A Signal-to-Noise optimization model has now been extended to explain the range of species-specific polarization sensitivities of insects. The different polarization sensitivities are shown to represent optimizations for the detection of plane polarized (Rayleigh-scattered) skylight over a range of atmospheric polarization conditions. Rhodopsin absorption spectra with peaks in the Blue (λmax≈450 nm) maximize detection efficiencies under conditions of high polarization. Rhodopsin absorption spectra peaking in the UV (λmax≈350 nm) maximize Signal-to-Noise Ratios for the detection of polarized skylight at the other extreme of low polarization.

Blue through UV polarization sensitivities in insects

Exploration of faint absorption bands in the reflectance spectra of the asteroids by method of optimal smoothing: Vestoids

The spectral reflectivity ρ in the region 0.36–2.1 μm and its change Δρ with irradiation by 30 keV electrons versus the average grain sizer av in a TiO2 (rutile) powder has been studied in the range 1–7.5 μm. It has been established that the dependence of ρ onr av differs for different regions of the spectrum, but there is a common increase of ρ in the size range 2.5–4 μm. The value of Δρ after irradiation is also less in powders with this range of sizes. It has been shown that the dependence Δρ=f(r av) with increasing electron fluence from 2·1015 to 4·1016 is strengthened for one band and weakened for another.

A size effect in the optical properties of powdered TiO2

The problems of the construction of laser systems based on the methods of linear adaptive optics and designed for energy transport over large distances in outer space are analysed. New approaches are proposed to the organisation of the linear phase conjugation of output and beacon-signal radiations. For definite ratios of the beacon-signal ({omega}{sub b}), heterodyne ({omega}{sub h}), and power ({omega}{sub p}) radiations ({omega}{sub b} > {omega}{sub h} > {omega}{sub p} or {omega}{sub b} < {omega}{sub h} < {omega}{sub p}), the phase conjugation loop may play simultaneously the role of a precision frequency matching loop. This feature permits the phase locking of independent single-mode laser emitters, including phase locking in the far-field zone, to achieve the modular principle of system design and to generate the wavefront of radiation with a large cross section. (control of laser radiation parameters)

Linear conjugate phase-locking of independent single-mode emitters

Characteristic times of photoionization from the ground 3S- and excited 3P-states of the sodium atom have been calculated. A model of balance equations of ionization and recombination kinetics of atmospheric sodium has been constructed for the optically thin case based on the experimental scheme of reactions of the formation of complex ions with the participation of sodium. The model also takes into account photoprocesses for the ground and excited levels of sodium. The numerical solution of the balance equations describes the density dynamics of sodium atoms, sodium ions, and Na+H2O, Na+N2, and Na+CO2 complex ions with allowance for laser illumination at the resonance transition with a wavelength of 0.589 μm.

E.A. Makarova

Papers

Energy distribution in the solar spectrum and the solar constant; Raspredelenie energii v spektre solntsa i solnechnaya postoyannaya