The Eye
A brief review of how the eye forms an image will aid in understanding the VRD.
A point source emits waves of light which radiate in ever-expanding circles about the point. The pupil of an eye, looking at the source, will see a small portion of the wavefront. The curvature of the wavefront as it enters the pupil is determined by the distance of the eye from the source. As the source moves farther away, less curvature is exhibited by the wavefronts. It is the wavefront curvature which determines where the eye must focus in order to create a sharp image.
If the eye is an infinite distance from the source, plane waves enter the pupil. The lens of the eye images the plane waves to a spot on the retina. The spot size is limited by the aberrations in the lens of the eye and by the diffraction of the light through the pupil. It is the angle at which the plane wave enters the eye that determines where on the retina the spot is formed. Two points focus to different spots on the retina because the wavefronts from the points are intersecting the pupil at different angles.
Neglecting the aberrations in the lens of the eye, one can determine the limit of the eye's resolution based on diffraction through the pupil. Using Rayleigh's criteria the minimum angular resolution is computed as follows:
| Where |
|---|
| D = diameter of the pupil |
| lambda = wavelength of light |
Read more about this topic: Virtual Retinal Display
Famous quotes containing the words the eye and/or eye:
“The body was still resting on its legs, leaning against the end of the side of the bed, while one of the arms was close clasped round the bed-post. The mouth was rigidly closed, but the eyes were open as though staring at him.”
—Anthony Trollope (1815–1882)
“And all my days are trances,
And all my nightly dreams
Are where thy dark eye glances,
And where thy footstep gleams—
In what ethereal dances,
By what eternal streams.”
—Edgar Allan Poe (1809–1849)
“For any eye is an evil eye
That looks in onto a mood apart.”
—Robert Frost (1874–1963)