We describe high-speed Fourier domain optical coherence tomography (OCT) using optical demultiplexers (ODs) for spectral dispersion. The OD enables separation of a narrow spectral band of 14 GHz (0.11 nm) from a broadband incident light at 256 different frequencies in 25.0 GHz intervals centered at 192.2 THz (1559.8 nm). OCT imaging of 60,000,000 axial scans per second was achieved through parallel signal acquisition using 256 balanced photoreceivers to simultaneously detect all the output signals from the ODs in a Fourier domain OCT system. OCT imaging at a 16 kHz frame rate, 1100 A-lines per frame, 3 mm depth range, and 23 microm resolution was demonstrated using a resonant scanner for lateral scanning.

Abstract. The virtual height of the bottom side F-region (h F ) and equatorial spread-F (ESF) onsets at Chumphon (10.7 • N, 99.4 • E; 3.3 • N magnetic latitude) were compared with the behaviour of equatorial electrojet (EEJ) ground strength at Phuket (8.1 • N, 98.3 • E; 0.1 • N magnetic latitude) during the period from November 2007 to October 2008. Increase in the F-layer height and ESF onsets during the evening hours were well connected with the EEJ ground strength before sunset, namely, both the height increase and ESF onsets were suppressed when the integrated EEJ ground strength for the period from 1 to 2 h prior to sunset was negative. The finding suggests observationally that the pre-sunset E-region dynamo current and/or electric field are related to the F-region dynamics and ESF onsets around sunset.

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We describe a high-speed long-depth range optical frequency domain imaging (OFDI) system employing a long-coherence length tunable source and demonstrate dynamic full-range imaging of the anterior segment of the eye including from the cornea surface to the posterior capsule of the crystalline lens with a depth range of 12 mm without removing complex conjugate image ambiguity. The tunable source spanned from 1260 to 1360 nm with an average output power of 15.8 mW. The fast A-scan rate of 20,000 per second provided dynamic OFDI and dependence of the whole anterior segment change on time following abrupt relaxation from the accommodated to the relaxed status, which was measured for a healthy eye and that with an intraocular lens.

Disilane, silylgermane, and digermane radical anions have been studied by ab initio molecular orbital theory, using the unified level of basis set as prototypes of polymer anions with Si and Ge backbones. These prototype anions have the same kind of minimum geometry (C2/, or C2*-like symmetry) with an unpaired electron occupying the Si-Si, Si-Ge, or Ge-Ge a* antibonding orbital with a large Si or Ge s diffuse orbital contribution. Little Si 3d or Ge 4d orbital participation is found for these anions. All these anions can exist as kinetically bound anions with positive first vertical ionization potential values. The stability of an unpaired electron is in the order SÍ2H6" < SiH3GeH3-< Gc2H6". The origin of this stability difference is also discussed. These results suggest that polymer anions with Si and Ge backbones have the same kind of molecular and electronic structures with no dir-dir conjugation and that their stability is in the order polysilane anion < Si-Ge copolymer anion < polygermane anion.