混合阵列像元间电容耦合引起的天文测量误差
Astrometric Errors Introduced by Interpixel Capacitive Coupling in Hybridized Arrays
摘要：
杂交阵列中相邻像素之间的像素间电容（IPC）引起静电串扰。这种串扰导致MTF退化和使用这些设备收集的图像或光谱的模糊。当像素尺寸从H2 RG读出电路的18微米像素间距向下驱动到10或15微米H4 RG时，IPC被向上驱动，导致更大的串扰，所有其他条件都相同。越来越多的证据表明，IPC作为光敏二极管的耗尽状态的函数而变化。对于单像素事件，增加事件强度对应于减少分数耦合。如果不进行校正，IPC可能会在精密天体测量和光度测量中产生系统误差，特别是在处理用于形状测量的混淆点源或空间扩展结构时，如通过比较ESO HAWK-I和HST ACS WFC数据集的注册源所示。此外，当在这些装置的灵敏度极限附近操作时，这些误差将是最显著的。基于去卷积的校正方法由于这种相同的信号依赖性而无效。相反，可以使用逐次逼近的数值方法来校正由于良好表征的IPC而引起的耦合。平场上方的单个像素复位数据的检查可以用于表征相邻像素的IPC的函数关系。这种更高质量的表征可以导致更准确的校正。
英文摘要：
Interpixel capacitance (IPC) between adjacent pixels in hybridized arrays gives rise to an electrostatic cross talk. This cross talk causes MTF degradation and blurring of images or spectra collected using these devices. As pixel size is driven down from the 18 micron pixel pitch of the H2RG read out circuits to the 10 or 15 micron H4RGs IPC is driven up resulting in greater cross talk, all else being equal. Mounting evidence indicates that IPC varies as a function of depletion state of the photo-active diodes. For single pixel events, increasing the event intensity corresponds to a decreasing fractional coupling. If left uncorrected, IPC can give rise to systematic errors in precision astrometric and photometric measurements, in particular when dealing with confused point sources or spatially extended structures for shape measurements as demonstrated through comparison of registered sources from ESO HAWK-I and HST ACS WFC datasets. Furthermore these errors will be the most significant when operating near the sensitivity limit of these devices. Deconvolution based correction methods are invalidated by this same signal dependence. Instead a numerical method of successive approximation can be used to correct coupling due to a well characterized IPC. Examination of single pixel reset data above flat fields could be used to characterize IPC's functional relationship for neighboring pixels. This higher quality characterization can result in more accurate correction.
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