histo lab 1

microscope

precision instrument that produces

enlarged images of small objects

• allows the observer an exceedingly close view

of minute structures at a scale convenient for

examination and analysis.

Zacharias Janssen

1585 - died pre-1632

• Developed the first compound microscope in

Middleburg, Holland (1590's).

• His microscope enlarge the image of a

specimen three and nine times thespecimen's

actual size.

Simple Microscopes -

single

magnifying lens magnifying glass;

magnifies images of an object

from 3 to 20x the actual object

size

Compound Microscopes -

2 magnifying lens systems and a

visible light source that passes thru

the specimen and the lenses to the

observer's eye

Aperture Iris Diaphragm Knob

• The iris diaphragm is a shutter within the

condenser that can be controlled by a

knob/lever to adjust the amount of light

passing through the condenser.

• The knob can be moved to close the

diaphragm and improve contrast.

• If your field of view is too dark, you can

open the diaphragm to let in more light.

Base Microscope Frame

• Connects the head and base.

• Houses the focusing mechanism,

nosepiece, stage, and condenser.

Coarse Adjustment Knob

• This knob allows you to make large

adjustments to the height of the stage to

initially focus your specimen.

Condenser

• Small non-magnifying lens located

beneath the stage that concentrates the

light on the specimen.

Condenser centering screw

• Raises and lowers the condenser to vary the

light delivery.

• Generally, the best position is close to the

inferior surface of the stage.

Diopter Adjustment Ring

• Changes the focus of the eyepiece.

• Used to make adjustments when the user

has better vision in one eye and is not

using corrective lenses.

Fine Adjustment Knob

• This knob is used for precise focusing once

the initial coarse focusing has been

completed.

Binocular microscopes

-

have two lenses located in the eyepieces at

the superior end of the head.

• Most ocular lenses have a magnification

power of 10x.

High Power Objective

• aka High Dry Objective

• this objective lens magnifies the image

40× than its normal size.

Low Power Objective

• this objective lens magnifies the

image 10× than its normal size.

Oil Immersion Objective

• this objective lens magnifies the

image 100× than its normal size

usually at 1000x total power.

Scanner

• The lowest-power objective lens that

magnifies the specimen four times

normal size.

parts of objective lens

manufacturer/ maker

magnification

cover slip thickness

magnification color code

objective field number

immersion medium

objective lens name

numerical aperture

Interpupillary Distance Scale

• Scale which is used to measure the

distance between the pupils of the eyes.

• Once measured, the observer can use it

to properly set the eyepieces for their

eyes.

Light Intensity Control Knob

• Typically a rotating or sliding knob that

alters the voltage going to the substage

lamp to regulate the brightness of the

light.

Light source/Filter holder

• Located in the base

• The light from the lamp passes directly upward

through the microscope.

• When it is turned on, light passes through the

specimen on the stage, through the lenses of

the microscope, and ultimately hits your eye,

allowing you to see the specimen.

Microscope filters

are placed in the path of

light and are used to adjust the color for either

observation or photo microscopy.

Mechanical Stage

• Platform that holds the specimen. It

contains clips to hold a slide in place

and knobs for positioning the slide on

the stage

Main Switch

• Usually located on the base of the

microscope; used to turn the power

on or off.

Revolving nosepiece

• It connects the objective lenses to the

headof the microscope

• to change objective lenses.

specimen holder

• also known as Slide Clip

• holds microscope slide in position so

that it can be moved precisely

Simplified Prefocusing Dial

• Ensures that the objective does not come in

contact with the specimen and damage it.

Observation tube clamping screw:

• a screw that holds the observation tube of a microscope in

place

Translation Mechanism/

Mechanical stage controls

• Used to enable the head of the microscope to

rotate

X Translation Mechanism

• This knob will move a slide in the X-axis

(horizontally) on the mechanical stage.

Y Translation Mechanism

• This knob will move a slide in the Y-axis

(vertically) on the mechanical stage.

Bright-Field Microscopy

• the method most commonly used in

stained specimen

• uses ordinary light and the colors are

imparted by tissue staining

dark - field microscopy

ideally used to illuminate

unstained samples causing

them to appear brightly lit

against a dark background.

Fluorescence Microscopy

• uses ultraviolet light, under which

only fluorescent molecules are

visible, allowing localization of

fluorescent probes which can be

much more specific than routine

stains and allow the identification

of these structures under the

microscope.

Phase-Contrast Microscopy

• uses the differences in refractive

index of various natural cell and

tissue components to produce an

image without staining, allowing

observation of living cells.

Confocal Microscopy

• involves scanning the specimen

at successive focal planes with a

focused light beam, often from

a laser, and produces a 3D

reconstruction from the images.

Magnifying power

allows you to make whatever your'e looking at appear bigger.

Resolving power (theoretical limit of resolution )

gives you the ability, through the lens, to

separate two closely spaced objects so that you can see two distinct images instead of

one.

Wavelength:

A smaller wavelength improves resolving power

Numerical aperture:

A larger numerical aperture improves resolving power

Refraction index:

Increasing the refraction index improves resolving power

Angle of light:

Increasing the angle of light coming from the object improves resolving power

Parfocal

refers to objectives that

can be changed with minimal or no

refocusing.