Papers published on the mechanism and the performance of the human visual system during these several years are reviewed following the process of the vision, and dynamic chara-cteristics of the visual response, such as the detection of the movement, are also surveyed. Among various newly developed techniques, the psychological methods, that is, Stile's two color incremental threshold technique and Ikeda's summation index technique, as well as a microelectrode method, seem to be most powerfull means in analyzing the mechanism of visual phenomena, especially the color vision.
Effects of annealing time and temperature on Seebeck coefficients of Bi2Te3, Bi2Se3 and Sb2Te3 compounds have been investigated. p-type Bi2Te3 compound changes to n-type after a short annealing time at 400°C and 500°C. (for example l hr. at 400°C.) For n-type Bi2Se3 and p-type Sb2Te3 compounds, Seebeck coefficient at the annealing temperature of 400°C is larger than that at 500°C. The formation energy of Schottky defect in Bi2Se3 is estimated to be 0.35 eV. In case of Sb2Te3, the formation energy of the complex defect which derives from Schottky defect and a substitutional atom is estimated to be 0.12 eV.
The heat treatment of quenched materials (Bi1-xSbx)2 (Te1-ySey)3 have been done at 400°C for 10 hours, and Seebeck coefficients have been measured in the temperature range of 80°-300°K. The experimental results are as follows: (1) The annealed compounds for vanishing Seebeck coefficient contain less Bi than quenched materials. The composition showing vanish-ing Seebeck coefficient has no relation with measurement temperature. (2) The composition dependence of Seebeck coefficient shows an anomlous decrease on compounds with vanishing Hall coefficient. The ratio α(=√6μL0/μ10) is calculated at 100°K, where μL0 is the carrier mobility limited by acoustical scattering in the absence of degeneracy and μ10 is that limited by ionic scattering also in the absence of degeneracy. α is found to be large in compounds rich in Sb2Te3 or Bi2Se3. It seems that the electrical properties of these compounds are appreciably affected by ionic scattering even at room temperatures.
The characteristics of a plasma electron gun utilizing the electron beam mode discharge phenomena with a hollow screen-mesh cathode and N2 as ambient gas are experimentally studied. Voltage-current characteristics and diagnostical results of the plasma internal to the cathode, the cathode fall, the plasma of the external glow and the electron beam are given for various values of gas pressure. It is shown that there exists a distinct difference between voltage-current characteristic in steady-state operation and that in pulse operation for the same value of gas pressure. It is inferred that this is mainly due to the difference between the temperatures or the densities of the gas near the cathode under the different operating conditions, since the rise of cathode temperature due to the cathode bombardment of high-speed ions and gas molecules is different for the two cases. Finally, the physical mechanisms of sustaining the discharge are discussed.
Construction and measurement of an experimental He-Se laser are described. Laser tube configurations are improved to prevent the Se vapor from diffusing toward the Brewster windows. The laser, which has an effective discharge region of 70cm in length and 2.8mm in diameter, yields 23mW on 11 lines lasing simultaneously. Saturation current of a He-Se laser is considerably higher than that of a He-Cd laser and reaches up to 220_??_460mA with oven temperatures between 210° to 250°C. This result is attributed to the energy difference between Hell (2S1/2) and He (3S1), which are used for the excitation of SeII and CdII, respectively. We have mainly analyzed the relation between Se density nse (temperature) and saturation current IS and it has turned out that Is2 is linear to nse with a good approximation. By selecting with a prism, we obtained a few mW power output in each of the 4976, 4993, 5068, 5176, 5228, 5305 Å lines.