Microscopy Compound Flashcards
There are two general categories of microscopes
light microscope
electron type
uses light waves and lenses that are associated with the light microscope
light microscope
employs electron beams and magnetic fields to produce the image.
electron type
Other types of microscope:
where the microscope field is brightly lighted and the object to be observed appears dark die to its ability to absorb or refract some of the incident light
bright field
Other types of microscope:
where the object appears luminous against a dark background since it reflects some of the incident light in all directions
dark-field
Other types of microscope:
which uses UV light, thereby allowing greater resolution and
magnification. It is used principally to detect or even measure substances in specimens of living tissues that are known to absorb UV light at particular wavelengths. UV is not visible to the eye, so the image formed is recorded with the use of cameras or a television screen.
Ultraviolet (UV)
Other types of microscope:
which makes use of the property of certain chemical substances that release light at a different wavelength when exposed to UV rays. Such substances convert UV light into visible waves of greater length. Bacteria and other
microorganisms are stained with fluorescent stain that can be detected in a microscope illuminated with UV light.
Fluorescent
Other types of microscope:
which utilizes the refraction that occurs when light passes from
one medium into another of different density. The special objectives and condenser intensify slight differences in contrast produced by this bending of right. It is useful in studying the internal structures of microorganisms because
structures differing in refractive index from the surrounding protoplasm become visible, and their sizes and locations can be determined.
Phase-contrast
The wide ___ keeps the microscope steady at any position of the stage.
base
The ___, fastened to the base through the inclination joint, permits the ___
arm; adjustment of the stage to a desired angle.
The ____ reflects the light into the condenser.
concave mirror
The ____ concentrates the light rays received from the mirror and sends them to the objective.
condenser
The___ is a horizontal platform upon which the specimen to be examined is placed. At the center of the stage is a circular aperture.
stage; circular aperture.
The ____ hold the slide in place on the stage.
stage clips
The ___ is that part of the optical system of the microscope which produces the specimen’s initial magnified image (real) within the body tube.
objective
The student microscope has three objectives:
a dry low power
a dry high power
oil immersion objective
an optical constant of the lens system, is the distance from the center of the lens to the point where parallel rays entering the lens are brought to a focus
Focal length
an objective is that property to recognize features of a specimen that are close to each other as separate or distinct. The greater the resolving power, the greater the definition of an objective. This property is dependent on the wavelength of light used and an optical property of the objective lens known as a numerical aperture
Resolving power
a measure of the resolving power of an objective. An
objective with a 0.25 N.A. allows the viewer to distinguish as separate 25,000 lines per inch. If the specimen is known to be of the order of 26,000 lines per inch, the observer
can never see the line as separate no matter how much magnification is employed. Lenses with higher magnification usually have higher N.A. but the medium through which the
light passes also affects N.A. N.A. is indicated in the side of the lens.
Numerical aperture (N.A.)
means that the objectives are optically ad mechanically designed so that the distance between the specimen and the aerial image is always constant. Slight refocusing
with the aide of the fine focus knob is sufficient to restore critical sharpness of the image after changing from one objective to another, thus, the coarse focus knob need not to be operated.
Parfocal
which parfocal objectives are attached, allows convenient
shifting of the objectives.
revolving nosepiece
is a hollow cylindrical tube through which light passes from the objective to the eyepiece. The upper portion of this is called the ________.
body tube; draw tube
is that part of the optical system through which the specimen is viewed. The intermediate image projected by the objective is enlarged by the eyepiece. Hence, the term compound microscope is derived from the fact that the specimen is magnified twice, first by the objective and second by the eyepiece. The final image formed is a virtual image.
eyepiece or ocular
used to bring the objective into approximate focus
coarse focus knob
For maximum definition, the __ is used
fine focus knob
Consist of systems of lenses
The condenser, the objective and the eyepiece
Comprise the optical system.
The mirror, the condenser, the objective and the eyepiece
