Abstract A filter light source within a compound optical filter includes a flat sheet consisting of a plurality of fine particles of a phosphor in a transparent matrix having a refractive index greater than that of air but less than that of the particles. To measure the absorbance of light by a fluid, light that has passed from a primary light source through the fluid is transmitted by an interference filter in the compound filter to the filter light source. The phosphor has a high excitation efficiency at the wavelength of light that is transmitted by the interference filter and a high emission efficiency for light with a longer wavelength, which light is reflected by the interference filter, with both the reflected light and directly emitted light being transmitted in the direction of a photocell.
An apparatus for emitting light of a first wavelength in a predetermined direction in response to light of a second wavelength, comprising: transducer means for emitting light of said first wavelength when excited by light of said second wavelength; said transducer means including means for emitting light of said first wavelength in at least one direction other than said predetermined direction: said transducer means including controlled light scattering means for changing the direction of at least some of said light emitted in said one direction other than said predetermined direction to said predetermined direction and light-propagation means for reducing the amount of light of said first wavelength traveling in said predetermined direction that is scattered into other directions by said controlled light-scattering means; said light-propagation means including means for reducing the backscattering of light of said second wavelength.
Claim 2
Independent Claim
138 words
An apparatus for emitting light of a first wavelength in a predetermined direction in response to light of a second wavelength, comprising: transducer means for emitting light of said first wavelength when excited by light of said second wavelength; said transducer means including means for emitting light of said first wavelength in at least one direction other than said predetermined direction: said transducer means including controlled light scattering means for changing the direction of at least some of said light emitted in said one direction other than said predetermined direction to said predetermined direction and light-propagation means for reducing the amount of light of said first wavelength traveling in said predetermined direction that is scattered into other directions by said controlled light-scattering means; said light-propagation means including means for reducing the backscattering of light of said second wavelength.
Claim 3
Dependent Claim
23 words
Apparatus according to claim 1 in which said transducer means includes a phosphor having an excitation spectrum into which said second wavelength falls.
Claim 4
Dependent Claim
41 words
Apparatus according to claim 2 in which: said phospor includes a plurality of small phosphor particles; and said light-propagation means includes a transparent matrix having a refractive index greater than that of air and less than that of said small particles.
Claim 5
Dependent Claim
14 words
Apparatus according to claim 3 in which said phosphor is manganese activated zinc silicate.
Claim 6
Dependent Claim
14 words
Apparatus according to claim 4 in which said transducer matrix is a sodium silicate.
Claim 7
Dependent Claim
13 words
Apparatus according to claim 4 in which said transparent matrix is polyvinyl alcohol.
Claim 8
Dependent Claim
16 words
Apparatus according to claim 4 in which said phosphor is activated by a rare earth element.
Claim 9
Dependent Claim
14 words
Apparatus according to claim 7 in which said transparent matrix is a polyvinyl alcohol.
Claim 10
Dependent Claim
14 words
Apparatus according to claim 7 in which said transparent matrix is a sodium silicate.
Claim 11
Dependent Claim
50 words
Apparatus according to claim 2 in which: said controlled light-scattering means includes a plurality of small phosphor particles; and said light-propagation means includes a transparent matrix in which said small particles are embedded having a refractive index greater than that of air and less than that of said small particles.