Details

These are the steps to make the beam pass through the two points by rotating the two mirrors.

0. The beam does not pass through either point .

1. Turn mirror 1 to make the beam pass through point 1 .

2. Turn mirror 2 to make the beam pass through point 2 .

3. Repeat steps 1 and 2 sequentially as needed.

For example:

1.

2.

1.

2.

1.

2.

1.

2.

2.

The beam now passes through the two points.