Patent ID: 7312435

Claim:
A method of determining a physical state of an optical device with the steps of: coupling a first optical signal to the optical device, wherein a first optical property of said first optical signal is varied according to a first function over the time, measuring a second optical property over the time of a first response signal returning from the optical device in response to the first optical signal and establishing a first result function of said second optical property in dependence of the first optical property of the first optical signal, coupling a second optical signal to the optical device, wherein the first optical property of said second optical signal is varied according to a second function of the time that is different from the first function over the time, measuring the second optical property over the time of a second response signal returning from the optical device in response to the second optical signal and establishing a second result function of said second optical property in dependence of the first optical property of the second optical signal, and determining the physical state based on a combination of the first and the second result functions, wherein a combination of the first and the second result functions is performed by determining a first center value of at least a part of the first function and a second center value of at least a part of the second function and determining a resulting center value in dependence of said first and second center values.