optic chiasma

(noun)

found at the base of the brain and coordinates information from both eyes

Related Terms

Examples of optic chiasma in the following topics:

  • Visual Processing

    • The myelinated axons of ganglion cells make up the optic nerves.
    • This crossing of optical pathways produces the distinctive optic chiasma (Greek, for "crossing") found at the base of the brain and allows us to coordinate information from both eyes.

  • Optic (II) Nerve

    • The optic nerve is also known as cranial nerve II.
    • The optic nerve is the second of twelve paired cranial nerves.
    • As a consequence, optic nerve damage produces irreversible blindness.
    • The optic nerve leaves the orbit, which is also known as an eye socket, via the optic canal, running posteromedially toward the optic chiasm, where there is a partial decussation (crossing) of fibers from the nasal visual fields of both eyes.
    • An illustration of the brain highlighting the optic nerve and optic tract.

  • Development of Vision

    • Development of the optic vesicles starts in the three week embryo from a progressively deepening groove in the neural plate called the optic sulcus.
    • As this expands, the rostral neuropore (the exit of the brain cavity out of the embryo) closes and the optic sulcus and the neural plate becomes the optic vesicle.
    • The lens acts as an inducer back to the optic vesicle to transform it into the optic cup and back to the epidermis to transform it into the cornea.
    • Iris is formed from the optic cup cells.
    • After the closure of the tube they are known as the optic vesicles.

  • Lasers

    • A laser consists of a gain medium, a mechanism to supply energy to it, and something to provide optical feedback.
    • A laser consists of a gain medium, a mechanism to supply energy to it, and something to provide optical feedback (usually an optical cavity).
    • When a gain medium is placed in an optical cavity, a laser can then produce a coherent beam of photons.
    • The gain medium is where the optical amplification process occurs.
    • The most common type of laser uses feedback from an optical cavity--a pair of highly reflective mirrors on either end of the gain medium.

  • Problems

    • At $t=t_0$ the sphere is optically thin.
    • What is the total luminosity of the sphere as a function of $M_0, R(t)$ and $T_0$while the sphere is optically thin?
    • What is the luminosity of the sphere as a function of time after it becomes optically thick in terms of $M_0, R(t)$ and $T_0$?
    • Give an implicit relation in terms of $R(t)$ for the time $t_1$ when the sphere becomes optically thick.

  • Enhancement of Microscopy

    • In this section we will discuss both optical and electron microscopy.
    • You have probably used an optical microscope in a high school science class.
    • In optical microscopy, light reflected from an object passes through the microscope's lenses; this magnifies the light.
    • Although this type of microscopy has many limitations, there are several techniques that use properties of light and optics to enhance the magnified image:
    • Electron microscopes use electron beams to achieve higher resolutions than are possible in optical microscopy.

  • Limits of Resolution and Circular Aperatures

    • In optical imaging, there is a fundamental limit to the resolution of any optical system that is due to diffraction.
    • However, there is a fundamental maximum to the resolution of any optical system that is due to diffraction (a wave nature of light).
    • An optical system with the ability to produce images with angular resolution as good as the instrument's theoretical limit is said to be diffraction limited.
    • The denominator $nsin \theta$ is called the numerical aperture and can reach about 1.4 in modern optics, hence the Abbe limit is roughly d=λ/2.
    • There are techniques for producing images that appear to have higher resolution than allowed by simple use of diffraction-limited optics.

  • Using Interference to Read CDs and DVDs

    • Optical discs are digital storing media read in an optical disc drive using laser beam.
    • Compact disks (CDs) and digital video disks (DVDs) are examples of optical discs.
    • They are read in an optical disc drive which directs a laser beam at the disc.
    • In this early version of an optical disc, you can see the pits and lands which either reflect back light or scatter it.

  • B.5 Chapter 5

    • At $t=t_0$ the sphere is optically thin.
    • What is the total luminosity of the sphere as a function of $M_0, R(t)$ and $T_0$ while the sphere is optically thin?
    • What is the luminosity of the sphere as a function of time after it becomes optically thick in terms of $M_0, R(t)$ and $T_0$?
    • Give an implicit relation in terms of $R(t)$$t_1$ for the time $t_1$ when the sphere becomes optically thick.

  • Orbits

    • To the rear of the orbit, the optic foramen opens into the optical canal through which the optic nerve and ophthalmic artery pass.
    • Finally, the sphenoid bone forms the posterior wall of the orbit and also contributes to the formation of the optic canal.