The superposing angle of the viewing zone forming optics and the display panel in the contact type 3 dimensional imaging systems for minimizing $moir{acute{e}}s$ is found for a rectangular shape pixel with different aspect ratios. The angles are $26.2609^{circ}$ for square shape pixels and $13.9858^{circ}$ for the rectangular with aspect ratio 2. These angles result in the $moir{acute{e}}s$ with the smallest period for the respective aspect ratio. The effectiveness of the angles is also experimentally demonstrated.