A compound light microscope works by using a system of lenses to magnify a small object or specimen, making it visible to the human eye. This is achieved by passing light through the specimen and then through two sets of lenses: the objective lens and the eyepiece lens.
Here's a breakdown of the process:
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Illumination: A light source, usually located at the base of the microscope, shines light upwards through the specimen. Some microscopes have adjustable light intensity.
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Specimen Preparation: The specimen is typically mounted on a glass slide. If needed, the specimen can be stained to enhance contrast and highlight specific structures.
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Objective Lens: The light then passes through the objective lens, which is located directly above the specimen. Compound microscopes usually have several objective lenses with different magnifications (e.g., 4x, 10x, 40x, 100x). The objective lens collects the light that has passed through the specimen and forms a magnified, real image.
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Eyepiece Lens (Ocular Lens): This magnified real image is then projected upwards towards the eyepiece lens, which further magnifies the image. The eyepiece lens is usually a 10x lens, although other magnifications are available.
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Total Magnification: The total magnification of the microscope is calculated by multiplying the magnification of the objective lens by the magnification of the eyepiece lens. For example, if the objective lens is 40x and the eyepiece lens is 10x, the total magnification is 400x.
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Focusing: Focusing knobs are used to adjust the distance between the objective lens and the specimen to achieve a sharp, clear image. Coarse and fine focus knobs allow for different levels of adjustment.
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Image Formation: The final image observed by the viewer is a virtual, magnified, and inverted image of the original specimen.
In summary, the compound light microscope uses a two-lens system (objective and eyepiece) to magnify a specimen illuminated by a light source, allowing for detailed observation of small structures.
