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Microbiological imaging in compact and integrated devices allows for a variety of applications such as endomicroscopy or neuroscience. Typically, such devices require a large field-of-view with a high resolution to visualize cellular details and a high light collection efficiency to improve the signal-to-noise ratio and reduce exposure times. Thus, high numerical apertures are required. Miniature objectives with a numerical aperture of 0.7, a field-of-view diameter of 264 μm in the sample plane and color correction for a wide spectral range (450 nm – 900 nm) are offered by the company GRINTECH GmbH. However, while these accept curved sample fields as a degree of freedom, many demanding applications in the area of endo- and point-of-care-microscopy desire a field as flat as possible. In the scope of this work a broad optical design study was conducted to minimize the optical curvature of the object field. After having worked out 16 design approaches, the three best designs were shortlisted and investigated considering optical and mechanical design tolerances. The best as-built design was chosen and prototypes made of 6 lenses were manufactured. The diameter of the mounted objective is 2.2 mm with a total length of 13 mm. The performance of the novel micro system was experimentally evaluated by means of a confocal laser-scanning-microscope. |
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