Bright Field Microscope

The light microscopes use the visible light for observation, hence the specimen should be as thin as possible for better resolution. The light microscope can identify the objects up to 0.2 micrometers clearly. (Bisen and Sharma 2012).Student microscopes are compound light microscopes. These microscopes magnify the objects using two lenses, the objective lens, and the ocular lens. The total magnification is thus the multiple of the magnifying power of the two lenses. (Total magnification = objective magnification x ocular magnification). The light microscopes use the visible light for observation, hence the specimen should be as thin as possible for better resolution. The light microscope can identify the objects up to 0.2 micrometers clearly. (Bisen and Sharma 2012). The light microscope can be used to study two types of slides. Permanent mounts and wet mounts. The permanent slide is a prepared slide, which is ready to use with pre-staining, fixing and sealing. These slides are easier to use. The main drawback of these slides is that live microorganisms cannot be studied. A wet mount is the slides that are prepared at the place and viewed. Wet mounts are very useful to study the live cells. Field of view and depth of focus are the two main characteristics that affect the clarity in the light microscope. When the magnification increases, the depth of focus decreases and the lenses must be moved up or down. In the light microscopes, bright field microscope and phase contrast microscopes are used in the lab. Bright-field microscopy is also called a student microscope. Bright-field microscope can be used to study live microorganisms and pre-prepared slides. (Fixed stained smears). (Bain 2008). In this lab, a bright-field microscope is used. The main parts of the microscope are lens system, revolving nose piece, stage, condenser and Iris diaphragm, light source, course focusing knob, and fine focusing knob. The lens system consists of ocular and objectives. The ocular lens is the eyepiece lens through which the specimen is viewed. Oculars have a magnifying power of 10 x in student microscope and the level of magnification is marked in the ocular. (Bisen and Sharma 2012). There are three objectives with different magnifying power. The scanning objective has the shortest magnifying power of 4x and it is the lowest magnifying power in a microscope. This lens is used to locate the specimen in the slide and to observe the large structures. The low power objective has the magnifying power of 10 x and used to observe the smaller structures at little detail. The high power objective of the student microscope has the longest objective and magnifying power of this objective is 40 x. fine details about the specimen are studied using this high power objective. The revolving nose piece has the objectives. The objectives with different magnifying power are chosen using this revolving nose piece. The stage is the flat surface on the present below the objective on which the specimen is mounted. The center of the stage has an opening through which the light passes on the specimen. (Bain 2008). The stage is mechanical and geared. The mechanical stage can be a move to obtain a better resolution. The mechanical stage is moved up and down using the two adjustment knobs.