Microscope Functions and Types

Study Notes

Microscopes are primarily used to magnify small objects, making them visible to the human eye.
Electron microscopes use beams of electrons to achieve higher resolution than light microscopes.
Scanning probe microscopes (SPM) create 3D images of surfaces by scanning the sample with a sharp probe to create a topographical map.
Confocal microscopes produce 3D images of a specimen by illuminating a single point at a time, creating a series of 2D images that are then stacked to create a 3D reconstruction.

Compound microscopes use lenses to bend light and magnify specimens, often used in microbiology and general biology labs.
Electron microscopes can be used to study internal structures of cells, creating high-resolution images.
There are two main types of electron microscopes: scanning electron microscopes (SEM) and transmission electron microscopes (TEM).
SEM is designed to create 3D images of surfaces, while TEM is used to study the internal structures of transparent specimens.
Atomic force microscopes (AFM) are used to study surface topography at the atomic level, often for observing nanomaterials.
Dark-field microscopes are used to illuminate opaque specimens, where light is scattered by the specimen and only the scattered light reaches the objective lens, making the specimen appear bright against a dark background.
Phase-contrast microscopes are used to study the internal structures of transparent specimens, enhancing the contrast between different structures within the specimen by manipulating the phase of light passing through it.
Fluorescence microscopes use fluorescence to detect specific molecules in cells.
Oil immersion technique involves using a drop of oil between the objective lens and the specimen to improve the resolution of the image by reducing light scattering. This technique is often used with compound microscopes.

The objective lens magnifies the specimen, and a variety of objective lenses with different magnifications are available.
The condenser concentrates light from the illuminator onto the specimen, controlling the amount of light reaching the specimen.
The diaphragm regulates the amount of light passing through the specimen.
The stage holds the specimen in place for observation, allowing for movement in multiple directions for manipulating the specimen.
The illumination provides a source of light for illuminating the specimen.

Resolution refers to the ability of a microscope to distinguish between two closely spaced objects. It is related to the wavelength of light used, the numerical aperture of the objective lens, and the quality of the lens.
Numerical aperture refers to the light-gathering ability of the objective lens, impacting the resolution of the microscope.
Field of view refers to the area visible when looking through the eyepiece.