During open brain surgery we acquire perfusion images non-invasively using laser Doppler imaging. The regions of
brain activity show a distinct signal in response to stimulation providing intraoperative functional brain maps of
remarkably strong contrast.
In this paper we demonstrate real-time <i>in vivo</i> and <i>in vitro</i> OCT images of human dental tissue obtained in a clinical setting. For the first time we have used a compact, commercial prototype OCT system with a surgical microscope as a beam delivery system for investigations of dental tissue. We have imaged demineralised tissue, caries lesions and restored teeth and demonstrate the detection of changes in tissue microstructure. We discuss the details of this system and its potential and limitations with respect to dental applications.
A stationary low coherence interferometer for optical coherence tomography (linear OCT, LOCT) based on Young's two-pinhole experiment is characterized theoretically. All OCT sensors either work in the time (TDOCT) or Fourier domain (FDOCT). In contrast to these setups, the interferometer described in this paper employs no moving parts in the reference arm and no spectrometers for depth profiling. Depth profiling is achieved by detecting the interference signal on a linear CCD-array. Different positions of the interference signal on
the CCD-array correspond to different depths inside the sample. The
interference signal of the setup and the sensitivity in the case of shot noise limited detection are derived theoretically and compared to sensors in the time domain. In-vitro images of porcine cornea demonstrate the clinical potential of the setup.
Optical coherence tomography (OCT) is a noninvasive imaging technology, which provides subsurface imaging of biological tissue with a resolution in the micrometer range. OCT sensors either work in the time or Fourier domain. We present a new interferometer setup based on a ﬁber double pinhole arrangement. Two ﬁbers are placed in parallel similar to Young’s two-pinhole interference experiment with spatial coherent and temporal incoherent light. The interference pattern is observed on a linear CCD-array. A complete A-scan can be derived from a single readout of the CCD-array. The experimental setup is described in detail. The main parameters of the setup are derived theoretically and compared with experiments. First images of technical and biological samples are presented.
Time-resolved backscattering from randomly scattering media is studied experimentally with the aim of human skin diagnosis. The experimental setup consists of a self-modelocked Ti:Sapphire laser and a light gating technique based on sum-frequency generation. Aqueous solutions of latex microspheres were used as scattering medium. The experimentally determined temporal profiles of the recorded backscattered photons significantly depend on the specific conditions of the whole optical system. A systematic variation of the optical parameters was performed and an optimum arrangement was determined. In a first set of experiments, relatively weak concentrations of the scatterers were investigated and scattering lengths were determined. In a second series of experiments two-layered samples of latex suspensions with scattering properties similar to human skin were studied. Under these scattering conditions penetration depths of more than 1 mm could be obtained.