The specular image is formed when light information is redirected from its incidental direction to the occupant. There is an intrinsic relationship between the image and surface that holds the optically virtual image. The fragility of the image is matched only by the necessary order of the smoothness of the receiving surface. In order to offer the image to the viewer as if it were its own, the surface must be optically smooth, and is so only "if any surface feature height... is much smaller than the wavelength of the incident light."1 The preservation of the image is possible only because the directionality of all incident rays relative to one another is preserved.
Architecture must very carefully consider the incidental outcomes of introducing mirror surfaces in space. In "The Poetics of Light," Henry Plummer cautions against mirrors: "The plane mirror is always susceptible to squandering its incident light and, by complete reflection, annihilating its very existence."2 Not only does the image have the power to supersede the surface, but the precise directionality of the reflected rays will often render the intended image only perceptible to the viewer from a certain position.
In a sense, the mirror will fulfill its intended role only through the specific, successful choreography of the orientation of both the architecture and the body. The mirror also has the ability to fragment and distort. When two different choreographies of surface orientation are placed next to one another, the virtual image disrupts the real image. Plummer addresses this strange phenomenon in his analysis of the mirror 'windows' of Amalienburg: "...each slippery sheet is actually a terrain of cold silver, shimmering and shadowy, possessing radiant images that are somewhat warped, broken up, and disarranged".3 His evocation of the mirror as a terrain of cold silver is not without value - the life of the mirror outside its designed viewing is integral to the atmosphere of the space.
The limitation of the specular image lies in its flattening of information and fleeting existence. The precision of the archetype is wholly determined by the quality of its host surface. As the optical smoothness of the surface deteriorates, so does the quality of the image, until the image is indiscernible and another archetype is born.
1. Duree, Optics, 46.
2. Henry Plummer, “Poetics of Light,” A+U December Extra Edition (December 1987): 25.
3. Plummer, "Poetics of Light," 25.