OBJECTIVE: To identify the parts of the microscope compound, learn to perform a different approach and see samples. INTRODUCTION
MICROSCOPY
The human eye can not distinguish objects smaller than 50 microns in diameter or unable to resolve two lines separated by less than 100 microns (ie, seen as one line).
To observe such small items is necessary to have a magnifying glass. These lenses are known since the time of Archimedes, but the optics as a discipline began to develop in the thirteenth century the Franciscan monk Roger Bacon. Anton Van Leeuwenhoek
(Netherlands, 1632-1723), an amateur lens grinder, it succeeded in manufacturing lenses powerful enough to observe bacteria, fungi and protozoa, which he called "animalcules."
The first microscope was developed by Robert Hooke. From this, technological advances allowed the modern microscopes reach of our time, there are several types and are used for different purposes. Leeuwenhoek Microscope
TYPES OF MICROSCOPES
ultraviolet light Microscope: its results are recorded photographically because the UV light is not visible and damage the retina. It is used in the detection of nucleic acids, which absorb this light.
dark field microscope, using a light intense in the form of a hollow cone concentrate on the specimen. The field of view of the target is located in the hollow cone of light and only reflects the light that is reflected in the object. Thus the clear portions of the specimen appear as a dark and tiny objects under analysis appear as a bright light on the bottom.
phase contrast microscope: enables the observation of samples without color, so it is useful to study live specimens.
transmission electron microscope (TEM) using an electron beam to produce the image. Allows the observation of macromolecular scale details.
electron microscope (SEM): in this case the electron beam does not pass through the sample, but that hits its surface. Allows high magnification images.
interference microscope, uses a source of polarized light. Useful to distinguish cellular structures that take on an appearance trimensional.
polarized light microscope, is a modification of the light microscope. Due to the phenomenon of birefringence can be observed fibrous crystalline substances and molecules.
stereoscopic microscope, is used to provide a stereoscopic (3D) of the sample. For this, as occurs in vision conventional binocular, it is necessary that the two eyes to observe the image with slightly different angles.
With the compound microscope are difficult to see organisms due to their lack of contrast and must be pigmented and the other types of microscopes such as the phase contrast is no longer necessary. The other types are more specialized microscopes can visualize different tissues and even detect DNA. MATERIAL
Compound Microscope coverglass
Porta and silk paper
Immersion oil
Newsprint
METHODOLOGY
opens first diaphragm condenser climb to the top, using the screw of the capacitor. Select the target
lowest increase. We focus
preparation with the coarse screw, for use fine focus micrometer screw.
Close the diaphragm to find a light. Capacitor using screw it descended to clearly see the diaphragm appears as a hexagon. The focus with the rear screws.
Open the diaphragm to fill the same.
To observe the samples with the objective of 40X and 100X only refine the approach with micrometer screw. COMMENTS
newsprint was observed at 10X, 40X and 100X
scale sample
Dirt nail
Hair
QUESTIONNAIRE
1.Definir resolving power, power penetration and power of definition.
Resolving power: the ability to display the image in its finest details. Is inversely related to the resolution limit. Power
penetration: is the property of allowing the simultaneous observation of various levels of preparation. Is inversely proportional to the scale of reproduction or increase. Power
definition: the ability of the lens to form sharper image contours.
2. What is the role of coarse screw condenser and diaphragm? Screw
coarse, large knob, which allows you to rotate or zoom in the object being observed.
Iris: Adjusts the amount of light passing through the object under observation.
3. What is the role of ocular lenses and lens and as you know the total increase in the system?
Eye: lens near the eye of the beholder. Click the image of the target.
Objective: lens located near the preparation. Click an image of it.
to get the total system gain value is multiplied by the eyepiece lens.
4. Why do you use cedar oil immersion objectives?
The role of immersion oil is to restrict the movement of the sample, and avoid friction between the coverglass and the objective, it is usually used when we observe with the 100x objective. Another function of immersion oil is to keep the light away: on the contrary the aim is that the light gets focused onto the sample.
5. In the scheme of the microscope point out all its parts and mention the three systems comprising the microscope indicating the parties que los conforman
Sistema óptico: El sistema óptico es el encargado de reproducir y aumentar las imágenes mediante el conjunto de lentes que lo componen. Está formado por los oculares y los objetivos
Ocular: Lente situada cerca del ojo del observador. Amplía la imagen del objetivo.
Objetivo: Lente situada cerca de la preparación. Amplía la imagen de ésta.
Condensador: Lente que concentra los rayos luminosos sobre la preparación.
Diafragma: Regula la cantidad de luz que entra en el condensador.
Foco: Dirige los rayos luminosos hacia el condensador.
Sistema mecánico: La parte mecánica del microscopio comprende el pie, el tubo, el revólver, the handle, deck, truck, screw coarse and fine adjustment. These elements hold the optics and lighting as well as allowing the movement necessary to approach the object.
Support: Maintains the optics. It has two parts: the foot or base and arm.
Plate: Place where the preparation is deposited.
Header: Contains the ocular lens systems. It can be monocular, binocular, ... ..
Revolver: Contains the objective lens systems. Allows to turn, change the objectives.
approach Screws: Coarse approximating the approach and fine to get the right approach.
Lighting System: Este sistema tiene como finalidad dirigir la luz natural o artificial de tal manera que ilumine la preparación u objeto que se va a observar en el microscopio. Comprende los siguientes elementos:
El espejo. Tiene dos caras: una cóncava y otra plana. Goza de movimientos en todas las direcciones. La cara cóncava se emplea de preferencia con iluminación artificial, y la plana, para iluminación natural (luz solar). Modernamente se prescinde del espejo en la fabricación de microscopios, ya que éstos traen incorporada una lámpara colocada en el eje del microscopio.
Condensador. El condensador está formado por un sistema de lentes, cuya finalidad es concentrar los rayos luminosos sobre el plano de la preparación. El condenser is located beneath the deck. The capacitor can slide on a rack with a screw that determines its movement up or down.
diaphragm. Generally, the condenser is equipped with an iris diaphragm, which regulates the opening and controls the quality of light that must pass through the condenser. Conclusions
learned in this lab is to use the compound microscope, from the parts that make up how to make an approach to the different targets and prepare a sample. To become familiar with this, for use in subsequent practice.
BIBLIOGRAPHY
Brock Biology of Microorganisms, Pearson Prentice Hall, Mexico 2004, 56 - 63 pp. Michael J. Pelczar
Microbiology, McGraw - Hil fourth edition, Mexico 1982. 225 to 230 pp.
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