Research Assignment II

Kristian Thompson

Sept 06, 2012

of 9

1 Photon EmissionHow light is created.

Digital Technology Design II

What’s The Story??

“Light is comprised of packets of electromagnetic energy called photons. Photons are produced sporadically when electrons (yel) are accelerated by close approaches to ions (bl). As the temp. rises the photon production increases”

2 WaveLight is PART OF a wave of energy that travels

3 Reflection (impact)When light strikes an object, some of it bounces off. That light bouncing back to your eye is what enables you to see things.

Photon “bundle of energy without a charge” collides with a particle creating matter and antimatter

secondary concepts

a giant wave of energy crashing into an object

Shadows and their characteristcs(in bg)

Kristian Thompson

Sept 06, 2012

of 9

STRAIGHT DIAGRAMS!!!

GEMS (beauty) HALF ++SCIENCE HALF

The amount of energy reflected depends on the angle the light strikes it at and the material’s chemical composition.

4) AbsorbtionPart of light the light that strikes the object is absorbed. It is the light which an object can not absorb which gives it most of it’s colour.

//Why does a material absorb some colours but not others?

well..

“modifies the colour gradually as it moves through the medium”

4A) Idochromatic Materials

“Coloration which is caused by the presence of an element foreign to the crystal lattice, whether in mixture or in trace amounts, is termed allochromatism. Certain elements are strong pigmenting agents and may lend vivid colors to speci-mens when they are present, whether as a part of the crys-tal lattice, in mixture, or as an impurity. These elements are termed the chromophores.”

“ Ions of certain elements are highly absorptive of select-ed wavelengths of light. Such elements are called chromo-phores; they possess strong pigmenting capabilities. The elements vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), and copper (Cu) are chro-mophores. A mineral whose chemical formula stipulates the presence of one or more of these elements may possess a vivid and distinctive color.” (Physical Characteristics of Minerals)

Kristian Thompson

Sept 06, 2012

of 9

B) Allochromatic

“Most minerals which are composed entirely of elements other than the chromophores are nearly colorless...The property of color may sometimes be highly dependent on the inclusion of trace amounts of impurities. The presence of even a minute quantity of a chromophore within the crystal lattice can cause a mineral specimen to exhibit vivid color. For example, trace inclusions of chromium (Cr) in beryl are responsible for the deep green of emerald, while the purple of amethyst is due to trace amounts of iron (Fe) in quartz and the pink of rose quartz is due to trace inclusions of tita-nium (Ti). Samples of the mineral corundum which include tiny amounts of chromium are deep red, and the gem is then called a ruby, while samples containing iron or titanium im-purities produce blue gems termed sapphire.”

C) Pseudochromatic

Pseudochromatic colors are not caused by any actual color in the mineral, but by physical or optical effects resulting from the manner in which their structure affects light’s path(s) through them.

//SO HOW DOES LIGHT MOVE THROUGH A MATERIAL??

5 DispersionSpectrum appears as refractive index varies with wavelength

terms make me look smarter

4 Refraction (101)On penetration, light slows and changes directionLoved the car hitting a puddle analogy - visual metaphor?

Kristian Thompson

Sept 06, 2012

of 9

6 StructureThe manner in which light moves through the object, creating the optical effects we percieve, is determined by the mate-rial’s structure.

a) Isotropic (rotational symmetry) one refractive index = no funky business

link cause and effectmacro and micro

b) Anisotropic (most)(posesses optical axis) light behaves diff. depending on direction (and polarization but don’t mention that yet)

birefringence = the property birefraction = the effect

(Yellow Line)When light enters the optical axis of anisotropic crystals, it acts in a manner similar to interaction with isotropic crystals and passes through at a single velocity.

(Any other direction)However, when light enters a non-equivalent axis, it is re-fracted into two rays each polar-ized with the vibration directions oriented at right angles to one another, and traveling at different velocities. This phenomenon is termed “double” or “bi” refrac-tion and is seen to a greater or lesser degree in all anisotropic crystals.

Kristian Thompson

Sept 06, 2012

of 9

7 PolarizationCrystal lattice acts as a filter as a result, light traveling through acquires an oreintation.

8 Thin Film InterferenceInterference = processLight waves reflected by upper and lower boundaries of a thin film combine to create a new wave.

Iridescence (Goniochromism) = resulting optical phenomenon (hue changes in correspon-dence with angle from which a surface is viewed.)

Iridescent ‘dragon skin’ patter in Ammolite

Kristian Thompson

Sept 06, 2012

of 9

9 Dichroism, PlechorismDifferently oriented/polarized beams move through the crys-tal at different paths and speeds resulting in varied appear-ance based on viewing angle & direction of light

Opalescence :A type of dichroism seen in highly dispersed systems with little opacity. The material appears yellowish-red in trans-mitted light and blue in the scattered light perpendicular to the transmitted light. (sky & sunset)

Note the orange caustics / might wanna mention rayleigh scattering in conjunction with this

Kristian Thompson

Sept 06, 2012

of 9

10 Sheen Various optical phenomena resulting from reflections of light beneath the surface of an object

‘Play of Colour’ (Schiller)Tiny spheres beneath the surface create light interference effect all over surface (opals)

Labradorescence Sheen of metallic colours arising from light interference be-tween layers with the object.

AventurescenceMetallic glitter, arising from minute, preferentially oriented mineral platelets within the material.

Kristian Thompson

Sept 06, 2012

of 9

AdularescenceMilky, bluish luster or glow originating from below the sur-face of the gemstone - Appears to move as the stone is turned (or as the light source is moved)

Chatoyancyparalell oriented inclusions (hollow tubes) reflect the light from beneath the surface creating cat’s eye effect

Asterismmultidirectional inclusions create star effect. Differently di-rected inclusions create 4/6/12 pointed stars(diasterism vs epiasterism)

Kristian Thompson

Sept 06, 2012

of 9

16 Glow Flourescence: Emission of light by a substance that has ab-sorbed light or other electromagnetic radiation. Most notice-able when viewed under UV (invisible to us) because the sub-stance appears to ‘glow in the dark’

Phosphorecence: The continued emission of light after the removal of the source of the substance’s energy (light).

Kunzite - Appears green under incandescent light, pink under short-wave UV and orange under long-wave UV

Research Assignment II

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