11:00 am to 12:00 pm
Fibre-coupled Multiphoton Microscope with Adaptive Motion Compensation for in vivo Imaging
Optical imaging devices have played a huge role in enabling our understanding of complex biological systems. One area which is heavily reliant upon the use of optical microscopes is the diagnosis of diseases in plants, animals and humans. The current gold standard for diagnosis of cancer in humans is histopathology which, although highly successful has some significant short comings. In particular, clinicians would like to image suspect tissues areas without having to remove them from the patient first as this can cause changes to the cellular structure and composition. If the quality of images acquired in vivo could match those from conventional histopathology then a major goal of the biophotonics community will have been achieved. One of the many experimental challenges posed by this aim is how to account for the motion present in all living things. Breathing, heartbeat, peristalsis are fundamental biological processes in humans that result in motion sufficient to degrade the resolution and contrast of microscope images to point where they have limited diagnostic value.
In this talk I will present details of research undertaken at Imperial to develop a fibre-coupled high resolution optical imaging system that is designed to image human skin in vivo, with the aid of an adaptive motion compensation system. Diffraction limited, optically sectioned images are acquired using a laser scanning multiphoton microscope that uses light from a mode locked Ti:Sapphire laser which is coupled down a hollow core photonic crystal fibre. The sample fluorescence is collected by a multimode fibre bundle and guided to a photon multiplier tube. The motion compensation system is based on the optical range finding properties of spectral domain optical coherence tomography (SDOCT). The SDOCT system exploits the principles of low coherence interferometry to measure the optical path length difference in the two interferometer arms by analysing the optical interference pattern recorded on a spectrometer. The sample is placed in one interferometer arm and a fixed position reference reflector in the other. Changes in the axial location of the sample will be detected by the SDOCT system and in response a signal is sent to a piezo actuator to adjust the axial position of the objective lens.