geometric optics

(noun)

Optics that describes light propagation in terms of "rays".

Related Terms

Examples of geometric optics in the following topics:

  • The Ray Aspect of Light

    • This is called geometric optics.
    • Since the movement of the light rays can be shown geometrically, if a mirror is one-half your height, you could see your whole body in the reflection.

  • Refraction Through Lenses

    • Lenses are found in a huge array of optical instruments, ranging from the simple magnifying glass to a camera lens to the lens of the human eye.
    • Additionally, we will explore how image locations and characteristics can be quantified with the help of a set of geometric optics equations.

  • Resolution of the Human Eye

    • As soon as the eye moves, it re-adjusts its exposure, both chemically and geometrically, by adjusting the iris (which regulates the size of the pupil).
    • The eye includes a lens not dissimilar to lenses found in optical instruments (such as cameras).
    • About 12–15° temporal and 1.5° below the horizontal is the optic nerve or blind spot which is roughly 7.5° high and 5.5° wide.

  • 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.

  • Synchrotron Absorption

    • We are particularly interested in the form of the spectrum from a power-law distribution of particles for frequencies where the region is optically thick.
    • We know from the formal solution of radiative transfer that the spectrum approaches the source function at large optical depth.
    • Because the optically thin emission spectrum increases more slowly with frequency than the source function (or even decreases), we expect synchrotron absorption to be important at low frequencies where the the integrated optically thin emission exceeds the source function.