[en] A LIDAR system combined with a streak camera was investigated to get higher spatial resolution than the present LIDAR on JET (spatial resolution 100 mm). In order to realize the system, i) confirmation of the detection limit of a streak camera and ii) optimization of the system were necessary. Regarding i), we estimated the Signal-to-Noise ratio of a streak system with a CCD camera for read out of the streak image theoretically and checked the estimation by observing Rayleigh scattering using a sub-ns YAG laser/SHG. The results showed that the Signal-to-Noise ratio of the system near the detection limit was dominated by read out noise and dark current of the CCD chip and it could be improved to the value determined by photon statistics by getting sufficient light gain at the streak stage. Regarding ii), the observable length along the laser beam is determined by a) a spot size of the observation volume at the entrance slit of the streak camera, b) length of the output screen of the streak tube, and c) streak speed. On the other hand, loss of scattered light due to vignetting becomes larger when the spot size is made smaller. Therefore, the system was optimized to get as long an observable length as possible under the constraint of deterioration of the detection limit due to vignetting. A grating spectrometer was shown to be feasible for certain conditions. (author). 6 figs