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US 6,636,319 B1Granted
Spectrometer with dual digitizer for high-dynamic range spectroscopic data collection
OwnerGerald Auth, Roger Haddad +1inventors
InventorsGerald Auth, Roger Haddad, Warren Vidrine
Life of this patent
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Abstract
A spectrometer (110) having an interferometer, a detector (120) that produces a detector signal (20), and a dual-digitizer system including two analog-to-digital converters that simultaneously digitize low-gain and high-gain versions of the detector signal, and suitable data structures and associated firmware for merging the two resulting sets of digitized data into a single, high dynamic range set of data.
Claims20
A method of operating an FTIR spectrometer to digitize an analog detector signal comprising the steps of:
- passing an IR source signal through an interferometer;
- receiving an analog detector signal corresponding to the IR source signal;
- processing the analog detector signal with a low gain circuit to produce a low gain analog signal;
- processing the analog detector signal with a high gain circuit to produce a high gain analog signal;
- digitizing the low gain analog signal with a first ADC converter to produce a set of low gain samples;
- digitizing the high gain analog signal with a second ADC converter to produce a set of high gain samples, some of the high gain samples being below a predetermined threshold and some of the high gain samples being above the predetermined threshold;
- and
- merging the in-range high gain samples with the low gain samples to produce a combined set of samples by:
- identifying a plurality of pairs of low-gain and high-gain samples where the high-gain samples are below the predetermined threshold;
- normalizing the high-gain samples relative to the low-gain samples;
- and
- assembling a combined set of low-gain sample and high-gain samples.
9 more elements
A method of operating an FTIR spectrometer to digitize an analog detector signal comprising the steps of:
- passing an IR source signal through an interferometer;
- receiving an analog detector signal corresponding to the IR source signal;
- processing the analog detector signal with a low gain circuit to produce a low gain analog signal;
- processing the analog detector signal with a high gain circuit to produce a high gain analog signal;
- digitizing the low gain analog signal with a first ADC converter to produce a set of low gain samples;
- digitizing the high gain analog signal with a second ADC converter to produce a set of high gain samples, some of the high gain samples being below a predetermined threshold and some of the high gain samples being above the predetermined threshold;
- merging the in-range high gain samples with the low gain samples to produce a combined set of samples;
- wherein the step of processing the analog detector signal with a high gain circuit to produce a high gain analog signal is accomplished with an amplifier;
- and
- wherein the step of processing the analog detector signal with a low gain circuit to produce a low gain analog signal is accomplished by attenuating the high gain analog signal with an attenuator.
7 more elements
A method of operating an FTIR spectrometer to digitize an analog detector signal comprising the steps of:
- passing an IR source signal through an interferometer;
- receiving an analog detector signal corresponding to the IR source signal;
- processing the analog detector signal with a low gain circuit to produce a low gain analog signal;
- processing the analog detector signal with a high gain circuit to produce a high gain analog signal;
- digitizing the low gain analog signal with a first ADC converter to produce a set of low gain samples;
- digitizing the high gain analog signal with a second ADC converter to produce a set of high gain samples, some of the high gain samples being below a predetermined threshold and some of the high gain samples being above the predetermined threshold;
- identifying a plurality of pairs of low-gain samples and high-gain samples where the high-gain sample are below the predetermined threshold;
- performing a least squares fit to normalize the high-gain samples to the low-gain samples according to the equation y=Ax+B where each y value is a high-gain sample and each x value is a low-gain sample;
- and
- merging the in-range high gain samples with the low gain samples to produce a combined set of samples by using:
- a low-gain sample when a corresponding high-gain sample exceeds the predetermined threshold;
- and
- a high-gain sample, normalized relative to the low-gain samples as (y−B)/A, when the high-gain sample is less than the predetermined threshold.
10 more elements
A method of operating an FTIR spectrometer to digitize an analog detector signal comprising the steps of:
- passing an IR source signal through an interferometer;
- receiving an analog detector signal corresponding to the IR source signal;
- processing the analog detector signal with a low gain circuit to produce a low gain analog signal;
- processing the analog detector signal with a high gain circuit to produce a high gain analog signal;
- digitizing the low gain analog signal with a first ADC converter to produce a set of low gain samples;
- digitizing the high gain analog signal with a second ADC converter to produce a set of high gain samples, some of the high gain samples being below a predetermined threshold and some of the high gain samples being above the predetermined threshold;
- identifying a plurality of pairs of low-gain samples and high-gain samples where the high-gain sample are below the predetermined threshold;
- performing a least squares fit to normalize the low-gain samples to the high-gain samples according to the equation y=Ax+B where each y value is a low-gain sample and each x value is a high-gain sample;
- and
- merging the in-range high gain samples with the low gain samples to produce a combined set of samples by using:
- a normalized low-gain sample when a corresponding high-gain sample exceeds the predetermined threshold;
- and
- a high-gain sample when the high-gain sample is less than the predetermined threshold.
10 more elements
An FTIR spectrometer adapted for analyzing a sample with high dynamic range comprising:
- an interferometer for creating an interferogram from a source of IR radiation;
- a detector that produces an analog detector signal corresponding to the IR source signal;
- a low-gain circuit receiving the analog detector signal and producing a low-gain signal;
- a high-gain circuit receiving the analog detector signal and producing a high gain signal;
- a first analog-to-digital converter for digitizing the low gain signal to produce a set of low gain samples;
- a second analog-to-digital converter for digitizing the high gain signal to produce a set of high gain samples where some of the high gain samples are below a predetermined threshold and some of the high gain samples are above the predetermined threshold;
- and
- means for merging the high gain samples that are below the predetermined threshold with the low gain samples to produce a combined set of samples, wherein the means for merging the high gain samples with the low gain samples further comprises:
- means for storing a full set of low-gain samples;
- means for storing a full set of high-gain samples;
- and
- means for pairing the low-gain samples with high-gain samples that are below the predetermined threshold.
9 more elements
An FTIR spectrometer adapted for analyzing a sample with high dynamic range comprising:
- an interferometer for creating an interferogram from a source of IR radiation;
- a detector that produces an analog detector signal corresponding to the IR source signal;
- a low-gain circuit receiving the analog detector signal to and producing a low-gain signal;
- a high-gain circuit receiving the analog detector signal and producing a high gain signal;
- a first analog-to-digital converter for digitizing the low gain signal to produce a set of low gain samples;
- a second analog-to-digital converter for digitizing the high gain signal to produce a set of high gain samples where some of the high gain samples are below a predetermined threshold and some of the high gain samples are above the predetermined threshold;
- means for merging the high gain samples that are below the predetermined threshold with the low gain samples to produce a combined set of samples;
- and
- wherein the low-gain circuit receiving the analog detector signal and producing a low-gain signal is an attenuator.
6 more elements
An FTIR spectrometer adapted for analyzing a sample with high dynamic range comprising:
- an interferometer for creating an interferogram from a source of IR radiation;
- a detector that produces an analog detector signal corresponding to the IR source signal;
- a low-gain circuit receiving the analog detector signal to and producing a low-gain signal;
- a high-gain circuit receiving the analog detector signal and producing a high gain signal;
- a first analog-to-digital converter for digitizing the low gain signal to produce a set of low gain samples;
- a second analog-to-digital converter for digitizing the high gain signal to produce a set of high gain samples where some of the high gain samples are below a predetermined threshold and some of the high gain samples are above the predetermined threshold;
- means for merging the high gain samples that are below the predetermined threshold with the low gain samples to produce a combined set of samples;
- and
- wherein high-gain circuit receiving the analog detector signal and producing a high gain signal is an attenuator.
6 more elements
Dependencies are inferred from the claim text.