Optical measuring apparatus

Claim 2

An optical measuring apparatus, comprising shielding means made from a substance, which is permeable to light having a first wave length and shields .light having a second wave length different from the first wave length, changing a ratio of shielding said light having the second wave length in correspondence to a physical quantity to be measured, two light sources for radiating said light having the first wave length and said light having the second wave length to be supplied to said shielding means through the same transmission path, a photo-detector for receiving the light having the second wave length, which passed by said shielding means without being shielded, and the light having the first wave length, which passed through or by said shielding means, through the same transmission path, and a calculating means for calculating a ratio of an optical output corresponding to said light having the second wave length to an optical output corresponding to said light having the first wave length on the basis of an output from said photo-detector to calculate said physical quantity.

Claim 3

An optical measuring apparatus as set forth in claim 1, in which said two light sources are alternately driven.

Claim 4

An optical measuring apparatus as set forth in claim 2, in which said calculating means subtracts a dark current of the photo-detector from the output from the photo-detector, when the light sources have been driven, to calculate the ratio of the optical output corresponding to the light having the second wave length to the optical output corresponding to the light having the first wave length.

Claim 5

An optical measuring apparatus as set forth in claim 1, in which the light having the first wave length and the light having the second wave length are radiated from said two light sources in the form of modulated light having different frequencies and the output from the photo-detector receiving the radiated lights is divided by a filter to calculate the ratio of the optical output corresponding to the light having the second wave length to the optical output corresponding to the light having the first wave length.

Claim 6

An optical measuring apparatus as set forth in claim 1, in which said shielding means comprises a sensor portion responding to the physical quantity and shifting means being connected with the sensor portion and changing a ratio of shielding said light having the second wave length by shifting in correspondence to a responding degree of the sensor portion.

Claim 7

An optical measuring apparatus as set forth in claim 5, in which said shifting means is shifted in the direction vertical to the transmission path.

Claim 8

An optical measuring apparatus as set forth in claim 5, in which said shifting means is a semiconductor.

Claim 9

An optical measuring apparatus as set forth in claim 7, in which said semiconductor is crystalline.

Claim 10

An optical measuring apparatus as set forth in claim 7, in which said semiconductor is amorphous.

Claim 11

An optical measuring apparatus, comprising shielding means made from a substance, which is permeable to a light having a first wave length and shields a light having a second wave length different from the first wave length, changing a ratio of shielding said light having the second wave length in correspondence to a physical quantity to be measured, two light sources for radiating said light having the first wave length and said light having the second wave length to be supplied to said shielding means through the same transmission path, a first photo-detector for receiving the light having the second wave length, which passed by said shielding means without being shielded by said shielding means, and the light having the first wave lengthy which passed through or by said shielding means, through the same transmission path, a second photo-detector for receiving the light having the first wave length and the light having the second wave length radiated from two light sources, and a calculating means for calculating a quotient of the value of the ratio of the optical ' output corresponding to the light having the second wave length to an optical output corresponding to the light hav - ing the first wave length in the second photo-detector by the value of the ratio of the optical output corresponding to the light having the second wave length to the optical output corresponding to the light having the first wave length in the first photo-detector.

Claim 12

An optical measuring apparatus, comprising shielding means made from a substance, which is permeable to a light having a first wave length and shields a light having a second wave length different from the first wave length, changing a ratio of shielding said light having the second wave length in correspondence to a physical quantity to be measured, two light sources for radiating said light having the first wave length and said light having the second wave length to be supplied to said shielding means through the same transmission path, a first photo-detector for receiving the light having the second wave length, which passed by said shielding means without being shielded by said shielding means, and the light having the first wave lengthy which passed through or by said shielding means, through the same transmission path, a second photo-detector for receiving the light having the first wave length and the light having the second wave length radiated from two light sources, and a calculating means for calculating a quotient of the value of the ratio of the optical ' output corresponding to the light having the second wave length to an optical output corresponding to the light hav - ing the first wave length in the second photo-detector by the value of the ratio of the optical output corresponding to the light having the second wave length to the optical output corresponding to the light having the first wave length in the first photo-detector.

Claim 13

An optical measuring apparatus as set forth in claim 10, in which said two light sources are alternately driven.

Claim 14

An optical measuring apparatus as set forth in claim 11, in which said calculating means subtracts a dark current of the first and second photo-detectors from the output from the first and second photo-detectors when the light sources have been driven, to calculate the quotient of the value of the ratio of the optical output corresponding to the light having the second wave length to the optical output corresponding to the light having the first wave length in the second photo-detector by the value of the ratio of the optical output corresponding to the light having the second wave length to the optical output corresponding to the light having the first wave length in the first photo-detector.

Claim 15

An optical measuring apparatus as set forth in claim 10, in which the light having the first wave length and the light having the second wave length are radiated from said two light sources in the form of modulated light having different frequencies and the output from the first and second photo-detectors receiving the radiated lights is divided by a filter to calculate the quotient of the value of the ratio of the optical output corresponding to the light having the second wave length to the optical output corresponding to the light having the first wave length in the second photo-detector by the value of the ratio of the optical output corresponding to the light having the second wave length to the optical output corresponding to the light having the first wave length in the first photo-detector.

Claim 16

14 . An optical measuring apparatus as set forth in claim 10 , in which said shielding means comprises a-sensor portion responding to the physical quantity and shifting means being connected with the sensor portion and changing a ratio of shielding said light having the second wave length by shifting in correspondence to a responding degree of the sensor portion.

Claim 17

An optical measuring apparatus as set forth in claim 14, in which said shifting means is shifted in the direction vertical to the transmission path.

Claim 18

An optical measuring apparatus as set forth in claim 14, in which said shifting means is a semiconductor.

Claim 19

An optical measuring apparatus as set forth in claim 16, in which said semiconductor is crystalline.

Claim 20

An optical measuring apparatus as set forth in claim 16, in which said semiconductor is amorphous.