Glass Aurorascope
This device is inspired directly by my affection
towards victorian science and art. The secret is "ground glass". Glass
that is ground or etched so that it refracts the light which hits it.
It is opaque and milky unless an image is projected upon it with a lens
or pinhole. The projected image shows on both sides of the glass with
no glare (like one gets with a reflective screen). The effect is quite
magical. Ground glass was used in camera obscuras, magic lanterns and
many pre-cinematic viewing devices and light boxes. It is also used in
motion picture film editing machines.
In this photo, I am using a wireless color camera to
control video feedback patterns which are being projected by a digital
projector off camera. The effect is a shimmering plasma like fire or
glow that is highly manipulatable by changing the camera angle. Colored
ligts and LEDs can also be used to make the entire surface to glow. The
sunrise-like glow of the colors on this screen inspired the name --
aurora is latin for sunrise.
This Aurorascope was constructed from scrap tempered safety glass I
found in a junkyard. I sandblasted it in a blast cabinet at about 60psi
with calcium silicate in MANY passes - starting 2" from the surface and
backing away with each pass to about 8" or more. The outside edges were
masked with heavy duty masking tape to remain transparent. Glass can
also be ground with wet sanding or via acid etching. This Aurascope
prefers to be hung from its wooden frame, but was screwed to 2x4s and
placed on the floor for this performance.