of the slit is 250 microns, the half-width of the pulse beam is about 2 micro-seconds and the interval of each pulse is 14 micro-seconds. With the cycle, the polystirene-film is heated and cooled, alternately. In relation to the pulse beam of CO_2 laser, the beam of He-Ne laser (wavelength of 3.39 microns) modulated by the same chopper is incident on the same point of the film. The reflected beam intensity of He-Ne laser is measured by P … More bS detector. In this case, the delay time between two pulse beams can be set up arbitrarily. That is, with increasing delay time the time history of the reflectivity of the film for the wavelength of 3.39 microns is obtained after the film is heated by one pulse of CO_2 laser.In experiment, since it is not clear when the two pulse beams are synchronized completely, the delay time is increased from an arbitrary time, i.e., zero second, to the time interval of 14 micro-seconds at an regular intervals of 300 nano-seconds. As a result, at a delay time the reflected beam intensity begins to increase drastically and then decreases sharply with increasing delay time. That is, only for about 2 micro-seconds the reflected beam intensity changes, which may mean that the two pulse beams are synchronized around the time. Consequently, it is disclosed that the thermo-modulation spectroscopy is successfully applied for the investigation of a high speed heating process by an infrared laser, with the time resolution of an order of a few hundred nano-seconds.The frequency of CO_2 laser is close to that of deforming vibration of C=C-H in the benzene nucleus in the polystirene, while the frequency of He-Ne laser is much the same as that of the stretching vibration of -CH_2-. Since the time resolution of the thermo-modulation spectroscopy is close to the relaxation time from a vibrational mode to other vibrational and/or rotational modes (<100 nano-seconds), the relaxation process in nano-seconds laser heating is expected to be captured through the infrared-ray thermo-modulation spectroscopy. Less

利用热调制光谱技术研究了纳秒激光加热聚苯乙烯薄膜的弛豫过程。将1微米厚的薄聚苯乙烯膜粘贴在抛光的铜表面上。薄膜加热采用波长为10.6 μ m的CO_2激光脉冲，激光束由直径为120 mm、厚度为0.2 mm的不锈钢圆盘制成，由同步电机驱动，转速为24000 rpm。由于圆盘圆周上有180个缝隙，当缝隙宽度为250微米时，脉冲束的半宽约为2微秒，每个脉冲的间隔为14微秒。随着循环，聚苯乙烯膜被交替地加热和冷却。相对于CO_2激光的脉冲光束，He-Ne激光（波长为3.39微米）光束经同一斩波器调制后入射到薄膜的同一点上。本文用P法测量了He-Ne激光器的反射光束强度 ...更多信息 bS探测器。在这种情况下，两个脉冲束之间的延迟时间可以任意设置。在实验中，由于不清楚两束激光何时完全同步，延迟时间从任意时刻开始增加，即延迟时间从任意时刻开始增加。从零秒到14微秒的时间间隔，以300纳秒的规则间隔。结果，在延迟时间处，反射光束强度开始急剧增加，然后随着延迟时间的增加而急剧减小。也就是说，反射光束强度仅改变约2微秒，这可能意味着两个脉冲光束在时间上同步。结果表明，热调制光谱技术已成功地应用于红外激光快速加热过程的研究，其时间分辨率可达几百纳秒量级，CO_2激光的频率与聚苯乙烯中苯环C=C-H的形变振动频率接近，而He-Ne激光的频率与-CH_2-的伸缩振动频率基本相同。由于热调制光谱的时间分辨率接近于从振动模式到其他振动和/或旋转模式的弛豫时间（<100纳秒），因此预期通过红外线热调制光谱捕获纳秒激光加热中的弛豫过程。少