论文标题
光谱扁平场可用于精确的CCD增益和噪声测试
Spectroscopic flat-fields can be used for precision CCD gain and noise tests
论文作者
论文摘要
CCD摄像机的基本参数之一是增益，即每次输出单位的检测到的电子数量（ADU）。通常，这是通过从一系列扁平场暴露的统计方差来确定的，在实质区域上具有几乎恒定的水平，并利用光子（Poisson）噪声等于平均值的事实。但是，当将CCD安装在由许多光纤饲喂的光谱仪器中，或具有梯形格式时，不再有可能在大面积上获得恒定的照明。这里表明，光谱“平面”中信号水平的广泛变化与其与所选的小区域进行操作，可用于获得CCD增益的准确值，只需要一对匹配的暴露（在噪声的实现方面有所不同）。一旦知道增益，就可以从一对偏置帧中很容易找到CCD读数噪声（在电子中）。图像在两个扁平场中的空间稳定性很重要，尽管表明对小移位的校正是可能的，以进一步的分析为代价。
One of the basic parameters of a CCD camera is its gain, i.e. the number of detected electrons per output Analogue to Digital Unit (ADU). This is normally determined by finding the statistical variances from a series of flat-field exposures with nearly constant levels over substantial areas, and making use of the fact that photon (Poisson) noise has variance equal to the mean. However, when a CCD has been installed in a spectroscopic instrument fed by numerous optical fibres, or with an echelle format, it is no longer possible to obtain illumination that is constant over large areas. Instead of making do with selected small areas, it is shown here that the wide variation of signal level in a spectroscopic `flat-field' can be used to obtain accurate values of the CCD gain, needing only a matched pair of exposures (that differ in their realisation of the noise). Once the gain is known, the CCD readout noise (in electrons) is easily found from a pair of bias frames. Spatial stability of the image in the two flat-fields is important, although correction of minor shifts is shown to be possible, at the expense of further analysis.
