Synopsis
Many different types of microscopes are used in virtual microscopy that are tailored to specific purposes. The main difference is in the objective lens used, which is a special lens responsible for magnifying and focusing on the specimen. The objective lens used has a direct influence on the clarity and resolution of the image obtained. It is therefore important to consider the capabilities and number of lenses available when choosing a virtual microscope. By referring to guides or asking for expert advice, you can make an informed decision and exploit the full potential of the virtual microscope. By understanding the importance of objectives and their role in virtual microscopy, you can achieve high quality results and improve the overall experience of using the instruments.
Objectives in Virtual Microscopy
The design of an objective lens in a virtual microscope system is complicated due to its multi-element composition. The use of lenses depends on the platform used and the type of microscope. It also depends on the magnification level and the desired application. In general, digital microscopes offer a variety of possible objectives to choose from based on typical working needs.
Why is Objective Lens Important?
In a traditional optical microscope, the objective lens is mounted on a rotating disk that allows you to switch between different magnifications. In a virtual microscope, the objective lens is accessible via an on-screen interface that allows you to select the desired magnification using a mouse or other input device.
Number of Objective Lenses
Some microscopes have a limited number of objectives, while others offer a variety of options depending on your needs and preferences. If researchers need to observe small specimens, the lens intensity of a virtual microscope will serve this purpose, while low-resolution lenses will serve this purpose in education.
Importance of Magnification Power
Microscope objectives are available in magnifications of x25, x50, x100, x200, x500, and x1000. These magnifications are used for different purposes depending on the nature of the work to be carried out. In pathology, histology, hematology and biology, it is necessary to observe different types of specimens and their properties. In these fields, higher magnifications are necessary to obtain accurate results.
What Are the Different Types of Objectives?
The performance of a microscope depends on the objective and the lens used. When choosing an objective, it is important to consider factors such as magnification and design complexity, as well as to have a clear understanding of the correct quality correction. Correction of chromatic aberration is particularly important. There are two general levels of correction: achromatic and apochromatic.
- Achromatic Objectives: These lenses are the simplest and cheapest way. They are specifically designed for the correction of chromatic aberration at blue and red wavelengths and for the correction of spherical aberration at green wavelengths. However, their performance is limited by insufficient correction of chromatic aberration and the lack of a flat field of vision.
- Apochromatic Objectives: These objectives are designed to provide excellent accuracy and color correction over a wide range of colors including red, blue, and yellow. They are also capable of correcting spherical aberration over a wide spectral range and usually have a long working distance due to their large numerical aperture (NA). These lenses are particularly suitable for white light applications. In contrast, color lenses are more suitable for monochromatic applications.
What Are Achromatic and Apochromatic Designs?
As the magnification of an image increases, the distortion and field curvature of chromatic aberration and achromatic design increases. This can further have a significant effect on its performance. It is therefore important to assess the overall performance of the system rather than focusing on the quality of the target.
In a Nutshell
Plan objectives also referred to as planar, semi-plan, semi-planar, or micro-plan objectives, are specifically designed to correct the field curvature. This type of aberration occurs when an off-axis image cannot be centered in the planar image plane, resulting in an image far from the optical axis appearing blurred. A chromatic aberration lens centers the image 65% flat, while a planar lens provides the best overall correction as more than 90% of the field of view is flat and in focus. Semi-plan objectives are in between the other two types, with 80% of the field of view being flat.
What Are Fluorite Objectives?
Fluorite objectives use an advanced glass material containing fluorspar or synthetic substitutes to provide more accurate aberration correction. Like achromatic objectives, they are used to correct color differences in red and blue wavelengths. However, they go one step further by correcting spherical aberrations in two or three wavelengths instead of just one (usually green). They also usually have a larger numerical aperture, which gives higher resolution and contrast.
Conclusion
Objectives are very important in virtual microscopy. The use of a lens depends on your needs. When using a virtual microscope, you have many magnification options ranging from x25 to x1000. Different objectives and their characteristics affect the magnification and resolution, which are important for the results. It is important to remember that the same microscope, magnification and objective are rarely used for research, scientific, and educational purposes. It is important to learn more about colour, chromaticity, fluorescence, microscopes and fluorescence objectives before deciding which objective to use.
