Tips for Using the Comparison Microscope

Most people think of comparison microscopes as the type of microscopy used mainly for ballistics. Thanks to many police and crime shows on TV, the technology behind the equipment has become familiar, although by no means perfectly understood. What is known, however, is that comparison microscopes allow the viewing of two different specimens side by side with the use of only one instrument?

In terms of convenience, comparison microscopes are some of the best instruments to use for observing and analyzing specimens. They also offer a reliable means to view and observe two samples at the same time. This allows the observer to view differences or similarities between bullets, bullet casings, hair, clothing fibers, marks on metal surfaces, insects, tissues, fingerprints, paint chips, textiles, grains, soils and other substances being processed.

Comparison microscopes are not limited for use in detective work. They are actually very valuable as tools for many fields of study and industries, such as medicine, biology, chemistry, mining, construction, jewelry making, geological and metallurgical research, among others. Comparison microscopes are highly versatile, even if they are usually equipped with low power magnifications.

Using the comparison microscope
The comparison microscope is used in a similar manner as traditional microscopes. However, the features are just not the same, considering there are two stages for specimen or sample mounting. Check the comparison microscope for two optical systems that are mounted next to each other. There should be an optical bridge that connects the two. This bridge keeps the two optical systems in place and at the correct distance from one another, which helps the instrument provide accurate results.

The bridge also helps minimize eye strain during viewing. Most importantly, the optical bridge is the component responsible for bringing the two images together, so they appear next to each other.

Mounting and viewing the specimen
Before specimens are mounted onto the microscope stage, it is important to make sure that they have been prepared for viewing. Generally, this means cleaning the specimen (unless the procedure indicates otherwise), cutting it or polishing it. Sometimes, the specimen will have to be prepared on a glass slide. Again, the preparation process will depend on the procedures required. If samples are to be viewed unadulterated, then they should be left alone.

Next, mount the specimens on the stages found on the lower area of the comparison microscope. There are restraining devices that often come with microscopes at the stage area which hold the specimens in place. These will help keep the specimens in place. However, for some specimens, temporary adhesive material might be required. Mount the specimens one after the other, making sure that they are positioned for best viewing. The role of the comparison microscope is to compare two different specimens, so it's important that they are placed in such a position that will allow seamless viewing through the eyepiece. Any skews in visuals can be corrected later.

Viewing the specimen
The best way to view a specimen through the comparison microscope is to first use a lower power magnification and then gradually increase it to the desired image size. Adjustments may be performed using the focus mechanism in order to refine the image. On the comparison microscope, images of the two samples will appear side by side, separated only by a thin demarcation line. This dividing line can also be manipulated to move left or right, allowing the observer to view a larger image of one object.

At this point, the focusing mechanism should be manipulated in order to adjust the image's clarity. Illumination may also be adjusted. Depending on the comparison microscope unit, illumination sources may vary, with a pair of different light source types. This feature allows for more flexibility in handling different kinds of specimens. Check the light source types on the comparison microscope to see if they are appropriate to use with the specimen in question. Some comparison microscopes, for example, may have a combination of a halogen lamp and a fiber optic illumination source. This allows for variable intensity. Lighting also can be mounted on different locations in the microscope, so it's important to check this feature as well because it allows for more versatility.

Adjusting the specimen
The comparison microscope allows for the rotation of the stage, so either or both specimens may be manipulated in different directions – left, right, up or down. This makes it easy to view certain specimens, such as bullets and bullet casings, three-dimensionally. Simply turn the stages for either or both specimens to observe any similar identification markings.

Care for the comparison microscope
The comparison microscope, like all types of optical microscopy, is a fragile instrument. It's important that care and maintenance suggestions and schedules are followed in order to keep the equipment in top shape. Turn off the power source after use, unplug and store in a safe location when not in use. Here is a link to the article