System and method of measurement frequency shifting to isolate external environmental conditions for interferometric dispersion measurements
A system and method including a semiconductor laser source configured to output radiation over a range of wavelengths at a prescribed rate to a device under test. The prescribed rate is sufficiently above environmental frequency bands. A detector is configured to detect output radiation from the device under test to obtain a detected signal associated with at least one physical property associated with the incident radiation over the range of wavelengths at the prescribed rate. The detected signal includes environmental signal and target signal from the device under test. A processor isolates the environmental signal from the detected signal; and processes the target signal to obtain dispersion information of the device under test. A system output is configured to output the dispersion information of the device under test.
1. A method for measuring dispersion in an interferometric measurement system, the method comprising:
directing incident radiation over a range of wavelengths at a prescribed rate to a device under test, wherein the prescribed rate is sufficiently above environmental frequency bands;
detecting output radiation from the device under test to obtain a detected signal associated with at least one physical property associated with the incident radiation over the range of wavelengths at the prescribed rate, wherein the detected signal includes environmental signal and target signal from the device under test;
isolating the environmental signal from the detected signal; and
processing the target signal to obtain dispersion information of the device under test.
2. The method of claim 1 , wherein the prescribed rate is above 1 kiloHertz.
3. The method of claim 1 , wherein the environmental frequency band is in an audio range of 1 to 20,000 Hertz.
4. The method of claim 1 , wherein the step of isolating the environmental signal from the detected signal includes:
converting the detected signal from time domain to frequency domain; and
filtering the detected signal to isolate the environmental signal from the detected signal in the frequency domain.
5. The method of claim 4 , wherein converting the detected signal from time domain to frequency domain includes performing a Fourier transform or a Laplace transform on the detected signal.
6. The method of claim 1 , wherein the prescribed rate is above 20,000 Hertz.
7. The method of claim 1 , wherein the step of isolating the environmental signal from the detected signal includes isolating signals below the prescribed rate.
8. The method of claim 1 , wherein the environmental signal is isolated from the detected signal using a Finite Impulse Response Filter or an Infinite Impulse Response Filter.
9. A dispersion measurement system, the system comprising:
a semiconductor laser source configured to output radiation over a range of wavelengths at a prescribed rate to a device under test, wherein the semiconductor laser source is configured to receive an input signal to discretely change the radiation over the range of wavelengths at the prescribed rate and the prescribed rate is sufficiently above environmental frequency bands;
a detector configured to detect output radiation from the device under test to obtain a detected signal associated with at least one physical property associated with the incident radiation over the range of wavelengths at the prescribed rate, wherein the detected signal includes environmental signal and target signal from the device under test;
one or more processors coupled to the detector, wherein the one or more processors are configured to isolate the environmental signal from the detected signal; and process the target signal to obtain dispersion information of the device under test; and
a system output configured to output the dispersion information of the device under test.
10. The system of claim 9 , wherein the prescribed rate is above 1 kiloHertz.
11. The system of claim 9 , wherein the environmental frequency band is in an audio range of 1 to 20,000 Hertz.
12. The system of claim 9 , wherein isolating the environmental signal from the detected signal includes:
converting the detected signal from time domain to frequency domain; and
filtering the detected signal to isolate the environmental signal from the detected signal in the frequency domain.
13. The system of claim 12 , wherein converting the detected signal from time domain to frequency domain includes performing a Fourier transform or a Laplace transform on the detected signal.
14. The system of claim 9 , wherein the prescribed rate is above 20,000 Hertz.
15. The system of claim 9 , wherein isolating the environmental signal from the detected signal includes isolating signals below the prescribed rate.
16. The system of claim 9 , wherein the one or more processors are further configured to isolate the environmental signal from the detected signal using a Finite Impulse Response Filter or an Infinite Impulse Response Filter.