Terahertz spectroscopy system and method
AssigneeNovatrans Group SA
InventorsJohn F. Roulston, Daniel Mandelik
Life of this patent
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Abstract
A terahertz spectrometer includes a terahertz-wave emitter and a terahertz receiver elements. The terahertz wave generated by means of generating beat frequency corresponding to the difference between two rapidly tunable continuous wave lasers. A difference in time exists between the interrogating signal and the reference signal at the receiver end side, which corresponds to intermediate frequency (IF), not centered around the baseband, i.e. zero Hertz. The offset step size of the intermediate frequency from zero Hertz is linearly correlated to the position of the interrogated object position.
Claims16
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.
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) radiation in a THz-range with a frequency sweep to cause a THz radiation response of the sample, wherein the irradiating comprises operating at least a first laser diode and a second laser diode configured to produce radiation of predetermined properties, the operating comprising:
- gradually changing, by a temperature controller, an operational temperature of an active region of the first laser diode, thereby causing a substantially monotonic change in a frequency output of the first laser diode and producing frequency modulation of the first radiation;
- and controlling, by an electric current controller, an electric current through the second laser diode so as to modulate the electric current of the second laser diode concurrently with the gradual changing of the operational temperature of the first laser diode, thereby inducing a frequency sweeping pattern in a frequency modulated output of the at least the first laser diode and the second laser diode;
- and
- 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.
Dependencies are inferred from the claim text.