Miniature Dual Axes Confocal Microscope for Real Time In Vivo Imaging

Today, disease interpretation of excised tissue is performed by analyzing biopsy specimens with a tabletop microscope [1]. While this method is effective, the process can be limited by sampling error, processing costs, and preparation time. In addition, the interpretive accuracy of the specimens can be affected by artefacts associated with tissue sectioning, paraffin embedding, and histochemical staining. Thus, a lot of effort has gone into the development of new methods that perform real time in vivo imaging with sub-cellular resolution. Confocal microscopy is a powerful optical imaging method that can achieve sub-cellular resolution in real time. The technique of optical sectioning provides clear images from “optically thick” biological tissues that have previously been collected with large, tabletop instruments that occupy the size of a table [2, 3]. They can be used to collect either reflectance or fluorescence images to identify morphological or molecular features of cells and tissues, respectively. Moreover, images in both modalities can be captured simultaneously with complete spatial registration. This approach uses a “pinhole” placed in between the objective lens and the detector to allow only the light that originates from within a tiny focal volume below the tissue surface to be collected. For miniature instruments, the core of an optical fiber is used as the “pinhole.” Recently, significant progress has been made in the development of endoscope-compatible confocal imaging instruments for visualizing inside the human body. This direction has been accelerated by the availability, variety and low cost of optical fibers, scanners, and light sources, in particular, semiconductor lasers. These methods are being developed for use in the clinic as well as in small animal imaging facilities. The addition of a miniature real-time, high resolution imaging instrument can help guide tissue biopsy and reduce pathology costs. However, these efforts are technically challenging because of the demanding performance requirements for small instrument size, high image resolution, deep tissue penetration depths, and fast frame rates. The performance parameters for miniature in vivo confocal imaging instruments are governed by the specific application. An important goal is the early detection and image