This is not such an easy task as you would think at the first sight! This device models the operation of the periscope.
How to use?
Turn the mirrors with the knobs into a position where the point of the laser ray hits the centre of the dartboard!
The essence of the periscope is that with the help of the mirrors it projects such images that the viewer cannot see directly. For instance, a periscope makes it possible for the crew of a submarine to look around on the surface of the sea without leaving it. But it can be also very useful at places where it would be important to peep in but too dangerous to enter.
In fact, here we placed two periscopes in front of each other. The upper mirror of one of the periscopes directs the laser ray onto the upper mirror of the other periscope (this ray behaves as if it was the element of the image we wish to see) that projects it onto the bottom mirror. The dartboard symbolises our eyes, the bottom mirror projects the rays of light to here.