High-resolution confocal transmission microscope Part II: determining image position and correcting aberrations

摘要

In order to produce high resolution images of complex biological specimens in a confocal transmission microscope, two phenomena must be overcome. Firstly, non-uniform refractive index variations in the specimen cause deflection of the focused image spot in three-dimensional space which presents a problem for the usual confocal approach of imaging onto a fixed pinhole. The second effect is optical aberrations (especially spherical aberration) which arise as a natural function of imaging through the thickness of a refractive specimen. This paper discusses how both effects may be monitored and overcome, while still providing confocal imaging, using a CCD array as the detector.