We used Optical Coherence Microscopy (OCM) to monitor structural and functional changes due to ischemic stroke in
small animals brains in vivo. To obtain lateral resolution of 2.2 μm over the range of 600 μm we used extended focus
configuration of OCM instrument involving Bessel beam. It provided access to detailed 3D information about the
changes in brain vascular system up to the level of capillaries across I and II/III layers of neocortex. We used
photothrombotic stroke model involving photoactive application of rose bengal to assure minimal invasiveness of the
procedure and precise localization of the clot distribution center. We present the comparative analysis involving
structural and angiographic maps of the stroke-affected brain enabling in-depth insight to the process of development of
A novel, time-resolved interferometric technique is presented allowing the reconstruction of the complex electric field output of a fast frequency swept laser in a single-shot measurement. The power of the technique is demonstrated by examining a short cavity swept source designed for optical coherence tomography applications, with a spectral bandwidth of 18 THz. This novel analysis of the complete electric field reveals the modal structure and modal evolution of the device as well as providing a time-resolved real-time characterization of the optical spectrum, linewidth and coherence properties of a dynamic rapidly swept laser.
We analyse the dynamical behaviour of a short cavity OCT swept-source laser experimentally and theoretically. Mode-hopping, sliding frequency mode-locking and chaos are all observed during the laser sweep period. Hetero- dyne measurements of laser dynamics allows some insight into the behaviour of the laser, while interferometric techniques allow the full phase reconstruction of the laser electric field. A delay differential equation enables modelling of the laser output, and laser parameters can be altered to provide optimisation conditions for future laser designs.
Tunable semiconductor laser for 1025-1095 nm spectral range is developed based on the InGaAs semiconductor optical amplifier and a narrow band-pass acousto-optic tunable filter in a fiber ring cavity. Mode-hop-free sweeping with tuning speeds of up to 10<sup>4</sup> nm/s was demonstrated. Instantaneous linewidth is in the range of 0.06-0.15 nm, side-mode suppression is up to 50 dB and polarization extinction ratio exceeds 18 dB. Optical power in output single mode fiber reaches 20 mW. The laser was used in OCT system for imaging a contact lens immersed in a 0.5% intra-lipid solution. The cross-section image provided the imaging depth of more than 5mm.
A novel digital scanning microscope (DSM) for observing cellular fluorescent micro-images is proposed and
manufactured in this study. DSM applied in the biomedical field has been designed based on a concept of fast access
time of an optical pick-up head (PUH) in optical disc devices; hence, DSM has been developed based on a blue-ray
PUH module with a triaxial scanning actuator (TSA) system. High-resolution and high-speed scanning is effectively
realized by TSA system instead of utilizing high-precision transpose stage mechanism. In consequent, a PUH module can
work with a time-correlated single photon counting (TCSPC) module and serve as DSM for detecting fluorescent signals