<microscopy> In microscopy, the lens mounted before the microscope stage, which transmits light to the object. There are two main categories of condensers: (1) bright field and (2) dark field. Bright field condensers are of four distinct types: (a) Abbe condenser,, an uncorrected condenser composed of two separable lenses, (b) aplanatic condenser, (c) achromatic condenser which has full corrections for colour and spherical aberrations, (d) aplanatic achromatic condenser. The dark field condenser for low powers may be nothing more than a low-power bright field condenser with a central stop. Medium- or high-powered dark field condensers are usually of the cardioid or paraboloid type. The lamp lens is loosely called a condenser lens, but light-collecting lens is a more definite term. All microscope condensers must be carefully focused and aligned for best results.

(05 Aug 1998)