Exam 1 Flashcards by Sal Trejo

Anatomical Orientation

Terminology used when describing the location where evidence was found
1. superior vs. inferior
2. medial vs. lateral
3. dorsal vs. ventral
4. proximal vs. distal

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Antony Von Leeuwenhoek

made the simple microscope spheres of ground molten glass

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Hans and Zacharias Janssen

3 tube , 2 lense microscope (compound microscope)

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Robert Hooke

Invented modern micrscope and used it to see cells

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Carl Zeiss

Built microscope with Ernest Abbe, the Stereo-microscope ; Zeiss Microscope

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august Kohler

developed Kohler illumination

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Kohler Illlumination Steps

Focus on whats on the slide and make sure condenser 0.5 cm from the bottom of the coverslip
close the field diaphram until you see a circle
move condenser up and down until the edges of the circle become sharp like a hexagon
center condenser
open the field diaphram
take out one of the eye pieces and focus the back field by adjusting the substage aperature

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Visible light

red: 750-620
orange: 620-580
yellow: 580-570
green: 570-500
blue: 495-450
indigo: 450-425
Violet: 450-380

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Electromagnetic spectrum

longest wavelength to shortest; longer equals less energy while shorter means more energy

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Converging Lenses

Lenses that produce a real image that you can see, wider middle

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Diverging lenses

Lenses that produce a virtual image apart of the image forming plane, thin middle

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Lens Formula

1/f = 1/p + 1/q

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Magnification formula

m = q/p

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Reduction equation

p/q (1/Magnification)

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How compound microscopes form images

Specimen is illuminated from below, this light goes into the objective lens
Objective lens produce a real, inverted image
This image form is then inverted again in the microscope tube
Eye piece magnifies this real image and projects a virtual image onto the viewer’s eyes.

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Back focal plane of objective

Plane behind the objective lense

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Conjugate focal planes

optical planes responsible for image forming and illumination

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List the Image-forming ray planes that should be in conjugate focus in order to ensure good Kohler illumination.

Field diaphragm, specimen, eyepiece field stop, and retina or the eye or film plane.

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List the Illuminating-forming ray planes that should in conjugate focus in order to ensure good Kohler illumination.

Light source, substage condenser, aperture diaphragm, the back focal plane of the objective lens and eyepoint of the eyepiece.

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Least distance of vision?

25 cm.; least distance which the eye can see

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Stereoscope

to help view at two images separately

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Angular Aperture

maximum angle made by the image forming light rays

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Infinity optics

When light rays pass though the objective lens and become parallel light ray, this then allows for optical components to be added without affecting the image formation.

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Color temperature

color characteristics of light based on temperature, warmer is redder while hotter is bluer

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Numerical Aperture (NA) + resolving power

the lenses ability to capture light from the specimen and use it to make an image off certain angles. - Tied with resolving power, higher resolving power means higher NA is desired

NA equation

NA = n*Sin*(AA/2) NA= n*sin*u n = refraction u = angle formed aa = angular aperture

Field Diaphragm

limit the area of illumination to the part of the image field actually being viewed

Condenser

provides converging cone of light through the specimen

substage aperture

allows control of specimen contrast and image quality by controlling angle of illumination

Objective lens

capture light emitted or reflected by the specimen

Ocular lens

magnifies image produced by the objective so you can see it

Plan

Flat field optical corrections

Oil

Oil immersion

N.A

Numerical aperture

Infinity symbol

infinity corrected tube length

Cover glass thickness

0.17 mm

Working Distance

distance between objective front lens and the cover slip, WD decrease, magnification increases

Tube Length

length of microscope body tube from nosepiece to objective, usually 160 mm

airy's disk

sin (a) = 1.22(lambda)/ When light hits a perfectly circular aperture, a bright central peak forms, followed by a series of rings that decrease in brightness)

Abbe's rule of thumb

maximum useful magnification equals NA*1000, excess results in empty magnification

Max and min magnification formulas

max: NA * 1000 min: NA * 500

Index of Refraction equation

RI = Speed of light in air / speed of light in substance

Snell's law

n = sin(i)/ sin(r)

Refraction is when

light passes from one medium through another.

specular vs diffuse reflection

specular is on smooth surfaces and light rays reflect at the same angle. Diffuse is on rougher surfaces and scatters light rays in different directions

Refraction

Bending of light through a medium into another due to a change in the speed of light ray or the wave

Dispersion equation

Nd-1/Nf-Nc

Critical Angle

smallest incident angle where inflection occurs

Dispersion Curve

refractive index vs wavelength, at some point the grain and oil intersect

Becke line dispersion

Higher RI particle than medium, line moves inwards. Lower RI than medium then line moves outwards

Oblique illumination method

When you cover half of the field diaphragm and see where the shadow lies. RI on same side means particle is higher while on opposite side means RI is lower.

Resolution

optically distinguish two points when they're close together

Calibrated ocular micrometer

micrometers per ocular scale division

Stage micrometer

Slide with with the ruler on it

GRIM 3

modern microscope used in most crime labs

Aberration

changes in focal points based on where waves entered

Spherical aberration

Focal points change depending where light enters the lens, light rays entering farther away from the center are unable to converge at a focal point therefore causing a fuzzy image.

Chromatic Aberration

Each color refracts differently

Curvature of Field

Image is focused on one particular plane and produced a curved image. can be corrected using an expensive lens or the poor man’s method (closing down in the edges)

Barrel Distortion

Barrel magnification decreases as you go out

Pin cushion distortion

Magnification increases as you go out

Astigmatism

eye is shaped different internally which causes light to bend differently when it enters your eyes.

Diffraction equation

n(lambda)=dSin(theta)

Abbe's diffraction Theory of Image Formation

(0.5)(lambda)/NA - image is formed by the diffraction of light waves from an object. More diffracted orders means more resolution.

Lord Rayleigh's Criteria

0.61(lambda)/NA - standard for determining the the minimum resolvable detail in an optical device

4. How should you measure the thickness of a strongly trilobal fiber?

You measure from the middle to the ends.

Exam 1 Flashcards

(66 cards)