Bathroom mirrors and regular mirrors show a normal image because they have a flat surface that reflects the incoming light waves in the same direction as the incoming angle. This is called specular, or regular reflection. The reflected rays maintain their intensity, color, and shape, and form a virtual image at the same distance behind the mirror as the object is in front of it. This is why we can see our own reflection in a clear and undistorted way.
However, mirrors at fairs and amusement parks use a different type of reflection called diffuse reflection. The surface of these mirrors is curved, uneven or twisted in various directions, causing the incoming light waves to scatter and reflect off different points of the surface at different angles. This creates a distorted, or anamorphic, reflection that can bend, stretch, compress, or twist the objects and shapes reflected in them.
The distortion effect depends on the specific shape and orientation of the mirror's surface. For example, a concave mirror that curves inward can make a person's reflection appear taller and thinner, as the incoming light waves converge towards a single focal point. On the other hand, a convex mirror that curves outward can make the reflection appear smaller and wider, as the light waves diverge away from the focal point.
This distortion happens because the incident light waves interact with the mirror's surface irregularities, which act like tiny mirrors in themselves. This produces a scattering of reflected light waves that do not maintain their directionality, polarity, or phase. In contrast, regular mirrors produce a coherent reflection that preserves the wave properties of the incident light.
In summary, the difference between regular and 'goofy' mirrors lies in the type of reflection they use. While regular mirrors produce specular reflection that shows an undistorted image, 'goofy' mirrors rely on diffuse reflection to create a distorted image based on the shape and curvature of the mirror's surface.