Imaging Filters' Optical quality
Images of the optical ghosts introduced by the filters alone
Some of the filters have strong optical ghosts. Some optical ghosts might appear depending on the setting and the position of the star on the detector, but these are not addressed here.
In order to get an idea of the filter induced ghosts, images of the NAOS PSF fiber have been taken for different filters.
The integration time has always been set so that the pick intensity is closed to or slightly saturated. The images with the lamp off have been subtracted from images taken with the lamp (PSF fiber) on. After that the peak intensity in each image has been normalised to 100. The images presented here have been plotted with a linear scale. The cuts used for each filter is provided in the Tab.1. For information all images have been taken with the S27 camera. Due to thermal effect, it is not always easy to differentiate the ghosts from the PSF &/or background noise. For these cases, the ghosts have been highlighted in yellow.