排序方式: 共有38条查询结果,搜索用时 0 毫秒
1.
2.
3.
提出了一种利用电加热丝作为校准源的高能激光能量计校准方法,将水流从吸收腔前端导入至加热容器,在加热后流入吸收腔。通过精确计量水流吸收的热能并与能量计测量结果进行比较,达到对高能激光能量计校准的目的。研究表明校准系统的热交换模型与吸收腔内的热交换模型一致,均经历了储能和功率平衡两个阶段。水流及相变气体的散射效应对测量结果的影响较小,经过修正后可以忽略其影响。通过深入分析各个环节的测量不确定度表明,残留能量和流量变化对测量不确定度的影响最显著,增加水箱的容积可以有效降低残留能量对测量不确定度的影响。在对各个环节的影响修正后估算出系统的测量不确定度约为4.8%(k=2),被校高能激光能量计校准后的测量结果与其他类型的参考高能激光能量计进行比对,两者具有很好的一致性,修正因子仅为1.006,标准偏差为1.4%。 相似文献
4.
A virtual probe is a novel immaterial tip based on the near-field evanescent wave interference and small aperture diffraction, which can be used in near-field high-density optical data storage, nano-lithography, near-field optical imaging and spectral detection, near-field optical manipulation of nano-scale specimen, etc. In this paper, the formation mechanism of the virtual probe is analysed, the evanescent wave interference discussed theoretically, and the sidelobe suppression by small aperture is simulated by the three-dimensional finite-difference time-domain method. The simulation results of the optical distribution of the near-field virtual probe reveal that the transmission efficiency of the virtual probe is 102-104 times higher than that of the nano-aperture metal-coated fibre probe widely used in near-field optical systems. The full width at half maximum of the peak, in other words, the size of virtual probe, is constant whatever the distance in a certain range so that the critical nano-separation control in the near-field system can be relaxed. We give an example of the application of the virtual probe in ultrahigh-density optical data storage. 相似文献
5.
由于超短脉冲激光器的谐振腔大都采用多镜折叠的形式,像散已成为影响锁模激光器性能优劣的重要问题.本文提出了一种基于传播圆补偿像散的被动锁模激光器谐振腔设计方法,该方法简单、直观、高效,容易找到补偿像散的最佳位置.理论研究表明,当SESAM位于子午和弧矢传播圆交汇处附近时,SESAM处的子午光斑和弧矢光斑大小几乎相等,像散得到补偿.该谐振腔对外界干扰引起的腔镜振动和热透镜焦距的变化均不敏感,谐振腔的抗干扰性很强.实验研究表明,当SESAM位于子午和弧矢传播圆交汇处附近时,锁模激光器可获得稳定连续的锁模激光脉冲,且激光器的抗干扰性很强.本文的理论研究与实验结果相一致. 相似文献
6.
差分吸收光谱法(DOAS)是基于朗伯比尔定律的光谱法测量气体的重要方法,按此原理建立的测量系统是测量痕量气体的主要方法。用于测量痕量气体的DOAS系统的关键是其检出限的校准,传统的方法是使用标准气体进行校准。但是由于标准气体自身的量值确定问题,在ppb甚至ppt级的不确定度大于10%,而一般的ppt级的DOAS测量系统本身的不确定度也会高于标准气体,导致传统方法失效。提出一种基于光谱密度的DOAS系统校准方法,利用朗伯比尔定律将DOAS系统的检出限和光谱密度建立关系。由于光谱密度作为光学量值可以测量到10-6甚至更高,所以通过该方法可以实现DOAS系统在ppb乃至ppt级的校准。本方法需要根据待校准的测量系统光学结构的基本参数计算其总的标准光学密度值,然后把标准光学密度片放入测量系统光程中,测得其光学密度值,根据前后两次光学密度计算测量系统的测量偏差,进而分析计算测量系统的标准不确定度和标定的扩展不确定度,所得到的标定的扩展不确定度即为测量系统的检出限。该方法完全基于光学测量,不需引入标准气体评估,基于光学密度的精密测量和测量系统光学结构的装调误差,实现测量系统在较小不确定度水平上的标定,提高检出限标定的精度。本方法在开放光程式的DOAS系统上进行了实验验证。 相似文献
7.
8.
Direct Measurement of Evanescent Wave Interference with a Scanning Near-field Optical Microscope 下载免费PDF全文
Evanescent wave interference is studied theoretically and experimentally. The interference patterns were directly measured with a scanning near-field optical microscope. The acquired image of the interference pattern is clear and has better contrast than that previously acquired with a photon-scanning tunnelling microscope or lasertrapped particles. The spatial period of the interference fringes is 180 nm, which agrees with the theoretical value. The results indicate that the probe of the scanning near-field optical microscope has a resolution beyond 100nm. The relation between the evanescent field intensity and the distance is also measured. When the separation between the probe and the interface is up to 18Ohm, the intensity can decrease to 1/e of the maximum. 相似文献
9.
10.