Apparatus for measurement of soil moisture content
First Claim
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1. Apparatus for monitoring the moisture content of a soil sample comprising:
- a light source for radiating light energy at a plurality of selected wavelengths;
light transmission means establishing first and second transmission paths each having first and second ends, the first end of said first path being disposed for receiving light radiated from said light source;
a soil probe insertable in a bore formed in the soil sample, said soil probe including a window for directing light from the second end of said first light transmission path to said soil sample at selected depths within said bore and for directing light reflected from the soil sample to the first end of said second light transmission path;
displacement measuring means secured to said soil probe for providing an indication of the relative position of said window within said bore;
means coupled to the second end of said second light transmission path for determining the reflectance factors of said reflected light at said selected wavelengths; and
means responsive to said reflectance factors and to said position indications for computing the moisture content of the soil sample as a function of the position of said window within said bore.
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Abstract
An apparatus for measuring the moisture content of a soil sample at selected depths is disclosed. Light is conducted from a source via a fiber optical cable to a soil probe which is inserted at selected depths into a bore hole formed in the soil sample. Light from the source and reflected light from the soil sample is conducted via fiber optic cables to a reflectometer, which determines reflection factors of the soil sample at three selected infrared wavelengths of a water absorption band. Means are provided to compute the moisture content of the sample at the selected depths from the measured reflectance factors.
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Citations
12 Claims
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1. Apparatus for monitoring the moisture content of a soil sample comprising:
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a light source for radiating light energy at a plurality of selected wavelengths; light transmission means establishing first and second transmission paths each having first and second ends, the first end of said first path being disposed for receiving light radiated from said light source; a soil probe insertable in a bore formed in the soil sample, said soil probe including a window for directing light from the second end of said first light transmission path to said soil sample at selected depths within said bore and for directing light reflected from the soil sample to the first end of said second light transmission path; displacement measuring means secured to said soil probe for providing an indication of the relative position of said window within said bore; means coupled to the second end of said second light transmission path for determining the reflectance factors of said reflected light at said selected wavelengths; and means responsive to said reflectance factors and to said position indications for computing the moisture content of the soil sample as a function of the position of said window within said bore. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. Apparatus for monitoring the moisture content of a soil sample comprising:
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a light source for radiating light energy at least at a plurality of selected wavelengths; reflectometer means having an object channel and a reference channel for determining the reflectance factors at said selected wavelengths of light coupled to said object channel relative to light coupled to said reference channel; light transmission means comprising a first bundle of continuous fiber optics extending between said light source and said soil sample, a second bundle of continuous fiber optics extending between said optic channel and said soil sample and a third bundle of continuous fiber optics extending between said light source and said reference channel, the individuals fibers of said first and second fiber optic bundles being mixed with each other at their ends opposite said light source and said object channel for forming a combined fiber optics bundle having a soil viewing end disposed in association with said soil sample; an elongate soil probe receiving said combined fiber optics bundle, said soil probe being insertable in a bore formed in said soil sample and having a window formed near the distal end thereof, said soil viewing end of said combined bundle being disposed in juxtaposition with said window; displacement measuring means secured to said soil probe for providing an indication of the relative position of said window within said bore formed in said soil sample; and means responsive to said determined reflectance factors for computing the moisture content of the soil sample. - View Dependent Claims (11, 12)
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Specification