Throughout the PercepZone are many important optical words and concepts. The most important of these are defined below for quick reference. Click on any word to go to the page in the PercepZone where you will find more detail about the subject.
20/20 Vision : 20/20 Vision indicates perfect visual acuity.
Adaptation : This allows us to see in many different intensities of light.
Amplitude : The distance in which a wave travels from its horizontal axis.
Angle : of Incidence: The angle at which light strikes a surface. This angle is measured from the light ray to the normal.
Angle : of Reflection: The angle at which light is reflected off of a surface. This angle, measured between the light ray and the normal, is equal to the angle of indicence.
Aperture : The opening in your eye that limits the quantity of light that enters.
Aqueous Humor : The limped, watery liquid that fills the area between the cornea and the lens.
Brightness : Measurement of the intensity of light/
Choroid : The Choroid is responsible for "normal" black irises and red eyes in photographs.
Ciliary Muscles : The smooth muscle in the ciliary body that accomodates the eye.
CMV : CMV is an abbreviation for Cytomegalovirus, which attacks epithelial cells in the body.
Cones : Cones are photo-sensitive cells used for front and high-light vision. It is also named after its shape.
Congenital : Compatible [with the eye]
Construction : The process of putting together a series of visual clues to understand an image.
Density : A measure of how much of a substance exists in a certain amount of space.
Diabetes : A disease that impairs the ability of the body to use sugar and causes it to appear abnormally in the body.
Diurnal : Types of animals that stay awake during the day, when there is sunlight. Humans are an example.
Electromagnetism : The relationship between a changing electric field and a changing magnetic field.
Frequency : A measure of a waveís speed of oscillation. Often measured by how many wavelengths pass a point in a period of time.
Hertz : Unit of measure for frequency. On Hertz represents one oscillation per second.
Hypoglycemia : An abnormally low level of glucose, when pertaining to blood
Hypothalamus : An important section of the brain that regulates body temperature, blood pressure, heartbeat, metabolism, expression of emotions and sexual behaviors.
Incidence : In Physics, incidence refers to the arrival of radiation or a projectile at a surface.
Lightness : Known usually as the "shade" of a color, and is measured and grey-scale, from black to white.
Luminance : Brightness and intensity of light.
Luminous : Luminous means "to glow." Cat's eyes seem to be creating light when they are actually reflecting it.
Macula : Area of discoloration on the skin, caused by lack or excess of pigment.
Mirror : Any reflective surface, usually a flat, transparent, polished glass backed with a silver coating.
Nanometer : One billionths of a meter.
Nocturnal : Types of animals that stay awake at night when there is little light present.
Normal : In Mathematics, the condition of being perpendicular.
Optical : Density: The measurement of how slowly light passes through an substance.
Oscillate : To swing back and forth with a steady, uninterrupted rhythm. (From the Latin oscillare, meaning swing.)
Peripheral Vision : Vision that is described as being "out of the corner of an eye," or in other words, out of the direct line of sight.
Phenomenal : Sense: Philosophers use the word phenomenal to mean an object that appears real to the mind, regardless of whether its underlying existence is proved or its nature understood.
Photometer : A device used to detect change and intensity of light.
Photopic : Phos is a Greek word meaning "light."
Pineal : Gland: A pea-sized gland in the brain that affects a humanís biological clock; including sleep and temperature patterns.
Pituitary : Gland: A small, oval gland at the base of the brain that controls hormone production, affecting growth, maturation and metabolism.
Plexiform Layer : Plexus means network, referring to the network of nerves in the eye.
Rays : Ray Model of Light A model which presents light as energy that travels in rays, or straight beams.
Real Image : An image that has light where the image appears to be.
Reflection : The act of returning a light wave upon its contact with a reflective surface
Refraction : The turning or bending of any wave, such as light and sound, when it passes
Relative : Sense: The sense in which we see objects that really do exist.
Retina : Reta is Latin for net, referring to the net of nerves that makes up the retina.
Rods : Rods are photo-sensitive cells used for peripheral and low-light vision. It is named after its shape.
Sclera : A dense, white membrane that, with the cornea, forms the external covering of the eyeball.
Scotopic : Skotos is a Greek word meaning "darkness."
Simultaneous : Brightness Contrast: Describes how we use the colors around an object to help to determine the color of that object.
Simultaneous Lightness Contrast : Uses inhibition to make similar images
Subjective : Generally, subjective refers to something particular to the point of the view of the viewer. In Psychology, subjective refers to something existing only in the observerís mind.
Three-dimensional : This term refers to height, width and depth.
Two-dimensional: : This term refers to only height and width.
Undulate : To move in a small wave-like formation. (From the Latin undulare, meaning small wave.)
View : Generic View Principle: The assumption our eyes make that accept you are seeing an object from a generic view, or a non-accidental view.
Virtual : Image: An image from which rays of reflected or refracted light appear to diverge, as from an image seen in a plane mirror.
Vitreous Humor : The transparent, gelatinous substance that occupies the eyeball behind the lens.
Wave : A disturbance traveling through a medium by which energy is transferred from one particle to another without causing permanent displacement of the medium itself.
Wavelength : The distance it takes a wave to make one full undulation.