Kabushiki Kaisha Ohara

Donald G Polensky

Naoyuki Goto

Mariko Kataoka

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

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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Morgan Hill, CA, United States of America

Donald G Polensky