ὅλος (holos; “whole”) and γραφή (graphe; “drawing”)
The act of making a hologram is an experience I have the chance to discover for myself as Artist in Residence in Organic Semiconductor Centre, at St. Andrews University.
First invented in the 60’s one can think that nowadays it will be easy to achieve satisfactory results in a couple of minutes. Surprisingly, this is not the case when it comes to building the set up and chemically processing the film/plate. A good four hours will vanish – while adjusting the optical alignment and testing the exposure time.
The set up for transmission hologram includes : a laser, a lens, [ a mirror (45 degrees)], a glass plate coated with silver halide , a highly reflective object.
Working with RED Laser it turned not to be ingenious decision the use of green plants for an object!
Rather satisfactorily results came from silver/metal coated object or white, or a red coloured one.
To get into the nits and bolts of holography one has to think of the interference pattern as of the pixels of the digital image. For example, if you have the pixels of an image far apart with dark gaps between them it will be hard to ‘read’ the image they are composing.
image: Nedyalka Panova
The interference pattern of the two beams: the transmitted and the reflected has to appear close enough, with no distinguishable lines for the eye, for a 3D object to look solid.
The nearer the object to the silver halide plate is and the more reflective it is, the better the results.
Horse hind legs, hologram, Nedyalka Panova, 2016
Why I am trying to make a hologram at a first place?
It is an optical illusion and it is not. One can see a hologram only in a special light conditions looking at a precise angle but it is physically present as an actual photograph and the Chemistry of it follows the steps of traditional dark room technique. NB: not red lit one!
This duality of physical/virtual existence evoke ambiguous interpretations on the subject matter.
In the project I am involved ‘ Explosive sensor detection’, the physicists from OSC has developed an organic fluorescent coating for explosive sensing. When the sample is exposed to aromatic explosive molecules of TNT/DNT and illuminated afterwards with UV the presence of these molecule attached to the sample quenches the light emission.
In the hologram the silver halide coating is exposed to the interference pattern of the beam: the one passing through it and when reflected from the object passes back interacting with itself.
The result is iridescent shifting mark from which in a second bolts, nuts or forks start floating: the coin thrown to ‘tell’ head or tail will never touch the ground.
to be continued….
Only now I can fully understand Hariette Casdin-Silver’s work ‘Equivocal Forks I’ http://www.jrholocollection.com/index.php/harriet-casdin-silver/item/118-equivocal-forks-i