Introduction To Microscopy🔬 Flashcards
True or False
for an image to be seen by the eye, the image must be presented to the eye in colors of the visible spectrum and/or varying degrees of light intensity.
True
What are the eye receptors of the retina for sensing color?
Cone cells
What are the cells for distinguishing levels of brightness, NOT IN COLOR?
Rod cells
Where is the location of cone cells and rod cells?
On the retina, at the back of the inside of the eye.
What are the mechanisms for admitting light and focusing it on the retina?
1- The front of the eye
2- the iris
3- the curved cornea
4- and the lens
The “message” is sent to the brain via what?
The optic nerve.
How the image must be spread to be seen clearly?
The image must be spread on the retina at a sufficient VISUAL ANGLE.
What happens if the light falls on non-adjacent rows of retinal cells (a function of magnification and the spreading of the image) ?
We will be unable to distinguish closely details as being separate (resolution).
Or
We wouldn’t see the details clearly.
How to see the details as being separate?
There must be sufficient contrast between adjacent details and/or the background to render the magnified, resolved image visible.
What are the tasks of the microscope?
Three tasks;
1- magnification: produce a magnified image of the specimen.
2- resolution: separate the details in the image.
3- contrast: render the details visible to the eye, camera, or other imaging device.
What are the five types of microscopies?
- Simplemicroscope.
- Compound
microscope. - Electron
microscope. - Stereomicroscope.
- Scanningprobe
microscope.
When using simple microscope the objects brought very close to the eye cannot have their images brought to focus on the retina?
Because of the limited ability of the eye’s lens to change its shape in simple microscopes.
What are the convex lenses?
Lenses that are thicker in the center than the periphery.
How the object can be focused while using simple microscopes?
The object could be focused by use of the magnifier placed between the object and the eye.
How can simple microscopes, cornea, and eye lenses spread the image on the retina?
By magnification through increasing the visual angle on the retina.
True or False
When you look into a compound microscope, you are not looking at the specimen, you are looking at an ACTUAL of the specimen?
FALSE
I’m actually looking at the IMAGE of the specimen.
When you should use an electron microscope?
- When I need to see the image in HIGH RESOLUTION as the image can be magnified in manometers.
- to see the very fine details of the specimen.
What are the types of electron microscope?
- The transmission electron
microscope (TEM)
-the beam is not scattered - The scanning electron microscope (SEM)
-scattered beam of electrons
What is the metal used in electron microscope ?
Tungsten
What type of lenses used in electron microscope?
Magnetic coils
Why magnetic coils are used in electron microscopes?
- magnetic coils are capable of focusing the electron beam on the sample.
What is the relationship between the flow of the Curran’s the strength of magnetic lens in electron microscopes?
As the flow of current INCREASES , the strength of the magnetic lens INCREASES.
How the electron beam flow is designed in electron microscopes?
is designed such that it cannot pass through the glass lens.
True or False:
Quality control and failure analysis in industries are done with the help of an simple microscope.
FALSE
- electron microscopes
How can The images obtained in an electron microscope?
The image can be captured as electron micrographs with the help of specialized cameras.
Choose the answer:
You can study metals and crystals with:
A) simple microscopes
B) electron microscopes
C) compound microscopes
D) stereo microscopes
B) electron microscopes
How can a stereo microscope be defined?
A microscope that provides a three- dimensional view of a specimen.
What is the microscope known as a dissecting microscope?
A) simple microscope
B) electron microscope
C) stereo microscope
D) compound microscope
C) stereo microscope
In what microscope there are separate objective lenses and eyepiece such that there are two separate optical paths for each eye?
Stereo microscope
What microscope works on the reflected light from the sample?
Stereo microscope
Why stereo microscope is suitable for magnifying opaque objects?
Because magnification of the microscope takes place at low power, and uses the light reflected from the sample.
The magnification is between 20x and 50x
What are the applications of stereo microscopes?
• Examination of historic coins and artefacts is possible with the help of the stereomicroscope.
• It finds application in microsurgery.
• Viewing of crystals became easy with the use of a stereomicroscope
What microscope used when the examination of the specimen is done at the nanoscale levels?
Scanning probe microscope
What microscope used in The study of a specimen’s properties, its reaction time and its behaviour when stimulated?
Scanning probe microscope
Why scanning probe microscope has a probe tip that is mounted on the end of a cantilever?
The tip is so sharp that it can move PRECISELY AND ACCURATELY across the surface of the sample scanning every atom.
What are the applications of scanning probe microscope?
• It is used in studying different properties of the sample such as electrical properties.
• The magnetic property of the sample is studied using this microscope.
• The transferring of information on the sample can be done with the help of this microscope.
What microscope uses visible light and optical lenses to detect and magnify very small objects?
Optical/light microscope
What are the main components of microscope?
- Optical components (Objective, Eyepiece, substage
condenser, Collector lens and tube lens). - Mechanical/Electrical components (The stand and its related parts, Light).
Types of light microscope?
Upright: light source is down and the cells are stained
Inverted: light source is up and cells culture is black and white (unstained)
Types of light microscope that use either visible or UV light to produce an image?
- Brightfieldmicroscope.
- Darkfieldmicroscope.
- Phasecontrastmicroscope. 4. Fluorescent
There are three structural parts of the microscope?
Head, base , and arm
What is the function of the main parts of light microscope ?
Head: carries the optical parts in the upper part of the microscope.
Base: supports and carries microscope illuminators.
Arm: support the head of the microscope and used when carrying the microscope.
— some microscope the arm is used for the head for better viewing.
What are the optical parts of the microscope to view, magnify, and produce an image?
1- Eyepiece
2- eyepiece tube
3- objective lenses
4- nose piece
5- adjustment knob
6- stage
7- aperture
8- illuminator
9- condenser
11- diaphragm
12- condenser focus knob
13- abbe conder
What is the function of the optical parts in microscope?
Eyepiece:
also known as the ocular.
used to look through the microscope.
Its found at the top of the microscope.
Eyepiece tube:
it’s the eyepiece holder. It carries the eyepiece just above the objective lens.
Nosepiece:
also known as the revolving turret. It holds the objective lenses. It is movable hence it can revolve the objective lenses depending on the magnification power of the lens.
Objective lenses:
These are the major lenses used for specimen visualization.
What are the types of objectives?
1.Plan- achromats
2. Plan-fluorites
3. Plan-apochromats
What OIL or HI or OEL labels mean?
the objective is designed to operate in a drop of oil between its front lens and the specimen.
What “dry objective” means?
means to operate with air between front lens and the specimen.
What does NA means on objective lenses?
1- estimate of how much light from the sample is collected by the objective lens.
2- determines the resolving power and depth of field of an objective
What is the relationship between the angle and the resolving power on objective lenses?
The WIDER the angle the lens can receive light, the GREATER its resolving power.
What is the relationship between NA and the working distance?
The HIGHER the NA, the SHORTER the working distance.
What are the small disks the appear when the light passes through the objective?
Airy disks
What is the relationship between the size of airy disks and the details of the specimen?
The SMALLER the airy disks the FINER the details of the specimen.
Why the details are finer when airy disks are smaller?
because the disks are less likely to overlap one another.
What is the ability to separate the details that are lying lose together?
Resolving power
