Prof Brotherton-Ratcliffe in his research lab.
Prof David Brotherton-Ratcliffe’s work in applied optics has to a large extent mirrored the fortunes of holography.
Having founded and managed LaserCraft in London in 1982, whilst completing a PhD in Plasma Physics and Controlled Nuclear Fusion, he moved to Australia in 1985. After working for 4-5 years as a research fellow in Fusion Physics at Flinders University in Adelaide he founded Australian Holographics Pty in 1989, making large format holograms for commercial advertising serving the Australasian market. In 1991, after the collapse of the Berlin Wall, he founded General Optics Pty which imported specialist optics and lasers from the ex-Soviet Union into Australia, and a year later he started a similar company, LMC France Instruments in Paris, serving the EU market.
David has also had a distinguished academic career, with recent connections to De Montfort and Wrexham Glyndŵr universities.
But it is perhaps his work at Geola Group, which he founded in 1992, for which David will be most familiar to readers of Holography News®. Geola’s commercial activity is centred around the facilities in Vilnius, Lithuania where the focus is on commercial holography, lasers and photo-materials.
I met up with David and his team at Geola’s research labs in the UK to find out more about his current research interests.
Q. Thank you for inviting me to this fantastic facility and for reaching out to the Holography News® readership. I know that much of Geola’s business is based out of Vilnius, so perhaps you can start by running through the origins of the organisation and how it grew to the size it is today?
A. Our principal facility is indeed situated in Lithuania’s capital city, Vilnius. The origins of Geola go back to just after the fall of the Berlin wall and to the opening up of the former Soviet Union to western markets. Most importantly, Vilnius had, for a long time, been an area well known for its key infrastructure in the fields of optics and lasers.
Initially Geola played the role of a research facility for my company, Australian Holographics, as well as exporting scientific equipment to the UK, EU and Australian markets. But by the end of the 90s, the business had started manufacturing its own neodymium pulsed lasers for the science and holography markets.
By the late 90s Geola had signed a global distribution agreement with the Russian holographic film manufacturer Slavich, and had also released a series of stand-alone holographic studio systems. These systems, for which there was a small but not insignificant market, allowed people with minimal training to produce large pulsed holograms of both people and animals.
Perhaps the key moment for Geola occurred in 1999, when we patented and produced the world’s first pulsed digital direct-write (DWDH) colour holographic printer. On the back of this, the company was able to secure very substantial investment and to spin out a Canadian operation called XYZ Inc. This led to the Geola group growing quickly; my UK company, Geola Technologies Ltd, was subsequently formed to help with the high demand for Geola’s RGB lasers by XYZ.
Today, while Geola’s primary market centres on the design and manufacture of scientific lasers for the international science community, we continue to be committed to holography. We have recently developed a range of lasers, originators and digital printers aimed specifically at the holographic security industry. Geola’s Blue Phoenix originators, which are available with pulsed or CW lasers, are capable of all the usual effects expected from competitive Image-Matrix machines at very competitive prices – they produce high quality holograms of excellent brightness.
In addition, drawing on our unique DWDH technology, we are able to provide effects not usually available - such as full-parallax ultra-realistic deep achromatic surface relief holograms with hogel sizes of 100 microns.
Q. While most of the commercial activity is based in Vilnius, the facility where we are meeting is dedicated to research and advances in ultra-realistic imaging. Can you give me a brief overview of your current research interests?
A. Currently my main research interests are in two completely separate areas. The first is electrical propulsion physics and the second is optical holography. I divide my time between Geola in Lithuania where I am Chief Scientific Officer, our UK Aerolab which has links to Wrexham Glyndŵr University and our UK OptoLab which has links to De Montfort University.
The OptoLab has basically grown out of the old Centre for Ultra-Realistic Imaging at Wrexham Glyndŵr University, which itself grew out of the Centre of Modern Optics at Glyndŵr and the Welsh company View Holographics Ltd. The main focus of this facility is the study of ultra-realistic full-colour digital holography. In this regard we have rebuilt the holographic printer that my colleagues and I designed for View Holographics. This tri-colour digital printer is based on a Geola Nd:YAG RGB pulsed laser and is capable of writing glass holograms up to well over a square metre.
I guess the general plan can be divided into ‘Art’ and ‘Science’. On the science side, we would like to refine the technique of direct-write digital holography (DWDH), study variants such as wavefront printing and to develop the associated technologies of light-field computation, light-field acquisition and general light-field displays (both holographic and other, static and real-time).
On the art side, we would like to understand how this science can be used most effectively in conjunction with modern origination tools such as virtual and augmented reality - and ultimately how digital holography might best be accepted as a serious art medium with proper archival properties.
One of the main aims of our research programme is the creation of DWDH holograms which simply transcend the medium – in the sense that an observer’s attention is no longer dominated by the fact that they are looking at a hologram per se, but is instead captured almost entirely by the image produced by the hologram.
Q. I notice that, in addition to the usual lasers, tables and optical equipment you would expect to see in an ‘analogue’ holographic lab, there are banks of servers that are more familiar to ‘digital’ holography. Can you say some more about that?
A. The banks of servers you describe are indeed used in our digital holography research.
Our DWDH printer is designed essentially as a research instrument, in that virtually all optics are configurable in real-time. This gives rise to quite a few racks of microcontrollers which are responsible for the control of all the motors. For a simple commercial DWDH printer this is over-kill in the extreme; for us it is useful in that we can use software to control absolutely everything to virtually any precision required. And this allows us to use the printer in different modes and to switch between these easily.
Other racks contain computers, mostly running Linux, which my colleague and a part-time PhD student at De Montfort, Tal Stokes, has built to process large light-fields. We also use them for our other area of research – computational fluid dynamics and aircraft propulsion simulations.
Over the past few years Tal has worked with our resident artist, Dr Ioana Pioaru, to manipulate the light-field datasets from Ioana’s digital sculptural drawings. Ioana produces these drawings using Google’s virtual reality Tilt-Brush application. However, before being able to be holographically printed, the drawings need processing in a program such as Blender and then the data must be digitally post-processed and ‘image-planed’.
The final datasets are written onto either photoresist or silver halide as holograms. Currently, our Vilnius facility does this, but we hope to start doing this also in the UK shortly. Typically, Ioana’s holograms contain up to 0.5TB of data, and special algorithms and custom computer architectures, which Tal and I have worked on, are key to keeping the computational time down.
In future we anticipate the dataset size to grow – perhaps even up to the 100TB range. Part of Tal’s PhD work is coping with these large datasets.
Q. There is also a beautiful exhibition space for viewing some truly remarkable 3D images. How does this tie into Geola’s research?
A. This space, which is on the second floor above the OptoLab, belongs to Dr Ioana Pioaru and is her art studio. As mentioned earlier, Ioana works at Geola as our resident artist and has been responsible for inventing the new technique of holographic sculptural drawing.
When you visited us, you saw two types of holograms which Ioana had made: RGB full-parallax digital reflection holograms made on silver halide film and transparent surface relief holograms made on glass. All were printed in Vilnius using Geola’s pulsed DWDH holographic printing systems.
Ioana generated the data for these holograms using Google’s Tilt-Brush program running on an HTC Vive Virtual Reality system. All the holograms were portraits of mostly famous people who Ioana ‘drew’ in 3D. I should point out that drawing in 3D means taking a digital ‘pencil’ and physically tracing 3D curves in space much as one would draw on a sheet of paper. The huge difference is, of course, the extra dimension and very few people have the technical ability to draw effectively in 3D.
As I also mentioned previously, a lot of data processing is required to manipulate the output of Tilt-Brush into a form compatible with Geola’s DWDH printers. This is where Ioana has collaborated closely with Tal Stokes. The first holograms Ioana made with this technique were standard 0.8mm hogel silver halide reflection holograms. She produced both full-colour and later achromatic versions. Importantly these were black or coloured lines over a white space. These ‘first generation’ holograms were exhibited at the 2017 Display Holography symposium in Portugal.
Ioana’s latest artworks are glass surface relief holograms made with 100 micron hogels. The much smaller size of these holograms allowed Ioana to perfect her sculptural drawing and to use white lines on a dark background, which routes the light energy into the drawing lines more effectively, enhancing the overall brightness of the hologram.
These ‘second-generation’ holograms have been exhibited in New York and Bucharest and will shortly form part of a solo exhibition scheduled for February 2022 at Gallery 286 in London.
Q. The effects of the pandemic have been hard on all businesses. How has Geola coped during this difficult time?
A. In Vilnius we certainly encountered problems. By December 2019 we had won quite a few government tenders for the manufacture of laser systems around the world – some of these were then postponed for over a year. With others, we couldn’t deliver or install our manufactured systems because we simply couldn’t send our technicians to the country in question. So, there was certainly an effect on our cashflow.
However, it wasn’t so big as to cause major problems. During the pandemic we were supported by two major EU grants for the development of laser and optical equipment; we were therefore able to fall back on research work to some extent during the leanest periods.
In the UK, since we are in a fairly isolated area, and since our principal activity is research, we were not greatly affected. The building of the new OptoLab did take longer than expected though, as only several people could be on site at a time.
Q. Finally, this is your chance to wave a magic wand. What would be the one advance in the industry that you would like to see that would accelerate growth in the hologram industry?
A. That’s quite a difficult one to answer. Because the industry is diverse. At the moment, the largest market for holography is still in security, packaging and authentication. The other applications such as medical imaging, head-up display systems, real-time displays, HOEs, cultural heritage, 3D maps, interior decoration, clothing, jewellery and fine art – to name just the main ones – are relatively restricted.
So different advances could certainly accelerate and promote different sectors of the industry.
I guess I’d go for a photopolymer that was sensitive to pulsed radiation. As you know, Geola has always concentrated on pulsed lasers rather than CW. The great advantage of the pulse laser is that you can write digital holograms and the digital HOEs you need for head-up displays much quicker than with CW lasers. Our current diode-pumped holography lasers can easily reach >200Hz and the latest SLM technologies support this.
But photopolymers generally don’t like nanosecond pulses because, unlike silver halide, the chemistry involves a diffusion process – which is innately long. We do know however how to make our laser pulses rather longer (let’s say >300ns) – not too long so that vibration and rail movement is a problem – but long enough to get us into the regime where photopolymers could be engineered to be sensitive to this light.
If such a ‘fast’ photopolymer were to appear commercially, I think it could really make a difference to applications such as medical imaging and automotive head-up displays.
Dr Ioana Pioaru’s studio.
