What is a Becke line forensics?

What does Becke line do?

The Becke line test is a technique in optical mineralogy that helps determine the relative refractive index of two materials. It is done by lowering the stage (increasing the focal distance) of the petrographic microscope and observing which direction the light appears to move.

What does a Becke line tell you when analyzing glass samples?

Becke line – Indication of Refractive Index

Notice the halo of light on the inside perimeter of the glass sample. When the Becke line is inside the perimeter of the glass fragment, the refractive index of the glass is higher than the refractive index of the surrounding medium.

What is the Becke line and how is it used to determine the refractive index of a glass sample?

Becke line method is a method for determining the refractive index of a transparent particle relative to its surrounding medium by noting the direction that the Becke line moves when the distance between the objective of the microscope and the preparation is changed.

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What is Kalb light test?

Kalb light line In optical mineralogy, a test made on polishing relief, which is visually similar to the Becke line test, but different in origin. The microscope is focused clearly on the boundary between the two mineral grains.

What is a normal line in glass?

The perpendicular line that forms at the interface of two media is called the normal line. In this figure, as the beam of light moves from the air into the glass, the light slows down and bends toward the normal line.

How will you know if the glass fragments did or did not originate from the same source?

Glass examiners compare samples of glass found on suspects or found at the scene of a crime with a suspected source of known origin by measuring the physical and optical properties of color, thickness, density, and refractive index. In most cases, these have been good methods for differentiation between glasses.

What are the 4 primary sources of sand?

What are the four primary sources of sand? mostly of quartz, mica, feldspar, and dark-colored minerals like hornblende or magnetite. Continental sand is composed of: mostly of quartz, mica, feldspar, and dark-colored minerals like hornblende or magnetite.

What methods are used to analyze glass evidence?

Forensic glass samples can be analyzed by comparing the refractive index of the sample to that of the possible source. Examination of samples under a regular microscope or a scanning electron microscope can give detailed information about the sample’s physical and chemical characteristics.

What is a Becke line what does it illustrate about the refractive index of the glass and the liquid?

-When a glass particle is mounted in an oil (or any liquid) having a different refractive index than the glass particle, light will undergo refraction around the edges of the glass. -The direction that the light “bends” depends upon what has the higher refractive index.

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What is refractive index describe how it is used to identify glass samples?

Optical properties, such as refractive index (RI), are defined by various manufacturing methods. RI is the manner in which light passes through the glass. This can be measured easily even on small fragments of glass. These properties help to indicate that two samples of glass could be from the same source.

What is glass refractive index measurement?

The refractive index of glass is a measurement of how much a beam of light is bent when it travels from the less dense medium air, to the more dense medium glass.