**3. Holographic Optical Element (HOE)**

The holographic optical element (HOE) diffracts light as though it had passed through some type of optical device such as a lens, focusing, fragmenting, expanding or collimating the light. The diversity of forms available with HOEs is so extensive that it is not possible to generalize however the two following examples give a sense of the scope of this representational system.

Seth Riskin *Figure With Crowns* (Fig. 3 and 4) employs the fundamental relationship of the replay light of the hologram to the support (the holographic plate) in determining the nature of the reconstructed image, to generate a dynamic performance.

Holograms are different from other image types in the way in which the image is formed at the moment of viewer observation. The image is frequently referred to as a "reconstruction" shorthand for the term wave front reconstruction, the event in which a wavefront of light is changed usually from being quite simple to complex through the process of diffraction. It is significant that all holograms are seen by the diffraction of light from a replay source from an interference pattern. The distance, orientation and wavelength of the replay source effects the way in which the image appears. The same diffraction pattern could produce quite different qualities in an image if the lighting used in replaying were to be altered. These changes in the image can range from a complete change in colour, to slight shifts in spectral range towards reds or blues, changes in scale of the subject from large to small or vice versa, the introduction of distortions and appearance of the image as virtual or pseudoscopic

representational systems additional elements are needed – the replay light, the image space in front and through the support and also the viewing zone. The holographic viewing zone, (the volume of space in which the viewer must be located in order to see the image) is rarely the same as the volume of physical space in front of the holographic picture plane that the beholder can occupy. The beholder, as is customary, looks towards the support (holographic picture plane) in order to see the subject. The holographic image may appear to extend behind and or out into the viewer's space but it can only be seen when the beholder is inside

Van Alphen has argued that though perspective's requirement of stability of the viewing position, which causes the viewer to become stationary and fixed to the ground, limits the viewer's response, compositions which bring attention to the surface exclude the viewer from pictorial space. The limited nature of the *ideal* viewing zone, or point, for perspective imagery does not prevent the beholder from seeing the image from a complete range of angles because the image and its support occupy the same two-dimensional space. However due to the physical properties of the hologram there is a limit to the range of angles through which light can be diffracted to produce an observable image and so if the beholder of a hologram walks outside this viewing zone, though still looking at the holographic picture plane, they will not see the subject at all. The beholder becomes conscious of the shape of the viewing zone and its boundaries when its edges occlude the subject, inside the angle subtended by the viewer's eyes and the perimeter of the plate. The following examples demonstrate the way in which aspects of holographic representational systems such as the viewing zone, the hologram plane and the position of the subject are used in conjunction with other pictorial agents to convey ideas. These are works which must be experienced, as they mobilise the beholder in a complex interplay of

embodied engagement over time, with spatially distributed visual information.

of the reconstructed image, to generate a dynamic performance.

The holographic optical element (HOE) diffracts light as though it had passed through some type of optical device such as a lens, focusing, fragmenting, expanding or collimating the light. The diversity of forms available with HOEs is so extensive that it is not possible to generalize however the two following examples give a sense of the scope of this

Seth Riskin *Figure With Crowns* (Fig. 3 and 4) employs the fundamental relationship of the replay light of the hologram to the support (the holographic plate) in determining the nature

Holograms are different from other image types in the way in which the image is formed at the moment of viewer observation. The image is frequently referred to as a "reconstruction" shorthand for the term wave front reconstruction, the event in which a wavefront of light is changed usually from being quite simple to complex through the process of diffraction. It is significant that all holograms are seen by the diffraction of light from a replay source from an interference pattern. The distance, orientation and wavelength of the replay source effects the way in which the image appears. The same diffraction pattern could produce quite different qualities in an image if the lighting used in replaying were to be altered. These changes in the image can range from a complete change in colour, to slight shifts in spectral range towards reds or blues, changes in scale of the subject from large to small or vice versa, the introduction of distortions and appearance of the image as virtual or pseudoscopic

**3. Holographic Optical Element (HOE)** 

representational system.

the prescribed viewing zone.

(inside out). Such changes to images which are painted, photographed or drawn cannot take place as these images and the surfaces to which they are recorded (the support) are synonymous.

Fig. 3. Seth Riskin, *Figure with Crowns*, 2002, HOE, installation, Sky Art Conference, 24" x 20", Ikaria, Greece.

"Display" holographic representational systems are seen though the conjunction of a light and some sort of screen or plate, which holds the interference pattern. These two elements, one intangible and the other imperceptable, the light and the interference pattern, are employed sending the diffracted light away from the screen or plate to other locations to form the image. In addition, there is residual light passing through or being reflected from the surface of the plate, depending upon on whether the hologram is played back with light passing from behind (transmission) or in front of the plate (reflection). Because the replay light is redirected by the interference pattern distributed within the volume of the photosensitive material attached to the substrate,which in the case of painting or drawing would be called the support, it is necessary for the viewer to look in the direction of this plate or film to see the image. The subject of the holographic image may appear to extend out into the viewers space but the subject can only appear in locations, which fall within the angle subtended by the viewer's eyes and the perimeter of the plate. For this reason the hologram viewing space constantly changes shape according to the position of the viewer. In most instances the replay beam is stationary and the beholder moves, whereas in this case the reference beam source, the laser diode, is attached to the moving performer who is viewed simultaneously with the changing holographic image he is influencing.

The Visual Language of Holograms 337

in the subject, which is perceived as the viewer's distance from the holographic picture plane changes along the z-axis. But most importantly the beholder can stand *in* these bands of light with the sensation of the light being at the eye. When this physical shift occurs a phenomenological transition takes place in the perception of viewing from exterior to interior. The light is not shone on the beholder, rather it is perceived as being inside the body of the beholder. The product of the large freedom of movement of the body in relation to the coloured bands is not so much the experience of entering a rainbow as of having a

When the piece is viewed from a distance, the focal lines drift and merge as the viewer moves from side to side in front of the sculpture until he or she is aligned with the three lines. At this point the colours blend towards an achromatic balance. This is a calm place, a balance point, where harmony is symbolized by a shift towards whiteness. Moving closer, the viewer sees the blending and shifting off the hues become more vibrant. When the viewer is aligned with the lines at the focus of the holographic image, he or she is surrounded by whirling, brilliant fans of colours that flow across the curve of the sculpture…Standing in this axis of light, the viewer experiences a physiological response as

Perhaps the only other artwork to achieve the sensation of a light image existing inside the body is the projected poetic words by Centre for Advanced Visual Studies MIT, Fellow, Elizabeth Goldring, which employ a scanning laser opthalmoloscope to draw imagery directly on the retina. The beholder is tethered to the apparatus and therefore the light can only exist as an image inside the eye, unlike *Alignment* in which the beholder roams between

experiencing the holographic image as an exterior and as an interior phenomenon.

the light seems to rush upward through the spinal chord (St. Cyr, 1989).

Fig. 5. Sally Weber, *Alignment*, 1987, HOE, 7'x 3'

rainbow enter the body.

Fig. 4. Seth Riskin, *Figure with Crowns* , 2002, HOE, 24" X 20", Installation, Sky Art Conference, Ikaria, Greece

In Riskin's *Figure With Crowns* performance the transparent hologram support is held on a tripod, which is placed at a vantage point overlooking the shoreline. The performer is up to 30' away from the hologram support on the shoreline. The performance and viewing of the HOE takes place at sunset to enable a mixing of the orange and golden hues of the natural environment with the blue monochromatic subject of the HOE. As described by Riskin:

The performer casts an enlarged beam of blue light onto the hologram as viewers look through it onto the figure, the shore and the sea. In the eyes of the viewer, two rings of blue light hover, flanking the body, "attached" to it as the figure moves in the landscape (Riskin, 2011).

The spatial locations of these discs are in a plane with the light source which is attached to the performers body and appear as extensions of the performers body. The subject of the HOE is therefore not a spatial object but rather it embodies the changing spatial relationship between the beholder and the performer through the translucent subject.

*Alignment*, by Sally Weber, is a HOE that projects blue, green and red vertical lines of light 6 to 8 feet in front from a 7-foot high curved acrylic structure. In the following discussion the z axis is a line perpendicular to the plane of the holographic plate. The beholder can mix colours and alter their intensity by moving towards and away from the acrylic support within the long z-axis viewing zone. The image of the coloured bars is available at every height on the y, (height) axis. An important characteristic of this viewing zone is the change

Fig. 4. Seth Riskin, *Figure with Crowns* , 2002, HOE, 24" X 20", Installation, Sky Art

In Riskin's *Figure With Crowns* performance the transparent hologram support is held on a tripod, which is placed at a vantage point overlooking the shoreline. The performer is up to 30' away from the hologram support on the shoreline. The performance and viewing of the HOE takes place at sunset to enable a mixing of the orange and golden hues of the natural environment with the blue monochromatic subject of the HOE. As described by Riskin: The performer casts an enlarged beam of blue light onto the hologram as viewers look through it onto the figure, the shore and the sea. In the eyes of the viewer, two rings of blue light hover, flanking the body, "attached" to it as the figure moves in the landscape (Riskin,

The spatial locations of these discs are in a plane with the light source which is attached to the performers body and appear as extensions of the performers body. The subject of the HOE is therefore not a spatial object but rather it embodies the changing spatial relationship

*Alignment*, by Sally Weber, is a HOE that projects blue, green and red vertical lines of light 6 to 8 feet in front from a 7-foot high curved acrylic structure. In the following discussion the z axis is a line perpendicular to the plane of the holographic plate. The beholder can mix colours and alter their intensity by moving towards and away from the acrylic support within the long z-axis viewing zone. The image of the coloured bars is available at every height on the y, (height) axis. An important characteristic of this viewing zone is the change

between the beholder and the performer through the translucent subject.

Conference, Ikaria, Greece

2011).

in the subject, which is perceived as the viewer's distance from the holographic picture plane changes along the z-axis. But most importantly the beholder can stand *in* these bands of light with the sensation of the light being at the eye. When this physical shift occurs a phenomenological transition takes place in the perception of viewing from exterior to interior. The light is not shone on the beholder, rather it is perceived as being inside the body of the beholder. The product of the large freedom of movement of the body in relation to the coloured bands is not so much the experience of entering a rainbow as of having a rainbow enter the body.

When the piece is viewed from a distance, the focal lines drift and merge as the viewer moves from side to side in front of the sculpture until he or she is aligned with the three lines. At this point the colours blend towards an achromatic balance. This is a calm place, a balance point, where harmony is symbolized by a shift towards whiteness. Moving closer, the viewer sees the blending and shifting off the hues become more vibrant. When the viewer is aligned with the lines at the focus of the holographic image, he or she is surrounded by whirling, brilliant fans of colours that flow across the curve of the sculpture…Standing in this axis of light, the viewer experiences a physiological response as the light seems to rush upward through the spinal chord (St. Cyr, 1989).

Perhaps the only other artwork to achieve the sensation of a light image existing inside the body is the projected poetic words by Centre for Advanced Visual Studies MIT, Fellow, Elizabeth Goldring, which employ a scanning laser opthalmoloscope to draw imagery directly on the retina. The beholder is tethered to the apparatus and therefore the light can only exist as an image inside the eye, unlike *Alignment* in which the beholder roams between experiencing the holographic image as an exterior and as an interior phenomenon.

Fig. 5. Sally Weber, *Alignment*, 1987, HOE, 7'x 3'

The Visual Language of Holograms 339

the reconstructed image is confined to the space behind the plate, viewers physically lean onto the plate in order to look at the image more closely. The result of the image being very spatially realistic and also behind the picture plane is to necessarily heighten the feeling of exclusion from the scene depicted. The holographic picture plane is not always interpreted as a physical boundary, except in one –step optical, and laser transmission and reflection

On a physical level the boundary of the plate can cause the viewer to want to occupy the space of the image or a conceptual interpretation could be that the image is a metaphor for an aspect of memory- imagery being present yet physical accessibility being blocked. The interaction of the spectator with the subject with some holograms, which have the image in front of the plate may relate to the way Alex Potts has characterized the work of the sculptor Richard Serra, in contrast to the way that this type of viewing zone behind the plate invites a

Serra was well aware that physically involving the viewer …in an interplay between exteriority and interiority involved not just formal or perceptual effects, but carried a certain psychological charge…but this psychological dimension was a muted one as he conceived it. It is striking how his work which allows the viewer to enter produces a much less psychologically charged sense of interiority than works such as Hesse's or even Judd's where the viewer feels drawn towards an interior space from which he or she is barred, and

Additionally the distance over which the eyes are able to travel in the x, y and particularly the z-axis has a bearing on beholder reception. Laser transmission holograms can depict scenes up to approximately ten meters in the z axis such as *To Absent Friends* by Paula Dawson (Popper, 1993). The experience of looking towards a distant space can be similar to daydreaming. The size of the support (holographic plate) also determines the distance at which the beholder will decide to stand. As has been discussed, resolution also plays a role in selecting a suitable viewing distance. Therefore z axis movement of the beholder before the hologram picture plane, similar to the viewing of two-dimensional imagery, is primarily

Darkness, which has always has been a pictorial device of great importance in traditional media has also frequently been employed by artists to create ambiguities in optical holograms. Michael Baxandall in *Shadows and Enlightenment* pointed to an example of a drawing of a Roman soldier by Tiepolo in which the overall lighting pattern has nested within it smaller zones in which the lighting behaves in a completely different way (Baxandall 1995). This enables the viewer to make two possible interpretations as to where the leg of the soldier is located. This ambiguity as to the position of the leg engages the viewer in perceptual switching. In Margaret Benyon's, one- step laser transmission work *Hot Air*, 1970 laser transmission hologram 20 X 25cm, the beholder sees within one composition still – life objects, which display a full range of tonal values, and also a hand– shaped black void area. Similarly to the Tiepolo example, there is one overarching lighting arrangement of the objects in the scene, however, within this arrangement is the totally black hand, which is inconsistent with the overall pattern. The primacy of the artist's presence being registered through a negative rendering of their hand is immediately brought to mind, but in reverse, for the precise volumetric rendition of the hand instead

creates a poignant sense of absence through the three-dimensionality of the trace.

response analogous to the work of other contemporary sculptors:

feels it to be strangely alluring and inviting yet separate (Potts, 2000).

dependent on the size of the support.

**4.1.1 Darkness** 

holograms.

Peter Zec in his paper for the International Congress on Art and Holography 1991 commented:

As light is not only a generative principal but also a subject and the basic substance of the holographic reconstruction as well, the self –referencing of light represents an essential form for the articulation of the holographic message (Zec, 1990).
