Parfokales

Parfokales refers to a class of microscope setups or objectives that are designed to maintain the focal plane when changing magnification. The concept, known as parfocality, is central to multi-objective microscopy. A parfokale system allows the operator to switch objectives with minimal refocusing, enabling faster imaging and reducing sample handling.

Origin and scope: The term arises from the adjective parfocal, which describes optics whose focal planes are aligned across objective changes. In some languages and vendor literature, the plural parfum “parfokales” is used to denote the set of parfocal objectives or configurations in a given instrument or kit. The concept applies to both standard brightfield and fluorescence microscopes, with tolerances tailored by manufacturer.

Calibration and use: Establishing parfokality typically involves selecting a calibration specimen and focusing with a reference objective, then adjusting the stage or using compensating optics so that the same specimen remains near-focused when switching to other objectives. Operators verify parfokal performance by checking a fixed stage position or a known feature across multiple objectives.

Advantages and limitations: Parfokales improve workflow speed, reduce overall photodamage by decreasing refocusing, and aid consistency across magnifications. Limitations include mechanical wear, objective design differences, and environmental drift. Some modern microscopes rely on electronic autofocus rather than depending on parfokal alignment.

See also: focusing, parfocal, microscope objectives, autofocus.