Refractometer

Claim 2

A refractometer operating with a source emitting bundles of light and having a measuring prism with an entrance face to receive different substances within a range of characteristics to be measured corresponding to refractive indices n, an objective having an image plane, a reticle disposed in said image plane and carrying a scale having a reference mark, said entrance face and said reticle being positioned in such a way that bundles of light from said source are refracted and deviated at said entrance face and directed to said objective, and focused by said objective to an optical image on said scale at a distance s from said reference mark, ds/dn being the rate of change in said distance s with said refractive index n, and d2s/dn2 being the nonlinearity of said rate of change in combination with: stationary refracting means positioned between said entrance face and said reticle, said stationary refracting means deviating said bundles of light by angles of deviation x, dx/dn being the rate of change of said angles of deviation with said refractive index n to be measured, said stationary refracting means being oriented so that dx/dn decreases as n increases thereby causing a reduction of said nonlinearity d2s/dn2, said stationary refractiNg means being constituted by an exit face of said measuring prism, said exit face producing a deviation of said bundles of light in the same direction as the deviation of the bundles of light at said entrance face.

Claim 3

A refractometer according to claim 1 wherein said measuring prism has a refractive index below 1.62 and a prism refracting angle larger than 90*.

Claim 4

A refractometer according to claim 1 wherein said measuring prism has a refractive index above 1.62 and a prism refracting angle larger than 75*.

Claim 5

A refractometer according to claim 1 wherein said measuring prism is composed of at least two components having different optical dispersion.

Claim 6

A refractometer according to claim 4 wherein said components have substantially the same refractive index for one line of the spectrum and are separated by curved faces.

Claim 7

A refractometer operating with a source emitting bundles of light and having a measuring prism with an entrance face to receive different substances within a range of characteristics to be measured corresponding to refractive indices n, an objective having an image plane, a reticle disposed in said image plane and carrying a scale having a reference mark, said entrance face and said reticle being positioned in such a way that bundles of light from said source are refracted and deviated at said entrance face and directed to said objective, and focused by said objective to an optical image on said scale at a distance s from said reference mark, ds/dn being the rate of change of said distance s with said refractive index n, and d2s/dn2 being the nonlinearity of said rate of change in combination with; stationary refracting means positioned between said entrance face and said reticle, said stationary refracting means deviating said bundles of light by angles of deviation x, dx/dn being the rate of change of said angles of deviation with said refractive index n to be measured, said stationary refracting means being oriented so that dx/dn decreases as n increases thereby causing a reduction of said nonlinearity d2s/dn2, said stationary refracting means including a fixed prism having refracting faces and being positioned between said measuring prism and said reticle.

Claim 8

A refractometer operating with a source emitting bundles of light and having a measuring prism with an entrance face to receive different substances within a range of characteristics to be measured corresponding to refractive indices n, an objective having an image plane, a reticle disposed in said image plane and carrying a scale having a reference mark, said entrance face and said reticle being positioned in such a way that bundles of light from said source are refracted and deviated at said entrance face and directed to said objective, and focused by said objective to an optical image on said scale at a distance s from said reference mark, ds/dn being the rate of change of said distance s with said refractive index n, and d2s/dn2 being the nonlinearity of said rate of change in combination with; stationary refracting means positioned between said entrance face and said reticle, said stationary refracting means deviating said bundles of light by angles of deviation x, dx/dn being the rate of change of said angles of deviation with said refractive index n to be measured, said stationary refracting means being oriented so that dx/dn decreases as n increases thereby causing a reduction of said nonlinearity d2s/dn2, said stationary refracting means including a fixed prism having refracting faces and being positioned between said measuring prism and said reticle.

Claim 9

A refractometer according to claim 6 wherein said fixed prism is oriented so that the angle of incidence of said bundles of light at at least one of said faces is positive and comprised between 40* and 75*.

Claim 10

A refractometer according to claim 6 wherein said fixed prism is oriented so that the angle of incidence of said bundles of light at at least one of said faces is negative and comprised between 20* and 50*.

Claim 11

A refractometer operating with a source emitting bundles of light and having a measuring prism with an entrance face to receive different substances within a range of characteristics to be measured corresponding to refractive indices n, said refractive indices varying with temperature changes, an objective having an image plane, a reticle disposed in said image plane and carrying a reference mark, said entrance face and said reticle being positioned in such a way that bundles of light from said source are refracted and deviated at said entrance face and directed to said objective, and focused by said objective to an optical image on said reticle at a distance s from said reference mark, ds/dn being the rate of change of said distance s with said refractive index n, and d2s/dn2 being the nonlinearity of said rate of change in combination with: temperature compensating means compensating for the temperature error resulting from the temperature coefficient of the refractive index of said different substances to be measured, said temperature compensating means comprising a thermal actuator to move one of said objective and said reticle so aS to cause displacement between said optical image and said reference mark in accordance with temperature changes, and stationary refracting means positioned between said entrance face and said reticle, said stationary refracting means deviating said bundles of light by angles of deviation x, dx/dn being the rate of change of said angles of deviation with said refractive index n to be measured, and being oriented so that dx/dn decreases as n increases thereby causing a reduction of said nonlinearity d2s/dn2, the stationary refracting means being constituted by an exit face of said measuring prism, said exit face producing a deviation of said bundles of light in the same direction as the deviation of the bundles of light at said entrance face.

Claim 12

A refractometer operating with a source emitting bundles of light and having a measuring prism with an entrance face to receive different substances within a range of characteristics to be measured corresponding to refractive indices n, said refractive indices varying with temperature changes, an objective having an image plane, a reticle disposed in said image plane and carrying a reference mark, said entrance face and said reticle being positioned in such a way that bundles of light from said source are refracted and deviated at said entrance face and directed to said objective, and focused by said objective to an optical image on said reticle at a distance s from said reference mark, ds/dn being the rate of change of said distance s with said refractive index n, and d2s/dn2 being the nonlinearity of said rate of change in combination with: temperature compensating means compensating for the temperature error resulting from the temperature coefficient of the refractive index of said different substances to be measured, said temperature compensating means comprising a thermal actuator to move one of said objective and said reticle so aS to cause displacement between said optical image and said reference mark in accordance with temperature changes, and stationary refracting means positioned between said entrance face and said reticle, said stationary refracting means deviating said bundles of light by angles of deviation x, dx/dn being the rate of change of said angles of deviation with said refractive index n to be measured, and being oriented so that dx/dn decreases as n increases thereby causing a reduction of said nonlinearity d2s/dn2, the stationary refracting means being constituted by an exit face of said measuring prism, said exit face producing a deviation of said bundles of light in the same direction as the deviation of the bundles of light at said entrance face.

Claim 13

A refractometer according to claim 9 wherein said measuring prism has a refractive index below 1.62 and a prism refracting angle larger than 90*.

Claim 14

A refractor according to claim 9 wherein said measuring prism has a refractive index above 1.62 and a prism refracting angle larger than 75*.

Claim 15

A refractometer according to claim 9 wherein said measuring prism is composed of at least two components having different optical dispersion.

Claim 16

A refractometer according to claim 9 wherein said components have substantially the same refractive index for one line of the spectrum and are separated by curved faces.

Claim 17

A refractometer operating with a source emitting bundles of light and having a measuring prism with an entrance face to receive different substances within a range of characteristics to be measured corresponding to refractive index n, said refractive indices varying with temperature changes, an objective having an image plane, a reticle disposed in said image plane and carrying a reference mark, said entrance face and said reticle being positioned in such a way that bundles of light from said source are refracted and deviated at said entrance face and directed to said objective, and focused by said objective to an optical image on said reticle at a distance s from said reference mark, ds/dn being the rate of change of said distance s with said refractive index n, and d2s/dn2 being the nonlinearity of said rate of change in combination with: temperature compensating means compensating for the temperature error resulting from the temperature coefficient of the refractive index of said different substances to be measured, said temperature compensating means comprising a thermal actuator to move one of said objective and said reticle so as to cause displacement between said optical image and said reference mark in accordance with temperature changes, and stationary refracting means positioned between said entrance face and said reticle, said stationary means deviating said bundles of light by angles of deviation x, dx/dn being the rate of change of said angles of deviation with said refractive index n to be measured, and being oriented so that dx/dn decreases as n increases thereby causing a reduction of said nonlinearity d2s/dn2, the stationary refracting means including a fixed prism having refracting faces and being positioned between said measuring prism and said reticle.

Claim 18

A refractometer operating with a source emitting bundles of light and having a measuring prism with an entrance face to receive different substances within a range of characteristics to be measured corresponding to refractive index n, said refractive indices varying with temperature changes, an objective having an image plane, a reticle disposed in said image plane and carrying a reference mark, said entrance face and said reticle being positioned in such a way that bundles of light from said source are refracted and deviated at said entrance face and directed to said objective, and focused by said objective to an optical image on said reticle at a distance s from said reference mark, ds/dn being the rate of change of said distance s with said refractive index n, and d2s/dn2 being the nonlinearity of said rate of change in combination with: temperature compensating means compensating for the temperature error resulting from the temperature coefficient of the refractive index of said different substances to be measured, said temperature compensating means comprising a thermal actuator to move one of said objective and said reticle so as to cause displacement between said optical image and said reference mark in accordance with temperature changes, and stationary refracting means positioned between said entrance face and said reticle, said stationary means deviating said bundles of light by angles of deviation x, dx/dn being the rate of change of said angles of deviation with said refractive index n to be measured, and being oriented so that dx/dn decreases as n increases thereby causing a reduction of said nonlinearity d2s/dn2, the stationary refracting means including a fixed prism having refracting faces and being positioned between said measuring prism and said reticle.

Claim 19

A refractometer according to claim 14 wherein said fixed prism is oriented so that the angle of incidence of said bundles of light at at least one of said faces is positive and comprised between 40* and 75*.

Claim 20

A refractometer according to claim 14 wherein said fixed prism is oriented so that the angle of incidence of said bundles of light at at least one of said faces is negative and comprised between 20* and 50*.