Image Preparation

series of translucent stripped images of vertical and horizontal orientation, which work at a perpendicular axis to the mirror. Their translucency allows the light to travel from the LED through the image frame, on to the mirrors and onwards trough the objective lens (which projects and magnifies the image).

Vertical and Horizontal Stripes
This week I was off the nano-lathe and focused instead on creating images to match the cut planes of the mirror facets. I put both of these into my optical system for testing and figured out that there would be lots of incremental changes to make. I began by printing a series of small scale translucent images to allow the light travel through the image and onto the mirror plane.

I created both vertically and horizontally striped images to reflect at 90 degrees to the cut mirror plane. That is, for the mirror with vertical cuts, I reflected/projected a horizontal stripe image and vice versa. This allows me to see how much the depth of cut bends the light and if my next program for the nano-lathe requires deeper cuts. These striped images are just for optical testing, when I work out how much the light bends I will create a series of images and matching mirrors.

Within the images I added a fine black stroke line in between each coloured stripe. This allows my eye to pick up the change in direction of the light (stripe) more easily – a trick I picked up from the 19th century artist-engineer Charles-Émile Reynaud! He used a black background in his image frames so that the viewer could more easily perceive the change in the characters in the foreground.

Horizontal striped image reflected in the vertically-cut mirror facet. Lines are bending only slightly, implying that the position of the mirror needs to be corrected and the cuts made by the nano-lathe could be deeper.

Image and mirror holders
After preparing the images,  I modelled up and 3D-printed some image holders so I could control their position in the optical system. Originally I thought that the image size needed to be exactly the same as the mirror, but when I tested this, it turned out that the image frame needs to be significantly larger than the mirror to compensate for the distance between the image-object and the surface of the mirror.

Original image holder, where dimensions match those of the mirror. After testing this proved to be too small and I made a series of larger images and image holder.
Larger model for a larger image which accommodates the distance from the image to the mirror facet.

 

Vertical and horizontal stripped translucent image frames and image placed in 3D-printed holder so I can adjust it within the optical system.

Before placing the facets onto the polygon gig, I needed to test a single mirror facet in my optical system and therefore modelled up a small holder for the mirror.

3D-printed polygon gig placed on top of the motor shaft.
3D-printed gig for the mirror. This gig allows me to slide the mirror along the track, positioning it to get the optimal optical effect of the cut mirror facet

At the same time Tom Cave from the School of Physics Workshop make a brass gig allowing me to easily attach the aluminium facets onto a holder for cutting. This will make centring the placement of the facet on the spindle much easier – for when I’m back cutting again next week on the lathe!

Brass holder/gig attached to the aluminium facet making it easier to centre the facet on the nano-lathe’s spindle.

Geoff and I have been working on a python script that we will use next week once back on the machine. We’ve been working towards achieving more stepped and deeper cuts on the aluminium facets, to see if this changes the reflected image more dramatically.

The code is generating the cut pattern, which is visualised in the graph at the bottom of the image. The scale is dramatically increased for legibility, these incremented steps are in microns.

 

 

 

Zooming in and out – from nano scale to millimetres

Inside the chamber of the nano-lathe

Zooming in and out – from nano scale to millimetres
Over the last few weeks I have been on a steep learning curve, venturing into the world of nano fabrication. It’s been quite a disorienting experience adapting my visual thinking to a Cartesian reference system to accommodate the different axes of the nano-lathe and understand how the g-code relates to the physical behaviour of the machine.

The constant moving back and forth between a such precision machine and 3D printers has forced me to continuously shift my focus. The shiny mirrored parts I’m making on the nano-lathe require my gaze to zoom in beyond what I can see without the aid of a powerful magnification lens. When I jump back onto the 3D printers, I feel my gaze zooming back out again and a millimetre now seems extraordinarily large! This shift in perception has made me think of a quantum physicist or astronomer, constantly oscillating between the ‘zoomed-in’ world of minuscule or faraway objects and the ‘zoomed-out’ world of everyday life.


What I’ve been testing, exploring, making

Setting trigger points to calculate the centre point of the tool relative to the machines X axis
Centring and balancing the spindle with probe and gauge

Cutting the mirrored facets
My collaborator Geoff Campbell has been patiently showing me the steps of the nano-lathe and there are many! After learning how to zero the various axis of the machine using a magnifying camera, probe and balancing system, I began facing components for a small 6-sided polygon, which I’ll place in one of my optical systems for testing – to see how these facets affect my image.

Neil Devlin cut a series of blanks for me to use on the nano-lathe and after facing them I’ve now begun to cut splines (patterns) into them. These patterns form the outer surface of the polygon and determine how the image-light, which travels through the image frame, is reflected off the mirrored surface and into the objective lens. By controlling the depth of cut to the mirror plane, the facets shift certain parts of the image. The images below with the wavy blue lines demonstrate how much the cut mirror surface changes the direction of the light. The wavy blue line is the reflection of a (very straight!) blue highlighter pen.

Polygon facets faced
High reflectivity of the facet facets
Reflection of a straight object (blue highlighter pen) in the vertically cut mirror
Reflection of a straight object (blue highlighter pen) in the horizontally cut mirror

 

 

This visual ‘relocation’ of certain areas of the reflected image will enable me to control the movement within the projected image, when placed into my optical system. We’ll be producing lots of iterations of these facets, experimenting with how the light ‘bends’ specific images and consequently creates the illusion of movement in the projected image. As the mirror cuts are so shallow on the lathe, I’m also exploring with Geoff how to calculate the distances required from the image source to the mirror facet to the objective lens and viewer. The next step is to play with how each cut on the mirrored facet bends specific sections of the image, so we can develop a sequence of cuts for the polygon facets.

 

Stepper motor and driver

Rotating the mirrored facets
I’m assembling the polygon components around a single rotating shaft, connected to a small stepper motor, controlled by a driver and some simple Arduino code. I 3D printed a set of gigs which will hold the individual mirror facets and sit on top of the motor’s shaft collar. As the motor rotates the polygon within the optical system, each uniquely patterned facet will refract the reflected image-light differently to create the illusion of movement in the projected image.

3D printed gig which attaches to the motor shaft and mirrored facets

Rotational speed is important for the perception of movement in the projected image. So far I have only been able to set the motor to rotate as slowly as 10 RPM, so I might need to add some gears to slow it down further.  Luke Materne from the Electronics Unit at the Research School of Physics has been helping me with this. More things to learn!

 

Cutting Splines into the facets
To begin a conversation with Geoff about the mirror cuts, I 3D modelled and printed some surface profiles. Understanding now how the nano-lathe works has modified my thinking about how to make the mirrored facets. Geoff wrote a python script to approximate the spline into a series of points and then turned this into g-code for the nano-lathe. The machine also cuts very slowly, for example a facet of 18mm x 25mm takes about 4 hours to cut about 120 microns (0.12mm).

Each cut has to be parsed several times with rough and finish cuts of different depths. It’s been really interesting to discover that the cut in the mirrored facet doesn’t have to be very deep. If it is combined with the correct focal length lens (that is, the distances from the mirrored facet to the objective lens and projected image) one’s visual perception still picks up the refraction (or change in the image).

 

Conversations with Geoff
There’s been lots of 3-way conversations been Geoff, myself and the whiteboard! As well as mirrors, we’ve started discussing how we can use the nano-lathe to cut some lenses using optical grade acrylic. We’ve also begun a dialogue about splitting up our optical system to have 2 mirrored polygons running on perpendicular axis. This will double the effect of the apparent movement in the projected image.

Quick whiteboard sketches

To explore this further I’ve been looking at Charles Wheatstone’s 19th century stereograph system, where he uses 2 image sources and angled mirrors to create a single image with a depth of field. I’ve also been exploring lots of historical optical device patents to look at different configurations for optically recombining the 2 separate images into a single projected image. The important difference between our system and Wheatstone’s stereograph system, is that our system only uses a single image source.

Top view of Charles Wheatstone’ stereoscope with angled mirrors. Image source: https://www.stereoscopy.com/library/wheatstone-paper1852.html
Nicholason Alexander McLean drawings from his 1933 US1906215 patent

MirrorMirror

MirrorMirror has emerged from wide ranging interests in historical and contemporary wonder and the projected image and its generating device. This introductory post will provide some context for my project – how I came to work with optical image systems as mechanisms for generating wonder and how I will use my ANAT Synapse Artist Residency to begin prototyping a new image system in collaboration with quantum optical physicist Dr Geoff Campbell at the ANU Research School of Physics (RSP). The title of this project alludes to the reflective properties of mirror being explored during the project, but it also references the project’s working process, whereby Geoff and myself will share, discover and learn from our collaborative endeavour.


Projected Image-Light

After several years of working with miniature architectural structures in glass and the moving image, projected image-light had firmly cast its spell on me. I projected video-animations or dreamscapes to wrap around my constructed glass buildings. The glass walls, which once encapsulated spaces full of life, now abandoned and empty, released fleeting memories in the form of nonsensical fragments of image-light. As an object maker, I carefully controlled the translucency of the glass, allowing the image-light to enter into the walls and remain there. I focused on glass as a material substrate with which to hold these fleeting images, rather than as part of the mechanism that generated them.

Then one wintery afternoon I stumbled across an exhibition on the magic lantern at the Cinémathèque Française and realised that the material of glass played another crucial role in the history of projected image making. Not just a material which holds the translucent image, glass was as important as light within the projecting mechanism itself. I began to invert my practice – instead of working with glass to create empty architectural structures with which to hold the fleeting dreamscapes, I explored how glass is optically embedded within the technological device that generates the image. Instead of focusing on objects per se, I started to explore how glass objects function as components within overall image systems. First off, I began investigating lenses and their ability to bend light, which led me down a rabbit hole to natural magic and wonder.

Technological objects and wonder

I spent many days in my studio deconstructing various old projection devices, extracting their lenses and light sources. Each time I held up one of the lenses in front of my studio window, the scene from outside was somehow magically transported onto the wall behind me. It seemed unfathomable to me that the material of glass, just by being formed and polished in a particular way and interacting with natural light, could transport an image across my studio, creating its own parallel space-time. Determined to understand the uncanniness of this deceptively simple technology, I looked to the history of lens making and its application.

I was amazed by the 17th century natural philosopher and lens maker Christiaan Huygens’ combined mathematical knowledge and material skill in forming telescopic lenses and Rene Descartes’ determined, but ultimately failed quest to build an automated machine to grind and polish a perfect hyperbolic lens. But when I encountered the early optical technologies of preternatural philosopher and natural magician Giovanni Battista Della Porta, (some 80 years before Huygens), a whole new world opened up. The experience of wonder witnessing the uncanny ability of glass to transfer and image of an object across space and time was explicitly used by Della Porta.

Preternatural philosophers from the mid-16th to 17th centuries had an obsession with wonder that was generated from the close observation of nature. They used early optical technologies in the form of lenses and mirrors to see what, until then had remained invisible to the unmediated eye. I was interested in how these optical objects served as illusionary devices to project images of the newly rendered visibilities and incite wonder. For example Della Porta’s contemporary Jean Pena placed a concave mirror (one wonders how precisely formed and polished this object was) inside a camera obscura, projecting images which appeared to hover in the air. Della Porta himself used optical objects to create moving simulacra as part of his performances inside a camera obscura theatre chamber. Reportedly, live performers acted outside the chamber and directly in line with the device’s lens (by 1557 Gerolamo Cardano had already thought to place a lens in a camera obscura). Projected images of their enactments were transported through the device’s aperture onto a wall inside the chamber, where Della Porta’s audience sat wondrously watching the projected images as they unfolded live before them.

I became interested in the interchange between (in)visible technological causes and how in accordance with his practice of natural magic, Della Porta’s audience never saw the source object (the performers) or the device (they were obliviously sitting inside it!), only its detached image. I wanted to create novel optical systems to incite wonder in contemporary audiences, but instead of hiding the apparatus that created my projected images, I would expose the technological mechanism to overtly include it in a system of image, device and viewer.


Charles-Émile Reynaud, optical mechanics and Ghost in the Machine

During the development of one of my image systems Ghost in the Machine, I came across the 19th century artist-engineer Charles-Émile Reynaud. Reynaud developed a system of optical mechanics first with his praxinoscope and later in his more elaborate Théâtre Optique. When I witnessed these devices in motion at the Cinémathèque Française, animated characters reflected themselves off mirrored polygons, which rotated around static sources of light. Brought to life through the movement of a mirrored polygon, these images appeared like spectres, suddenly re-activated from the dormant past of the nineteenth century.

The praxinoscope uses an optical mechanism of a mirrored polygon sitting inside an encircling metal drum twice its diameter. Reynaud described the polygon as a ‘cage of mirrors’, a series of twelve small vertical mirrors glued to each other and positioned in the centre of the drum. The polygon and the drum rotate on the same axis. Each mirrored facet of the polygon reflects a single and different image frame painted on the inside of the drum. Collectively, the images make up a frame-by-frame sequence of movement, so that when the device rotates in front of a viewer, it creates the appearance of a moving image. Reynaud later developed the praxinoscope device into a more elaborate form of the Théâtre Optique, which used hand-painted translucent glass slides on a rotating device allowing up to 250 image frames. He rear-projected these reflected images through an objective lens system onto a screen.

While developing Ghost in the Machine it proved challenging to generate a projected moving image that wasn’t blurred. To overcome this problem I applied Reynaud’s technique of individually reflecting each image frame on to a matching mirrored plane. This concept worked because in contrast to my image frames, where each image presents a different stage of movement, each segment of mirror is identical. It is the image reflected from the mirror (and not the translucent image frame per se) that travels through the objective lens and is projected on to the screen. So while the mirrored plane renders the moving image legible, its reflective properties hide the mirror in plain sight – as the viewer of the projected image, I don’t perceive the changing mirror plane, only the different stages of movement foregrounded on an apparently static background.

Reflective properties of the mirror have become a significant element in my continued exploration of projected moving image systems. Contemplating how the mirrored polygon renders itself invisible through its own materiality, mirror, in addition to glass and light, is a key material for my explorations of wonder and (in)visibility and will be the key material explored during the residency.

 

Polygon problems, new ideas and the ANAT Synapse Artist Residency

Fabricating the polygon proved to be the most problematic component of Ghost in the Machine, but also one that provided numerous ‘next steps’ in my practice. Machinist engineer Neil Devlin at the RSP who, being the innovative master he is, milled and polished the polygon by fly-cutting the surfaces using a diamond tool from the School’s ultra-precision lathe. The rotating polygon, the process of making it and understanding optical mechanics gave me new ideas for creating moving images in novel ways.

After learning so much from creating Ghost in the Machine, late last year I completed a small pilot study with Geoff at the RSP as part of my ANU Vice Chancellors Creative Research Fellowship. We used the precision lathe to cut and optically polish different mirrored facets to investigate if, instead of using an image carousel with 48 image frames, as in Ghost in the Machine, we could generate a moving image from a single image source. The optical premise was that having multiple reflective planes on a single mirror facet would change the direction of light. Therefore when an image was projected onto the mirrored plane, it could be controlled to bend or change in specific ways to create the illusion of movement.

Our results from this initial study were promising and we now plan to develop this idea further as part of our ANAT Synapse collaboration. Our main fabrication tool will be the ultra-precision lathe as it can achieve extremely high-level and precise polished surfaces. I will also prototype specific components using additional fabrication technologies in the MakerSpace located in the RSP. From precursory conversations between Geoff and myself, this residency will open up many more possibilities, other than mirrored components, within my optical systems. We will also explore different materials and fabrication processes using the lathe (transparent as well as reflective), and iteratively test how these novel components can bring to fruition previously unimagined ways of generating projected moving images. My task will then be to see if these systems evoke an experience of wonder in a contemporary audience.

Stay tuned for additional ‘experiments-in-progress’ blog posts during my residency.

Thank you ANAT for this wonderful opportunity!

 

 

 

Recipient of the 2020 Synapse Residency Program