Mirage optical illusion
The photograph shows a black dome with a green button on the top. The sign invites you to ‘Press button to see illusion’, but when you do your finger goes right through the button! This is because what you are looking at is not a button, but the virtual image of the button which is positioned inside, at the bottom of the dome. The illusion is angle sensitive but, if this is taken into account, the effect on an onlooker is one of astonishment and shock. Mirage was made in USA by Opti-Gone Associates Inc, Woodland Hills, California. US Patent 3647284.