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Instrumentation of Trace Evidence > Forensic Microscopy > Flashcards

Forensic Microscopy Flashcards

1
Q

The term “microscopy” describes:

A

Analytical approach in, which a microscope plays a central role in maximizing the extraction of useful information from a variety of samples.

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2
Q

The integration microscopical techniques with other instrumentation results in:

A

Powerful and versatile combination that cannot otherwise be equaled.

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3
Q

The microscope is routinely employed in areas of criminalistics for:

A

Document examination, tool mark comparison, firearms identification, serology, drug chemistry and trace evidence.

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4
Q

Good criminalistic technique demands the effective use of the:

A

Microscope

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5
Q

Among the types of problems faced by the forensic microscopist or criminalist dealing with trace evidence are the:

A
  • Characterization, identification and comparison of such and evidence types as paint, soil, minerals, dusts, glass, polymers, fibers (synthetic and natural), paper, starches, wood, hairs, pollens and trichomes.
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6
Q

A converging (or positive) lens can form images in two ways. These are termed:

A

Real and virtual images.

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7
Q

A ___________image is formed on the side of the lens opposite the object and is inverted with respect to the object.

A

Real

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8
Q

An image is_____________in the sense that knight rays from the object actually converge at a given plane in space and thus the image can be made to fall on a screen.

A

Real

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9
Q

The image produced by a movie or slide projector is a ___________image.

A

Real

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10
Q

When a lens is used as a magnifying glass, a _____________image is formed.

A

Virtual

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11
Q

The ____________is erect and cannot be directly registered on a screen or a piece of film.

A

Virtual

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12
Q

The use of another lens is necessary to convert a ____________image into a real image so it can be projected onto files or some other sensitive surface.

A

Virtual

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13
Q

The simple microscope, in which magnification takes place in one stage, is no more than a _________________.

A

Magnifying glass

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14
Q

The most common simple microscopes in use today are low powered types such as:

A

Hand lenses, eye loupes, linen testers and fingerprint magnifiers.

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15
Q

Compound microscopes have extremely short_____________lengths.

A

Focal

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16
Q

Compound microscopes can produce large___________________.

A

Magnifications

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17
Q

The principle of the compound microscope was developed and used successfully by:

A

Leeuwenhoek (1632-1723)

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18
Q

(Compound Microscope)

Producing lenses of shorter focal length with high power requires that:

A

Radius of curvature and size of lens be decreased

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19
Q

(Compound microscope)
With a small short focal length lens placed closed to the eye, refractive index inhomogeneities within the eye are accentuated.

A

True

20
Q

Modern compound microscopes circumvent accentuation by having magnification take place in ___________stages.

A

Two

21
Q

The performance of the compound microscope did not surpass that of a simple microscope as a research tool until the introduction of the____________.

A

Achromatic Lenses

22
Q

The last stage of magnification in the compound microscope is the same as for the____________microscope. A __________is formed and it takes place in the eyepiece (ocular).

A

Simple

Virtual

23
Q

An increase in magnification that continues to reveal details in the object is called:

A

Useful magnification

24
Q

Additional magnification that merely results in a larger image with no further detail is known as:

A

Empty magnification

25
Q

The two most common microscopes in the laboratories are:

A

Biological and stereoscopic binocular

26
Q

The stereoscopic binocular or stereo microscope is the most widely used instrument in the crime laboratory.

A

True

27
Q

The ____________is often the first instrument employed to make a preliminary evaluation of evidence or to sort and select items for further scrutiny.

A

Stereo Binocular microscope

28
Q

The most common type of illumination employed with the stereo microscope is variously termed:

A

Incident, reflected, vertical or epi

29
Q

The biological microscope is designed for_______________light illumination. It is not suitable for most thick or opaque specimens.

A

Transmitted

30
Q

The ________________microscope is the most versatile and powerful tool available for analyzing trace evidence.

A

Polarized Light

31
Q

Comparison microscopes find extensive use in forensic laboratories.

A

True

32
Q

A comparison microscope is basically two carefully matched ____________________.

A

Compound microscopes

33
Q

Images produced by two compound microscopes are____________in a common intermediate field plane within the ocular (s). In this way, objects from two different fields of view can be compared directly.

A

Juxtaposed

34
Q

______________distinct types of comparison microscopes find use in forensic laboratories. One is designed for comparison of __________objects such as bullets, cartridge cases and tool marks at low to moderate magnification; this type uses_________________.

A

Two
Opaque
Incident

35
Q

The second type of comparison microscope is used for:

A

Hair and fiber comparisons (transmitted light illumination)

36
Q

Magnification (comparison microscopes)on each side can be compared by using known scales such as _______________.

A

Stage micrometers

37
Q

_________________illumination is when the specimen is illuminated from the side opposite of the objective.

A

Transmitted Light

38
Q

Everyday objects are normally viewed in the macro world using ________________.

A

Reflected Light

39
Q

A compound microscope should have the following transmitted light illumination attributes:

A
  • Capable of illuminating the specimen uniformly with adequate intensity, allow precise control of light paths so the only area of the specimen being examined is illuminated; and angularity is appropriate for the objective used.
40
Q

Precise control of illumination permits____________for varied conditions and results in a reduction of ______________resulting in diminished glare.

A

Optimization

Stray Light

41
Q

Two primary components supply illumination in most microscopes:

A

Illuminator and substage condenser

42
Q

The most desirable illumination for a wide variety of applications was devised by:

A

August Kohler (1866-1948)

43
Q

6 volts is the nominal operating voltage for a high quality microscope illuminator.

A

True

44
Q

There is a considerable degree of interdependence among:

A

Resolution, magnification and visibility.

It is often not possible to effect an improvement in one without giving up optimum performance to the other.

45
Q

Interference microscopes involve:

A

Two beams of light are separated and brought back together to form the image.

One beam contains the sample; the other is a reference beam.

46
Q

The Phase Contrast Microscope can be thought of as the first ___________________.

A

Interference Contrast Microscope

47
Q

_______________won the Nobel Peace Prize for Physics in 1953 for his invention and development of the phase contrast microscope which he perfected between 1935 and 1942.

A

Dutch Physicist Frits Zernike (1888-1966)

Instrumentation of Trace Evidence (3 decks)

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