Stereo Microscope Objective Designed for Specimens in Aqueous Solution

By LabMedica International staff writers
Posted on 23 Jul 2014

A new stereo-microscope has been developed specifically for use with specimens immersed in aqueous solution. With this objective, users can obtain pin sharp visualization of specimens with up to a 5-mm water column between the specimen and the objective.

The objective solves a problem many stereo-microscope users have: looking at specimens in aqueous solution deteriorates image quality due to the refractive index mismatch between water and the air surrounding the microscope objective.

$Image: Studying Vascular Development using Zebrafish (somites). Left: without correction. Right: optics adapted to the refractive index of the water column by using the correction ring of the Leica Planapo 2.0x CORR objective (Photo courtesy of Mailin J. Hamm, angiogenesis laboratory, University of Muenster, Germany).$

Image: Studying Vascular Development using Zebrafish (somites). Left: without correction. Right: optics adapted to the refractive index of the water column by using the correction ring of the Leica Planapo 2.0x CORR objective (Photo courtesy of Mailin J. Hamm, angiogenesis laboratory, University of Muenster, Germany).

$Image: Studying Vascular Development using Zebrafish (eye). Left: without correction. Right: optics adapted to the refractive index of the water column by using the correction ring of the Leica Planapo 2.0x CORR objective (Photo courtesy of Mailin J. Hamm, Angiogenesis Laboratory, University of Muenster, Germany).$

Image: Studying Vascular Development using Zebrafish (eye). Left: without correction. Right: optics adapted to the refractive index of the water column by using the correction ring of the Leica Planapo 2.0x CORR objective (Photo courtesy of Mailin J. Hamm, Angiogenesis Laboratory, University of Muenster, Germany).

As the refractive index can be compensated with the Leica Microsystems (Wetzlar, Germany) Planapo 2.0x CORR objective for the Leica M series, interesting structures cannot be misread because of aberrations. Image quality is further enhanced by the objective’s high numerical aperture of up to 0.35.

Many stereo microscope applications such as zebra fish research, in vitro fertilization, or transgenics require aqueous solution to optimize the preparation process or to keep the specimen alive. Especially at high magnifications this poses an aberration problem, which results in blurred images with lower information content. The Leica Planapo 2.0x CORR objective overcomes this problem with the help of an adjustable correction ring. Turning the ring to the specified position enables users to adapt the optic to the correct refractive index according to the water column above the specimen. If users need to observe specimens in an airy surrounding, they simply return the correction ring to the home position.

“With our new objective we provide a high-quality tool for imaging specimens in liquid solution,” noted Jennifer Horner, product manager for stereo microscopes at Leica Microsystems. “It enables users to observe and document specimens as if the water was not there. So misinterpretations due to optical aberrations with water-immersed specimens are now things of the past. In addition, a numerical aperture of up to 0.35 is an outstanding value for objectives in this category. This, too, considerably boosts image quality.”

A working distance of 20 mm allows for easy access to the specimen. A quick-start guide comes with the microscope and helps users to quickly understand how to use the objective.

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