A property of some crystalline materials (e.g. calcite, quartz) which have different indices of refraction associated with different crystallographic directions. Therefore, the crystal splits incident transmitted light into two beams, each polarized perpendicularly to the other. Also called double refraction.
Došekast, from do- "two," → bi- + šekast "breaking," from šekastan "to break up," Mid.Pers. škastan, Av. skand- "to break."
došekastgar, došekasti (#)
Of or relating to → birefringence.
pâlâye-ye došekastgar, ~ došekasti
Fr.: filtre biréfringent
A type of narrow-band filter that uses the birefringence to produce selective absorption of polarized light.
Fr.: vide biréfringent
Empty space undergoing → vacuum birefringence.
fariz-e târik (#)
Fr.: frange noire
One of the successive dark and light bands produced by diffraction or interference of light.
From O.Fr. frange, from V.L. *frimbia alteration by metathesis of L. fimbria "fringe, edge of garment."
Fariz, variants farviz, farâviz "fringe, edge of garment."
1) One of the alternating bright or dark bands produced by
→ interference or → diffraction.
From M.E. frenge, from O.Fr. frange, from V.L. *frimbia, metathesis of L. fimbriæ "fibers, threads, fringe," of uncertain origin.
Fariz, contraction of farâviz "fringe, lace, edging," from far-, par-, variant pirâ- "around, about" (Mid.Pers. pêrâ; O.Pers. pariy "around, about," Av. pairi "around, over;" Skt. pari; Indo-Iranian *pari- "around;" PIE base *per- "through, across, beyond;" cf. Gk. peri "around, about, beyond;" L. per "through") + âviz "anything suspended; a place where things are hung up; a border, margin," from âvixtan, âvizidan "to hang, suspend;" Mid.Pers. âwextan "to hang;" Av. vij- "to shake, swing," frauuaēγa- "swinging forward;" cf. Skt. vej- "to dart up or back, move up;" Proto-Iranian *uij- "to shake, swing."
padidâri-ye fariz (#)
Fr.: visibilité des franges
Optics: If the intensity in an interference fringe pattern has the maximum and minimum values Imax and Imin, the visibility is defined by the relation ν = (Imax - Imin) / (Imax + Imin), where 0 ≤ ν ≤ 1. In terms of the intensities of the two interfering waves: ν = 2(I1 . I2)1/2 / (I1 + I2).
farizhâ-ye Haydinger (#)
Fr.: franges d'Haidinger
The interference fringes seen with thick plates near normal incidence.
W. K. von Haidinger (1798-1871), Austrian mineralogist and geologist; → fringe.
Fr.: franges d'interférence
One of the alternating bright or dark bands produced by optical interference.
Fr.: biréfringence du vide
A highly → magnetized vacuum behaving as a prism for the propagation of light, as predicted by → quantum electrodynamics (QED). Attempts to detect this phenomenon in the laboratory have not yet succeeded in the 80 years since it was predicted (Heisenberg & Euler, 1936, Z. Physik, 98, 714). This effect can be detected only in the presence of enormously strong → magnetic fields, such as those around → neutron stars. Owing to the large inferred magnetic fields (B ~ 1013 G, → gauss), radiation from these sources is expected to be substantially polarized, independently of the mechanism actually responsible for the → thermal emission. The strongest magnetic field so far created in a laboratory is less than 106 G lasting only for several tens of milliseconds. A large observed → polarization degree is, however, expected only if QED polarization effects are present in the magnetized vacuum around the star. The detection of a strongly → linearly polarized signal would therefore provide the observational evidence of QED effects in the strong-field regime. Recently a team of astrophysicists (Mignani et al. 2016, arXiv/1610.08323) have detected → linear polarization toward the neutron star RXJ1856.5-3754 (at a significant degree of around 16%). This finding is likely due to the boosting effect of vacuum birefringence occurring in the area of empty space surrounding the neutron star.