In some cases, in order to for the viewer to fully perceive an effect of light, a receiving surface must be present to register the operation that has been performed by the primary optic device. For two out of the five primary optic devices, namely mirrors and diffusers, it is often the case that the role of the receiving surface, a secondary optic device, is performed by the primary device. A water droplet that scatters light is also the material from which the effect’s light arrives to the viewer’s eyes. This secondary device is therefore not an essential component of every light effect, but it does have the capacity to transform the light arriving to it from a primary optic device through the adjustment of its own parameters. The receiving surface is not always solid, does not always have a certain order of texture, is not always uniform in colour, and is not always planar. All of these parameters affect how the surface registers light, and this in turn affects the patterns of light that we observe from the receiving surface and the sensations that they evoke.
The receiving surface plays a critical role in the formation of the specular image, secondary source, and textural light archetypes, as these archetypes of effect are produced as a result of the receiving surface’s parameter of roughness. At an extreme, the receiving surface can become a primary optic device (the mirror). Though primary optic devices can be deployed in combination, it is perhaps more common in architectural practice to observe a layering of receiving surfaces such as stone and glass. These compound interactions can be difficult to simulate and study, but can significantly influence the registration and subsequent perception of the light effect. The loose parameter of layering is therefore particularly applicable to this secondary optic device, and it must be given its due attention in the course of the design of light-driven tectonics.
Sample Series of parameters applied in sequence to the base optic device