Ch. 4 The Microscope and Forensic Identification of Hair, Fibers, and Paint Flashcards
amorphous material
a solid without order in the arrangement of its atoms
anagenic phase
the initial phase of hair growth, when the hair follicle is producing hair
anisotropic material
material that appears different when the direction of observation is changed
basecoat
the layer of automotive paint that contains the colored pigments
Becke line
a bright line that develops as the objective lens of a microscope is moved out of focus
binder
the material that hardens as the paint dries, forming a continuous film
birefringement material
an anisotropic material
catagenic phase
the intermediate stage of hair growth, which occurs between the anagenic and telogenic phases
cellulosic fibers
fibers that are produced from cellulose-containing raw materials, such as tress or other plants
clearcoat
outermost layer of automobile paint that contains no pigment
comparison microscope
two microscopes linked by an optical bridge
compound microscope
a microscope with one body tube that is used for magnification in the range of 25x to 1200x
condenser
a lens under the microscope stage that focuses the light on the specimen
cortex
the body of the hair shaft
cuticle
a scale structure covering the exterior of the hair
depth of focus
the depth of the area of the specimen that is in focus
electrocoat primer
first layer of paint applied to the steel body of an automobile
field of view
the part of the specimen that can be seen through the microscopic lenses
follicular tag
tissue surrounding the hair shaft that adheres to hair when it is pulled out
illuminator
the part of a microscope that illuminates the specimen for viewing
isotropic materials
materials that have the same optical properties when observed from any direction
keritin
the primary protein that forms hair and nails
medulla
a column of cells running down the center of the hair
micrometer
one-millionth of a meter (μm)
microspectrophotometer
a microscope that measures the interaction of infrared or ultraviolet radiation with a sample
objective lens
the lower lens of a microscope; the lens closest to the specimen
ocular lens
the upper lens of a microscope; the lens nearest to the eye
pigment
added to paint to give it color
plane-polarized light
light that oscillates in only one plane
pleochroism
a property of a substance in which it shows different colors when exposed to polarized light from different directions
polarizer
a lens that passes light waves that are oscillating only in one plant
polarizing microscope
a microscope that illuminates the specimen with polarized light
polymer
a large organic molecule made up of repeating units of smaller molecules (monomers)
primer surfacer
a layer of automobile paint that slows corrosion of the underlying steel
“real” image
the actual nonmagnified image
refraction
the bending of light waves
refractive index
a ratio of the velocity of light in vacuum to its velocity in another medium
regenerated fibers
fibers made by treating cotton or wood with a variety of chemicals
scanning electron microscope (SEM)
a microscope that illuminates the specimen with a beam of electrons
solvent
the liquid in which the components of paint are suspended
spectroscopy
measurement of absorption of light by different materials
stereoscopic microscope
a microscope with 2 separate body tubes that allow both eyes to observe the specimen at low or medium magnification
synthetic fibers
fibers produced from chemicals made from refined petroleum or natural gas
telogenic phase
the final phase of hair growth, during which hair falls out of the follicle
virtual image
an image that is seen only by looking through a lens
warp
lengthwise strand of yarn on a loom
weft
crosswire strands of yarn on a loom
working distance
the distance between the object being investigated and the objective lens
A magnifying glass is a(n) ______ that is thicker in the middle than at the edge.
bi-convex
How much light bends depends on the change in ______ as the light enters and leaves the magnifying glass.
refractive index
When using a magnifying glass, the magnified image is known as the _______ image.
virtual
A(n) ______ microscope has two lenses that are at fixed distances from one another in a hallow tube.
compound
The lower lens in a compound microscope is the _____ lens.
objective
The upper lens in the eyepiece of the compound microscope is the _____ lens.
ocular
A compound microscope can magnify objects up to _____ times.
1500
As the numerical aperture (NA) of a microscope lens doubles, it is able to resolve details that are ______ as close to one another.
twice
The thickness of the region that is in focus when using a compound microscope is called the ______.
depth of focus
The light rays from the illuminator are condensed and focused through the ______ lens.
condenser
Side-by-side comparisons of specimens are best performed by using a(n) _____ microscope.
comparison
The ______ microscope has two eye pieces.
stereoscopic
The distance between the objective lens and the specimen is the ______.
working distance
______ materials have the same optical properties when observed from all directions.
isotropic
As the direction of observation is changed, _____ materials will change their appearance.
anisotropic
______ is the property of a substance in which it shows different colors when exposed to polarized light coming from different directions.
pleochromism
The microspectrophotometer is an instrument that attaches a spectrophotometer to a(n) ______.
microscope
With a microspectrophotometer, the UV, visible, and _____ spectrum of the sample can be measured.
infrared (IR)
A spectrophotometer measures the light intensity as a function of ______ after the light has interacted with the sample.
wavelength
Hair is composed primarily of the protein ______.
keratin
The electrons that are immediately reflected back toward the electron source in a scanning electron microscope are called ______ electrons.
backscattered
A human hair has three layers: the ______, the ______, and the ______.
cuticle, cortex, medulla
The medulla of human hair is ______ (cylindrical/patterned).
cylindrical
The initial phase of hair growth is known as the ______ (catagenic/ anagenic/ telogenic) phase.
anagenic
During the final phase of hair growth, known as the ______ phase, hair becomes loose and falls out.
telogenic
The three most basic weaves in fabrics are ______, ______, and ______.
plain, twill, satin
Cellulosic fibers are produced from raw materials from trees or plants that contain ______.
cellulose
Synthetic fibers are produced from chemicals made from refined ______.
petroleum
Synthetic fibers made from cellulose fibers are also known as ______ fibers.
regenerated
______-shaped synthetic fibers reflect more light and give an attractive sparkle to textiles.
trilobal
The first step in comparing two synthetic fibers is to examine the fibers with a(n) ______ microscope.
refractive index
Synthetic fibers can be identified by comparing their ______ & ______.
physical and chemical compositions
Paints have three major components. They are ______, ______, and ______.
pigment, solvent, binder
Paint evidence is very important in ______ and _____.
burglary, automobile crimes
Other than color, what is the most important physical property of a paint chip when making a comparison? ______.
texture and layer sequence
Paint chips can be picked up by sliding a piece of ______ under the chip.
paper
A reference paint sample can be obtained from an automobile by using a(n) ______.
scalpel
A unique fit of the edges of two paint chips is called a(n) ______ match.
jigsaw
Sometimes a paint chip is cast into a block of epoxy and cut with a microtome to reveal its ______ structure.
layer
Infrared microspectrophotometry will reveal the ______ components of a paint chip.
major organic
Destructive chemical tests can be carried out on paint chips by applying ______ to the paint chips.
solvent
