Hologram In the words of Stephen Benton, the inventor of the rainbow hologram and holo-video... " a hologram is like a window with a memory." The word hologram is derived from the Greek roots 'holos' - complete and 'gram' - message. A holographic image can be thought of as a complete visual message in that it replicates exactly the size and three dimensionality of an object as an immaterial light field.The theory of the hologram was developed in the early 1950's by Dennis Gabor for which he was awarded the 1971 Nobel prize in Physics. The basic principle of the hologram and the property which makes it different from all other types of images is 'interference'.In photography, light from the subject is focused by a lens onto light sensitive film. In holography light from the subject combines with an additional beam of light shone directly onto the film or plate. Only laser light can expose both the subject and the plate to record a hologram. The interference pattern formed by the superimposition of the two beams of laser light is permanently fixed to the plate by a processes similar to photographic development. This exposed and developed glass plate is the one which the viewer looks into to see the Shrine of the Sacred Heart images. The interference pattern incorporates the complete information about the light field of the subject by recording minute differences in the time which laser light takes to travel from all parts of the three dimensional subject to the plate. Any slight movement of the object during the exposure which is greater that an quarter of a wavelength of light, is registered as a variation in time of light travel. In a photograph of a moving object the image looks blurry. In a hologram anything which moves simply appears black. Holograms are usually recorded in vibration isolation laboratories. With the Shrine of the Sacred Heart images, the amount of exposure time which Paula Dawson selected divided the behaviour of the object elements into two groups so that the inanimate object materials such as plaster and ground glass were stable enough to appear bright. The transpiration of the frangipanni flowers and the rising heat plume were unstable enough to appear as darkness. In looing through the glass plates of the Shrine of the Sacred Heart , viewers see the virtual image because the laser shines onto the plate from the same position as it was in during the exposure. The interference pattern recorded onto the glass plate diffracts the light shining on to it to reconstruct an image of the light field shed by the hemisphere and cross and flame during the time of their exposure. The hologram incorporates 750 frangipani flowers gathered in the parish when the hologram was made. The darkness of the image of the flowers reminds us that the light in this artwork is not 'behaving naturally', suggesting its Divine Origin. < Back to Public Commissions