The Microscope Flashcards
A magnifying glass used to magnify an object to a point where it can be seen by the human eye.
The Microscope
The science of investigating small objects and structures using such an instrument.
Microscopy
Means invisible to the eye unless aided by a microscope.
Microscopic
14th century
History of the Microscope
The art of grinding lenses is developed in Italy and spectacles are made to improve eyesight.
Where did the art of grinding lenses develop
what was made to improve eyesight
Italy
Spectacles were made to improve eyesight.
What was made in 1590
who made it
The first microscope
Dutch lens grinders Hans and Zacharias Janssen
how did dutch lens grinders Hans and Zacharias Janssen make the first microscope
Dutch lens grinders Hans and Zacharias Janssenmake the first microscope by placing two lenses in a tub.
who studied various object with his microscope in 1667
was his work
Robert Hooke studies various object with his microscope and publishes his results in Micrographia.
Among his work was a description of cork and its ability to float in water.
In 1675, who uses a simple microscope with only one lens to look at blood, insects and many other objects.
He was first to describe cells and bacteria, seen throughhis very small microscopes with, for his time, extremely good lenses.
Anton van Leeuwenhoek (Father of Microscopy)
who was Anton van Leeuwenhoek
The Father of Microscopy, who used a simple microscope with only one lens to look at blood, insects and many other objects.
He was first to describe cells and bacteria, seen throughhis very small microscopes with, for his time, extremely good lenses.
what happenned in the 18th century
what was an important discorvery then
Several technical innovations make microscopes better and easier to handle, which leads to microscopy becoming more and more popular among scientists.
An important discovery is that lenses combining two types of glass could reduce the chromatic effect, with its disturbing halos resulting from differences in refraction of light.
what does chromatic effect mean
blur images due to the differences of colors
what happened in 1830
Joseph Jackson Lister reduces the problem with spherical aberration by showing that several weak lenses used together at certain distances gave good magnification without blurring the image.
Who reduced the problem with the microscope with spherical aberration by showing that several weak lenses used together at certain distances gave good magnificationwithout blurring the image.
when did he do it
Joseph Jackson Lister
1830
Three structural parts of the microscope:
- Head
- Arm
- Base
It carries the optical parts in the upper part of the microscope
Head
It acts as the microscope’s support; it also carries the microscopic illuminators
Base
The part that connects the base to the head and the eyepiece tube to the base of the microscope; it gives support to the head and used when carrying the microscope
Arms
Usually equipped with 10x lenses. The lenses magnify the intermediate image formed by the objective lens in the optical tube. They also limit the area of visibility.
Eyepiece or oculars
prevents scratching of lens by the user’s eyeglass orvice versa
Eyepiece rubbers
for differences in eye grading especially for those wearing prescription glasses
Numbers on the eyepiece
used to adjust the lateral separation of the oculars for each individual
Interpupillary tube
provides a structural site of attachment for the revolving nosepiece.
Arms or neck
holds the objectives and allows for easy rotation from one objective to another.
Revolving nosepiece
Function of the Inner knob before the coarse adjustment knob
Also known as the coarse tension adjustment knob
- Prevents the stage from going down and losing focus on the specimen
- Clockwise - to tighten
- Counterclockwise – to loosen
Function of the Knob/screw at the back of the microscope
-
Controls the height limit of the stage to prevent breakage of glass slides
- Clockwise – to tighten the screw
- Counterclockwise – to loosen the screw
Functions of the Numbers on the objectives
refers to the thickness of the coverslip to be used;coverslip to be used must be compatible with the objective to be used for microscopic examination
what does FN20 mean
Field Number (diameter)
(ideal) 20mm
Objectives
- Scanner objective (4x)
- Low Power Objective (10x)
- High Power Objective (40x)
- Oil Immersion Objective (100x)
a hole on the microscope stage through which the transmitted light fromthe source reaches the stage
Aperture
supports the prepared microscope slide to be reviewed.
Mechanical stage
Most microscopes have mechanical stage, which make it much easier to manipulate the object beingobserved
Function of the Mechanical stage knob
also available by turning the knob left and right or backward and forward
Function of the Stage numbers
determines the positioning of the cells under the microscope; provides the coordinates or location of important cells
Present to keep the slide stationary.
Stage clip
focuses or directs the available light into the objective as it raised or lowered.
Condenser
Lowering the condenser will increase the contrast of unstained specimens.
used to focus with the low power objective only.
Course Adjusment Knob
must be the same with the magnification of the objective for better viewing of the specimen details
Condenser numbers
regulates the amount of light that strikes the object being viewed. May be adjusted by a movable lever
Iris Diaphragm
Located within the base. For adjustment of the illumination for brightness
Brightness adjustment knob/Microscopic illuminator
gives a sharper image after the object is brought into view with coarse adjustment
Fine Adjustment Knob
a firm, horseshoe-shaped foot on which the microscope rests’it contains the light or mirror
Base
Remember! Working distance is the distance between the objective andthe slide when objective is sharp focus.
The higher the magnification of the objective the shorter the working distance will be.
Coarse adjustment should not be used when using higher magnifications.
Types of Microscope
1.Compound/Upright
2.Inverted
3.Stereomicroscope
Objective lens faces downward, and specimens is observed from above
Compound/Upright
Suitable for observation of glass slides or prepared slides
Compound/Upright
Objective lens faces upwards, and specimen is observed from below
Inverted
Used for routine microscopic examinations
Compound/Upright
Used for observation of culture container (stem cells/unstained cells)
Inverted
Utilized more on Microbiology
Inverted
2 separate light path, enables observation of specimen from different angles at both eyes
Steromicroscope
Allows 3D observation of sample
Stereomicroscope
Suitable for animal works and large sample imaging
Stereomicroscope
Applications of the Microscope
- Bright Field Microscopy
- Dark Field Microscopy
- Phase Contrast Micoscopy
- Electron Microscopy
- TransmissionElectronMicroscope (TEM)
- Scanning Electron Microscope(SEM)
Bright Field Microscopy
Preferred Slides
- The simplest of all the optical microscopy illumination techniques
- Specimen’s image appears dark against a bright background
- Light source is usually tungsten lamp
- Generally used with compound microscopes
Stained Slides
Ability to distinguish between two adjacent points
Depends on two factors
Revolving Power
White light & Numerical aperture
Composed of a mixture of colored lights of various wavelengths
White light
Expression relating to the cone of light that is delivered to the specimen by the condenser and gathered by the objective
Numerical Aperture
the ocular magnification multiplied by the objective magnification
Total Magnification
Phase Contrast Microscopy
Uses a special optic system which converts differences in phases into differences in intensity such that some structures appear darker than the others
Reveals the gross details of the internal structures in a living cell
Uses only unstained slides
Darkfield Microscopy
- Objects appear brilliantly illuminated against a black background
Used to demonstrate spirochetes which are difficult to observe in transmitted light
Darkfield Microscopy
Develops an image resulting from variable electron density of the specimen interposed in the electron beam
Electron Microscopy
Transmission Electron Microscope (TEM)
Develops an image resulting from variable electron density of the specimen interposed in the electron beam
Electron Microscopy
Transmission Electron Microscopy
Resolving power is 0.001 um, which is 200X that of light microscopes
Electron Microscopy
Transmission Electron Microscope (TEM)
- Specimens must be fixed, stained and dried
- Used to observe internal ultra-structural detail of cells and observations of viruses or small bacteria
Transmission Electron Microscopy (TEM)
Has a practical limit of resolution of 0.005um or five-fold less than that of TEM
Electron Microscopy
Scanning Electron Miscroscope (SEM)
It has more details on the surface (outside details)
Produces monotone, tri-dimensional image by detection at a 90degrees angle of secondary electrons emitted from the specimensurface as a result of bombardment by the primary electron beam
Scanning Electron Microscope (SEM)
Located too close to mechanical appliances or machinery that can cause external vibrations
Consequence
Treatment
Blurred image because of vibrations
- Remove the microscope from the source of vibration
- Use a strudy table as a support or use a vibration proof table
Microscope is located near a window
Consequence
Treament
Bright light from the window prevents correct focusing
- Set up the microscope near a wall
- Position the microscope in such a way that the overhead light falls slightly in front of the microscope
A place where the room light enters the eyepiece
Consequence
Treatment
Room light or flares are reproduced on the photo
- Cover the eyepiece with caps
- Shut out stray light getting into the eyepiece or the focusing telescope by changing the optical path selector
A dusty and dirty room; placed near window where the dust can enter from the outside
Consequence
Treatment
Black spots are reproduced on the specimen image
- Set up the microscope in another room
- Cover the whole microscope with a dust proof covering
Possible causes of no light
- Power cord is not connected, power switch is off
- Wrong bulb is installed
- The bulb has burnt out
- Light intensity control is turned down too low
- Objective is not properly in position
- If using the 100x objective immersion oil has not been applied
Possible causes of Image is too dark
- Increase light intensity
- Sub-stage iris diaphragm is not open enough
- Condenser is too low
Possible causes of image is too light
- Decrease light intensity
- Sub-stage iris diaphragm is open too much
Possible causes of spot in the field of view that doesn’t move when the slide is moved
Lens is dirty. Clean both the objective and eyepiece.
Possible causes of poor image quality, poor resolution, image not sharp (100x oil objective)
- Clean objective, eyepiece and condenser.
- Check if immersion oil is contaminated or cloudy or air bubbles are present.
- Slide is wrong way up.
Possible causes of poor image quality, poor resolution, image not sharp (40x objective)
There is dirt or oil on the lens
Possible causes of Uneven illumination
- Adjust condenser
- Make sure objective has clicked into place
Possible causes of Flickering light
- Bulb needs replacement
- Loose connection at the outlet
- Bulb not properly inserted
- Check voltage supply
Possible causes of Half the viewing field is illuminated
Make sure the objective is clicked into place
Possible causes of Unable to focus the slide
- Coverslip is too thick
- Slide is the wrong way up
- The stage is slowly dropping, adjust tension of coarse adjustment knob
- Clean the slide, objective and eyepiece
First step in Microscope Handling and Storage
When work is completed, lower the stage, remove the slide, rotate in the lowest power objective, wrap the cord loosely around the base and cover with a dust cover.
Take care not to wrap the cord around a hot(built in) light source
Step two in Microscope Handling and Storage
Always keep your microscope covered when not in use. Optics and mechanical parts must be protected from dust.
Step three in Microscope Handling and Storage
Always move the microscope with one hand under the base and the other hand gripping the arm or frame.
Step four of Microscope Handling and Storage
Keep microscopes away from vibration, moisture, high temperatures and direct sunlight.
Step five of Microscope Handling and Storage
Never store microscopes in chemical storage areas as corrosive fumes may damage metal and lenses.
Step one in Microscope Maintenance
Treat lenses with great care as they can be easily scratched. Never use anything abrasive.
Step two of Microscope Maintenanace
When cleaning lenses, first blow away any dust with a blower brush then use lens tissue and lens cleaning fluid to clean the objectives and eyepieces.
Do not use paper towel or regular tissues, as they willscratch the lens. Do not use other solvents.
Step three of Microscope Maintenance
Do not remove eyepieces or objectives from their location but clean only their external surfaces.
Step four of Microscope Maintenance
Remove immersion oil from the 100x objective immediately after use with lens tissue and lens cleaning fluid.
Step five of Microscope Maintenance
Wipe dust off the body of the microscope with a damp cloth
Step six of Microscope Maintenance
Never attempt to take a microscope apart. This could impair operation,efficiency and accuracy.
Step seven of Microscope Maintenance
Have the microscope serviced regularly by a professional, as most microscopes require periodic lubricating and minor adjustment of their mechanical parts.
Step eight of Microscope Maintenance
Follow your user’s manual for instruction in replacing the bulb. Always allow a bulb to cool before replacing it. When replacing bulbs avoid touching the glass with your hands, use a tissue. Fingerprints can reduce bulb quality and reduce its life.
