System and method for a self-calibrating non-invasive sensor
View Patent ↗A non-invasive emitter-photodiode sensor which is able to provide a data-stream corresponding to the actual wavelength of light emitted thereby allowing calibration of the sensor signal processing equipment and resulting in accurate measurements over a wider variation in emitter wavelength ranges.
1. A self-calibrating sensor system having at least one light source, the self-calibrating sensor system comprising:
a probe receiving incident light radiation from the at least one light source, the probe including a wavelength sensor comprising:
a first diode configured to receive short wavelengths from the incident light radiation and produce a first photocurrent signal; and
a second diode configured to receive short wavelengths from the incident light radiation and produce a second photocurrent signal; and;
a calibration circuit in signal communication with the probe, the calibration circuit producing a calibrated signal corresponding to the received incident light radiation at the probe;
wherein the probe further includes a probe output circuit in signal communication with the calibration circuit, the probe output circuit producing a known sensor probe output signal when the first photocurrent signal and second photocurrent signal are approximately equal in magnitude.
2. The self-calibrating sensor system of claim 1 , wherein the probe output circuit is a differential amplifier.
3. The self-calibrating sensor system of claim 1 , further including software that operates on the controller.
4. The self-calibrating sensor system of claim 1 , wherein the software is capable of determining the wavelength of the incident light radiation.
5. The self-calibrating sensor system of claim 4 , wherein the software is capable of compensating for wavelength variation of the incident light radiation caused by changes in temperature.
6. The self-calibrating sensor system of claim 1 , further including a look-up table in signal communication with the controller.
7. A self-calibrating sensor system having at least one light source, the self-calibrating sensor system comprising:
first means for receiving incident light radiation from the lightsource, including means for receiving short wavelengths from the incident light radiation and producing a first photocurrent signal, and means for receiving long wavelengths from the incident light radiation and producing a second photocurrent signal;
means for producing a calibrated signal corresponding to the received incident light radiation at the first means; and
means for controlling the calibration circuit; signal producing means
wherein the first receiving means further includes a second means for producing a known output signal when the first photocurrent signal and second photocurrent signal are approximately equal in magnitude.
8. The self-calibrating sensor system of claim 7 , wherein the second producing means is a differential amplifier.
9. The self-calibrating sensor system of claim 7 , further including software that operates on the controlling means.
10. The self-calibrating sensor system of claim 7 , wherein the software is capable of determining the wavelength of the incident light radiation.
11. The self-calibrating sensor system of claim 10 , wherein the software is capable of compensating for wavelength variation of the incident light radiation caused by changes in temperature.
12. The self-calibrating sensor system of claim 7 , further including a look-up table in signal communication with the controlling means.
13. A method for self-calibrating a sensor system having at least one light source, the method comprising the steps of:
receiving incident light radiation from the at least one light source;
receiving short wavelengths from the incident light radiation; at a probe
receiving long wavelengths from the incident light radiation; at the probe
producing a first photocurrent signal in response receiving short wavelengths from the incident light radiation;
producing a second photocurrent signal in response to receiving short wavelengths from the incident light radiation;
comparing the first photocurrent signal to the second photocurrent signal;
determining the wavelength of the incident light radiation; and
producing a calibrated signal corresponding to the received incident light radiation at the probe.
14. The method of claim 13 , further comprising the step of determining whether the first photocurrent signal and second photocurrent signal are approximately equal in magnitude.
15. The method of claim 13 , further comprising the step of compensating the determined wavelength of the incident light radiation for temperature variation.
16. A computer-readable medium for self-calibrating a sensor system having at least one light source, the computer-readable medium comprising:
logic configured for receiving incident light radiation from the at least one light source at a probe;
logic configured for receiving short wavelengths from the incident light radiation at a first diode;
logic for receiving long wavelengths from the incident light radiation at a second diode;
logic configured for producing a first photocurrent signal from the first diode in response to receiving short wavelengths from the incident light radiation;
logic configured for producing a second photocurrent signal from the second diode in response to receiving long wavelengths from the incident light radiation;
logic configured for producing a calibrated signal corresponding to the received incident light radiation at the probe; and
logic configured for determining the wavelength of the incident light radiation by comparing the first photocurrent signal to the second photocurrent signal.
17. The computer-readable medium of claim 16 , further comprising logic configured for determining whether the first photocurrent signal and second photocurrent signal are approximately equal in magnitude.
18. The computer-readable medium of claim 17 , further comprising logic configured for compensating the determined wavelength of the incident light radiation for temperature variation.