COSCH Profile: Haida Liang
Anna Bentkowska-Kafel interviews Haida Liang, a Reader in Physics and Head of the Imaging Science for Archaeology and Art Conservation group at Nottingham Trent University in the UK.
Haida Liang. Photo: Dr C. S. Cheung, Nottingham Trent University, 2015
You hold a Ph.D. in Astronomy and Astrophysics from the Australian National University (1996). You worked for the Institut d'Astrophysique Spatiale at Orsay in France before moving to the UK. How does this international background help in your daily scientific practice?
This international background means extra language skills (French in this case) and an understanding of the different cultures including scientific culture which helps me in collaborations with international partners especially in EU collaborations such as COSCH.
What is your vision for the Imaging Science for Archaeology & Art Conservation research group you lead?
We have been developing new instruments, especially portable non-invasive optical imaging devices such as hyperspectral imaging and optical coherence tomography instruments, tailored to problems in art conservation, history and archaeology. We will continue this activity and in the immediate future we need to make our existing instruments more widely available to the community and I hope that COSCH will help us to do so. We welcome new collaborations. On the other hand, while we have developed applications for these devices with collaborators in heritage institutes, we have not focused enough on any particular application. The plan is to devote more effort in specific archaeology, art history and conservation problems.From a personal point of view, I would like to work more on projects that use science to provide material evidence for historical research, more interdisciplinary I guess. For example, our recent project on ‘Culture & trade through the prism of technical art history' is a good example of the kind of work that I'd like to devote more time on.
Do you recall any particular event or experience that inspired you to become an astronomer?
As a student, I always wanted to work on either particle physics or astronomy. When I was a third year undergraduate student at the University of Sydney, I signed up on a project to observe the Moon using the university radio telescope which was actually a telescope for research use and we had to drive 3 hours to get to the site (Molonglo Observatory) for observations. It was this experience that made up my mind to be an astronomer. It was a beautiful experience - the opportunity to use a ‘real' telescope, the peaceful sun rise and the kangaroos hopping around …
Jan Matejko, The Astronomer Copernicus, or the Conversation with God.
An oil on cardboard sketch, 1871. National Museum, Kraków. Reproduced with kind permission.
In a popular 19th-century painting Copernicus is portrayed watching stars on a roof terrace, surrounded by instruments, books and diagrams. Agitated, his hair in disarray, he seems bewildered by an unexpected observation. I remember my physics teacher at school commenting with skepticism on this portrayal of the great astronomer's eureka moment. The scene has also been interpreted as receiving a divine inspiration. My teacher believed none of these and argued that the process of scientific discovery is slow and laborious. What's your experience?
I think I would agree with your teacher. As a lecturer, I always wonder how much we should focus on the final exciting discovery and how much we should let the students know about the laborious side of scientific research. One of our research areas is Optical Coherence Tomography which is based on the Michelson interferometer. (By the way, you may know that Michelson came from roughly the same geographic location as Copernicus but a few centuries younger.) One of our undergraduate lab experiments is on Michelson interferometer, but many students get put off by the patience required to align the instrument despite the initial excitement of working on an instrument that earned Michelson his Nobel prize.
SPIE Optics, Electronic Imaging and other scientific organisations host woman subgroups, publish calendars profiling prominent women in science. What's different about being a woman scientist?
When it comes to scientific research, I have never really had to think of myself as a woman. It is only when I encounter sexism that I suddenly am reminded that I am a woman scientist. I think it is easier as an astronomer because it is a tightly knit community and once you have established a reputation for doing good science, less of the superficial things gets in the way, that is people do not have to judge you by initial impression. The initial impressions are the least objective and often makes gender, title and position more important than they should be. In my current field, it is very multi-disciplinary and therefore being a woman does have its disadvantages as it is harder for someone from a totally different field to judge how good you are as a scientist.
The Nobel awarded in recognition of the discovery of pulsars was given in 1974 not to Jocelyn Bell Burnell, who as a postgraduate student first observed and analysed the phenomenon, but to her supervisor and another radio astronomer. Her work was at first dismissed as a study of green men. Many years later, talking in a radio interview about being left out of this first Nobel in astronomy, she showed no bitterness. She argued that a Nobel, being the highest accolade, is likely to remove the incentive to further discovery. What's your view of recognition and what kind of recognition you value most?
I guess recognition from colleagues and students.
The ease, simplicity of language and excitement with which Brian Cox talks about the universe and science in popular TV and radio programmes, explaining quantum mechanics in one minute, disguise the complexity of these areas. Does any aspect of communicating science to non-scientists strike you as particularly challenging? For example, when explaining your research into the rate of expansion of the universe.
Nowadays, since I work mostly in a field that applies science to conservation and history/archaeology research, talking to non-scientists is part of the daily job. I find it hardest to explain it to the media as it is difficult to present truth without ifs and buts. I think the general public actually has more time for complexity.
You worked on a project that involved the application of astrophysics to the analysis of paintings. Can you say more about it?
Astronomy is about imaging faint signals from far away astronomical objects, so the imaging techniques employed in astronomy has always pushed the boundaries in imaging science. Since these objects are so far away, imaging in astronomy is necessarily non-invasive which is what we need for imaging of cultural heritage. I guess the project you are thinking of is the one on remote multispectral imaging where we built PRISMS (Portable Remote Imaging System for Multispectral Scanning) for imaging of wall paintings at standoff distances of tens of metres. PRISMS operates like an astronomical telescope taking a series of multispectral images. In fact over the years I found more and more links between astronomy and what I do now. The links go beyond imaging (for more details you can refer to a short paper I wrote on the subject http://pos.sissa.it/archive/conferences/170/027/Antikythera%20&%20SKA_027.pdf). I don't think this just applies to astronomy. I am sure people with other backgrounds moving into this multi-disciplinary field will find similarly interesting links between the various disciplines.
Art galleries have to negotiate between protecting objects and keeping them on public display. You worked with conservation scientists and conservators at Tate, assessing the safe level of exposure to light. How are such findings implemented? What happens when your team leaves the museum?
In this particular example, it was a true collaboration. Tate came to me to help them with building an instrument (microfade spectrometer) for in situ micro accelerated ageing test on watercolours. Tate provided funds for a PhD student who was both a Tate staff and a PhD student at NTU. Tate, as I understand, continues with microfade test to decide on how to store and display works of art.
[ a link to the Tate conference on microfade where I also gave a talk on our work :http://www.tate.org.uk/context-comment/video/anoxia-and-microfading-the-impact-on-collection-care-video-recordings-day-2]
At the COSCH meeting at i3mainz, in March 2013, you spoke about non-invasive optical investigation of wall paintings in the Buddhist temple in the Mogao caves, a UNESCO world heritage site in the Gobi desert. This work posed particular challenges. Can you explain.
First it is in the Gobi desert and we have to take our instruments such as PRISMS, OCT (Optical Coherence Tomography), microfade spectrometer and XRF to the site.The instruments had to be portable (fit into suitcases and often we fit the fragile instruments into carry-on cases) and robust enough to travel all the way. The dust can cause damage to the instruments and laptops. It can be very hot in the summer but the caves are always at a pleasant temperature. Usually we have to make some adjustments when we get there, since many of the instruments are sensitive optical instruments. Sometimes we have to rely on generators for electricities either because the voltage from the mains is unstable or if it is just after the flooding season, the floods can damage the electricity supply to the caves. Yes there can be floods in the desert! Luckily the Dunhuang Academy on site (in charge of the protection of the wall paintings) is a modern institute with a good lab facility.
Mogao caves - a UNESCO world heritage site in the Gobi desert along the ancient Silk Road
Haida Liang and her team in Cave 386 with the visible PRISMS (foreground) imaging the ceiling and the NIR PRISMS (to the left) at Mogao caves in 2011. Photos © Imaging Science for Archaeology and Art Conservation grou, Nottingham Trent University, UK.
Has this work inspired you to join COSCH?
It was a coincidence that just as we were writing up our paper on simultaneous 3D topography and multispectral imaging of the wall paintings in Mogao caves http://www.sciencedirect.com/science/article/pii/S0924271614001336, I heard about COSCH which is almost exactly on the same topic!
What do you hope the COSCH network can achieve?
It has certainly helped create new collaborations and I hope long lasting collaborations will come out of it. People are already getting together to apply for EU funding.
23 February 2015