Exercise 1_The Compound Microscope Flashcards by LORRAINE ANN GANUELAS

What does “mikrós” means?

small

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What does “skopeîn” means?

to look or see

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It is an instrument designed to produce magnified visual or photographic images of small objects.

microscope

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What kind of microscope is used for routine microscopic work in clinical parasitology?

light compound microscope

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(4) classification of the parts of microscope

(1) support system
(2) magnification system
(3) illumination system
(4) adjustment system

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the overall support

base or foot

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supports the observation tube

arm or limb

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objective changer

revolving nosepiece

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holds the slide specimen in place

stage

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The first group of lenses at the bottom of the tube, just above the object.

objective

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The second group of lenses at the top of the tube.

eyepiece or ocular

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Microscope that has only 1 eyepiece for viewing objects.

monocular microscope

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Microscope which has 2 eyepieces for viewing objects , is used in most clinical laboratories because both eyes are used to view an object, thus reduces eyestrain.

binocular microscope

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It refers to the ability of an optical system to enlarge an image of a specimen.

magnification

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The number of times the image of an object is enlarged is expressed as:

magnifying power

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magnifies 4 times

4x (scanning objective)

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magnifies 10 times

10x (low-power objective/LPO)

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magnifies 40 times

40x (high-power objective/HPO)

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magnifies 100 times

100x (oil-immersion objective/OIO)

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4x-, 10x-, and 40x- are called _____ objectives

dry

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the _____ objective is called the oil immersion objective

100x

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It has an electric bulb into the microscope beneath the stage, turned on by a main switch found near the the base of the microscope or arm of the microscope; can be halogen lamp or light emitting diode (LED)

light source or illuminator

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located between the mirror and the stage; it brings the rays of light to a common focus on the object to be examined

condenser

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a series of thin plates found inside the condenser, has a central aperture that can be adjusted to control the amount of light that passes into the condenser

iris diaphragm

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it is fitted below the condenser, allows the passage of light of desired wavelength only

filter

used to balance light created by tungsten or halogen microscopic light

daylight blue filter

used to move the object slide on the stage

mechanical stage control knobs

What knob moves the specimen in a horizontal direction?

x-axis knob

What knob moves the specimen in a vertical direction?

y-axis knob

enables the observation tube of the microscope to rotate

observation tube adjustment clamp

The largest screw; used first to achieve an approximate focus. It is rotated to bring the specimen as close as possible to the objective.

coarse adjustment knob

This moves the objective more slowly; to bring the object into perfect/precise focus.

fine adjustment knob

used to raise the condenser for greater illumination or to lower it to reduce the illumination

condenser adjustment screw

can be moved to close or open the diaphragm; thus reducing or increasing both the angle and intensity of light

iris diaphragm ring

controls the mechanism for preventing collision between the specimen and the objective

pre-focusing knob

regulates the eyepieces according to the distance between the eyes to observe only a single image through the eyepieces

interpupillary distance adjustment

compensate for the difference in the eyesight between 2 eyes; it is adjusted by first focusing the right eye

diopter adjustment ring

(3) properties of a good microscope

(1) magnification, (2) resolution, (3) contrast

a point where parallel rays of light pass through a bi-convex lens and light rays are refracted (bent)

focal point

the vertical plane in which the focal point lies

focal plane

the distance from the center of the bi-convex lens to the focal plane

focal distance (or focal length)

distance between the front principal lane of the lens and the object

object distance

distance from the rear principal plane to the image

image distance

- an image which is located in the plane of convergence for the light rays (back focal plane) - appears inverted (reversed and upside-down)

real image

- perceived on the same side of the lens as the object - e.g: the image produced by a simple magnifying lens - formed in the retina of the eye, cannot be projected on a screen - ALWAYS appear upright (not inverted) to the observer

virtual image

a primarily enlarged image is called?

intermediate image

a secondarily enlarged image is called?

final image

How is the total magnification of the microscope is derived?

(magnification values of the objective) x the eyepiece ex: (10x objective) x (10x eyepiece) = 100x magnification

- the ability of the optical system to separate two closely adjacent objects into 2 distinct entities - determines microscopic image clarity and richness of detail - AKA "resolving power"

resolution

What is the limit of resolution of unaided human eye?

0.1 mm

What is the maximum resolving power of a light microscope with the highest magnification possible?

0.2 μm (or 0.0002 mm)

Resolving power mathematical equation:

RP= λ/2ΝΑ or RP= 0.5 λ/ΝΑ

= represent the wavelength of light used

NA (numerical aperture)

a measure of the microscope's objective to gather light and resolve fine specimen detail at a fixed objective distance 0. 1 = 4x 0. 25 = 10x 0. 65 = 40x 1. 25 = 100x

formula for numerical aperture

NA = n (sin μ) where; n (eta) = refractive index μ (mu) = one-half of the angular aperture

______ measure of the light-bending ability of the medium

refractive index

angle between the microscope optical axis and the direction of the most oblique light rays captured by the objective

angular aperture (A)

TRUE OR FALSE: high magnification = loss of resolution (reduces image quality)

TRUE *At high magnifications, the accompanying loss if resolution reduces image quality.

TRUE OR FALSE: lower numerical aperture = more highly resolved image

FALSE *Higher values of numerical aperture allows increasingly oblique rays to enter the objective front lens, producing a more highly resolved image.

it refers to the difference in the intensity between the object and its surroundings

contrast

gathers light from the microscopic light source and concentrates it into a cone of light that illuminates the specimen with uniform intensity

substage condenser

TRUE OR FALSE: ↓ aperture of the iris diaphragm = ↓ brightness, ↑ contrast

TRUE

the distance from the front lens element of the objective to the closest surface of the coverslip when the specimen is in sharp focus

working distance

TRUE OR FALSE: ↓ working distance = ↑ magnification, ↑ numerical aperture (NA)

TRUE

working distance of 10x objective

5-6 mm

working distance of 40x objective

0.5 - 1.5 mm

working distance of 100x objective

0.15 - 0.20 mm

TRUE OR FALSE: ↑ field number (FN) = greater range of specimen features visible thru the eyepiece

TRUE

- the diameter (in mm) of the viewable specimen area with the fixed eyepiece magnification; varies between 6-8 mm - can be found etched beside the magnification of the eyepiece

field number (FN)

the ability of an optical system to retain focus even when objective magnification is changed

parfocality

enables the user to switch between objective magnification and keep specimen still within the field of view

parcentrality

the recommended mechanical tube length of an optical microscope

usually 160 mm

the recommended thickness in millimeters of the coverslip used to cover the object slide

0.17 mm

the diameter of the view field measured in the specimen plane

actual field of view

actual field of view computation

actual field of view = field number/ objective magnification

10x LPO

- for initial scanning during microscopic work in parasitology

40x HPO

- used for parasite morphologic studies

100x OIO

- used for microscopic examination of permanently-stained smears (esp. for morphologic examination of protozoa)

4x objective

- generally not used; provides too low magnification for detection of parasite

TRUE OR FALSE: Most microscopes are parfocal.

TRUE

TRUE OR FALSE: The coarse adjustment knob must be used when higher power objective is in position.

FALSE *The fine adjustment knob should be used in HPO.

TRUE OR FALSE: A good quality microscope is also parcentral so the image remains within the view field even when objectives are changed.

TRUE

Exercise 1_The Compound Microscope Flashcards

(82 cards)