Then the aspherical screen could be designed with the back-projection of the plane wave from the observer. As every ray from the aspherical screen went to only one observation point, there was a fixed observation point, which was determined by the shape of the aspherical screen. Once the size of the concave mirror was determined, it became possible to focus on designing the surface of the aspherical screen. For manufacturing convenience, it was assumed that the lower concave mirror was a part of the spherical mirror because of the latter's size. To provide a complementary effort to this need, a collimated display system with an optically designed aspherical screen is proposed herein. There have been several researches that attempted to come up with a compact collimated system, but they failed to produce perfect collimated light, produced collimated light only for the vertical direction, or provided other benefits of stereoscopy for the improvement of the training effects. For these reasons, there is a demand for a compact system that can produce a collimated display with a wide field of view (FOV). As the conventional collimated display system requires a huge optical system to generate collimated light, it entails an enormous cost and many engineering problems. In contrast, to date, there has been minimal academic research regarding this technology because the principle of the collimated display is not very complicated. Creek in 2005, which was cited by many major projection display cooperators, such as Barco and Institu National d'Opique. The most detailed technology of the collimated display was patented by R.E. The collimated display can express an image from afar because it uses collimated light, which is assumed as the plane wave starts from infinity distance from an observer, as shown in Figure 1.
For this reason, a collimated display can be used for the virtual flight simulator. To provide a realistic environment, a display that could express a high perceptional depth should be made available because a pilot in a real airplane usually sees objects from afar. In the flight training procedure, pilots should practice in a virtual flight simulator before they take a real flight.