Readings 1 PDF

# 9 - Introduction to Microscope ## Types of Microscope ### 1- Simple Microscope * It's single lens microscope with simple magnification. * Used to obtain small magnifications such as morphology. * Used to see the magnified view of different particles present in diverse soil form. ### 2- Compo...

# 9 - Introduction to Microscope ## Types of Microscope ### 1- Simple Microscope * It's single lens microscope with simple magnification. * Used to obtain small magnifications such as morphology. * Used to see the magnified view of different particles present in diverse soil form. ### 2- Compound Microscope: or Optical Microscope: * We use it when we need to look at something so small that we can't see it with our naked eye. * For the microscope to work properly, the specimen also needs to be at least partially translucent so that the light can pass through and make it visible. * This microscope uses compound two lenses to magnify objects (Eye lens and objective lenses). * The lenses bend or refract light to make the object beneath them appear closer. * It also contains the source lighting (mirrors or lamp electric). We will discuss all about it later. **Compound light microscope divided into 3 types according to number of eyepiece as the following figure shows** * Monocular * Binocular * Trinocular ### 3 - Florescence Microscope * It is a microscope that uses fluorescence to generate an image. ### 4- Phase-Contrast Microscope * The phase-contrast microscope used for biologists to study living cells and how they proliferate through cell division. * It is one of the few methods available to quantify cellular structure and components that does not use fluorescence. * It makes living, unstained microscopic structures visible. ### 5 - Stereo Microscope * It is an optical microscope that provides a three-dimensional view of a specimen. * It is also known by other names such as dissecting microscope and stereo zoom microscope. ### 6 - Electron Microscope * Used electrons rather from light radiation in this microscope types. That's where electrons short wavelength are given this microscopes magnification high up about 1000 twice the microscopes common. **Electron microscope has two types:** * **Scanning electron microscope (SEM):** Used to study the superficial parts of the cell and organism. * **Transmission electron microscope (TEM):** Use to check the clear structure of cells. ## Parts of a Microscope The parts of the microscope and their functions are explained below in the table. ### There are two types of lenses in compound microscope 1. **Ocular lens (eyepiece)** 2. **Objective lenses** **Usually, a compound microscope comes with 3 or 4 objective lenses.** | Name of the parts | Function | | :------------------------ | :------------------------------------------------------------------------------------------------------ | | Arm (limb) | Connects ocular tube and base. It also helps carry the microscope | | Base | Provides support to help microscope stand upright | | Coarse adjustment knobs | Focus of image under high power and moving the stage up and down. | | Condenser | Forming a cone of all the dispersed light rays from the illuminator | | Diaphragm (Iris) | Controls the intensity of illuminating light | | Eyepiece (ocular lens) | Magnification of image produced by objective lens | | Fine adjustment knobs | Focus the image when viewing under high power | | Illuminator | Provides high-intensity light at the field aperture | | Mirror | Reflects light from an external source | | Objective lens | Primary magnifier of microscope | | Ocular tube | Maintains the correct distance between the ocular and objective lens | | Revolving nose piece | Holds the objective lens. Its rotation helps to change the power of the objective lens | | Stage | Place for holding sample | | Stage clips | Keeps the slide with a specimen in place on the stage | ## The different types of objective lenses are: ### Scanning objective lens (4x) * A scanning objective lens provides the lowest magnification power of all objective lenses. * The name "scanning" objective lens comes from the fact that they provide observers with enough magnification for a wide overview of the slide, essentially a "scan" of the slide. ### Low power objective lens (10x) * The low-power objective lens has more magnification power than the scanning objective lens, and it is one of the most helpful lenses for general viewing purposes. ### High Power objective lens (40x) * The high-powered objective lens (also known as the "high dry" lens) is ideal for observing fine details within a specimen sample. ### Oil Immersion objective lens (100x) * The oil immersion objective lens provides the most powerful magnification. * However, the refractive index of air and your glass slide are slightly different, so a special immersion oil must be added to bridge the gap. * Without immersion oil, the 100x lens will not function correctly. * The specimen appears blurry, and you will not achieve an ideal magnification or resolution. * Objective lenses with higher magnification are usually longer. As a result, the tip of high magnification objective lenses (100x) is very close to the specimen. Please be very careful when viewing and handling high magnification objective lenses.