Scotti Filippo, Bell Ronald E
Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA.
Rev Sci Instrum. 2010 Oct;81(10):10D732. doi: 10.1063/1.3489975.
Spectroscopic applications for plasma velocity measurements often require wavelength accuracies ≤0.2 Å. An automated calibration, which is stable over time and environmental conditions without the need to recalibrate after each grating movement, was developed for a scanning spectrometer to achieve high wavelength accuracy over the visible spectrum. This method fits all relevant spectrometer parameters using multiple calibration spectra. With a stepping-motor controlled sine drive, an accuracy of ∼0.25 Å has been demonstrated. With the addition of a high resolution (0.075 arc sec) optical encoder on the grating stage, greater precision (∼0.005 Å) is possible, allowing absolute velocity measurements within ∼0.3 km/s. This level of precision requires monitoring of atmospheric temperature and pressure and of grating bulk temperature to correct for changes in the refractive index of air and the groove density, respectively.
用于等离子体速度测量的光谱应用通常要求波长精度≤0.2 Å。为一台扫描光谱仪开发了一种自动校准方法，该方法在时间和环境条件变化时保持稳定，无需在每次光栅移动后重新校准，以在可见光谱范围内实现高波长精度。此方法使用多个校准光谱来拟合所有相关的光谱仪参数。通过步进电机控制的正弦驱动，已证明精度达到约0.25 Å。在光栅平台上增加一个高分辨率（0.075 弧秒）的光学编码器后，可实现更高的精度（约0.005 Å），从而能够进行精度在约0.3 km/s以内的绝对速度测量。这种精度水平需要监测大气温度和压力以及光栅本体温度，以分别校正空气折射率和槽密度的变化。
