Kabushiki Kaisha Ohara

Mariko Kataoka

Naoyuki Goto

Donald G Polensky

Toshitaka Yagi

Katsuhiko Yamaguchi

Junko Ishioka

Kousuke Nakajima

Holding member for information storage disk and information storage disk drive device

Glass-ceramics for a light filter capable of preventing variation of refractive index in a band-pass filter have a coefficient of thermal expansion within a range from 95&times;10 /&deg;C. to 140&times;10 /&deg;C. within a temperature range from &minus;20&deg; C. to &plus;70&deg; C. and, preferably, Young's modulus of 85 GPa and bending strength of 10 kg/mm , and light transmittance for plate thickness of 10 mm of 60% or over within a wavelength range from 950 nm to 1600 nm. Predominant crystal phases of these glass-ceramics should preferably be (a) lithium disilicate and (b) one selected from the group consisting of &agr;-quartz, &agr;-quartz solid solution, &agr;-cristobalite and &agr;-cristobalite solid solution.

Glass-ceramics for a light filter

Glass-ceramics fo a light filter capable of preventing variation of refractive index in a band-pass filter have a coefficient of thermal expansion within a range from 95&times;10 /&deg;C. to 140&times;10 /&deg;C. within a temperature range from &minus;20&deg; C. to &plus;70&deg; C. and, preferably, Young's modulus of 85 GPa and bending strength of 10 kg/mm , and light transmittance for plate thickness of 10 mm of 60% or over within a wavelength range from 950 nm to 1600 nm. Predominant crystal phases of these glass-ceramics should preferably be (a) lithium disilicate and (b) one selected from the group consisting of &agr;-quartz, &agr;-quartz solid solution, &agr;-cristobalite and &agr;-cristobalite solid solution.

Light filter using glass ceramics

There are provided glass-ceramics containing, as a predominant crystal phase or phases, at least one selected from the group consisting of &agr;-cristobalite, &agr;-cristobalite solid solution, &agr;-quartz and &agr;-quartz solid solution, containing substantially no lithium disilicate (Li O&middot;2SiO ), lithium silicate (Li O&middot;SiO ), &bgr;-spodumene, &bgr;-eucryptite, &agr;-quartz, mica or fluorrichterite, containing substantially no Cr ingredient or Mn ingredient, and having average linear thermal expansion coefficient within a range from &plus;65&times;10 /&deg; C. to &plus;140&times;10 /&deg; C. within a temperature range from &minus;50&deg; C. to &plus;70&deg; C., said predominant crystal phase or phases having an average crystal grain diameter of less than 0.10 &mgr;m. The glass-ceramics are suitable for use as a substrate for an information storage medium and also for use as a substrate for a light filter.

Glass-ceramics

Glass-ceramics of a light filter capable of preventing variation of refractive index in a band-pass filter have a coefficient of thermal expansion within a range from 95&times;10 /&deg; C. to 140&times;10 /&deg; C. within a temperature range from &minus;20&deg; C. to &plus;70&deg; C. and, preferably, Young's modulus of 85 GPa and bending strength of 10 kg/mm , and light transmittance for plate thickness of 10 mm of 60% or over within a wavelength range from 950 nm to 1600 nm. Predominant crystal phases of these glass-ceramics should preferably be (a) lithium disilicate and (b) one selected from the group consisting of &agr;-quartz, &agr;-quartz solid solution, &agr;-cristobalite and &agr;-cristobalite solid solution.

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Sagamihara, Japan

Mariko Kataoka