The comparison microscope is probably the most vital piece of equipment used for criminological analysis. Also known as a dissecting microscope and stereomicroscope, the comparison microscope has helped forensic experts solve numerous cases and bring justice to victims and their families.

What is a Comparison Microscope?
A comparison microscope is more or less made up of two microscopes and is mainly used for analyzing specimen side-by-side. The two microscopes are linked to each other through an optical bridge and consequently produce a split view window. Comparison microscopes can help forensic experts compare and determine origins of microscopic patterns. Side-by-side comparisons allow forensic experts to make actual comparisons simultaneously. This process offers a lower margin of error than comparisons made on the basis of human memory.

The Role of Comparison Microscopes in Forensic Ballistics
Ballistics and firearms identification are the terms used for determining whether bullets or other types of ammunition used came from a single firearm. It can also help determine the type and model of firearm used. Such information is obtained by comparing microscopic patterns produced by and from cartridge cases and fired bullets. Comparisons have to be made one at a time until a perfect match has been found.

Every barrel of gun has its own unique signature. The interior of a gun barrel possesses grooves which force the bullet to rotate as it’s fired. Grooves, together with its counterpart lands, both create impressions on the bullets. Any other imperfection on the barrel is also imprinted on the bullet. Such imperfections occur randomly and due to use or during the gun’s manufacture. All these make up a gun’s signature. With the help of comparison microscopes, forensic experts are able to compare impressions made on the bullet with the patterns on a casing.

Ballistic fingerprints of bullets, cartridge cases, and other ammunition and gun components taken from the crime scene are also compared to each other to determine if all bullets come from any of the guns recovered from the scene. When a match is made, the forensic experts will then turn over the evidence together with their analyses to the proper authorities. Consequently, the investigative team assigned to the case will search for a trail of evidence to determine the owner of the recovered guns. The owner will then be considered a suspect or a source of information critical to the case.

Advancements of Modern Comparison Microscopes Used for Criminological Analysis
As the 1990’s entered the scene, forensic techniques and methods have greatly improved and there was parallel progress with the evolution of comparison microscopes. Now, forensic experts can rely on highly sophisticated systems to analyze recovered ballistics data and get the answers they’re looking for.

Precision is no longer a problem with today’s range of comparison microscopes. Almost all kinds of state-of-the-art technology have been employed to provide their products with the greatest levels of accuracy.

Comparison microscope models have varying magnifications. One model, for instance, allow forensic experts to view objects at a magnification of up to 1500x – allowing users to produce even more reliable evidence in terms of color, texture, and microstructure.

There are also other comparison microscopes specifically designed for teaching forensic science. These models allow students to view specimens simultaneously and separately.

One well-known virtual model of a comparison microscope allows forensic experts to confirm the degree of comparison or likeness between any two tool mark samples. Although it’s not an actual comparison microscope, it’s still capable of producing two-dimensional images of objects with 3D planes just like what an actual comparison microscope would do.

This virtual model could also translate both samples to each other, overlap both samples, change the illumination used, choose zoom options, adjust your point of view (POV), and even produce split images on the screen with the two tool mark samples separate by a hair-line from each other.

The advantages don’t end there. This virtual model can also simulate any palette to help the forensic expert adjust light intensity and angle of incidence of the light used on the object to make it more visible. It is integrated with other well-known systems like the Integrated Ballistics Identification System and MatchPoint Plus to enter and store data and correlate them to each other with the utmost convenience.

Among other things, these systems can produce search results that are ranked according to probability and facilitate the search itself by automatically eliminating unlikely matches from previous cases. These systems are presently used in over thirty countries and territories.

The comparison microscope will continue to be in use for criminological analysis and people can only hope that it will advance further in the future to resolve mysteries of the past, present, and future.