INTERFEROMETRIC HOLOGRAMS

Interferometry is a method by which one measures the 'phase relatioship' between two co-incident wavefronts of energy (e.g. visible light) which are of the same frequency (wavelength), such as that produced by a laser. Typically, an experiment is set up where a 'reference wavefront' is measured against a combination of two 'object' waves. The resulting interference patterns - patterns of 'disturbance' of the object or medium - are seen as light and dark ribbons or 'contour lines'.

In the (above) metallic subjects for the holograms, physical stress was applied to specific points resulting in 'deformations' which 'map' the point of stress (eg. concentric circles appearing around the point) in ribbons projected into space.

In a simple case, one creates a interferogram  , by 'double-exposing' a illuminated scene, and recording this superimposition of 'before and after' states (of disturbance) on a holographic plate (as a hologram), using a standard object-reference beam configuration. Further than simply being a 'holographic recording' of a object/scene, the interferometric hologram contains information that is specific to changes occuring in a material-substrate-medium over time.

In scientific measurements/tests, it is used to reveal resonance patterns, properties of elasticity, stress, deformations in materials or media, and it is used in technical-industrial evaluations of structures, integrity of materials, hidden flaws in manufacturing, etc.

In holographic art, it becomes a medium of creating ribbon-like contour mappings and textures in objects or seemingly translucent media (water, air, glass, etc.) by the direct introduction (by the artist) of deformations.

In the art works depicted in the gallery section on STRESS TOPOGRAPHY, the intent is to explore the manner in which art forms can be created from these 'interventions'. The resulting 'contour patterns' become the expression of what appears to be a 'music-like interplay' between interfering wavefronts. In the hands of a skilled artists, these contour patterns become maleable, controllable creations which resemble 'energy patterns' in space (as distinct from the depiction of 'objects in space').

BELOW:  "FIELD" (1984), A multi-colored white-light transmission interferogram derived from multiple stress points occuring on a stainless steel plate. Produced at Fringe Research, Toronto, with the assistance of Michael Sowdon.  FIELD is one element of a series titled: "STRESS TOPOGRAPHY".

Compare this hologram to the contour lines produced by a FACTAL IMAGE RENDERING of mathematical calculations. The resemblance between FRACTAL images and certain interferograms is striking. FRACTALS which exist on the borders of chaos, and INTERFEROGRAMS which depict near-invisible disturbances of matter in time could hardly be thought of 'existing in the same universe'. Yet they do, and perhaps reveal the 'workings' of our universe.