photo-, phot-, -photic

A physical condition that is caused by excessive exposure to sunlight: Aphotesthesia is characterized by a reduced retina sensitivity of the eyes to light.

The retinas are the areas at the back of a person's eyes which send light signals to the brain and where those signals are changed into images that may result in aphotesthesia when they are overexposed to sunlight.

1. A description of those parts of the ocean that are not reached by sunlight, or plants that grow there without synthesizing light: The remote controlled camera was able to explore the aphotic depths of the ocean, looking for rare life forms.
2. A reference to any environment or habitat that has no sunlight of any biological significant intensity: The fish that lived for a long time in the dark cave evolved into a state of blindness because of their aphotic environment.
3. Etymology: from Greek a-, "not, without" + phos, "light"; literally, "no light".

The absence of any response to a light stimulus by an organism that can move: The aphototaxis of organisms is a condition that is characterized by their failure to react to light; neither moving toward the source of light (positive phototaxis) nor away from it (negative phototaxis).

1. An orientation response away from light; negative phototropism.
2. The absence of an orientation response to light.

Photography which is used in astronomical investigations.

Someone who specializes in a type of photography that entails making photographs of astronomical objects in the night sky; such as, planets, stars, and deep sky objects including star clusters and galaxies.

1. The art of photographing astronomical objects and events for astronomical studies>
2. The photography of stars and other celestial objects.
3. The use of photographs to record extraterrestrial objects in order to study their surface features, positions, motions, radiation, and spectra.

1. A photometer (light meter) for measuring the brightness of stars.
2. The measurement of the intensity of light of celestial objects.

Relating to the measurement of the intensity of light of celestial objects.

An instrument for detecting photoluminescent signals in marine environments: A bathyphotometer integrates the system of using photodiodes to convert the optical signals into electrical signals which are sampled, integrated, and coupled to output terminals for transmission to a surface host vehicle.

Here is more information about bathyphotometry.

The production and emission of light by plants or by animals; bioluminescence.

1. The hypothetical process of splitting water by solar energy to produce hydrogen.
2. The action of light on a biological system; such as, certain algae and bacteria, that results in the dissociation of water to produce hydrogen.

An obsolete instrument once used for measuring the rate and degree of dark adaptation, as in vitamin "A" deficiency.

1. The biological applications of photonics, a technology that utilizes light and other forms of radiant energy in which a quantum unit is the photon (the smallest unit used to measure a physical property).
2. A combination of biology and photonics, with photonics being the science and technology of generation, manipulation, and detection of photons, quantum units of light.

Photonics is related to electronics in that it is believed that photons will play a similar central role in future information technology as electrons do today.

It includes the study or application of electromagnetic energy whose basic unit is the photon, incorporating optics, laser technology, electrical engineering, materials science, and information storage and processing.

One photograph of a series taken at regular intervals: Chronophotographs are important for showing successive phases of a motion.