Ha ha mirror is actually a combination of concave mirror and convex mirror. Concave mirror will reduce the mirror image, and convex mirror will magnify the image, thus achieving the effect of distortion. Moreover, the imaging characteristics of the ha-ha mirror are plane mirror imaging, light reflection and becoming a virtual image. Focusing on the ball can make people short or fat, and spreading out of the ball can make people long and big.

The imaging characteristic of ha ha mirror is the principle of plane mirror imaging. The reflection of light becomes a virtual image. Because the mirror surface is uneven, it is the principle of concave-convex mirror imaging, forming a virtual image, big or small.