Fluid index of refraction sensor
First Claim
1. An index of refraction sensor comprising:
- a transparent block having upper and lower surfaces and an index of refraction nw, wherein the upper surface is exposed to a material having an index of refraction nf, wherein nf is less than nw ;
a light emitting device mounted on the lower surface; and
a first array of light detecting devices mounted on the lower surface parallel to the lower surface and spaced from the light emitting device by a predetermined separation, wherein light detecting devices nearest the light emitting device are smaller than light detecting devices farthest from the light emitting device.
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Accused Products
Abstract
An index of refraction sensor having a photo detector array with variable sized elements is provided. The photo diode array comprises a plurality of diodes with varying area. The diodes farthest from a light emitting diode having a larger area than those closer to the light emitting diode. Preferably the diode area is designed so that each of the diodes produces approximately the same current output when exposed to light from the LED. Each diode in the photo diode array is sequentially powered and the photo diode outputs are summed together. A power input from a first diode in the array is coupled to a start input of a time measurement circuit. The summed output of the photo diode array is coupled to a stop input of the time measurement circuit. Elapsed time measured by the time measurement circuit is thus a function of reflected light edge location, and therefore a function of index of refraction of the fuel mixture.
15 Citations
12 Claims
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1. An index of refraction sensor comprising:
- a transparent block having upper and lower surfaces and an index of refraction nw, wherein the upper surface is exposed to a material having an index of refraction nf, wherein nf is less than nw ;
a light emitting device mounted on the lower surface; and
a first array of light detecting devices mounted on the lower surface parallel to the lower surface and spaced from the light emitting device by a predetermined separation, wherein light detecting devices nearest the light emitting device are smaller than light detecting devices farthest from the light emitting device. - View Dependent Claims (2, 3, 4)
- a transparent block having upper and lower surfaces and an index of refraction nw, wherein the upper surface is exposed to a material having an index of refraction nf, wherein nf is less than nw ;
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5. An index of refraction sensor comprising:
- a transparent block having upper and lower surfaces and an index of refraction nw, wherein the upper surface is exposed to a material having an index of refraction nf, wherein nf is less than nw ;
a light emitting device mounted on the lower surface; and
a first array of light detecting devices mounted on the lower surface and spaced from the light emitting device by a predetermined separation, wherein light detecting devices nearest the light emitting device are smaller than light detecting devices farthest from the light emitting device; and
a second detector array comprising a plurality of elements which correspond to elements in the first detector array and an opaque coating shading the second detector array.
- a transparent block having upper and lower surfaces and an index of refraction nw, wherein the upper surface is exposed to a material having an index of refraction nf, wherein nf is less than nw ;
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6. An index of refraction sensor comprising:
- a transparent block having upper and lower surfaces and an index of refraction nw, wherein the upper surface is exposed to a material having an index of refraction nf, wherein nf is less than nw ;
a light emitting device mounted on the lower surface; and
a first concentric array of arc shaped light detecting devices mounted on the lower surface and spaced from the light emitting device by a predetermined separation, wherein the light emitting device is at the center of the concentric array. - View Dependent Claims (7, 8)
- a transparent block having upper and lower surfaces and an index of refraction nw, wherein the upper surface is exposed to a material having an index of refraction nf, wherein nf is less than nw ;
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9. An index of refraction sensor comprising:
- a transparent block having upper and lower surfaces and an index of refraction nw, wherein the upper surface is exposed to a material having an index of refraction nf, wherein nf is less than nw ;
a light emitting device mounted on the lower surface; and
a first concentric array of arc shaped light detecting devices mounted on the lower surface and spaced from the light emitting device by a predetermined separation, wherein the light emitting device is at the center of the concentric array; and
a second detector array comprising a plurality of elements which correspond to elements in the first detector array and an opaque coating shading the second detector array. - View Dependent Claims (10, 11, 12)
- a transparent block having upper and lower surfaces and an index of refraction nw, wherein the upper surface is exposed to a material having an index of refraction nf, wherein nf is less than nw ;
Specification