Optics—general, relief
Angstrom, nm, l,  n
Becke line
polychromatic, monochromatic
relief
polarization, propagation direction, vibration direction
index of refraction
differential absorption
dispersion
isotropic, anisotropic
coefficient of dispersion
interference
Fraunhofer lines
Snell's law
incident, reflected, refracted rays
oblique illumination

What is the range in wavelengths for visible light?

Describe, using V = n * l, how light changes as it passes from a vacuum to a solid medium.

Explain what is meant by index of refraction, and give typical values for some common substances. Is there a unique value of refractive index for a particular substance? Explain why or why not.

What is meant by negative relief?

Do isotropic substances ever show birefringence?

How is an isotropic substance recognized microscopically? Remember holes and bubbles are isotropic.

Sketch a diagram illustrating the ray paths for the three possible cases of N(oil) < N(grain), N(oil) > N(grain), and N(grain) = N(oil).

Explain what is meant by coefficient of dispersion using a diagram of n vs. l .

Explain the effect of temperature on refractive index.

What are some factors affecting the accuracy and precision of immersion techniques?

Describe the difference between a positive and a negative uniaxial mineral.

Explain the relationship between the refractive index of light traveling through a crystal in some orientation and the shape of the indicatrix.

What is the best word to describe the shape of the indicatrix representing a uniaxial positive mineral.

There are a three basic orientations of a uniaxial mineral from which different R.I. information may be derived. Sketch these three orientations relative to light and the microscope axis, and indicate what may be measured in each.

Outline the procedure you would use to find the R.I.'s of a uniaxial mineral.

Sketch how a mineral with a) basal, b) rhombohedral, c) prismatic cleavage might appear in a grain mount.

What are the two factors affecting the retardation in an anisotropic substance.

Explain qualitatively and briefly the whys of the interference color chart.

Sketch and explain why in a grain mount, concentric interference colors occur in most grains.

Explain the effect of inserting a quartz accessory plate on a mineral displaying first order red interference color given
a) coincidence of the high and low refractive indices of the plate and mineral, and
b) opposing orientations of the same.
c) What, physically is happening? One would see the same effects if what were to change in the mineral?

What must one do to the microscope in order to obtain an interference figure, i.e., change from orthoscopic to conoscopic observation?

Sketch a uniaxial optic axis figure, indicate and label the vibration directions, and label the visible features. Sketch an arrow in a direction of increasing interference color. Draw a cross section containing the microscope axis showing the stage, grain, c-axis, objective, and light paths through the crystal

Sketch a uniaxial optic normal figure and show the vibration directions.

With diagrams, show how optic axis and optic normal figures may be used to obtain the optic sign of a uniaxial mineral.

Describe the fundamental difference between biaxial and uniaxial minerals.

Describe the shape of an optical indicatrix for an isometric, a tetragonal, and a triclinic mineral.

Sketch a cross section through a positive biaxial indicatrix in a plane containing the Z direction, and label Z, X, the circular sections, the optic axes, Bxo, and Bxa.

Discuss the differences between a biaxial indicatrix with e = w, and a positive uniaxial indicatrix.

What refractive indices can be measured from a positive biaxial crystal with two principal sections orthogonal to the stage, when the Bxo direction is parallel to the microscope axis.

What R.I.s may be measured from a biaxial crystal with no principal planes orthogonal to the stage?

Discuss the difference between a Bxo figure and Bxa figure when the 2V is 90° .

Discuss what information Kamb's method yields.

Define and contrast birefringence, retardation, and interference color.

Sketch a Bxa figure at the 45° position for 2Vs of approximately 40° and 60° , and label the vibration directions visible in the field of view. Sketch an optic axis figure for a mineral with a 2V of 80° , label the vibration directions, and describe how you would determine the optic sign.

Describe the relationship between the crystallographic axes of orthorhombic, monoclinic, and triclinic minerals, and the possible positions of the principle vibration directions.

For what kinds of objects and for what purposes are a spindle stage and a universal stage used?