A miniaturized laser scanning endoscope is presented which makes use of three lasers to illuminate a sample with a red, a green and a blue wavelength simultaneously. Scattered light from the sample is descanned and chromatically separated into the three channels for detection and postprocessing to compose a color image. The scanning subsystem consists of two micro-electro-mechanical mirrors suitable for mass production. The endoscope head can be assembled fast and at low cost. A resolution of the order of 16 lines per mm is achieved for a working distance common in endoscopy. Considerations of the system design include the operation of the mico mirrors, the filtering of reflected light by using polarization effects and a strategy to cope with color metamery. An expert system based on a neural network was found able to analyze endoscopic images to identify suspicious lesions.
While endoscopic optical coherence tomography has been established successfully in vivo ,implementation of endoluminal optical coherence microscopy remains demanding,s suitable confocal probe is lacking. A miniaturized confocal laser scanning microscope is presented,which fulfills the requirements for endoluminal optical coherence microscopy. First,imaging experience gained for optical coherence microscopy of nimal gastrointestinal tissue samples is described. For this purpose,laboratory scale optical coherence microscope with
an image acquisition time of 1min 30 s was employed. Cellular membranes can be identified throughout the gastrointestinal organs. Frequency domain image analysis can be used to distinguish columnar from squamous epithelium. Profilometric information on sample surfaces can be obtained directly as isophase lines. Second, the miniaturized confocal laser scanning microscope is characterized. Having an effective diameter of 25 mm, it houses single-mode optical fiber,scanning mirror and an objective lens. The micro-electro-mechanical mirror with gimballed suspension allows two dimensional scanning without introducing an optical path difference. The sinusoidal movement of both axes has to be considered to approximate cartesian image coordinates. Field geometry is illustrated s function of excitation amplitude and frequency. Acceptable image quality is chieved for frame rate of 0.5 Hz. A strategy to position the focal plane axially within the sample volume is discussed.
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