Bright field microscope

Bright field microscope

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  SIVASANGARI SHANMUGAM BRIGHT FIELDMICROSCOPY
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  CONTENTS 1. Introduction 2. Principles 3.Parts of Microscope 4. How does it works? 5. Application 6. Advantages 7. Disadvantages
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  INTRODUCTION  It isalso known as a compound light microscope.  This is the most basic optical Microscope.  Used in microbiology laboratories.  The name bright - field is derived from the fact that the specimen is dark and contrasted by the surrounding bright viewing field.  The specimen appears darker on a bright background.  Its functionality is based on being able to provide a high-resolution image, which highly depends on the proper use of the microscope. This means that an adequate amount of light will enable sufficient focusing of the image, to produce a quality image.
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  PRINCIPLES  For aspecimen to be the focus and produce an image under the Microscope, the specimen must pass through a uniform beam of the illuminating light. Through differential absorption and differential refraction, the microscope will produce a contrasting image.  The specimens used are prepared initially by staining to introduce color for easy contracting characterization.  The colored specimens will have a refractive index that will differentiate it from the surrounding, presenting a combination of absorption and refractive contrast.  The functioning is based on its ability to produce a high-resolution image from an adequately provided light source, focused on image, producing a high-quality image.  The specimen is placed on a slide is viewed under oil immersion and covered with a cover slip.
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  PARTS OF BRIGHTFIELD MICROSCOPE 1. Ocular lens 2. Eye piece 3. Light source 4. Objective lens 5. Fine and Course adjustment 6. Specimen stage 7. Specimen
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   Two lenseswhich include the objective lens and the eyepiece or ocular lens.  Objective lens -made up of six or more glasses, which make the image clear from the object  The condenser - mounted below the stage which focuses a beam of light onto the specimen. It can be fixed or movable, to adjust the quality of light, but this entirely depends on the microscope.  The stage- where the specimen is placed, allowing movement of the specimen around for better viewing with the flexible knobs and it is where the light is focused on.
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   Two focusingknobs i.e the fine adjustment knob and the coarse adjustment knob, which can move the stage the sharpen the image clarity.  It has a light illuminator found at the base.  The nosepiece- has about three to five objective lenses with different magnifying power. It can move round to any position depending on the objective lens to focus on the image.  An aperture diaphragm also is known as the contrast, which controls the diameter of the beam of light that passes through the condenser, in that, when the condenser is almost closed, the light comes through to the center of the condenser creating high contrast. But when the condenser is widely open, the image is very bright with very low contrast.
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  HOW DOES ITWORKS?
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  HOW DOES ITWORKS?  A specimen is placed on the stage of the microscope and incandescent light from the microscope’s light source is aimed at a lens beneath the specimen.  This lens is called condenser.  The condenser usually contains an aperture diaphragm to control and focus light on the specimen.  Then is collected by an objective lens.  The objective lens magnifies the light and transmits it to an ocular lens and into the user’s eye.
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  APPLICATIONS 1. Used tovisualize and study the animal cells. 2. Used to visualize and study the plant cells. 3. To Visualize and study the morphologies of bacterial cells. 4. To identify parasitic protozoans such as Paramecium. 5. Viewing stained specimens. 6. Bright field microscope is best suited to viewing stained (or) naturally pigmented specimen.
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  ADVANTAGES 1. It isvery simple to use few adjustments involved while viewing the image. 2. Some specimen can viewed without staining. 3. It can be used to view both stained and unstained.
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  DISADVANTAGES 1. It cannot be used to view live specimen such as bacteria. 2. Only fixed specimen can be viewed. 3. It has low contrast. 4. Use of oil immersion may distort the image. 5. The use of cover slip may damage the specimen. 6. The microscope needs a strong light source for magnification and sometimes the light source may produce a lots of heat which may damage the specimen.
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  REFERENCE 1. Caprette, D.R.(2012). Light Microscopy. Rice University. Retrieved from: https://www.ruf.rice.edu/~bioslabs/methods/microscopy/microscopy.h tml [5 December 2019] 2. https://conductscience.com/bright-field-microscopy/ 3. Willey, J. M., Sherwood, L., & Woolverton, C. Prescott’s Microbiology. New York: McGraw-Hill (Page# 19-22). 4. https://www.med.unc.edu/microscopy/files/2018/06/lm-ch-8-bright-field.pdf 5. https://www.microscopemaster.com/brightfield-microscopy.html 6. https://www.thomassci.com/scientific-supplies/Brightfield-Microscope
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  THANK YOU