Abstract:

Confocal laser endomicroscopy (CLE) has found an increasing number of applications in clinical and pre-clinical studies, for it allows intraoperative in-situ tissue morphology at cellular resolution. CLE is considered as one of the most promising systems for in-vivo pathological diagnostics. Miniaturized imaging probes are designed for intraoperative applications. Due to less sophisticated optical design, CLE systems are more prone to image aberrations and distortions. While diagnostics with CLE takes reference from the corresponding histological images, the determination of the resolution and aberrations of the CLE systems becomes essential. Thereby on-site quality check of system performance is required. Additionally, these compact systems enable a field of view of less than half square millimeter without zooming function, which makes it difficult to correlate human vision to the microscopic scenes. Therefore, it is necessary to have defined microstructures working as a test target for CLE systems. We have extended the 2D bar pattern in 1951 USAF test chart to 3D structures for both lateral and axial resolution assessment, since axial resolution represents the optical sectioning ability of CLE systems and is one of the key parameters to be assessed. The test target was produced by direct laser writing. Yellow-green fluorescence emission can be excited at 488 nm. It can also be used for other fluorescence microscopic imaging modalities in the corresponding wavelength range.