Auto-stereoscopic display means that the observers can obtain 3D images only using naked eyes

without any other assistant devices. This paper introduced the system using LEDs as the illumination to implement the stereo display for multi-users. Based on the LCD display

Fresnel lens was used to control the path of the LED light which was responsible for the parallax images. Cooperated with the head tracking programme

the LED arrays can offer the exact light to different observers independently. So the observer can see the right-left images and the gain the 3D images. The system uses Fresnel lens with the focal length of 930 mm

sets the light source 839 mm back from the LCD. Then we can get free view areas at the distance about 490~550 mm before the LCD display.Based on the optic angle enlarging structure

the stereo view angle can be up to 30

responding time of the system is less than 30 ms.