High sensitivity acousto-optic tunable filter spectrometer
First Claim
Patent Images
1. A spectrometer comprising in combination:
- incoherent radiation source;
an AOTF crystal for passing selective bands of light, having an RF input;
a radio frequency source connected to said AOTF RF input, said source having an output which is continuous and which varies in frequency,and wherein said selected bands of light are the birefringent beam from said crystal.
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Abstract
An acousto-optical filter (AOTF) is used in a spectrometer for analysis of samples. The spectrometer provides continuous wave RF excitation through the crystal, and the spectrometer provides control and modulation for said RF source. The signal to noise ratio is improved by use of a lock-in amplifier which demodulates the modulation frequency. Fiber optics are used to connect the crystal to the source, and the source to the detection system. A digital lock-in amplifier is designed which increases the efficiency, accuracy, sensitivity and decreases the cost of conventional analog lock-in amplifier.
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Citations
23 Claims
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1. A spectrometer comprising in combination:
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incoherent radiation source; an AOTF crystal for passing selective bands of light, having an RF input; a radio frequency source connected to said AOTF RF input, said source having an output which is continuous and which varies in frequency, and wherein said selected bands of light are the birefringent beam from said crystal. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A spectrometer having an AOTF crystal having in combination:
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a radiation source; a AOTF crystal for passing selected bands of light, having a RF input; a source of radio frequency connected to said AOTF RF input, said source having an output which is continuous and which varies in frequency; means for passing light from said light source to said AOTF crystal; means for passing light from said AOTF crystal into a sample cell; means for detecting light from said sample cell; means for passing light from the sample cell to a detector means; and wherein said selected bands of lights are the birefringent beam from said crystal. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A spectrometer having an AOTF crystal comprising in combination:
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a light source; means for passing light from said light source into a sample cell; means for passing light from said sample cell to a detector; said detector comprising; (1) a AOTF crystal for receiving light from said means for passing light from said sample cell, said AOTF crystal having an RF input and passing selected bands of light; (2) a radio frequency (RF) source connected to said AOTF input, said RF source having an output which is continuous; (3) means for detecting the magnitude said selected bands of light from said AOTF crystal; and wherein said selected bands of light are the birefringent beam from said crystal. - View Dependent Claims (18, 19, 20, 21, 22, 23)
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Specification