On the 27th August 2008 AILU held its latest one-day Medical Group meeting as part of the Industry and Technology Programme at Photon08. Duncan Hand of Heriot-Watt University, and a member of the AILU Committee, chaired the event.
The meeting was organised into three themes: Laser-based medical procedures; Laser-based manufacturing for medical applications; and Laser-based bioresearch. It was well attended and there were vibrant exchanges during the discussions.
The Laser-based medical procedures session started the day where Professor Holger Lubatschowski of Laser Zentrum Hannover spoke on Refractive Surgery of the Eye with Ultrashort Laser Pulses. Ultrashort laser pulses can be used in refractive eye surgery, where femtosecond (fs) pulses create a flap in the corneal tissue remodelling the curvature of the eye beneath and improving visual acuity. Holger described work using fs-pulses to influence the biomechanics of the crystalline lens of the eye and improve accommodation on eyes who suffer from presbyopia (resulting in longsightedness). Holger’s excellent presentation set the scene for the talks that followed. Following on Jon Exley of Lynton discussed Lasers and Light Sources in Aesthetic Dermatology. Jon described how lasers are commonly used to treat a variety of cosmetic and dermatological skin conditions such as unwanted hair growth, tattoo removal, and the reduction of wrinkles. More recently, Intense Pulsed Light (IPL) sources have been developed as an alternative. The final presentation before lunch was called Dentistry and Light. John Colles of Denfotex explained the increasing role of lasers, the repair of teeth and surrounding soft tissue, the relatively new process of photo-activated disinfection and continuing attempts to provide a useable optical drill. John presented some impressive uses of lasers in root canal work, drilling and disinfecting of dentine tubules, allowing the dentist to produce more robust fillings and restoration work.
After lunch the dental theme continued in the Laser-based manufacturing for medical applications session with Jon Parry of Heriot-Watt University and Nick Jones of Renishaw PLC discussing Laser Machining of Zirconia Ceramic for Manufacture of Dental Restorations. Currently dental restorations manufactured from Y-TZP at Renishaw are machined into their final state using diamond grinding tools. Recent work focused on laser machining of Y-TZP as an alternative, or complementary process, to diamond grinding with the aim of reducing machining times and cost. Afterwards, David Richardson of the University of Southampton discussed Harnessing the power of light – the fibre laser revolution. David described recent advances in high power diodes, diode-to-fibre coupling schemes and doped fibre design and fabrication, describing both CW fibre lasers and those using a MOPA architecture you can achieve ultrashort pulsed fibre systems operating at the multi-100W level with pulse energies now up at the 1 mJ level. Reviewing the state-of-the-art in both CW and pulsed fibre laser systems, David outlined some of the issues limiting further power and energy scaling, and described various applications. Before the afternoon break Dermot Brabazon of Dublin City University discussed Fabrication of micro-fluidic channels with Nd:YVO4 and CO2 laser systems. He described two new laser micromachining processes developed for the production of devices that are used for applications such as microfluidic lab on a chip, strain measurement, sub-micrometer cooling systems and various photonic guiding systems. Dermot has a lot of experience in the characterisation and optimisation of these processes developed in-house. Details of the systems and the high efficiency achieved from these processes were presented.
The final session of the day was discussing Laser-enabled bioresearch; it began with Graham Gibson of Glasgow University discussing optical tweezers and the developments made by Glasgow University’s Optics Group in Getting a Grip on the Micro-world. They have a long track record in optical trapping and innovative research. They have developed a clever system that has a real time interface for holographic optical tweezers in which the operator’s ﬁngertips are mapped to the positions of silica beads captured in optical traps. The beads act as the ﬁngertips of a “microhand”. This is used to manipulate objects that are otherwise impossible to control by optical trapping. High-speed video microscopy is used to measure the sub-thermal forces between interacting cells and particles, measuring the residual Brownian motion of many objects simultaneously the results showed force sensitivity of 10 femtonewtons. This method may be used to produce extremely sensitive sensors. The penultimate presentation was given by Tom Brown of the University of St Andrews who talked about Cellular Nano-Surgery. Tom discussed the transfection of cellular materials, in which a DNA plasmid is injected into a cell and a protein is subsequently expressed. This is important in the Life Sciences and is an active area of research. In 2002 Tirlapur et al  described how to use a fs-Ti:Sapphire laser source operating around 800nm for transfection. Using lasers offers several advantages over other methods including selected targeting, sterility, and the ability to combine them with other optical techniques such as micromanipulation and spectroscopic analysis. In his presentation, Tom discussed enhanced techniques for optical transfection by use of femtosecond lasers. Using a pseudo-Bessel beam, the critical alignment condition of the beam focus and the cell membrane can be greatly reduced allowing the development of a near alignment-free optical transfection system. Finally, Gail McConnell from the Centre for Biophotonics at the University of Strathclyde discussed Lasers for single-photon and multi-photon excitation microscopy. Gail discussed the development of laser scanning microscopy techniques for life science applications places greater demands on laser technology. She described the ability to control the temporal, spectral and spatial properties of robust, simple to use and preferably inexpensive laser sources is crucial for successful and efficient imaging. Gail demonstrated an overview of her groups current photonics research with the aim of improving sources for various imaging optical techniques including confocal imaging, multi-photon flash photolysis and coherent anti-Stokes Raman scattering microscopy.
Overall the day was a great success and each meeting that goes by increases AILU’s and the Photonics KTN profile in the Medical area and presents new opportunities for collaboration with companies and research centres well established in the Medical arena.
 U.K. Tirlapur and K. Konig, Nature, 418, pp.290-291 (2002)