The history of Optics at Imperial
Although prior research in optics had been undertaken at Imperial College of Science and Technology, the origins of an identifiable Optics Section can be traced back to 1917 when, supported by Government funding, the Higher Education Committee of the London County Council established an Optical Engineering Department. F.J. Cheshire was appointed as the Director and Professor A.E. Conrady as Professor of Optical Design. At the same time, L.C. Martin, who was already undertaking optics research at the College, was also appointed as a lecturer. Originally, the Optical Design Department was located in the Physical Sciences building of the Royal College of Science. Within two years of establishment, both undergraduate and postgraduate courses in optical design were being offered. Despite being the first course in technical optics to be instituted in Britain, the in-take of full time students was low and during the lifetime of the Associateship in Optical Engineering from 1919 - 1926, less than twenty students graduated. Clearly, the economic situation of the twenties affected the viability of the Department and by 1925 undergraduate work was terminated.
The eminent physicist, A.O. Rankine, was the second Director to be appointed. Rankine, well known for the Trouton-Rankine experiment, was distinguished for his contributions in many fields in physics, including molecular dynamics, acoustics and electromagnetics. Although he was not an optics specialist, he had made considerable contributions to the field including an early, yet effective, technique for the transmission of speech by sunlight, - a primitive optical communications demonstration similar to Bell's photophone. At Rankine's request, the name of the department was changed to Technical Optics and its uncertain existence ended in 1931 when it was officially absorbed by the Physics Department as a postgraduate section. At the same time, L.C. Martin, who had extensive knowledge and experience of optical instrumentation, took over as head of the Technical Optics Section. Being subsumed into Physics gave the Technical Optics Section security and a sound, albeit modest, financial basis for growth, ensuring the future of optics research and postgraduate teaching at Imperial College. In 1931 the Optics Advisory Committee was also founded " ..to advise the Governing Body of the Imperial College on Higher Education and Research in the Optical Sciences with special reference to industry". This committee continues to this day, advising and supporting the Optics Section, and the interface with industry continues to be a strength of the Optics Section.
Martin retired in 1951 and was replaced by Professor W.D. (David) Wright who was appointed to the Chair in Applied Optics. Wright's speciality was in colour science and colour vision, an area of research that had been investigated as early as 1877 by Sir William Abney at the South Kensington campus. Under Wright's leadership, the section flourished, benefiting from the general expansion of the College and in particular from the rapid growth of the Physics Department under the vision and leadership of P.M.S. Blackett.
When Wright retired in 1973, the laser era was introduced under the dynamic leadership of Professor D.J. Bradley. Dan Bradley was a leading international figure in ultrashort laser pulse generation and measurement and made pioneering contributions to the science of mode locked dye lasers and picosecond/femtosecond streak camera development. With Dan Bradley's appointment and the arrival of his group, incorporating both experimental and theoretical laser physicists, the Optics Section doubled in size. His legacy of applied ultrafast laser physics persists in the Section to the present day.
When Dan Bradley left in 1980, Professor W.T. Welford, a key figure in optical design, led the Optics Section until his retirement in 1983. At this point the Section was restructured with the formation of two associated yet distinct groups: a Laser Optics Group, headed by Professor G.H.C. New and an Applied Optics Group, headed by Professor J.C. Dainty. Geoff New is a leading laser theorist who had arrived at Imperial College with Dan Bradley in 1973. Chris Dainty, who had been a postgraduate student of Walter Welford and who was then particularly known for his work on speckle interferometry and astronomical optics, returned from the Institute of Optics in Rochester, USA as the inaugural recipient of the Pilkington endowed Chair of Applied Optics, assuring a continuation of Applied Optics within the Optics Section. The Rochester link provides another historical footnote in that Rudolf Kingslake moved from Imperial College to set up the Technical Optics Department at Rochester University with his wife Hilda - Rudolph was one of Conrady's students and Hilda was Conrady's daughter. Chris Dainty brought with him the concept of the Industrial Associates Scheme, interfacing academia with the optics industry. This interaction, in the economic situation of the eighties, was profitable both financially and scientifically for the Optics Section.
In 1988, the Optics Section was again expanded, amalgamating the Laser Optics Group with the Spectroscopy Group, a group also with a distinguished history within the Physics Department. Geoff New was appointed as head of the new LASP (Laser Optics and Spectrosc opy) Group and Professor R. W. Smith was appointed as head of the Applied Optics Group. In 1992, Chris Dainty returned as Head of Applied Optics and Professor Peter Knight, renowned for his seminal contributions to quantum optics, became Head of LASP, adding also to the Rochester connection - Peter Knight had been a research associate with Professor J. Eberly in Rochester during the early seventies.
In 2001 the Optics Section was again restructured and divided into two new groups that reflected the various research themes within the section. The Photonics Group (PHOT), launched by Chris Dainty, was established to incorporate the more applied and industry-facing research, combining the former Applied Optics research with the more applied research from LASP, while the Quantum Optics and Laser Science Group (QOLS), led by Peter Knight, was established to incorporate the more fundamental research, notably in quantum optics and high-field laser physics. The Experimental Solid State Group (EXSS) led by Professor G. Parry (a PhD student of Walter Welford and Chris Dainty), was also counted within the Optics Section, reflecting its wide-ranging optoelectronic research interests and contributions to teaching on the MSc course.
The Optics Section continued in this form, albeit with some changes in leadership. In 2001 Professor P.M.W. French, an alumnus of the Physics Department and an expert in ultrafast laser technology and applications to biomedical imaging, was appointed as the Head of the Photonics Group, which has expanded in terms of personnel and increasingly interdisciplinary research themes while still retaining the original remit of the Optical Engineering Department of a strong emphasis upon applications-orientated optics research and training. Also in 2001 Professor D.D.C. Bradley (son of Professor Dan Bradley), was appointed as Head of the EXSS Group, having moved back to College from Sheffield in 2000 to take up the Chair in Experimental Solid State Physics, as an Imperial alumnus from the same undergraduate Physics year as Paul French. Alongside the established optics-related research into inorganic semiconductor devices and photovoltaics, Donal Bradley developed a new strategic programme in Molecular Electronic Materials and Devices research with a strong focus on optical devices, developing polymer based LEDs, photovoltaic devices, and lasers. Molecular electronics is now the largest activity within EXSS. Following Peter Knight's appointment to Head of the Physics Department in 2003, Professor Jon Marangos, another alumnus of the Dep artment and an expert in coherent short wavelength light sources and high field physics, wa s appointed as Head of the QOLS Group, which has grown in the last few years to include world leading activities in experimental Cold Matter research and Attosecond Science and continues to expand its activity in theoretical Quantum Optics and Quantum Information Science.
In 2005 Donal Bradley was appointed Head of the Physics Department, following Sir Peter Knight's appointment as Principal of the Faculty of Natural Sciences, and Gareth Parry returned as Head of the EXSS Group. The Optics Section continues to flourish within the Physics Department and optics plays an ever increasing role in research across the College.
Our biophotonics research dates back to the 1990's when our adaptive optics imaging technology was first applied to ophthalmology and ultrashort pulses lasers were applied to the challenge of imaging in highly scattering media, including biological tissue.
Electromagnetic theory has underpinned our optics and photonics research since the Optics Section was first established in 1917.
Imaging science and technology
Imaging and vision has been at the heart of the Optics Section since its inception in 1917. Research achievements include the theory of colour vision, the development of computerised ray tracing for lens design, the development of the rigid (Hopkins) endoscope and the first commercial display unit for holograms.
Laser physics and technology
Research into laser physics at Imperial dates back to the arrival of Dan Bradley's group in1973 and has always has a strong emphasis on the application of lasers to scientific measurement and real-world applications. From the beginning there was a strong emphasis on the generation, application and measurement of ultrashort optical pulses. Highlights of the 1970's included world-leading picoscond dye lasers, the first theoretical description of passive mode-locking with a slow saturable absorber, the development of streak camera systems including the invetion of "Synchroscan", the 28th harmonic generation of Nd:Glass and pioneering mode-locked semiconductor diode lasers. The 1980's saw unprecedented spectral coverage from passively mode-locked femtosecond dye lasers and the demonstration of the world's first subpicoscond Ti:Sapphire laser, which led to a wide-range of novel ultrafast solid-state lasers in the 1990's. These included the first all-solid-state diode-pumped vibronic lasers and regenerative amplifiers (based on Cr:LiSAF), the first solid-state (Cr:LiSAF and Ti:Sapphire) lasers mode-locked with intracavity MQW saturable absorbers. In parallel, novel ultrafast fibre laser technology was pioneered, including the first tunable ultrafast sources based on nonlinear supercontinuum generation in optical fibres and the first soliton Raman lasers in the 1980's and the development of novel dispersion compensation schemes, THz pulse repetition rate lasers and the demonstration of the MOPFA (master oscillator-power fibre amplifier) laser systems in the 1990s. For a general overview of the development of ultrafast lasers, reviews by New (1983) and French (1995) may be useful.
Nonlinear fibre optics
Nonlinear fibre optics was established as a new field of research at Imperial College with the setting up of the Femotsecond Optics Group in 1986 by Professor Roy Taylor.