Five-lens, easy-to-implement miniature objective for a fluorescence confocal microendoscope.

A fluorescence confocal microendoscope requires a high-performance miniature objective. We present a miniature objective comprising four glass lenses and one plastic aspheric lens. The 0.5 NA objective is achromatized in the wavelength range of 488-550 nm, has a field of view (FOV) of 360 μm, and an outer diameter of 2.6 mm. The assembled miniature objective can resolve features separated by as little as 0.78 μm. The imaging quality of the fluorescence confocal microendoscope with the miniature objective is similar to that of a commercial confocal microscope. It can resolve cellular structures such as crypt structures and epithelial cells.