Infrared source modulation and system using same
A method of modulating an infrared radiation (IR) source that includes applying a time-varying, periodic voltage signal to the IR source, measuring a parameter of the voltage signal, and adjusting the voltage signal to maintain a substantially constant delivered power to the IR source. Adjusting the voltage signal is done based on the measured parameter and a predetermined relationship between the measured parameter of the voltage pulse and a resistance of such an infrared radiation source. Alternatively, the method includes applying a the voltage pulse, measuring a first parameter of the voltage pulse and a second parameter of a current passing through the infrared radiation source resulting from the applying step, and adjusting the voltage pulse to maintain a substantially constant delivered power to the infrared radiation source based on the first parameter and the second parameter.
1. A method of regulating infrared radiation output from an infrared radiation source comprising:
applying a time-varying, periodic voltage signal to an infrared radiation source;
measuring a parameter of the voltage signal; and
adjusting the voltage signal to maintain a substantially constant delivered power to such an infrared radiation source, wherein adjusting the voltage signal is accomplished based on the measured parameter and a predetermined relationship between the measured parameter of the voltage signal and a resistance of such an infrared radiation source.
2. The method of claim 1 , wherein the voltage signal is a uni-polar or a bi-polar voltage pulse.
3. The method of claim 1 , wherein the parameter of the voltage signal is amplitude.
4. The method of claim 2 , wherein adjusting the voltage signal includes adjusting a width of a voltage pulse in the voltage signal.
5. A method of regulating infrared radiation output from an infrared radiation source comprising:
applying a voltage pulse to an infrared radiation source, wherein the voltage pulse has a duty cycle less than 100%;
measuring a first parameter of the voltage pulse;
measuring a second parameter of a current passing through the infrared radiation source resulting from the applying step; and
adjusting the voltage pulse to maintain a substantially constant delivered power to the infrared radiation source based on the first parameter and the second parameter.
6. The method of claim 5 , wherein the voltage pulse is a uni-polar or a bi-polar voltage.
7. The method of claim 5 , wherein the parameter of the voltage pulse is amplitude.
8. The method of claim 5 , wherein adjusting the voltage pulse includes adjusting a width of the voltage pulse.
9. A system for generating pulses of infrared radiation comprising:
an infrared radiation source;
a current sensor operatively coupled to the infrared radiation source so as to measure an electrical current passing through the infrared radiation source;
a voltage sensor coupled to the infrared radiation source so as to measure an electrical voltage applied to the infrared radiation source; and
means for applying electrical pulses to the infrared radiation source such that a substantially constant power is delivered to the infrared radiation source.
10. The system of claim 9 , wherein the infrared radiation source comprises an emissive, electrically resistive material.
11. The system of claim 9 , wherein the means for applying electrical pulses includes a uni-polar supply voltage.
12. The system of claim 11 , wherein the voltage sensor measures the uni-polar supply voltage.
13. The system of claim 9 , wherein the means for applying electrical pulses includes a bi-polar supply voltage.
14. The system of claim 13 , where the voltage sensor measures the bi-polar supply voltage.
15. The system of claim 9 , wherein the current sensor comprises a sense resistor and a measurement circuit to measure the voltage across the sense resistor.