A brief History of
How does a Stereo Microscope work?
What are microscope parts and
World's most powerful microscope
Microscopy and Digital Imaging
What is a Video
What is a Video
|A video microscope is a microscope which generates a
live video feed of the object being viewed. There are a
number of uses for video microscopes, and a
range of styles are available from models designed for use
by hobbyists to high tech versions used in scientific
laboratories. Scientific supply companies and science stores
often carry video microscopes, and it is also possible to
order them directly from manufacturers. It is also possible
to purchase video adapters for existing microscopes which
can be used to turn them into video microscopes.
With some styles, the microscope is hand held, allowing the
user to manipulate it around an object to obtain a magnified
image. Other video microscopes have conventional microscope
stages on which a specimen is mounted. Hand held versions
tend to be popular among hobbyists, while microscopes with
stages are used in laboratories.
A video microscope can be extremely useful for things like
demonstrations and group instruction. Using the video
microscope, a user can manipulate the specimen and area of
focus, and people can see the image on a television screen
or monitor. The wide field and size of the video image can
also be an advantage in a variety of situations, such as a
laboratory where people need to be able to manipulate
specimens very precisely, and looking through an eye piece
while performing delicate work could be challenging.
The microscope can typically connect to a wide variety of
screens, ranging from laptop computers to ordinary
televisions. This makes the video microscope a highly
flexible tool, which can be appealing to hobbyists and
useful for fieldwork situations, as the microscope can be
carried into the field with a laptop for quick viewing of
interesting specimens. A still camera may also be integrated
into the design for the purpose of capturing images of
In addition to providing a live feed, a video microscope may
also be able to record what it sees. This can be useful when
a microscope is used to evaluate forensic evidence, as it
provides documentation of exactly what happened to the
evidence while it was examined. It can also be helpful in
the scientific community, as it provides a clear record of a
specimen which can be reviewed at a later juncture to look
for material which may have been missed during the
microscopy session. Videos can also be used in presentations
at conferences and scientific events to demonstrate new
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How does a
Stereo Microscope work?
|A stereo microscope is generally known as a comparison
microscope and it is used in scientific fields primarily for
comparing two side by side specimens. A stereo microscope is
made up of two regular microscopes connected together with
an optical bridge. For instance in forensics, it may be
necessary to compare to samples to each other, using a
traditional microscope the viewer will need to memorize the
contents and switch slides, however with the stereo
microscope, the viewer can see both slides side by side at
the same time.
The stereo microscope was invented in the 1920's primarily
for forensic ballistics tests and was used in famous cases
resulting in convictions. Today the stereo microscope is for
the most part the same; however there are a few important
enhancements such as digital imaging, fiber optic
illumination, video capabilities and attachments to take
A stereo microscope is part of the group of microscopes
called optical microscopes. Optical microscopes use
refractive lenses to help focus light into the eye. These
lenses are usually made from glass; however plastic lenses
are also used. Most stereo microscopes can reach a
magnification of 1500x, but stereo microscopes are often
used for lower power magnifications. In addition, stereo
microscopes are primarily used to study larger specimens.
Besides using ordinary light to study specimens, ultra
violet light can be used to study specimens that are
biological in nature, infrared light is also used for thick
slices of biological tissue.
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Microscopy and Digital Imaging
|There has been a major shift in video microscopy over
the past decade. Because of advances in imaging technology,
video microscopy coupled with digital imaging is moving from
a luxury seen only on a few factory floors to becoming the
norm in industry today. The days of holding a camera up to
an eyepiece on a microscope to capture an often elusive
image have ended. Today systems are available that allow
users to instantly capture an image, share it and view it on
a monitor simultaneously.
The most popular types of vision inspection systems used
today are a trinocular stereo microscope or a video lens
system. The microscope or lens system is connected to a
camera �� generally CCD or CMOS �� and tied into a PC or
monitor. Each system has its own pros and cons depending on
the application. In addition, by not forcing users to
constantly look into microscope eyepieces reduces eye
A trinocular stereo microscope system gives a user the
ability to see the image in 3-D (when looking into the
microscope eyepieces) or a 2-D image when projected onto a
monitor. In some applications the ability to see a true 3-D
image may be very important. One common complaint when using
this type of system is "What I see in the eyepieces of the
microscope is different than what is projected onto the
video screen." This will almost always be the case. The
reason: moving from a 3-D image to a 2-D image, so losing
some depth of field is inevitable. In addition to the depth
of field loss, depending on the monitor size, the image will
be magnified so the field of view will also decrease.
Video lens systems offer a higher magnification range and
more lens options than a typical stereo trinocular
microscope. While most stereo microscope systems tend to
magnify up to 200x, a video lens system can magnify up to
3000x or higher.
Too Many Components
Most systems today are configured with four or five
components, and each one is typically provided by a
different manufacturer. This integration process of many
different components can cause problems. The camera mount
may not match the video systems mount thus the need for an
adapter. The PC or Laptop may not be compatible with the
camera hardware requirements. The measurement/analysis
software may not recognize the camera software driver.
To avoid many of these integration problems it is important
purchase each individual product from a firm specializing in
such integration with the experience to know which
components are compatible. If possible it would be advised
to see a working demo to insure all components are
Today, thanks to improvement in technology we are now able
to integrate several of the previously individually
purchased components into a single product, thus insuring
compatibility. One such product is the new scientific camera
from Hipower. The scientific camera combines the camera,
image capture ability and monitor into one unit.
Direct Image Capture
The system captures images directly onto an SD card. The SD
card slot is built directly into
the camera. By moving the image capture function directly
onto the camera a PC or laptop is no longer needed to
capture an image. A small 2-inch monitor has also been built
into the camera thus removing the need for a monitor. While
the unit consolidates many features, it still leaves room
for expansion by providing a USB output in the event one
wants to use a laptop or PC for image capture. In addition
to the USB output a video output is also provided to
accommodate a larger monitor. Many other features such as
digital zooming, time/date stamp, image manipulation have
also been incorporated into the camera.
Ease of Setup
The use of such self-contained plug-and-play systems
provides numerous benefits to the manufacturing process and
user over traditional microscopes and field built video
Because of the easy setup, there are no wires to run,
software to install, additional hardware to purchase etc.
Such a system reduces eye fatigue as well as neck, back and
shoulder fatigue from constantly looking down a microscope
eyepiece. Less eye and physical fatigue results in higher
The new system can provide tighter quality control, since
each operator has the ability to document all work
performed. Overall information sharing among colleges is
greatly enhanced. A defect might be exposed in one
manufacturing location. Being able to instantly capture that
image and email it may prevent it from being duplicated,
saving considerable expense.
The all-in-one system means that employee training becomes
and greatly enhanced. All students are now looking at the
same image, unlike the situations when individually viewed
under a microscope. Instructors may also record a video file
of the training.
The strides made in camera technology have now also allowed
for portable digital microscopy. Until recently, portable
microscopes had virtually no image capture ability. The
specimen had to be taken to the lab to be photographed. The
Aven iLoupe camera with a magnification range of 10x-150x
allows microscopic images to be taken in the field. This
product is essential for quality assurance personnel to be
able to instantly capture defects while on the production
floor. Field service technicians can now obtain images and
send them in real time for evaluation, saving time and
money. In addition to the manufacturing industry, this
product is used in forensics, archeology, botany and
numerous other fields.
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A brief History of
|Oddly enough, the compound microscope was invented
before the single lens microscope. But the instruments were
not very good to start with and much more could be seen with
very small lenses of short focal length.
In about 1597 two Dutch eyeglass makers, Zaccharias Janssen
and his son Hans were experimenting with lenses in a tube.
They observed that nearby objects viewed through two lenses
in line were magnified. Their device was the first compound
microscope. However, their lenses were rather large and the
magnification obtained was only about 10X. Galileo also
designed a compound microscope, but it was only useful for
reflected light. Robert Hooke built the first useable
British compound microscope in about 1655.
The single lens microscopes made by a Dutch amateur lens
grinder Antonie van Leeuwenhoek were far superior to the
early compound instruments. Van Leeuwenhoek, in about 1670,
developed a method for grinding very small glass lenses.
They were tiny, of the order of a millimeter in diameter,
and could magnify several hundred times. Mounted in a brass
plate these lenses could use transmitted light to image
objects in a drop of water on the end of a metal pin. Screws
were used to move the pin and focus the specimen. Van
Leeuwenhoek was probably influenced by Robert Hooke¡¯s
Micrographia (1665) which he might have seen when he visited
London in about 1668. Amongst his vast number of discoveries
were bacteria, sperm, blood cells and a myriad of protozoa.
He also laid the foundations of plant anatomy. His
discoveries were reported to the Royal Society in a series
of famous letters. Van Leeuwenhoek made hundreds of
microscopes over the years and many people copied them,
including Hooke himself. Nine of van Leeuwenhoek¡¯s original
microscopes still exist today.
Hooke confirmed Van Leeuwenhoek's work and one of the
important discoveries he made with his own compound
microscopes was that of the cell. He examined the structure
of cork. At that time cork was a very valuable commodity for
the English ship building industry. He found that cork was
made up tiny chambers that he called cells, coining the term
to describe what we know today as the building block of all
animal and plant life.
Minor mechanical and optical improvements were made to
compound microscopes over the years, but no major
improvements were made until the 19th century. In 1847 Carl
Zeiss started making simple microscopes in Jena, Germany. By
1857 he was producing a compound microscope, the Stand I.
The business grew and in 1872 Ernst Abbe joined the firm.
Abbe worked on optical design and this led to the discovery
of many basic facts about optics and lens design. After Otto
Schott, an optical glass expert, joined the firm in 1886 the
lenses produced by Zeiss soon became the best in the world.
Apochromatic, Planapochromatic and Immersion lenses
originated in the Zeiss laboratories. Compound microscopes
were soon being made all over the world and Germany, Great
Britain and the USA led the market. Hundreds of different
designs of microscope appeared, especially in the USA and
Great Britain and in such a short article it is impossible
to deal with them all.
There have been great advances made over the last 70 years
and firms such as Zeiss, AO Spencer, Vickers, Leitz, Wild,
Reichert, Nikon and Olympus and many others have produced a
vast selection of different kinds of light microscope. Some
of these will be described in the other sections.
The Electron Microscope was invented by Ruska in 1933 and
the first commercial instruments came from the Siemens
factory in Berlin in about 1937. An Electron Microscope
which employs a focused beam of electrons instead of light
to image the specimen is capable of far greater
magnification and resolution than a light microscope.
Resolution in the Light Microscope is limited by the
wavelength of the light used and is usually about 250
nanometers, or millionths of a millimeter. The wavelength of
the electron is far shorter and resolutions of 0.3nm are
routinely possible at magnifications that go to 1 000 000X.
Later the Scanning Electron Microscope was developed and in
1980 the Scanning Tunneling Microscope and variations. These
will all also be discussed in later sections.
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|There are several types of microscopes available on the
market, selection of the proper type is not a simple
assignmen as you would need to determine what exactly it
would be used for. Below you can see all the types of modern
microscopes for any scientific and hobby task.
A compound microscope is an optical device made for
of a number of lenses forming the image by the lens or a
combination of lenses positioned near the object, projecting
it to the ocular lens / lenses or eyepieces. The compound
microscope is the most used type of a microscope.
optical microscope, also called "light
microscope", is a type of a compound microscope that uses a
combination of lenses magnifying the images of small
objects. Optical microscopes are the oldest type and
simplest to use and manufacture.
A digital microscope has a digital CCD camera
attached to it and connected
to a LCD or a computer monitor. A digital microscope usually
has no eyepieces to view the objects directly. The
trinocular type of digital microscopes have the possibility
of mounting the camera, that would be an USB microscope.
A fluorescence microscope or "epifluorescent
microscope" is a special type of a light microscope, instead
of light reflection and absorption used fluorescence and
phosphorescencea to view the samples and their properties.
An electron microscope is one of the most advanced
and important types of microscopes with the highest
magnifying capacity. In electron microscopes electrons are
used to illuminate the tiniest particles. Electron
microscope is a much more powerful tool in comparison to
commonly used light microscopes.
A stereo microscope, also referred to as "dissecting
microscope", uses two objectives and two eyepieces which
makes it possible to view a specimen under angles to the
human eyes forming a stereo 3D optical vision.
Most compound types of light microscopes consist of the
following parts: Eyepiece Lens, Arm, Base, Illuminator,
Stage, Revolving Nosepiece, Objective Lenses, Condenser
Lens. Details on microscope parts.
Microscope camera is a digital type of a video
capturing device mounted on light microscopes and equipped
with USB or AV cable. Digital microscope cameras are usually
good with trinocular microscopes.
A few words for the beginners
The most important feature of a microscope is of course to
give a larger image, and the increased image is probably the
determining factor of this device. A very important
parameter of optics is "aperture". We will not bore you with
the formulas, in simple words - the more the aperture is,
the stronger the lens refract light rays and the more of
those rays pass through the lens.
A simple glass lens (the "dry", as experts say) can reach
the aperture value of 0.95. If you get close to 0.65, the
lens can be classified as a high aperture lens. But really
high values of aperture can be achieved by immersion lenses,
which, unlike the "dry" ones, contain a so-called immersion
liquid. The liquid improves the optical parameters (the
aperture can reach the values of 1.40)
In addition, in order to achieve quality, and above all see
clear images, it is very important to have a high resolution
microscope. It is required not only eliminating the
distortions associated with inaccuracies in the lenses, but
somehow compensating the dispersion of light, ie expansion
of the "white" spectrum of seven colors of the rainbow,
arises due to unequal refraction in the glass of different
light waves. Achromatic lenses are used for this purpose,
they only slightly distort the color. The "image" in the
microscope with achromatic lens accurately conveys the
colors of the viewed object.
And finally, last but not least, an absolutely necessary
part of a microscope is a source of light. The simplest
source would be a mirror, which directs light to the object
being studied, the more advanced types of microscopes use a
special bulb with predetermined parameters of the spectrum
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The Virtual Microscope
Microscope is a NASA-funded project that provides simulated
scientific instrumentation for students and researchers
worldwide as part of NASA's Virtual Laboratory initiative.
This site serves as home base for the Imaging Technology
Group's contributions to that project¡ªnamely virtual
microscopes and the multi-dimensional, high-resolution image
datasets they view. Currently we provide 90 samples totaling
over 62 gigapixels of image data. The Virtual Microscope,
which is available for free download supports functionality
from electron, light, and scanning probe microscopes,
datasets for these instruments, training materials to learn
more about microscopy, and other related tools. The project
is open source and the code is available on Sourceforge.
Our Virtual Instruments
Our virtual instrument code currently supports data from
three different instruments in our Microscopy Suite: a
Philips Environmental Scanning Electron Microscope (ESEM), a
Fluorescence Light Microscope, and an Atomic Force
Microscope. We have also adapted a high-resolution Digital
SLR with a 5x magnifying macro lens to capture some
specimens, as well as included some artistic renderings of
The virtual microscope aims to present the user with a
method for exploring these pre-captured image data as if
they were using the real instrument in real-time. To fulfill
this goal, the virtual microscope provides the ability to
load/unload specimens, to navigate to any point on that
specimen, to change magnification, to adjust image
parameters (contrast and brightness), to change focus, to
analyze elemental composition, to measure features, and to
render data in three dimensions. Additionally, the interface
allows experts and laypeople alike to annotate specimens
and/or load previously-created annotations.
Beyond the user interface, we have written a backend suite
of custom software for the various tasks involved in
collecting and processing the image data. This includes
automated data collection of the thousands of images it
takes to describe a single specimen, and routines for
stitching and blending those tiled image datasets.
As part of our educational mission, we have produced
animations that teach the basics of electron, light, and
scanning probe microscopy, videos detailing sample
preparation for those instruments, videos of interviews with
graduate students about their career paths in the sciences,
and help videos about how to use our application. These
materials animations use a multitude of media to explore
various topics relevant to the theory and craft behind the
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are microscope parts and functions?
The eyepiece (sometimes called the 'ocular') is the lens of
the microscope closest to the eye that you look through. It
is half of the magnification equation (eyepiece power
multiplied by objective power equals magnification), and
magnifies the image made by the objective lens... sometimes
called the virtual image. Eyepieces come in many different
powers. One can identify which power any given eyepiece is
by the inscription on the eyecup of the lens, such as "5x",
"10x", or "15X". Oculars are also designed with different
angles of view; the most common is the wide field (W.F.).
Eyepiece Holder: This simply connects the eyepiece to
the microscope body, usually with a set-screw to allow the
user to easily change the eyepiece to vary magnifying power.
Body: The main structural support of the microscope
which connects the lens apparatus to the base.
Nose Piece: This connects the objective lens to the
microscope body. With a turret, or rotating nose piece as
many as five objectives can be attached to create different
powers of magnification when rotated into position and used
with the existing eyepiece.
Objective: The lens closest to the object being
viewed which creates a magnified image in an area called the
"primary image plane". This is the other half of the
microscope magnification equation (eyepiece power times
objective power equals magnification). Objective lenses have
many designs and qualities which differ with each
manufacturer. Usually inscribed on the barrel of the
objective lens is the magnification power and the numerical
aperture (a measure of the limit of resolution of the lens).
Focusing Mechanism: Adjustment knobs to allow coarse
or fine (hundredths of a millimeter) variations in the
focusing of the stage or objective lens of the microscope.
Stage: The platform on which the prepared slide or
object to be viewed is placed. A slide is usually held in
place by spring-loaded metal stage clips. More sophisticated
high-powered microscopes have mechanical stages which allow
the viewer to smoothly move the stage along the X
(horizontal path) and Y (vertical path) axis. A mechanical
stage is a must for high-power observing.
Illumination Source: The means employed to light the
object to be viewed. The simplest is the illuminating mirror
which reflects an ambient light source to light the object.
Many microscopes have an electrical light source for easier
and more consistent lighting. Generally electrical light
sources are either tungsten or fluorescent, the fluorescent
being preferred because it operates at a cooler temperature.
Most microscopes illuminate from underneath, through the
object, to the objective lens. On the other hand, stereo
microscopes use both top and bottom illumination.
Base: The bottom or stand upon which the entire
microscope rests or is connected.
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of steps to take
There is a clear sequence of steps to take to achieve
perfect viewing. These are detailed in the box below. A word
of warning: Take care when adjusting the focus knobs that
you do not advance the objective lens onto the slide! It is
very easy to break the slide and possibly damage the
When setting up the focus it is best to view from the side
and lower the objective so that it is nearly, but not,
touching the slide. Now adjustments can be made while
viewing through the eye-piece and slowly winding the
objective UP and AWAY from the slide - this way you avoid
any potential damage to either the slide or microscope.
Getting things in focus
Once the specimen is in focus, fine adjustments in
illumination and iris aperture can be made to improve
The slide should be scanned systematically, usually by
finding the top corner of the cover glass and then moving
the slide slowly across the stage to the adjacent corner.
When the opposite side is reached the slide is moved up
until a new field of view is visible and then moved slowly
across to the other side. This is repeated until the bottom
of the slide is reached.
Higher magnification are obtained by rotating the nosepiece
turret and selecting another objective and then re-focusing.
Parasites are often transparent
Since many parasites are transparent to light it is often
necessary to use various techniques to highlight them. The
two most popular methods are phase contrast and darkfield.
Both of these methods are outside the scope of these pages,
but essentially they manipulate the light so that
transparent objects are more readily visible. These
specialist methods usually mean adding special condensers of
objectives to your microscope. While these methods are
useful they are not essential for fish disease diagnosis.
If there is a problem with viewing any specimens with an
ordinary brightfield microscope it is possible to increase
the contrast by racking down the condenser or closing up the
iris aperture, although it does reduce resolution.
Scheme for setting up a simple monocular microscope
Make sure the 10x eyepiece is in place at the top of the
Raise the body tube a few inches above the stage - by
looking from the side and turning the course focus knob
Rotate the nosepiece and click the lowest power objective
into place above the stage (usually a 10x)
Adjust the illumination if using a mirror, turning the flat
side of the mirror towards the light source so that light is
reflected up towards the condenser
Rack the condenser up to within 2mm below the stage and
adjust the iris diaphragm until it is half open
Place the specimen on the stage making sure that the cover
glass is uppermost and secure it with either the stage clips
or the mechanical stage arms
Adjust the angle of the mirror so that a spot of light
appears on the slide directly below the objective lens
Looking from the side and using the course control knob,
lower the objective until it is just above the slide
Look through the eyepiece. Adjust the mirror to give an even
amount of illumination
Use the course control knob to slowly rack the objective
upwards and look through the eyepiece until the specimen is
in focus. (Tip) it is sometimes easier to focus on the edge
of the cover slip to start with as this gives a nice clean
edge when in focus - whereas mucus can sometimes be
difficult "to find"
Use the fine focus to obtain the sharpest possible image
If the light is too bright either use a bulb with a lower
wattage (if using a table lamp to illuminate the mirror) or
adjust the iris diaphragm to reduce glare
Focus the light source onto the slide by slowly racking down
the condenser - watch that this does not affect the mirror
angle. Adjust the condenser and iris diaphragm to give
optimum illumination. Ideally, once the condenser is set in
the optimum position, there shouldn't be any need to keep
While this long list may seem daunting, it is because I have
tried to cover every step. You will also note that much of
it revolves around optimizing the light source if it is
mirror based. With a fixed light source many of these steps
can be ignored. After you have set up the microscope a few
times it should become second nature.
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are Electron Microscopes?
Electron Microscopes are scientific instruments that use a
beam of highly energetic electrons to examine objects on a
very fine scale. This examination can yield the following
The surface features of an object or "how it looks", its
texture; direct relation between these features and
materials properties (hardness, reflectivity...etc.)
The shape and size of the particles making up the object;
direct relation between these structures and materials
properties (ductility, strength, reactivity...etc.)
The elements and compounds that the object is composed of
and the relative amounts of them; direct relationship
between composition and materials properties (melting point,
How the atoms are arranged in the object; direct relation
between these arrangements and materials properties
(conductivity, electrical properties, strength...etc.)
Where did Electron Microscopes Come From?
Electron Microscopes were developed due to the limitations
of Light Microscopes which are limited by the physics of
light to 500x or 1000x magnification and a resolution of 0.2
micrometers. In the early 1930's this theoretical limit had
been reached and there was a scientific desire to see the
fine details of the interior structures of organic cells
(nucleus, mitochondria...etc.). This required 10,000x plus
magnification which was just not possible using Light
The Transmission Electron Microscope (TEM) was the first
type of Electron Microscope to be developed and is patterned
exactly on the Light Transmission Microscope except that a
focused beam of electrons is used instead of light to "see
through" the specimen. It was developed by Max Knoll and
Ernst Ruska in Germany in 1931.
The first Scanning Electron Microscope (SEM) debuted in 1942
with the first commercial instruments around 1965. Its late
development was due to the electronics involved in
"scanning" the beam of electrons across the sample. An
excellent article was just published in Scanning detailing
the history of SEMs and I would encourage those interested
to read it.
How do Electron Microscopes Work?
Electron Microscopes(EMs) function exactly as their optical
counterparts except that they use a focused beam of
electrons instead of light to "image" the specimen and gain
information as to its structure and composition.
The basic steps involved in all EMs:
A stream of electrons is formed (by the Electron Source) and
accelerated toward the specimen using a positive electrical
This stream is confined and focused using metal apertures
and magnetic lenses into a thin, focused, monochromatic
This beam is focused onto the sample using a magnetic lens
Interactions occur inside the irradiated sample, affecting
the electron beam
These interactions and effects are detected and transformed
into an image
The above steps are carried out in all EMs regardless of
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World's most powerful microscope starts work
most powerful microscope is now peering away at tiny things
at the University of Texas at San Antonio.
You may be proud of the zoom on your camera, but the JEOL
transmission electron microscope, JEM-ARM200F, can magnify
by 20 million times.
Its developers hope it will accelerate the development of
new cancer therapies and disease treatments.
"We now have access to resolutions that will give us a
tremendous scientific advantage to solve problems that need
to be attacked," says Miguel Yacaman, chair of UTSA's
College of Sciences¡¯ Department of Physics and Astronomy.
"We¡¯ll be able to watch nanoparticles behave one atom at a
time. This is the Holy Grail for us."
The microscope will be housed in a specially-designed
laboratory that protects it from vibrations.
Yacaman¡¯s team is already using the microscope to study how
to develop optimally shaped nanoparticles that could be used
with a laser to pinpoint and destroy cancerous cells.
The university is also using it to study Alzheimer¡¯s
disease. The microscope will eventually be accessible to
researchers around the world, operating 24 hours a day,
seven days a week.
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