Patent ID: 6949734
Filing Date: 2005-09-27
Classification: G01J,G01N

Abstract:
1. A system for sensing a sample, comprising: a first tunable source configured to emit first optical radiation over a range of wavelengths that is swept at a first frequency; a second fixed source configured to emit second optical radiation at a predetermined fixed wavelength that is amplitude modulated at a second frequency, the first tunable source and the second fixed source emitted simultaneously; a first detector configured to detect the first and second optical radiation scattered/reflected from the sample and generate a first detection signal; a first lock-in amplifier configured to process the first detection signal based on the first frequency to produce a first output signal; and a second lock-in amplifier configured to process the first detection signal based on the second frequency to produce a second output signal, wherein the first and second frequencies are not harmonically related to each other and are preselected to reduce inter-modulation between each other.