Three-dimensional analysis of the optical functionalities of an autostereoscopic display with an array of slanted lenticular lenses was performed. The specification parameters of the lenticular lens for clear separation of the images were first determined using the geometrical optics, and the transmission characteristics of the light ray travelling through a single lenticular were then calculated by finite ray tracing. The properties of light transmission over the entire display panel were then determined by expanding the results obtained for the single lenticular to the entire lenticular lens array. Consequently, each view was confirmed to be located at an inter-ocular distance of 65 mm away from each other. Approximately 5% noise was observed between the views, and the shape of the viewing zone at the optimal viewing distance was tilted towards the direction of the slanted lenticular. Overall, numerical analysis enables a realistic evaluation of the optical functionalities, such as the shape of the viewing zone, of lenticular based autostereoscopic displays.