Development of a wide-field-of-view microscope objective system with high resolution and long working distance

This paper presents the wide-field-of-view microscope objective system designed and fabricated for large biological samples. In general, the image stitching needs to be used for the observation of large biological samples with commercial objectives. However, the movement of the objective lens will cause the stitched image with some splicing traces, and the image stitching is time-consuming. Therefore, a customized large field-of-view objective lens is indispensable. In this study, the objective lens is designed as a wide field of view of Φ 22 mm for large biological samples, which enables to detect the whole mouse brain. The working distance is larger than 30 mm for the space to scan the complete sample vertically. Most importantly, the resolving power should achieve a cellular spatial resolution of 1 µm. The correction of the longitudinal chromatic shift is critical for the objective lens, and it is especially challengeable for the wide-field-of-view objective lens. The ultra low dispersion material is employed in the achromatic doublets design to correct chromatic shift appropriately. The process of the optical design, opto-mechanical and measurement are described in this paper. The modulation transfer function of the objective lens is measured, which can meet the requirement specification. Finally, the prototype of the objective lens is successfully fabricated and verified.