Keywords:ultraviolet, spacecraft, efficiency
The remote observation with ultraviolet (30-330nm) lights is essential for planetary science because there are many effective lines emitted from the ion and atoms which compose the planetary magnetosphere or atmosphere (exosphere too). The straightest way to improve the quality of the data is to increase the efficiency of the instrument. In this presentation, we will show the way to improve the detection efficiency of the photon detector. Furthermore, the way to keep the efficiency during the ground operation (before the launch) is also shown from the experimental aspect.