Field-of-View | Field-of-View
Key Words: parfocal, digital imaging, Magnification, parcentred, virtual slide
Definition:The area of the specimen visible through the microscope eyepiece
The field-of-view observed through the microscope objective is inversely proportional to magnification - i.e. the greater the magnification the smaller the field-of-view. Parfocal and parcentred objectives facilitate switching between magnifications (and fields-of-view) without significant loss of focus or without 'losing' the subject under high power. In some digital analysis and imaging systems it is possible to display an overview (large field-of-view image) at the same time as viewing a high magnification image. This allows users to easily locate the high power region being imaged on the whole specimen. Digital imaging also enables larger fields-of-view to be created by 'stitching' adjacent images together for viewing on a PC screen.
A range of fields-of view (magnifications) is an advantage in providing an overall understanding of the specimen. A low power objective (large field-of-view) such as 1X - 5X times is particularly useful in clinical pathology applications where it provides a comprehensive overview to enable identification of features of possible diagnostic significance for further high power imaging.
As the field-of-view is dictated by the magnification, a range of objectives may be important in providing an overall understanding of specimen features. The precise range used will depend on the application.
For clinical applications the Coolscope digital microscope system provides an all-digital solution where specimens are viewed directly on a PC screen. The entire area of a single glass slide can be viewed on screen. This can be maintained as a thumb nail reference image while examining selected areas under high magnification. Areas being imaged at higher powers are automatically tracked on the overview image using a crosshair marker to maintain an overall understanding of the geography of the specimen.