Following [6] relating the matrix string theory to the light-cone superstring field theory, we write down two supercharges in the matrix string theory explicitly. After checking the supersymmetry algebra at the leading order, we proceed to discuss higherorder contact terms.

We developed a high density near field optical recording disc system with a solid immersion lens and two laser sources. In order to realize the near field optical recording, we used a phase change recording media and a molded polycarbonate substrate. The near field optical pick-up consists of a solid immersion lens with numerical aperture of 1.84. The clear eye pattern of 90.2 GB capacity (160nm track pitch and 62 nm per bit) was observed. The jitter using a limit equalizer was 10.0 % without cross-talk. The bit error rate using an adaptive PRML with 8 taps was 3.7e-6 without cross-talk. We confirmed that the near field optical disc system is a promising technology for a next generation high density optical disc system.

Thin-film CaS:Ce3+, Cl- has been successfully employed for the first time as the active layer of an a.c. thin-film electroluminescent device. In order to compare the performance of a device using this material with that of devices employing the usual ZnS:Mn2+ material, MISM (metal-insulator-semiconductor-metal), ISM, and MSM devices were fabricated. Of these three devices, the singly-insulated device had the highest brightness, of 100 cd/m2, at a frequency of 5 kHz and a pulse height of 200 V. The brightness of this device is still lower than that of devices employing the usual ZnS:Mn2+. This is attributed to the smaller number of internal carriers and the smaller amount of carrier accumulation in the vicinity of the interface between the active luminescent layer and the insulating layer.

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