Microscopy is the examination of objects that are too small to be seen with the naked eye. A microscope magnifies an object so that it appears larger than it actually is. There are two main types of microscopes: compound and stereo.
A compound microscope uses two lenses, an objective lens and an eyepiece lens, to magnify an object. The objective lens is located near the specimen, while the eyepiece lens is located at the top of the microscope. The eyepiece lens magnifies the image produced by the objective lens.
A stereo microscope also uses two lenses, but they are both located in front of your eyes. This type of microscope is often used for examining three-dimensional objects such as rocks or insects.
The most common type of simple microscope is the hand lens, which is a small magnifying glass that is held close to the eye. Hand lenses are often used by jewelers, watchmakers, and stamp collectors to examine small objects. A more powerful type of simple microscope is the monocular microscope, which uses a single eyepiece lens to magnify an image. Monocular microscopes are often used in educational settings because they are relatively inexpensive and easy to use.
Simple microscopes typically have low magnification power and can not be used to view very small objects such as viruses or cells. For this reason, compound microscopes are necessary for many scientific applications such as biology and medicine.
The transmission electron microscope works by passing a beam of electrons through a very thin specimen, which is typically mounted on a metal grid. The electrons interact with the atoms in the specimen, and the resulting pattern of deflection is used to create an image. The resolution of a TEM can be as high as 0.2 nanometers, which means that it can resolve features that are smaller than those visible with an optical microscope.
The scanning electron microscope works by bombarding the surface of the specimen with electrons and then detecting the resulting pattern of secondary electrons emitted from the surface. This information is used to construct an image. SEMs have lower resolution than TEMs but they can be used to examine larger specimens and they do not require special preparation like TEM specimens do.
The first stereo microscopes were invented in the early 1800s, but they did not become widely used until the middle of the 20 t h century. Today, there are many different types of stereo microscopes on the market. Some are designed for specific tasks such as analyzing electronic components or examining medical specimens, while others are more general-purpose instruments.
The most important part of a stereo microscope is its optics-the lenses and mirrors that collect and focus light from the object being viewed. Most microscopes use a compound lens system consisting of several lenses of different shapes and sizes; however, some stereo microscopes use a single large lens instead. The size and shape of the objective lenses (the lenses closest to the object being viewed) determine how much detail can be seen and how large an image can be magnified. For example, an insect might appear very small when viewed with a low-power objective lens but much larger when seen through a high-power objective lens.
The eyepieces (the lenses at the top of the microscope) also play a role in determining image quality; however, their main purpose is to magnify the images produced by the objective lenses so that they can be seen clearly by human eyesight. In most cases, both eyepieces have identical magnification power; however, some models allow one eyepiece to be removed so that even higher magnifications can be achieved using only one eye (monocular operation). Additionally, some stereo microscopes have special attachment points for photo or video cameras so that images can be recorded or shared electronically.
Scanning probe microscope
There are several types of scanning probe microscopes, including atomic force microscopes (AFM), scanning tunneling microscopes (STM), and magnetic force microscopes (MFM). Each type of microscope uses a different type of probe, and each offers different advantages and disadvantages.
Atomic force microscopes use a sharp tip mounted on a cantilever to measure the forces between the tip and the sample surface. AFMs can be used to image samples at resolutions down to 0.1 nm. However, AFMs require samples that can withstand high forces without damage, making them unsuitable for fragile samples such as living cells. In addition, AFMs can not be used to image electrically conducting samples due to electrostatic forces between the tip and sample.
Scanning tunneling microscopes use a sharp tip mounted on a cantilever to detect changes in electrical current as it is moved across the sample surface. STMs can be used to image both conductive and insulating samples with resolutions down to 0.1 nm. However, STMs require very precise control over bothtip-sample distance and temperature, making them difficult to operate for inexperienced users.”