Motokazu Yamada

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Highly efficient light-emitting diodes (LEDs) emitting ultraviolet (UV), blue, green, amber and red light have been obtained through the use of InGaN active layers instead of GaN active layers. Red LEDs with an emission wavelength of 675 nm, whose emission energy was almost equal to the band-gap energy of InN, were fabricated. The dependence of the emission(More)
The Hayabusa2 spacecraft has three framing cameras (ONC-T, ONC-W1, and ONC-W2) for optical navigation to asteroid 1999 JU 3. The ONC-T is a telescopic camera with seven band-pass filters in the visible and near-infrared range. These filters are placed on a wheel, which rotates to put a selected filter for different observations, enabling multiband imaging.(More)
Electro-magnetic (EM) wave amplifiers by utilizing traveling electron beam in vacuum come to have attention as devices covering over extremely wide frequency range from the microwave to the X-ray regions. We point out that two different amplification mechanisms should exist according to the relation between the EM wavelength and the electron size. The first(More)
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