Microscope

In various areas of industry, an optical magnification of the objects is needed, whether for just quality assurance or directly in the production. The microscopes are suitable for this perfectly well and since they are available in a wide range of types and variations, they must be selected carefully, according to the application.

There is the classic version of the monocular and binocular microscopes, when you look through an eyepiece (monocular microscope) or through two eyepieces (binocular microscope). In this case, every time each employee has to readjust the optics to his visual parameters.

The trinocular microscope has the third optics, for connecting a digital camera or a photo camera. Thus, the operator can additionally document the examination of the objects with the images, or even transfer the images to the additional screen or computer with the help of the camera for the other colleagues.

All of us since childhood have been familiar with a device that helps to see the tiniest parts of certain objects or substances. Microscope gives a multiple magnification of those things, it allows to measure the volume, shape, size or structure details of the parts that can be detected by the naked eye.

The principle is based on the combination of ocular and lens. The lens gives the actual inverse magnified picture. The intermediate picture can be seen by the eye through the ocular. It reminds the magnifying glass a bit. The ocular in the device should be placed in such a position so that the intermediate picture was in its focal surface. In that case the rays from each point of the object will be spread after the ocular in a parallel light pencil.

The application field of the microcopy is extremely wide – biology, botanic, geology, electronics and of course, medicine. The results of the researches conducted with the help of that device very often help to develop new preparations and become the base fro scientific discoveries.

Nowadays there are more that a score of different kind of microscopes. The first one created by mankind goes back to the 16th century. Nowadays there are a few groups which include different models of the device. One of them is an optical one.

Human eye itself is an optical system having a certain resolution system. Only at a certain distance from the object the eye can still tell different parts or elements from each other. The range of the optical illumination was quite limited and the first optical microscopes could give the magnification only up to 2000 times.

Binocular microscope is frequently used at the laboratories and educational institutions. It allows making observations with both eyes, as it has got a special binocular head. This device gives an image of a very good quality and is of a very high accuracy.

Stereomicroscope is equipped with an ocular and removable binocular head. It gives a smaller magnification than the other microscopes, but it has got a bigger focus distance which gives an opportunity to study bigger objects. In addition, the system of that device allows “not to turn” the objects. It is often used in studying of opaque materials, hard , rocks, metals, microsurgery etc.

Metallographic microscope - it works on the principle of reflected light and is good for studying piqué materials structure. The system of prisms and mirrors at first directs light to the object and then light is reflected from the opaque object and redirected back into the lens. Very big samples can be studied with that device.

Polarization microscope – the image is possible to get with the help of the polarized rays. The rays come from an additional device – polarizator. As a rule it is applied for those studies that cannot be conducted with the regular optical microscope. It has got a very good optics and professional software.

Some more kinds of the existing microscopes are luminescent (pharmacy, vet, plant-growing sphere, sanitary and epidemiological institutions etc.)

Electronic microscopes – as a rule it allows reaching a better magnification than the optical ones. They use an electron beam and that allows magnification up to 200.000 times. There are also magnetic lenses included which manages the electrons movement.

Radio graphical microscopes - Electromagnetic emission with the wave length from 0.01 to 1 nm and that allows studying the tiniest objects.

Scan probe microscope. That kind of microscopes gives 3-dimension image with a very high resolution. It allows to study atoms and molecules, as well as to influence them.

A 3D microscope provides perspective images of the magnified objects. Also the various types of stereo microscopes produce plastic images. But in contrast to these, in the case of the digital 3D microscope the image is not viewed through two eyepieces, but on a screen. In the following text, only the digital devices are referred to as 3D microscopes. By displaying the image on a monitor, the working conditions for the user – both in terms of eye and back strain – are considerably improved. However, the 3D microscope not only allows working in a relaxed posture, but also easy saving and further processing of the generated images. There is a device-specific software for each model, which is usually very easy to operate via icons. Often this software also offers special measuring and documentation functions. Because the images of the object are displayed on a monitor, it is possible for this image to be assessed by several people at the same time. The transmission of live images via computer also allows involving the experts who cannot be present on site.

Whether in biology, medicine, industry or other fields where the samples with a structurally rich surface need to be examined, the 3D microscope facilitates the visual assessment in all of them. But the 3D microscope can be used not only for examining and inspecting samples, but also directly in the processing of small objects. For example, restoration work on valuable works of art, the production or repair of dentures or adjustments to prototypes of electronic and microelectronic components can be carried out directly under the microscope and monitored on the screen.

The working area of a 3D microscope
First of all, the types of equipment can be distinguished according to whether they have a fixed working area that can only be adjusted in height or whether they have a flexible swivel arm. In the case of the 3D microscope with a fixed working range, care must be taken to ensure that the working height and working surface are large enough for the objects to be examined or processed. The usual working heights of ten to 175 or even 250 millimeters are usually sufficient for many applications, even when working with the tools. However, the support surface of the 3D microscope with a fixed working area – as in the other microscopes – is relatively small. In some models with a fixed support table, transparent specimens can alternatively be studied under microscope with the help of the transmitted light.For the other models without transmitted light, there are special black and white discs to place under the specimen to increase the contrast and improve visibility. The 3D microscope with a flexible swivel arm allows a much larger working area to be used. With a working distance of, for example, 430 millimeters and a depth of field of 12 millimeters, even larger elements can easily be placed on the work table or in special fixtures or rotated under the head of the microscope camera. It is also possible to place one or more templates for comparison directly next to the object under examination and view them simultaneously on the screen. Instead of direct comparison, it is also possible for the 3D microscope to show an image previously saved on the USB stick on a part of the monitor next to the examination object. If the 3D microscope has a foot switch, images can be saved even if both hands are needed to position the object.

The monitor of the 3D microscope
Another important criterion in the selection process is the monitor for image display. The 3D microscope can also be offered without a monitor, so that the user decides which monitor to use with the available interface. In the case of other devices, the monitor is a fixed part of the scope of delivery. This screen must either be mounted at the specified location or can be placed freely. Often, the live image can be displayed simultaneously on the second screen that is connected to the video signal output on the 3D microscope. For some types of equipment, 3D glasses are included in the scope of delivery for better recognition of the spatial structures.

The magnification and image resolution of the 3D microscope for industry
Unlike in medical research, a comparatively low magnification is desired in industry when inspecting or processing objects under the 3D microscope. This makes it possible to survey and evaluate larger areas. These are then only further magnified if necessary. Common magnifications are, for example, 15 to 30 times or 12 to 75 times. The image resolution of a 3D microscope is usually 1920 x 1080 pixels (Full HD). Some models with a small monitor, on the other hand, only offer a resolution of 800 x 600 pixels.

More and more specialised research institutions are equipped with a special laboratory microscope that can detect and evaluate even the smallest structures. In February 2021, for example, the researchers at the Universities of Giessen and Bielefeld used their laboratory microscope, which works with helium ions, to visualise coronaviruses, which are only about 100 nanometres in size, on the kidney cells of a monkey infected with SARS-CoV-2. Unlike a scanning electron microscope, where the electrons scan the surface, this laboratory microscope does not require the sample to be coated with an electrically conductive coating. In contrast to the other methods used, the helium ion microscope allows a direct view of the 3D surface and offers a higher resolution and greater depth of field. Of course, the images made possible by such a laboratory microscope are documented and shared with the other scientists. This makes it possible to coordinate further studies, taking into account the current results, and to make faster progress in curbing the proliferation of viruses.

At the department for Metallic Materials at the University of Jena, the laboratory microscope that can achieve resolutions to individual atoms was installed in summer2019. With a resolution of 80 picometres or 0.8 angstroms (ten million angstroms are one millimetre) and the additional spectrometers, it was probably the best laboratory microscope for chemical analysis in Europe at that time. The transmission electron microscope has a special correction lens that compensates for the imaging errors of the magnetic lenses. This rather extraordinary laboratory microscope will be used, among other things, to study the processes of phase transformation and the formation of various molecular structures in alloys.

A particularly high-resolution transmission electron microscope is also used at the University of Ulm. In December 2017, the four-metre-high laboratory microscope, which weighs several tons and was completed after years of development, was officially inaugurated. It works with low voltage so that the biomaterials that react sensitively to the electrons could also be studied under the microscope. This unique laboratory microscope offers the University of Ulm, which played a major role in its development, the opportunity to establish itself as one of the leading research centres in the field of microscopy. In many areas where visualisation of the tiniest details has previously been impossible, this low-voltage laboratory microscope offers new possibilities.