The numerical aperture is a measure of the solid angle covered by an objective. It indicates how the lens can resolve the smallest features of a specimen. Inscribed on every objective lens and on many condenser lenses, is a number called the numerical aperture. вЂњOilвЂќ designates oil immersion objectives 7. Tube length in mm or в€ћ for infinity-corrected objectives 4. Structures that lie closer to each other than this distance cannot be resolved in the lateral plane using a conventional optical microscope. This wavelength limits the resolution of the light microscope working in white light to about 200вЂ“250 nm. White light wavelength is in the region of 400 to 700 nanometers (nm) with an average wavelength of 550 nm. In the microscope that works using transmitted light, the lateral resolution is determined by only three parameters: the wavelength О» of the illuminating light and the numerical aperture of the condenser NA cond, and the objective NA obj. It is defined as the smallest distance in the plane of the specimen (called the X-Y plane) at which two points of the specimen can still be seen separately and not as one point. The resolving power of a microscope in the specimen plane is called lateral (or XY) resolution. This converter is designed only for transmission (bright-field) microscopy. Opening angles of the objective and the condenser 1 - objective, 2 - specimen, 3 - condenser, 4 - illuminator О± obj is the half the opening angle of the objective and О± cond is half the opening angle of the condenser

Angular resolution calculator of a lens