Sensing device and method for measuring emission time delay during irradiation of targeted samples
First Claim
1. An apparatus to measure emission time delay during irradiation of targeted samples by utilizing digital signal processing to determine the emission phase shift caused by the sample, said apparatus comprising:
- a source of electromagnetic radiation adapted to irradiate a target sample;
means for generating first and second digital input signals of known frequencies with a known phase relationship;
means for converting said first and second digital input signals to analog sinusoidal signals;
means for directing said first analog input signal to said electromagnetic radiation source to modulate said electromagnetic radiation source by the frequency thereof to irradiate said target sample and generate a target sample emission;
means for detecting said target sample emission and producing a corresponding first analog output signal having a phase shift relative to the phase of said first analog input signal, said phase shift being caused by the emission time delay in said sample;
means for producing a known phase shift in said second analog input signal to create a second analog output signal;
means for converting said first and second analog output signals to first and second digital output signals respectively;
a mixer for receiving said first and second digital output signals and comparing the signal phase relationship therebetween to produce a signal indicative of the change in phase relationship between said first and second digital output signals caused by said target sample emission; and
feedback means to simultaneously alter the frequencies of said first and second digital input signals while substantially continuously vary the phase offset between said first and second digital input signals based on said mixer signal to ultimately place said first and second digital output signals in quadrature while compressing the frequency range therebetween.
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Abstract
An apparatus for measuring emission time delay during irradiation of targeted samples by utilizing digital signal processing to determine the emission phase shift caused by the sample is disclosed. The apparatus includes a source of electromagnetic radiation adapted to irradiate a target sample. A mechanism generates first and second digital input signals of known frequencies with a known phase relationship, and a device then converts the first and second digital input signals to analog sinusoidal signals. An element is provided to direct the first input signal to the electromagnetic radiation source to modulate the source by the frequency thereof to irradiate the target sample and generate a target sample emission. A device detects the target sample emission and produces a corresponding first output signal having a phase shift relative to the phase of the first input signal, the phase shift being caused by the irradiation time delay in the sample. A member produces a known phase shift in the second input signal to create a second output signal. A mechanism is then provided for converting each of the first and second analog output signals to digital signals. A mixer receives the first and second digital output signals and compares the signal phase relationship therebetween to produce a signal indicative of the change in phase relationship between the first and second output signals caused by the target sample emission. Finally, a feedback arrangement alters the phase of the second input signal based on the mixer signal to ultimately place the first and second output signals in quadrature. Mechanisms for enhancing this phase comparison and adjustment technique are also disclosed.
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Citations
26 Claims
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1. An apparatus to measure emission time delay during irradiation of targeted samples by utilizing digital signal processing to determine the emission phase shift caused by the sample, said apparatus comprising:
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a source of electromagnetic radiation adapted to irradiate a target sample; means for generating first and second digital input signals of known frequencies with a known phase relationship; means for converting said first and second digital input signals to analog sinusoidal signals; means for directing said first analog input signal to said electromagnetic radiation source to modulate said electromagnetic radiation source by the frequency thereof to irradiate said target sample and generate a target sample emission; means for detecting said target sample emission and producing a corresponding first analog output signal having a phase shift relative to the phase of said first analog input signal, said phase shift being caused by the emission time delay in said sample; means for producing a known phase shift in said second analog input signal to create a second analog output signal; means for converting said first and second analog output signals to first and second digital output signals respectively; a mixer for receiving said first and second digital output signals and comparing the signal phase relationship therebetween to produce a signal indicative of the change in phase relationship between said first and second digital output signals caused by said target sample emission; and feedback means to simultaneously alter the frequencies of said first and second digital input signals while substantially continuously vary the phase offset between said first and second digital input signals based on said mixer signal to ultimately place said first and second digital output signals in quadrature while compressing the frequency range therebetween. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An apparatus to measure emission time delay during irradiation of targeted samples by utilizing digital signal processing to determine the emission phase shift caused by the sample, said apparatus comprising:
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a source of electromagnetic radiation adapted to irradiate a target sample; means for generating first and second digital input signals of known frequencies with a known phase offset; means for converting said first and second digital input signals to analog sinusoidal signals; means for directing said first analog input signal to said electromagnetic radiation source to modulate said electromagnetic radiation source by the frequency thereof to irradiate said target sample and generate a target sample emission; means for detecting said target sample emission and producing a corresponding first analog output signal having a phase shift relative to the phase of said first analog input signal, said phase shift being caused by the emission time delay in said sample; means for producing a known phase shift in said second analog input signal to create a second analog output signal; means for converting said first and second analog output signals to first and second digital output signals respectively; a mixer for receiving said first and second digital output signals and comparing the signal phase relationship therebetween to produce a signal indicative of the change in phase relationship between said first and second digital output signals caused by said target sample emission; and feedback means to simultaneously alter the frequencies of said first and second digital input signals while substantially continuously varying the phase offset between said first and second digital input signals based on said mixer signal to ultimately place said first and second digital output signals in quadrature while compressing the frequency range therebetween. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. An apparatus to measure emission time delay during irradiation of targeted samples by utilizing digital signal processing to determine the emission phase shift caused by the sample, said apparatus comprising:
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a source of electromagnetic radiation adapted to irradiate a target sample; means for generating first, second and third digital input signals of known frequencies with known phase offsets; means for converting said first, second and third digital input signals to analog sinusoidal signals; means for directing said first analog input signal to said electromagnetic radiation source to modulate said electromagnetic radiation source by the frequency thereof to irradiate said target sample and generate a target sample emission; means for detecting said target sample emission and producing a corresponding first analog intermediate signal having a phase shift relative to the phase of said first analog input signal, said phase shift being caused by the emission time delay in said sample; first signal down conversion means for combining the frequency of said third analog input signal with the frequency of said first analog intermediate signal to produce a first analog output signal representing the sum and difference frequencies of said first analog intermediate and said third analog input signals; means for producing a known phase shift in said second analog input signal to create a second analog intermediate signal; second signal down conversion means for combining the frequency of said third analog input signal with the frequency of said second analog intermediate signal to produce a second analog output signal representing the sum and difference frequencies of said second analog intermediate and said third analog input signals; means for converting said first and second analog output signals to first and second digital output signals, respectively; a mixer for receiving said first and second digital output signals and comparing the signal phase relationship therebetween to produce a signal indicative of the change in phase relationship between said first and second digital output signals caused by said target sample emission; and feedback means to simultaneously alter the frequencies of said first and second digital input signals while substantially continuously varying the phase offset between said first and second digital input signals based on said mixer signal and to alter the frequency of said third digital input signal to achieve desired downconversion frequency of said first and second digital output signals to ultimately place said first and second digital output signals in quadrature while compressing the frequency range therebetween. - View Dependent Claims (18, 19, 20)
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21. A method for measuring emission time delay during the irradiation of targeted samples by utilizing digital signal processing for determining the emission phase shift caused by irradiation of the sample, said method comprising the steps of:
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generating first and second digital input signals of known frequencies having a known variable phase relationship; converting said first and second digital input signals to analog sinusoidal signals; directing said first analog input signal to an electromagnetic radiation source to modulate the emissions of said electromagnetic radiation source by the frequency thereof; irradiating a target sample with the modulated emissions of said electromagnetic radiation source to generate a target sample emission; detecting said target sample emission and producing a corresponding first analog output signal having a phase shift relative to the phase of said first analog input signal, said phase shift being caused by the emission time delay of the emissions in said sample; producing a known phase shift in said second analog input signal to create a second analog output signal; converting said first and second analog output signals to first and second digital output signals, respectively; mixing said first and second digital output signals and comparing the signal phase relationship therebetween to produce an error signal indicative of the change in phase relationship between said first and second digital output signals caused by said target sample emission; and altering the frequencies of said first and second digital input signals while continuously varying the phase offset between said first and second digital input signals to ultimately place said first and second digital output signals in quadrature while compressing the frequency range therebetween. - View Dependent Claims (22, 23, 24)
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25. A method for measuring emission time delay during irradiation of targeted samples by utilizing digital signal processing to determine the emission phase shift caused by the sample, said method comprising the steps of:
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generating first, second and third digital input signals of known frequencies with known phase offsets; converting said first, second and third digital input signals to analog sinusoidal signals; directing said first analog input signal to an electromagnetic radiation source to modulate said electromagnetic radiation source by the frequency thereof; irradiating said target sample with the modulated emissions of said electromagnetic radiation source to generate a target sample emission; detecting said target sample emission and producing a corresponding first analog intermediate signal having a phase shift relative to the phase of said first analog input signal, said phase shift being caused by the emission time delay in said sample; down converting said first analog intermediate signal by combining the frequency of said third analog input signal with the frequency of said first analog intermediate signal to produce a first analog output signal representing the sum and difference frequencies of said first analog intermediate and said third analog input signals; producing a known phase shift in said second analog input signal to create a second analog intermediate signal; down converting said second analog intermediate signal by combining the frequency of said third analog input signal with the frequency of said second analog intermediate signal to produce a second analog output signal representing the sum and difference frequencies of said second analog intermediate and said third analog input signals; converting said first and second analog output signals to first and second digital output signals, respectively; mixing said first and second digital output signals and comparing the signal phase relationship therebetween to produce a mixer signal indicative of the change in phase relationship between said first and second digital output signals caused by said target sample emission; and simultaneously altering the frequencies of said first and second digital input signals while substantially continuously varying the phase offset between said first and second digital input signals based on said mixer signal and to alter the frequency of said third digital input signal to achieve desired downconversion frequency of said first and second analog and digital output signals to ultimately place said first and second digital output signals in quadrature while compressing the frequency range therebetween.
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26. An apparatus to measure emission time delay during irradiation of targeted samples by utilizing digital signal processing to determine the emission phase shift caused by the sample, said apparatus comprising:
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a source of electromagnetic radiation adapted to irradiate a target sample; means for generating first, second and third digital input signals of known frequencies with a known phase relationship; means for converting said first, second and third digital input signals to analog sinusoidal signals; means for directing said first analog input signal to said electromagnetic radiation source to modulate said electromagnetic radiation source by the frequency thereof to irradiate said target sample and generate a target sample emission; means for detecting said target sample emission and producing a corresponding first analog output signal having a phase shift relative to the phase of said first analog input signal, said phase shift being caused by the emission time delay in said sample; means for producing a known phase shift in said second analog input signal to create a second analog output signal; a first signal down conversion means positioned for combining the frequency of said third analog input signal with the frequency of said first analog output signal to produce a modified first analog output signal representing the sum and difference frequencies of said first analog output and said third analog input signals, and a second signal down conversion means positioned for combining the frequency of said third analog input signal with the frequency of said second analog output signal to produce a modified second analog output signal representing the sum and difference frequencies of said second analog output and said third analog input signals; means for converting said first and second modified analog output signals to first and second digital output signals, respectively; a mixer for receiving said first and second digital output signals and comparing the signal phase relationship therebetween to produce a signal indicative of the change in phase relationship between said first and second digital output signals caused by said target sample emission; and feedback means to alter the phase of the second digital input signal based on said mixer signal to ultimately place said first and second digital output signals in quadrature.
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Specification