摘要
光纤火警报警系统是用于保护重要仪器设备的一种有效的手段,是为了探测在变化的背景温度下(从室温到500-600℃),局部温度出现至少50-100℃的温度升高(对应出现火险的情形)。传感器保护的范围约1-3米,空间分辨率至少30cm。系统采用荧光寿命作为传感参量,有两种情形可以改变测得的荧光寿命,必须加以区分:一种情况是传感器局部出现高温点,意味着在该处出现火情;另一种情况是背景温收稿日期:2003 07 01 孙伟民,wmsun@optics teaching.org,本项目受到黑龙江省自然科学基金项目(A0308)支持。·771· 第2期NewDesignofFiber-BasedFireAlarmSystem2004年度整体发生变化,在实际应用时环境背景温度可能有几百度的温度波动。本文采用了两种方式来区分以上两种情况:一种是采用一小段高掺杂荧光光纤作为点式参考光纤,称为参考法:一种是对测得的荧光衰减信号进行修正,称为修正法。分别给出了两种方法的实验系统及测试结果。
Effective detection of potential fire hazards is important in industry, and especially in aerospace applications. Optical fiber methods may offer alternatives to well-established conventional devices and a fluorescence-based fire alarm system has been developed specially to address this requirement. The aim has been to investigate and develop a simple yet effective scheme to determine the presence of a localized temperature excursion (as low as 50-100℃) against a varying background in a system that can operate effectively at temperatures up to 500-600℃. The requirement for the device is for a sensing length in the range of 1 m to 3 m with a spatial resolution shorter than 30 cm. The optical fiber sensing system used in this work employs a scheme based on monitoring the exponential decay of the fluorescence from a doped fiber and thus to address two different temperature excursions derived from the monitoring needs thus identified. These are: * The presence of a 'hot-spot' - indicating the beginning of a fire at any point along the fiber length. * The change or drift of the background temperature. It may vary from room temperature to potentially several hundred degrees, under normal operation in some applications. Two different methods have been discussed in this paper to address the hot-spot linked parameters - these being termed the referential method and the correction method. The referential method requires a referential channel to assist the sensing system to identify a hotspot signal, irrespective of any change of the background that may occur. However, the correction method offers the absolute temperatures of both hotspot and average background without an additional referential channel, offering a simpler approach. Results obtained on the development and use of both systems will be presented.
出处
《光散射学报》
2004年第2期177-183,共7页
The Journal of Light Scattering
