Correction Collar | Correction Collar
Key Words: confocal, N.A., oil immersion, chromatic aberration, Spherical aberration, coma, water dipping
Definition:A collar fitted to an objective that can be rotated allowing the user to correct spherical aberrations caused by, for example, variations in cover glass thickness, temperature, specimen thickness and refractive index
TECHNOLOGY:
The majority of dry microscope objectives are intended for use with a cover glass of 0.17 mm standard thickness and a refractive index of 1.515. This is satisfactory when the N.A. is 0.4 or less but when the N.A. is 0.8 or greater, minute variations in cover glass thickness can result in image degradation (chromatic, spherical, and coma aberrations) that increases with increasing cover glass thickness. A correction collar allows the user to adjust the central lens group position in the objective to correct for fluctuations in cover glass thickness. Correction collars can also be used to correct for image degradation caused by factors such as changes in refractive index, changes in specimen thickness, deep tissue imaging, and temperature fluctuations.
APPLICATIONS:
Optical aberrations can compromise image quality in any imaging application, but can be a particular nuisance in high resolution confocal or multiphoton applications.
MICROSCOPE CONFIGURATION:
A variety of objectives with correction rings are now available from manufacturers that have been designed for particular imaging techniques and applications. Nikon's Plan 100xW objective (NA 1.1, W.D. 2.5mm), for example, is a water dipping lens with a correction ring that corrects spherical aberration induced by deep tissue imaging or by working at physiological temperatures. It provides outstanding z-axis resolution in IR-DIC imaging, as well as a tight point spread function for confocal applications.
RECOMMENDED SYSTEM:
Please consult your local Nikon representative for advice on your specific imaging needs.
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