| CPC G01J 3/108 (2013.01) [G01J 3/42 (2013.01); G01J 3/433 (2013.01); G01J 3/4338 (2013.01); G01N 21/3581 (2013.01); G01J 2003/4332 (2013.01)] | 16 Claims |

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1. A spectroscopic method for use in spectroscopic measurements in a sample, the method comprising:
irradiating the sample with an incident radiation having a frequency modulated continuous wave (FMCW) in a THz-range with a frequency sweep rate to cause a radiation response of the sample;
detecting an electromagnetic signal caused by an interaction between the radiation response and reference radiation, wherein the reference radiation comprises the FMCW in the THZ range with a time delay compared to the incident radiation, wherein the electromagnetic signal comprises a beat frequency associated with a frequency difference between the radiation response and the reference radiation; and
using the beat frequency to measure a time delay between the radiation response and the reference radiation and determine a radial dimension associated with a depth profile of the sample, a resolution of the radial dimension being based on the frequency sweep rate.
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