This paper formulates the notion of coarse integral imaging and applies it to practical designs of 3D
displays for the purposes of robot teleoperation and automobile HUDs. 3D display technologies are
demanded in the applications where real-time and precise depth perception is required, such as
teleoperation of robot manipulators and HUDs for automobiles. 3D displays for these applications,
however, have not been realized so far. In the conventional 3D display technologies, the eyes are usually
induced to focus on the screen, which is not suitable for the above purposes. To overcome this problem the
author adopts the coarse integral imaging system, where each component lens is large enough to cover
pixels dozens of times more than the number of views. The merit of this system is that it can induce the
viewer's focus on the planes of various depths by generating a real image or a virtual image off the screen.
This system, however, has major disadvantages in the quality of image, which is caused by aberration of
lenses and discontinuity at the joints of component lenses. In this paper the author proposes practical
optical designs for 3D monitors for robot teleoperation and 3D HUDs for automobiles by overcoming the
problems of aberration and discontinuity of images.