A comparison microscope is a device used
to analyze side-by-side specimens
. It consists of two microscopes connected by an optical bridge, which results in a split view window enabling two separate objects to be viewed simultaneously.
How is a comparison microscope a useful tool in forensic science?
The comparison microscope is used in forensic sciences
to compare microscopic patterns and identify or deny their common origin
. Without this device, the identification of toolmarks and firearms would be such a cumbersome process that it would be carried out on a very limited basis.
What is a comparison microscope?
:
an apparatus consisting essentially of a pair of microscope objective lenses and tubes connected by prisms in
such a way that images from both may be viewed side by side through a single ocular lens.
When was the comparison microscope first used?
The first comparison microscope came from Wetzlar
In
1911
the Optical Institute of Wilhelm and Heinrich Seibert in Wetzlar, which was incorporated into the Ernst Leitz company in Wetzlar in 1917, received the first suggestions for building a comparison microscope (Figure 2).
What is the microscope used to compare bullets?
Stereo microscopes
are used to determine basic class characteristics of fired bullets, bullet fragments and cartridge/shotshell cases.
What is the first step in the hair identification process?
The first step of the examination involves
verifying whether the hair in question
is that of a human or an animal. If the hair is from an animal, the examiner can potentially identify the species from which it originated, but it is usually impossible to assign the identity of a hair to a particular animal.
Who helped develop the comparison microscope?
Phillip O. Gravelle
developed the comparison microscope for use in firearm investigations with the assistance of Colonel Goddard in the early1920’s. An optical comparison microscope consists primarily of two relatively low powered, two-dimensional (2D) compound microscopes joined by an ocular unit or optical bridge.
What microscope is used to identify drugs?
Electron microscopy (EM)
has a wide variety of applications in forensic investigation. Numerous crime-scene micro-traces, including glass and paint fragments, tool marks, drugs, explosives and gunshot residue (GSR) can be visually and chemically analyzed with scanning electron microscopy (SEM).
Which type of microscope is the most commonly used in the crime lab?
The stereoscopic microscope
is the most frequently used and versatile microscope found in the crime laboratory. When you increase the compound microscope magnification its field of view decreases.
Which describes the technology used by the breathalyzer?
Which describes the technology used by the Breathalyzer? The Breathalyzer
uses a chemical reaction with ethanol and detects a color change
.
Who is known as the father of toxicology?
Mathieu Joseph Bonaventure Orfila
(1787–1853), often called the “Father of Toxicology,” was the first great 19th-century exponent of forensic medicine. Orfila worked to make chemical analysis a routine part of forensic medicine, and made studies of asphyxiation, the decomposition of bodies, and exhumation.
Who devised a method for typing dried blood?
In 1915 the
Italian scientist Leone Lattes
developed a simple method for determining the blood type of a dried bloodstain. The Rh blood group system, which classifies blood according to the presence or absence of the Rh antigen, was developed in 1939–40.
What can gunpowder residue tell us?
A gunshot residue (“GSR”) wipe test detects
the presence of distinctive chemicals that are deposited on a person’s skin or clothing or other nearby surfaces when a gun is fired
. GSR tests results are considered reliable, and should be admitted into evidence.
What is bullet comparison?
Home > Bullet Comparison and Identification > Microscopic Procedures > Recovered Firearm Without Related Evidence > Comparison Process. … Examine
the entire bearing
surface of the test bullet using low magnification (10x-20x) to determine the best area of individual characteristics.
What are the three categories of ballistics?
The science of projectiles and firearms is defined as ‘ballistics’ and it can be divided into three distinct categories:
internal, external and terminal
.
How accurate is ballistic testing?
Study finds
less than 1.2 percent error rate
in matching bullets fired from Glock semiautomatic pistol barrels to the actual firearm.
