February 22, 2008

What Is The Purpose Of A Microscope?

History Of The Microscope

A microscope makes a tiny object appear large. The earliest microscope dates back to the renaissance period or the age of enlightenment. Scientific temper was encouraged during this period as opposed to the dark ages, when scientific thinking was tempered down. Also in the past, discoveries and inventions were made without giving a thought to what caused them to happen.

The Age Of Enlightenment And Scientific Temper

This new age saw many inventions and discoveries and among them was the microscope, which was invented in 1590 by a father and son duo from Netherlands, Johannes and Zacharias Jansen. These optical microscopes were made of a pair of lens held in a small metal tube. These microscopes do not match up to the modern microscopes, but even then, they were of immense help in learning about plants and animals.
 
Francesco Stelluti of Rome drew a microscopical picture of a bee in the year 1630. It was one of the first of its kind. He found that a bee has compound eyes; a most fascinating discovery.
 
In 1663, Robert Hooke, an English scientist and inventor, was the first person to discover cells in a piece of cork. He coined the phrase ‘cells’ in his book called Micrographia.
 
In 1674, Anton Van Leeuwenhoek discovered microbes in water and caused a commotion. Many did not believe him as he was a school drop out and not a very social human being.
 
Man has taken great strides in conquering the tiny world, with the help of more and more advanced microscopes. Electron microscopes were built in the 1930s, acoustic microscopes in the 1970s and tunneling microscopes in the 1980s.

The Definition Of A Microscope

So, how do we define a microscope? A microscope is an optical instrument that uses either one or more than one lens to magnify the image of a tiny object that usually cannot even be seen with the naked eye. There are two types- optical theory microscopes and scanning probe microscopes.

Some Amazing Facts

Did you know that microscopes were first used only in wealthier homes as a form of recreation and only later were used for more serious purposes like the study of blood circulation and bacteria?
 
Microscopes can be successfully used in scientific research- to study human cells, in criminology, geology, to get to know how refrigeration affects food, find the causes of diseases in crops, and in metallurgy. Scientists can also find out, on the basis of the size and shape of the opium pod, seen under a microscope, where it was grown and therefore investigate the source of such illegal drugs. The cause of a person’s death can also be found out with the help of a microscope and finally, it helps in solving the mystery behind how deadly diseases such as malaria are caused. Now isn’t that quite amazing!
 
Most of the microscopes are light microscopes that use high powered lens to bend light rays. At the end of the nineteenth century, scientists discovered that electrons could be used as a light source in microscopes and that allowed even tinier objects to be researched and viewed under the microscope.

Futuristic Microscopes

You may soon be able to purchase a microscope with a built in camera or a built in computer that allows you to see magnified images of the tiniest of organisms and have automatic focusing as well.

Filed under Blog by Microscopes Guru

Permalink • Print

February 21, 2008

Understanding Reconditioned Microscopes

Reconditioned microscopes refer to microscopes that are used and refurbished for reuse. These microscopes can prove to be as good as any other if you show a little prudence while selecting them. In fact the reason why many people choose to go for reconditioned microscopes today is that they save money while purchasing them as they are available at heavy discounts which are a times as high as 60%.

Benefits Of Purchasing Reconditioned Microscopes

Does that mean that you cannot avail the benefits that you get while purchasing new microscopes, like warranty etc.? No, of course not! Like new microscopes, used microscopes also come with one year warranty or guarantee.
 
Who do you intend buying that used microscope for? You are doing the right thing if it is for you teenager daughter, a budding botanist. Reconditioned microscopes are ideal for school going children. You surely won’t want to give them a brand new microscope that would make a large hole in your pocket or give them a plastic microscope of low power that would be of no use to them. Nothing better than a used microscope for school children! Take my word for it. These refurbished microscopes are also of great utility in places where chances of damage to them is high.

Features Of Reconditioned Microscopes

Used microscopes are rebuilt and refurbished to suit our needs. Their worn out parts are replaced with new parts or parts that are in good working condition, All components of the reconditioned microscopes undergo stringent tests as required by factory specifications. The microscopes are also thoroughly serviced by experts to ensure a good working instrument for you.
And of course the biggest advantage is the price. New microscopes cost a bomb; so a used microscope is a good bargain, for after all you don’t have to display it on the mantel in your sitting room, you have to use it.
Reconditioned microscopes are especially a good buy for those who do not need to use a microscope so frequently. They are also useful in fields which require repeated replacing of equipment.

Buying Reconditioned Microscopes

Most reconditioned microscopes are available with factory repair centers. These are authorized centers that not only give good services at the time of purchase but also ensure a follow up, post purchase.
Online companies also provide reconditioned microscopes such as stereo microscopes, student microscopes, surgical microscopes, research microscopes and clinical microscopes. The benefit of making an online purchase is that you can select the best brand, type and price range by doing comparison shopping from the comfort of your home.
 
But a word of caution here! Before buy a particular reconditioned microscope,

You should ensure the following…

  • The instrument should have good and clear lenses.
  • All the parts should be properly serviced.
  • The center should have spare parts available for your used microscope.
  • The warranty/guarantee should clearly state the post-purchase servicing offer.
If you are not so ‘clued on’ reconditioned microscopes, you can also seek the advice of an experienced person.

Some more things to bear in mind while purchasing reconditioned microscopes are…

  • Never purchase a reconditioned microscope from an educational institution. Chances are that it would be worn out and quite damaged.
  • Go only for a new microscope if you intend to use it for clinical research.
Nowadays you can get decent deals on used microscopes for up to $100 for common compound microscopes and $800-$8000 for advanced clinical microscopes. Till some years ago, microscopes were sold by brand popularity, but today when one can trust one’s judgment to buy sound, good quality reconditioned microscopes for a fraction of the cost of new ones; then why not go for it!

Filed under Microscope Types by Microscopes Guru

Permalink • Print

How Are Microscopes Used Today?

Microscopes have come a long way from being instruments just used to see small objects in the 18th century. The invention of the microscope proved to be a major breakthrough in scientific and medical history. It was possible to look into human blood and see what was going on inside. Doctors and researchers could identify different bacteria and start creating medicines to counter them. It opened up avenues never explored earlier. In short it proved to be a huge boon to us human beings.

Microscopes Today

Microscopes are available in many different types and models. You can get economy ones as well as expensive ones. The best microscopes are made of metal alloys and are long lasting. Microscopes can be used in almost every sphere of life. They are used in schools, hospitals and clinical laboratories. They can be used for metallurgical and industrial work as well.

Types Of Microscopes

Different types of microscopes are used for different purposes. There are four types of biological microscopes that are used to examine tiny matter like blood cells and bacteria. These are the compound, dissection, transmission electron and scanning electron microscopes. Each one can be used for different functions. The compound microscope allows you to view specimens at a high magnification power. It uses a fluorescent light to illuminate the specimens. The dissection microscope is like a regular compound microscope. It also uses light to illuminate the specimen. It has a lower magnification power and can be used to examine larger organisms by dissecting them.
 
Electron microscopes use electrons instead of light to illuminate the specimens. These have very high magnifying power and resolution. They are used to examine blood and bacteria. They are especially useful in medical research.
 
The digital microscope is one of the latest innovations. It uses a USB to transfer images to a computer screen. This makes it easier to see the image and manipulate it on a larger screen. It also makes it easier to transmit such images to other scientists in other locations.
 
The atomic force microscope is also very useful in the field of scientific research. Instead of actually seeing the specimen, this microscope uses its tip to scan the surface of the sample. This scanning process is then transmitted to a computer where the images can be viewed. It can scan tiny areas at a time and has a very high magnification power.
 
Microscopes are used in many locations now. The introduction to microscopes begins in school where they are used for educational purposes. Students conduct experiments by using dissection microscopes to examine small organisms. Microscopes are used in clinical and medical laboratories to examine blood samples to determine the kind of bacteria in them. This helps doctors diagnose their patients correctly and treat them accordingly.
 
Microscopes are used extensively in research laboratories. Scientists are constantly examining different matter and specimens to learn more about them. Thanks to microscopes we discovered different diseases and the cures to many of them. Scientists are still conducting research by using microscopes to find cures and vaccines for many more life threatening diseases.
 
There are microscopes used to examine non-biological specimens as well. They are used to examine and understand the composition of metals, rocks and even fossils. As you can see, microscopes are used in most areas of our lives.  

Filed under Microscope FAQs by Microscopes Guru

Permalink • Print

February 20, 2008

When Was The Microscope Developed?

Meaning Of Microscope

Microscope is a Greek word. Micron in Greek means small and skopein means, to look at. Since ancient times, man has wanted to see tiny objects that he may be unable to see with the naked eye. A microscope is an instrument that is used for viewing objects that are too small to be seen with the naked eye. Microscopy is the science of studying objects through a microscope. The microscopes that we use today were developed about 400 years ago. They were a lot less sophisticated than the ones that are around today, but you could still learn a lot about plants and animals by looking at them using one.

A Few Good Men

The credit for the invention of the first microscope goes to Johannes and Zacharia Jansen from the Netherlands. They developed it in the year 1590.
 
In 1630, Fransesco Stulleti, published a picture of a bee that was drawn, as seen under the microscope. He discovered that the bee had compound eyes. This was the first time anyone had done this.
 
In 1663, Robert Hooke, sliced a piece of cork, and under the microscope he saw tiny rooms in it, that he called cells.
 
But it was Anton Von Leeuwenhoek, who in 1674, caused quite a stir when he saw microbes in lake water under a microscope. He also built a microscope from a small glass ball that he polished into a magnifying lens of 270x. So, the microscope was made using a single convex lens that was fixed to a metal holder and focused by using screws. He was completely devoted to his work. Among his discoveries are spermatozoa and bacteria. He also made about 400 microscopes in his lifetime.
 
In no time, there were many advances in the microscope, and in the 17th century, a compound microscope was made. This microscope had two lenses, instead of just one where the image was magnified by one lens and then was further magnified by the other, making the microscope many times more powerful. 
 
The German Theodor Shwann(1810-82) discovered that cells are the basis of plant and animal life using an improved microscope.
 
Schwann’s work was continued by another German Rudolf Virschaw (1821-1902) who discovered a new way of looking at diseases in the human body.
 
Louis Pasteur (1822-85) a French chemist, used the microscope to wage a war against germs. He is credited with the principal of pasteurization that holds immense value even today.
 
The electron microscope was invented in the 1930s by a pair of Germans- Enrst Ruska and Max Knott. Ernst Ruska shared the Noble prize for physics in 1986, with Henrich Rohrer and Gerd Binnig. Rohrer and Binnig were awarded for the invention of the Scanning Tunneling Microscope or the STM.

The Electron Microscope

The electron microscope is very powerful and though it cannot ‘see’ atoms, it can still see the breakup of molecules in a specimen. However, it has a serious problem. Because it requires a vacuum to see, no living creatures can survive in such a high vacuum and so there is no possibility of seeing how the bodies of living creatures behave under an electron microscope. 
 
Nowadays, there are microscopes used for various purposes based on their magnification capability. While low power microscopes are used by school children and beginners, high power ones are used for the purposes of education and very high powered microscopes are used in industry, research and in medicine.  

Filed under Microscope FAQs by Microscopes Guru

Permalink • Print

February 19, 2008

How Do Microscopes Improve Our Life Today?

Microscopes play a very important role in the field of science and technology. Scientists for research used earlier microscopes more significantly. Nowadays, you can see that it is not only used in laboratories for research purposes, but also found in schools and colleges. It is used to understand the operations and view nature’s smallest creation, which cannot be viewed by the naked eye.

What is a Microscope?

The word “microscope” can be divided into “micro” meaning small and “scope” meaning view. It is a device, which is used to view anything small. There are two types of microscope- simple and compound microscope. Simple microscope facilitates viewing through a single lens, while compound microscope uses multiple lenses. You can use microscope for several purposes, ranging from research to even viewing and enjoying the beauty of sea life organisms at a beach. Whatever be the purpose, it is important to understand the basics of a microscope and its working.

Basics of a Microscope

  • For basic functioning, it requires a source of light, which illuminates the object to be viewed
  • The light source can either be a mirror, which reflects light from the outside or the device has to have its own light
  • As light passes through the object under viewing, the image is magnified. This lens near the object is called the Objective Lens
  • The lens through which you look into is a sort of magnifying glass, which produces an enlarged image of the specimen that is already magnified by the objective lens near the specimen.
  • So the magnification takes place both by the power of the magnifier and the Objective Lens
  • A microscope can magnify image up to 2000x

Uses of a Microscope

Microscopes are used largely in the field of Biology, Geology, Genetics, Microbiology, and Biotechnology. Forensic sciences also make a good use of this device. By viewing the drug under a microscope, the scientists will be able to give the origin of the drug, as the shape of the crystals viewed indicates the country where the drug is grown. There is so much of technological advancement where this device helps to view the minute details of a human cell, study its behavior, and find its use in the field of medicine. You can also view the presence or absence of minerals, presence of metals in the field of Geology, and help solve crimes in criminology.
 
Students in schools and colleges use microscopes for their study. Students study the structure of virus and bacteria, and this lays the foundation in developing their interest in the field of science and technology.

Use of Optical Microscopes

It is the most common type of microscope and was the first to be invented. The optical instrument contains more than one lens, which produces an enlarged image of the object when placed in the focal plane of the lens. Optical microscopes can be used to view small pieces of material, by using light to pass underneath the object and enter the lens. Optical microscopes can also be used to view metal samples, in order to study the metal structures.
 
At low power, they can be used to view small living plants and animals and at high power, bacteria can be examined. Invention of optical microscopes has given a lot of scope in the field of medicine. For example, small blood vessels were studied in our body to understand the mechanism of blood flow in our body systems.

Filed under Microscope FAQs by Microscopes Guru

Permalink • Print

February 18, 2008

What Type Of Microscope Is Used To View Atoms?

The atomic force microscope (AFM) is used to view atoms. This microscope is a very high resolution microscope that has resolutions of the fractions of a nanometer. The term ‘microscope’ for this instrument is actually misleading because a microscope studies specimens by ‘seeing’ them but an AFM studies them by ‘feeling’ the specimens with a mechanical probe. This probe is made possible by piezoelectric elements that enable exact and specific movements on electronic command.
 
An earlier version of the AFM, the scanning tunneling microscope or the STM, was developed by Heinrich Rohrer and Gerd Binnig, two German scientists, who received the Nobel Prize for this invention in 1986. This year was a momentous one for microscopes that could view atoms. The AFM was invented by Binnig, Gerber and Quate in 1986.

Some Useful Pointers

A scanning probe microscope does not use lenses.
 
The AFM works by measuring attractive or repulsive forces between a tip and the sample (Bennig).
 
It can accomplish resolutions of 10 pm.
 
The AFM is different from an electron microscope because it can view specimens in air and under liquids.
 
The AHM basically works on the same principal as a record player but with a few modifications. These are - Force feed back, sharp tips, sensitive detection, high resolution tip sample positioning and cantilevers.

The Advantages Of An AHM Over A Scanning Electron Microscope

The dimension advantage-The SEM provides only a 2 dimensional image, but an AHM provides an actual 3 dimensional image.
 
No metal coatings required for viewing- Specimens or samples used under an AHM do not require undergoing any exceptional treatments.
 
The environment advantage- The AHM can function properly in air and liquid environments unlike a SEM which requires a high vacuum environment. Therefore biological macromolecules and living micro-organisms can also be observed under it.
 
The resolution advantage- The AFM provides a much higher resolution than the SEM, and it can cause atomic resolution in Ultra High Vacuum.

The Disadvantages Of An AHM Over An SEM

Disadvantage of image size- While an SEM can measure area and depth of millimeters, an AHM can only measure the height and scanning area of micrometers.
 
Disadvantage of image distortion- The image can get distorted if the wrong tip is used for a required resolution.
 
Disadvantage of speed- The AHM cannot scan images as fast an SEM.
 
That was an account on the Atomic Force Microscope. I hope you enjoyed reading it. For further information, you can read some superior science magazines and surf the net as well.

Filed under Microscope FAQs by Microscopes Guru

Permalink • Print

February 17, 2008

Powerful Tips For Buying A Microscope

Buying a microscope can be a rather daunting task, especially if you don’t have enough information about them. You’ll be overwhelmed by the different varieties available. The best thing to do is to get information on microscopes from any source. You could ask a friend, read books or check on the internet for information. Before you go to the store to buy a microscope, make sure you make a checklist of what you are looking for. This way you will not waste much time at the shop.
 
How do you know what you are looking for? That’s a very pertinent question especially if you are buying a microscope for the first time. Ask yourself a few basic questions. Are you buying it for personal use at home? Is it for your kids? Do you need it for scientific research or some personal projects? Once you have answered these questions, you can start looking for a microscope that suits your particular needs.

Buying For The Children

If you want to buy a microscope for your children, don’t think that any old microscope will do. Do not be fooled into thinking that a plastic one will be enough for them because they are young. A plastic microscope may be cheap but it will not last very long. It also does not have any accuracy and your kids will probably get bored with it soon if it does not perform the way a microscope should. There are other microscopes available which are specially made for young children. These have larger controls and are more accurate. They will also last long and will be worth their price in the long run.

Determine The Type Of Microscope You Want

What do you want a microscope for? What do you want to view with it? That is the next question you need to answer. If you want to see tiny specimens like cells and bacteria then you need a compound microscope. This can give you a highly magnified image of the specimen. You can get a compound microscope with 100 times magnification which will help you view these tiny specimens at a very close range.
 
If you want to look at larger objects like petals and insects, you can buy a stereo microscope. It has two eyepieces, which make it easier to look through. The magnification is not so high but it has a wider view which makes it easy to look at the specimens.
 
When you are buying a microscope, make sure it has a good light source. There can be different types of microscope bulbs used in a microscope. The best type of light to use is a fluorescent light which is brighter and does not heat the specimen. You could spend a little more and get a microscope with an inbuilt diaphragm. This can help you control the amount of light falling on the sample. You can even get one with a condenser which can control how the light falls on the specimen.
 
I have mentioned the basic things you need to look for in a microscope. This should help you in your quest for the right microscope. You can always search for more information on the net regarding specific details like the lenses and eyepieces. When you are buying a microscope, don’t be afraid to spend a little extra for quality.

Filed under Microscope Buying Tips by Microscopes Guru

Permalink • Print

February 16, 2008

USB Microscopes – An Overview

USB microscopes are devices capable of digital still image capture as well as live video capture. This is possible because of the USB digital microscope camera that is fitted to the device. These images can then be transferred to the computer via the USB port. These instruments are used in educational institutions as well as aids in research. These come in handy while teaching as the image can be displayed on a computer screen and can be stored too. Previously, it was a long process to obtain a microscopic digital image as its processing and developing time was significant. This caused delay in getting the image and in studying it. Today, people find it very convenient to capture live images and to store it without much ado. They can be carefully documented and indexed making them easy to access on demand. The digital images can be emailed to any destination within seconds and people can analyze them from reports and save them along with the digital images. There are hand held devices available that also come with inter changeable lenses. There are devices available that are compatible with Windows as well as Macintosh systems.

Digital Microscope Camera

People find a huge variety of digital microscope cameras available making it easy for them to get the right camera to suit their needs and one that is suited for their USB microscopes. The cameras vary in the digital resolution, clarity, video size and prize.

Customizable Microscopes

A wide variety of microscopes such as compound light microscopes and stereoscopic microscopes can be customized to be USB microscopes. Their plug and play characteristic makes them invaluable teaching aids.
 
Once you have purchased a USB microscope, you will have to install its software in your system. Connect the cables to the USB port of your system and you are ready to capture digital still or video images. You can save the images on your system for future references and can manipulate the image as you desire. Many devices are available that function as regular microscopes when not plugged to a computer. Some have web cameras that serve the purpose of capturing the microscopic images that can be used for purposes as such video conferencing when the microscope is not being used.
 
There are a wide variety of microscopes available and it is up to you to do some research, compare prices and features before purchasing your USB microscopes. You can opt for a hand held device that is compact and portable. You need to consider if you will settle for a used microscope which is more economical or purchase a new piece. You can seek guidance from a professional if you are in doubt about the kind of microscope that suits your needs. If you shop around and ask for demos, chances are that you will get the best microscope that your money can buy. If you can, try using it to check how easy it is to operate. Be sure that the device is compatible with your system as some devices only work in Windows while others are Mac compatible. Check out the warranty offered and if you are buying a used device make sure that it is in good working condition. With the right USB microscopes you can have many interesting and educational hours of microscopic digital still or video capturing.    

Filed under Microscope Types by Microscopes Guru

Permalink • Print

February 15, 2008

An Introduction To Scanning Probe Microscope

Scanning probe microscope are instruments that are utilized to analyze and study the surface properties of materials. The credit for inventing the first scanning probe microscope in the year 1981 goes to Gerd Binnig and Heinrich Rohrer of IBM laboratory who were recipients of the Nobel Prize in Physics for their invention. Soon, a variety of scanning probe microscopes were developed. They differed in the nature of the probe and the way it interacted with the surface. Scientists can use these instruments to image and typify materials at atomic levels. These microscopes have helped scientists make several ground breaking nanotechnology achievements that would not have been possible otherwise.

Basic Components Of Scanning Probe Microscope

The probe and the scanner are the basic components of the SPM. The probe is designed to sense and analyze the interaction that occurs at atomic levels when two surfaces are brought together. A piezoelectric scanner is used in SPM that can be made to bend, contract or even expand in a precise and calculated manner. This is used in maintaining probe-sample distance and in controlling the movement of the probe on the surface of the material. A set point is established and scanning begins when the detector signal and the set points are the same. The probe is moved over the surface in a raster pattern and when it senses a reaction it produces a detector signal. As the topography changes variations occur in the detector signal. The difference between the set point and the detector signal is referred to as the error signal. When these error signals are plotted point by point, the SPM image is generated.

Scanning Probe Techniques:

STM Or Scanning Tunneling Microscopy

The Scanning Tunneling Microscope was the first SPM that was invented in 1981. Such an instrument is also used in scanning tunneling spectroscopy techniques. In this technique the topography of a surface is studied using a tunneling current. The tunneling current is dependent on the distance between the probe tip and the surface. This technique is used to study conductive and semi-conductive surfaces, polypeptides, mono-layers, biological materials and polymers. It is also used to study the structure and behavior of metallic surfaces.

Atomic Force Microscopy

In this technique the tip of the probe is located in a cantilever which bends or deflects when it is brought near the surface. The deflections are measured when the tip scans the surface and a computer creates an image. They are used to study conductive, semi-conductive, biological surfaces and insulators. There are four basic AFM modes. They are the contact, non-contact, tapping and torsional resonance modes. An atomic force microscope is also known as the scanning force microscope. It was invented in 1986 by Binnig, Quate and Gerber. This instrument is also used in force spectroscopy techniques.

Near-field Scanning Optical Microscopy

In this technique the tip-surface is measured by a probe controlled by a piezoelectric scanner. This is done by passing light through an optical fiber which excites the surface. This technique makes it possible to get images with resolutions beyond the Abbé diffraction limit.
 
Scanning probe microscopes can also be used to alter, manipulate or modify the surface. Some of the techniques they are used in them are Nanolithography, Nanoscratching, Nanomanipulation and Nanoindentation. Obtaining a scanning probe microscope is not a hard task as many firms offer customers a wide selection of models to choose from. Be sure to compare rates and features of the instruments before you place an order.

Filed under Microscope Types by Microscopes Guru

Permalink • Print

February 14, 2008

Importance And Use Of Petrographic Microscopes

Petrographic microscopes, also known as polarizing microscopes, are specialized instruments used widely in the study of the optical properties of minerals and rocks under polarized light. They are used for the identification of rocks and minerals; arrive at their chemical compositions and identify micro-textures in a rock. Petralogists identify rock fossils with the help of these type of microscopes.

Polarizing microscopes were first developed in Germany in the later part of the 19th century. Their usefulness has increased manifold over time, and thus they have become much advanced as compared to their earlier counterparts. The latest models are quite expensive, and come for around $10,000 per piece. The technology used for the polarization of these microscopes leads to the high cost of production. Getting the perfect polarized lenses mounted adds further to the cost. 

Petrographic microscopes come in two varieties- 

1. Those that have the feature of transmitted polarized light only.
2. Those that have, in addition to the above-mentioned feature, vertically incident reflected polarized light through the objective lens. An instrument containing both types of light is known as an ore microscope. These have the property to examine solid, polished rock specimens. Here, the polarized light passes through another polarizing light filter known as an analyzer.

Common applications of polarized microscope includes mineral and rock classification, bio-medical research, medical applications including study of microscopic crystals in urine, meteorite thin sample study, use in the petroleum sector and in geological engineering. 

Structure Of A Petrographic Microscope 

Latest petrographic microscopes can be segregated into three well-designed parts –
i. the head.
ii. the stage and sub-stage assembly.
iii. the base.

The substage condenser (used with Bertrand lens) can be centered as well as focused, and it contains field and aperture diaphragms. The polarizer (used to determine mineral extinction) comprises of the upper/lower polarizing devices and an accessory lens for convergent light. It is possible to rotate the stage to a complete 360 degrees, thus allowing the thin section to be exposed to the polarized light at all angles.

The head consists of the eyepiece, magnifying lenses, and a prism. A still or video camera may be used in place of the eyepiece, so as to take photomicrographs. 

The base of this microscope houses the light source that gets reflected towards the stage, and subsequently passes through a blue colored filter. 

How To Study A Sample Under A Polarized Microscope 

A thin section of the sample must be recovered in order to study it under a polarized microscope. The first stage involves the cutting of the sample to size and then polishing one side smooth with a fine abrasive such as diamond powder. Next, a glass slide is used to mount the sample, and the other side is ground by a mechanical cutter to a thickness of about 30 microns, and covered by a thin cover glass. This allows light to pass through the sample and results in normal incidence. Due to the crystalline property of minerals, the light also gets refracted. In the final stage, a prism is used for the ray of light to pass through, thus giving the observer a completely lucid image. 

A normal petrographic instrument is unable to study certain minerals as they turn out to be opaque even in very thin sections. Examples of such minerals include ore-bearing sulfides eg. galena, chalcopyrite. In such cases, reflecting light microscope may be used where an exterior light source from above is shown on the sample. As the light gets reflected, studies are carried out subsequently. 

Mineralogy, geology and pictography students benefit the most from a pectographic microscope. It is quite uncommon to use such a microscope at home, but a hobbyist or a mineral collector might purchase one to examine rocks under this. 

Filed under Microscope Types by Microscopes Guru

Permalink • Print
« Previous Page • Next Page »