Hitachi Cable, Inc.

Hitachi, Ltd.

Shigeo Nishida

Mitsunobu Miyagi

Akihito Hongo

Yoshihiko Wagatsuma

Tsuneo Shiota

Masaru Kokubo

Tsuneo Suganuma

Kazuo Yamakido

Toshiki P Tanaka

Seiichi Onoda

Shojiro Kawakami

Masao Sumi

Koichi Mikoshiba

A radio frequency (RF) excited waveguide gas laser has a hollow wavegide defined by dielectric or lossy materials and metal electrodes coated by thin films with small absorptions so that the metal electrodes are separated from the filling gas and the waveguide loss is very low. With such thin films on the electrodes, a sealed-off, high-power, compact waveguide gas laser having an extended life is realized.

Thin-film coated waveguide laser

A radio frequency (RF) excited waveguide gas laser has a hollow waveguide defined by dielectric or lossy materials and metal electrodes coated by thin films with small absorptions so that the metal electrodes are separated from the filling gas and the waveguide loss is very low. With such thin films on the electrodes, a sealed-off, high-power, compact waveguide gas laser having an extended life is realized.

Disclosed is an interpolative A/D converter for converting an over-sampled analog signal into a digital signal without the occurrence of over slope distortions, wherein the difference between the analog input signal and an analog feedback signal derived from the converter output through D/A conversion is integrated, the integrated output is compared with several reference voltages and, after being converted into a digital signal, the comparison result is integrated in a digital manner to complete a digital output signal of the A/D converter.

Linear interpolative analog-to-digital converter

A low loss leakage transmission line including a cylindrical dielectric tube the wall thickness d.sub.2 of which is selected to satisfy ##EQU1## where .epsilon..sub.1 is the dielectric constant of the internal space within the tube, .epsilon..sub.2 is the dielectric constant of the material which forms the tube, and n is a positive odd integer. A loss layer may be disposed around the cylindrical dielectric tube to capture any lost wave energy. In one embodiment, a plurality of cylindrical dielectric tubes of different dielectric constants are coaxially arranged with the wall thickness of each of the tubes satisfying the above formula.

Low loss leakage transmission line

A three-layer structure optical fiber comprises a first transparent dielectric core layer having a relatively high refractive index, a second transparent dielectric intermediate layer having a relatively low refractive index and a third transparent dielectric cladding layer having an intermediate refractive index wherein the parameter of the optical fiber is determined as follows: ##EQU1## where B is the bandwidth of the signal to be transmitted, z is the transmission distance, C is the velocity of light in vacuum, .eta.o is the refractive index of the core layer, q is the ratio of refractive indices between the core layer and second layer, V = normalized frequency, ##EQU2## p is the ratio of refractive index between the core layer and the third layer, and U.sub.11 =2,405.

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Sendai, Japan

Shigeo Nishida