An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 14 Search : cohere
cohere
  همدوسیدن   
hamdusidan (#)

Fr.: adhérer, être cohérent   

1) To stick together; be united; hold fast, as parts of the same mass.
2) Physics (of two or more similar substances) to be united within a body by the action of molecular forces (→ cohesion).

From L. cohaerere "to cleave together," from → com- "together," + haerere "to stick."

Hamdusidan, from ham- "together," → com-, + dusidan (Dehxodâ) "to stick, to adhere," → adhere.

coherence
  همدوسی   
hamdusi (#)

Fr.: cohérence   

The property of two or more electromagnetic waves when they are in fixed phase relationship over time. If the crests and troughs of the waves meet at the same time and place they are said to be in phase.

cohere + -ence, → -ance.

coherence area
  پهنه‌ی ِ همدوسی   
pahne-ye hamdusi

Fr.: zone de cohérence   

Of an electromagnetic wave, the area of a surface perpendicular to the direction of propagation, over which the electromagnetic wave maintains a specified degree of coherence.

coherence; → area.

coherence length
  درازا‌ی ِ همدوسی   
derâzâ-ye hamdusi

Fr.: longueur de cohérence   

The distance over which an electromagnetic wave train maintains a specified degree of coherence.

coherence; → length.

coherence time
  زمان ِ همدوسی   
zamân hamdusi

Fr.: temps de cohérence   

The time over which a propagating electromagnetic wave may be considered coherent. The coherence time of an interferometer is the interval during which the fringe phase remains stable.

coherence; → time.

coherent
  همدوس   
hamdus (#)

Fr.: cohérent   

Two or more wave sources are said to be coherent sources if the phase difference between a pair of points, one in each source, remains constant.

Coherent, adj., → coherence.

coherent light
  نور ِ همدوس   
nur-e hamdus (#)

Fr.: lumière cohérente   

Light waves that have the same wavelength and possess a fixed phase relationship, as in a laser.

coherent; → light.

coherent optics
  نوریک ِ همدوس   
nurik-e hamdus

Fr.: optique cohérente   

A branch of optics that uses coherent radiation to produce holographic three-dimensional images of objects.

coherent; → optics.

coherent scattering
  پراکنش ِ همدوس   
parâkaneš-e hamdus

Fr.: diffusion cohérente   

A scattering process in which the scattered radiation bears the same frequency and phase as the incident radiation.

coherent; → scattering.

coherent source
  خن ِ همدوس   
xan-e hamdus

Fr.: source cohérente   

One of two light beams derived from the same source in → interference experiments. It is impossible to obtain interference from two separate sources because their → wavefronts do not have a constant → phase difference. In → Young's experiment, → Fresnel's biprism, → Fresnel's mirrors, and → Lloyd's mirror the two sources always have a point-to-point correspondence of phase, since they are both derived from the same source.

coherent; → source.

incoherent waves
  موج‌های ِ ناهمدوس   
mowjhâ-ye nâhamdus (#)

Fr.: ondes incohérentes   

The lack of a fixed phase relationship between two or more waves. → coherent.

Incoherent, from negation prefix → in- + → coherent; → wave.

non-coherent radiation
  تابش ِ ناهمدوس   
tâbeš-e nâhamdus (#)

Fr.: rayonnement incohrént   

Radiation having waves that are out of phase in space and/or time; radiation which is not → coherent.

non-; → coherent; → radiation.

noncoherent scattering
  پراکنش ِ ناهمدوس   
parâkaneš-e nâhamdus

Fr.: diffusion incohérente   

The absorption of a photon and its re-emission at a different frequency (in the observer's frame of reference) by scattering atoms.

non-; → coherent scattering.

spatial coherence
  همدوسی ِ فضایی   
hamdusi-ye fazâyi

Fr.: cohérence spatiale   

In a wave train, a correlation between the phases of waves at points separated in space at a given time.

spatial; → coherence.