An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

A → diffraction grating ruled appropriately so that a large proportion of the diffracted light is concentrated into a few, or even a single → order of interference.

Blazed, adj. of → blaze; → grating.

Turi, noun from tur "a net, a fishing net;" belizi adj. from beliz, → blaze.

A → diffraction grating ruled on a concave spherical mirror that eliminates chromatic aberration and transmits regions of the spectrum, such as the ultraviolet, which is not transmitted by glass lenses.

→ concave; → grating.

An optical device containing thousands of very fine parallel grooves which produce interference patterns in a way which separates out all the components of the light into a spectrum.

→ diffraction; → grating.

A diffraction grating in which the groves are relatively widely spaced and serves to provide high resolution and dispersion.

Echelle, from Fr. échelle "ladder," , from O.Fr. eschele, from L. scala "ladder;" → grating.

Turi, → grating; nardé, contraction of nardebân "ladder; échelle."

Same as → diffraction grating.

M.E. grating, M.L. grata "a grating," variant of crata, from crat-, stem of cratis "wickerwork."

Turi, from tur "fishing net, net, snare," variants târ "thread, warp, string," tâl "thread" (Borujerdi dialect), cognate with tanidan, tan- "to spin, twist, weave" (Mid.Pers. tanitan; Av. tan- to stretch, extend;" Skt. tan- to stretch, extend;" tanoti "stretches," tantram "loom;" tántra- "warp; essence, main point;" Gk. teinein "to stretch, pull tight;" L. tendere "to stretch;" Lith. tiñklas "net, fishing net, snare," Latv. tikls "net;" PIE base *ten- "to stretch").

The angle between the incident optical beam and the normal to the grating. It is the angle to which the grating must be set to place the desired wavelength at the center of the detector.

→ grating; → angle.

The measure of the light intensity diffracted from a grating.

→ grating; → efficiency.

One of thousands of long, narrow indentations in the surface of a → diffraction grating.

→ grating; → groove.

A → diffraction grating produced from a series of constructive → interference fringes. The fringes, whose intensities vary in a sinusoidal pattern, correspond to the grooves of the grating. They are recorded on a photosensitive substrate and subsequently treated using a chemical procedure. Since the grooves are created by the interference of light, such a grating is free from the random and periodic errors present in → ruled gratings.

→ holographic; → grating.

A function that converts a → differential equation, which is not exact, into an → exact differential equation. This is done by multiplying all terms of the original equation by the integrating factor.

→ integrate; → factor.

A diffraction grating placed over the aperture of a telescope in order to produce spectra of all the objects in the field of view.

→ objective; → grating.

A → diffraction grating with a series of grooves that have been ruled on a reflective surface with a diamond tool mounted on a ruling machine. Ruled gratings may have triangular or trapezoidal groove profiles, whereas → holographic gratings usually have sinusoidal groove profiles.

Ruled, → rule; → grating.

Turi, → grating; šiyârdâr "having grooves," from šiyâr, → groove, + -dâr "having, possessor," → property.

A diffraction grating that has grooves ruled onto a transparent material so that a beam of light passed through the grating is partly split into spectral orders.

→ transmission; → grating.