245. Light

See also 110. DARKNESS ; 387. SUN

actinology

the study of the chemical effects of light in the violet and ultraviolet wavelengths. — actinologic, actinological , adj .

actinometry

the measurement of the heating power of light in the violet and ultraviolet range. — actinometrist , n . — actinometric, actinometrical , adj .

albedo

the ratio between the light reflected from a surf ace and the total light falling upon that surf ace, as the albedo of the moon.

birefringence

double refraction; the separation of light into two unequally refracted, polarized rays, as by some crystals. — birefringent , adj .

catadioptrics

the study of the reflection and refraction of light. — catadioptric, catadioptrical , adj .

catoptrics

the study of light reflection. — catoptric, catoptrical , adj . — catoptrically , adv .

chatoyancy

the condition or quality of changing in color or luster depending on the angle of light, especially of a gemstone that reflects a single shaft of light when cut in cabochon form. — chatoyant , adj .

dichroism

a property, peculiar to certain crystals, of reflecting light in two different colors when viewed from two different directions. — dichroic , adj .

dioptrics

the study of light refraction. — dioptric , adj .

iridescence

the state or condition of being colored like a rainbow or like the light shining through a prism. — iridescent , adj .

iriscope

a polished black glass, the surface of which becomes iridescent when it is breathed upon through a tube.

levorotation

rotation toward the left; counterclockwise rotation, a characteristic of the plane of polarization of light. — levorotatory , adj .

lithophany

the process of impressing porcelain objects, as lamp bases, with figures that become translucent when light is placed within or behind them. — lithophanic , adj .

noctiluca

any thing or creature that shines or glows in the dark, especially a phosphorescent or bioluminescent marine or other organism. — noctilucine , adj .

opties

the study of the properties of light. Also called photology . — optic, optical , adj .

pharology

the study of signal lights, especially lighthouses.

phengophobia

an abnormal fear of daylight.

photalgia

pain in the eyes caused by light.

photangiophobia

an abnormal fear of photalgia.

photics

the study of light.

photodrome

1. an apparatus that regulates light flashes so that a rotating object appears to be stationary or moving in a direction opposite to its actual motion.

2. an apparatus for producing unusual optical effects by flashing light upon disks bearing various figures, patterns, etc.

photodynamics

the science or study of light in relation to the movement of plants. — photodynamic, photodynamical , adj .

photography

the process or art of creating and recording images of people, objects, and phenomena, essentially by means of reflected light or emanating radiation. — photographer , n . — photographic, photographical , adj .

photokinesis

movement of bodies, organisms, etc., in response to the stimulus of light. — photokinetic , adj .

photology

optics.

photolysis

the breakdown of matter or materials under the influence of light. — photolytic , adj .

photomania

an abnormal love of light.

photometry

the measurement of the intensity of light. — photometrician, photometrist , n . — photometric , adj .

photopathy

a pathologic effect produced by light. — photopathic , adj .

photophily

the tendency to thrive in strong light, as plants. — photophilic , adj .

photophobia

1. an abnormal fear of light.

2. Also called photodysphoria . a painful sensitivity to light, especially visually.

3. a tendency to thrive in reduced light, as certain plants.

photosynthesis

the synthesis of complex organic substances from carbon dioxide, water, and inorganic salts, with sunlight as the energy source and a catalyst such as chlorophyll. — photosynthetic , adj .

phototaxis, phototaxy

the movement of an organism away from or toward a source of light. — phototactic , adj .

phototherapy, phototherapeutics

the treatment of disease, especially diseases of the skin, with light rays. — phototherapeutic , adj .

phototropism

motion in a particular direction under the stimulus of light, as manifested by certain plants, organisms, etc. — phototropic , adj .

polarimetry

the measurement of the polarization of light, as with a polarimeter.

selaphobia

an abnormal fear or dislike of flashes of light.

spectrogram

a photograph of a spectrum. Also called spectrograph .

spectrograph

1. an optical device for breaking light down into a spectrum and recording the results photographically.

2. spectrogram. — spectrographic , adj .

spectrography

the technique of using a spectrograph and producing spectrograms.

triboluminescence

a form of Iuminescence created by friction. — triboluminescent , adj .