Analysing Evidence: Using Microscopes

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Microscopes are used to evidence found at the scene of a crime.

Most schools use Microscopes. These use lenses to magnify specimens, usually up to a of 400x.

microscope 1

A light microscope consists of

(a) A , to reflect light towards the specimen.

(b) A , to hold and support the specimen

(b) An lens, to refract and focus the light.

(c) An lens, to view the image of the specimen.

(d) knobs, to move the lenses so that a clear image of the object can be seen.

Light microscopes are often used by forensic scientists to analyse samples of hair.
They can be used to identify the of the hair, and to determine if the air is curly or . They can also be used to measure the of the hair.

Light microscopes can also be used to identify fibres collected at the scene of the crime. These fibres can be either natural or . Sometimes, it is more convenient to compare samples by using a microscope, so that the two samples can be seen side by side.

There are other types of microscopes used by forensic scientists.

1. microscopes

These microsopes are able to offer magnifications up to 1 000 000 x . They are able to offer a greater resoution than optical microscppes, so that finer details can be observed.
The focusing is achieved by using electromagnets.

2. microscopes

These microsopes are invaluable in comparing a sample found at the scene of a crime to a sample taken from the suspect. They can be used for comparing a test bullet from a suspect's to a bullet found at the scene of the crime. This amalysis is possible because marks, called , are different from gun to gun. These marks are caused as the bullet is from the gun.

3. microscpes

Two polarising are used. A sample is placed between the filters, on the stage of the microscope. When the sample is rotated, it changes when viewed though the eyepiece.
This method is particulary useful when analysing minerals, and crystals. It can also used for identifying the found in paint samples.