Microscopes are essential for studying specimens in colleges and industries. The optical and electron microscopes are more commonly used to study biological components, which comprises various parts, including objective lenses. Objective lenses or objectives are one of the two types of microscope lenses. They are usually already attached to the assembly, and you can switch them to change the magnification of the sample. But how do you switch objectives on a microscope?
Keep reading to learn about objective lenses and how to switch them on a microscope.
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What are Objective Lenses?
The objective lenses get their name from their closeness to the object under examination. Objective lenses come in varying magnifications ranging from as low as 2x to as high as 100x. You may also come across spring and oil immersion lenses that differ from the standard objective lenses. The spring objectives have better protection than normal lenses, while the oil immersion lens provides clearer imaging at higher magnification.
Microscope manufacturers produce objective lenses in various choices with specific features according to needs. The lenses may differ in optical characteristics, such as clarity and color correction, under different illumination conditions. The objective lenses also provide axial chromatic correction for blue and red wavelengths. You can see the optical parameters like the magnification, numerical aperture, optical tube length, and degree of aberration correction engraved or imprinted on the outside of the barrel. The latest objective lenses are created with Computer-Aided-Design (CAD) systems. The enhanced performance of the lenses allows researchers to study historical artifacts better than ever before.
How to Switch Objectives on a Microscope?
Handling a microscope requires intense care, as slight negligence can cause damage. Thus, when new to using a compound microscope, people often think twice when doing anything, even switching lenses. Microscopes come with three or four types of objective lenses mounted above the stage to observe the specimen. Switching between these objectives allows you to study the specimen under varying magnifications. But how do you switch objectives on a microscope?
Switching objectives is incredibly easy. All you have to do is rotate the disk on which the objective lenses are mounted, also known as the turret. It usually has a black band around it for easy identification. Rotate the turret containing the objective lenses until you obtain the magnification of your requirement.
How to Install an Objective Lens?
Installing an objective lens in a microscope is not difficult but requires vigilance not to scratch or break the lens. When installing a new objective, the first step is to remove the previous one. Hold the lens barrel tightly and rotate it to remove the damaged lens. Now, hold the new lens carefully and insert it into the socket. Hold it in the socket and rotate until it has tightened. Place a slide under the objective lenses to see if it is working properly.
The Bottom Line
The objective lenses are a crucial part of all types of microscope assembly and contribute to clear imaging of the specimen. The lenses are present on the lower part of the nosepiece and are in the closest contact to the sample. Optical microscopes typically come with three or four objective lenses that are switchable and changeable. Switching objectives on a microscope is incredibly easy. All you have to do is rotate the platform on which the objective lenses are mounted; it is also called the turret. Stop when you reach the objective lens you need.
What is used to change objectives on a microscope?
The objective lenses are on the turret or the revolving nosepiece, allowing you to rotate the objectives to study specimens in different magnifications.
What happens when you shift from one objective to another in microscope?
The change in the objective lens impacts the magnification and depth of focus. Objectives on the lowest power have the greatest depth of focus, and it reduces with a higher magnification.
How do you turn the objective lens up and down?
The coarse or focus knob allows you to move the lens up and down per need. The focus knob is the larger knob on the right side that lets you move the lens or stage.
Why do you have to watch from the side when changing objectives?
Experts suggest watching the objectives from the side when switching to ensure the objective lens does not touch the specimen and gets damaged.