# US 11,029,261 B2 · Methods and apparatus for direct multiplication Fourier transform millimeter wave spectroscopy > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,029,261 B2 - Document ID: US11029261B2 - Status: Granted - Kind: B2 - Application number: 16/807,270 - Filed: 2020-03-03 - Published: 2020-07-02 - Granted: 2021-06-08 - Earliest claimed: 2016-01-07 - Assignees: BrightSpec, Inc. - Applicants: BrightSpec, Inc. - Inventors: Justin L. Neill; Brent Harris; Brooks Hart Pate - Web page: https://patentgrep.com/patent/US11029261B2 ## CPC - G01N 22/00: Investigating or analysing materials by the use of microwaves or radio waves, i.e. electromagnetic waves with a wavelength of one millimetre or more (G01N3/00 - G01N17/00, G01N24/00 take precedence) - G01J 3/42: Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry (beam switching arrangements G01J3/08) - G01J 3/44: Raman spectrometry; Scattering spectrometry {; Fluorescence spectrometry} - G01J 3/453: by correlation of the amplitudes - G01N 21/636: {using an arrangement of pump beam and probe beam; using the measurement of optical non-linear properties; (non-linear optics per se G02F1/35)} - G01N 21/3581: using far infrared light; using Terahertz radiation - G01N 2021/3595: {using FTIR} - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N) ## Abstract Methods and apparatuses for direct multiplication Fourier transform millimeter wave spectroscopy are disclosed herein. A sample method includes generating at least one pulse of microwave electromagnetic energy. The sample method also includes frequency-multiplying the pulse(s) to generate at least one frequency-multiplied pulse and filtering at least one spurious harmonic of the frequency-multiplied pulse to generate at least one filtered pulse. The spurious harmonic is generated by frequency-multiplying the pulse. The method also includes exciting a sample using the filtered pulse. The method further includes detecting an emission from the sample. The emission is elicited at least in part by the filtered pulse. ## Claims ### Claim 1 An apparatus, comprising: a signal generator configured to generate at least one pulse of microwave electromagnetic energy in response to a trigger signal; a frequency multiplier circuit coupled to the signal generator, the frequency multiplier circuit configured to frequency-multiply the at least one pulse to generate at least one frequency-multiplied pulse, the frequency multiplier circuit further configured to excite a sample using the at least one frequency-multiplied pulse; and an emission detector configured to detect an emission from the sample, the emission elicited at least in part by the at least one frequency-multiplied pulse. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein the signal generator is further configured to generate the at least one pulse as at least one chirped pulse within a frequency range from about 1 GHz to about 3 GHz. ### Claim 3 (depends on 1) The apparatus of claim 1, wherein the emission detector is further configured to detect the emission in response to the trigger signal. ### Claim 4 (depends on 1) The apparatus of claim 1, wherein the at least one pulse comprises a first pulse, wherein the signal generator is further configured to generate a second pulse of microwave electromagnetic energy, the second pulse in phase with the first pulse, wherein the frequency multiplier circuit is further configured to frequency-multiply the second pulse generate a second frequency-multiplied pulse, and wherein the emission detector is further configured to mix the second frequency-multiplied pulse and the emission to generate a downconverted emission signal within the bandwidth of an analog-to-digital converter (ADC). ### Claim 5 (depends on 1) The apparatus of claim 1, wherein the emission detector is further configured to detect the emission via heterodyne detection. ### Claim 6 (depends on 1) The apparatus of claim 1, wherein the signal generator comprises an internally derived timebase configured to generate the trigger signal. ### Claim 7 (depends on 1) The apparatus of claim 1, wherein the emission detector is configured to detect the emission in response to the trigger signal. ### Claim 8 (depends on 1) The apparatus of claim 1, wherein the signal generator is configured to receive the trigger signal from a variable frequency source external to the signal generator. ### Claim 9 A method comprising: generating, with a free-running signal generator, a first microwave pulse and a second microwave pulse in response to a first trigger signal; frequency-multiplying the first microwave pulse to form a first millimeter-wave signal, the first millimeter-wave signal including a first millimeter-wave pulse and a first spurious emission; filtering the first spurious emission from the first millimeter-wave signal to yield the first millimeter-wave pulse; frequency-multiplying the second microwave pulse to form a second millimeter-wave signal, the second millimeter-wave signal including a second millimeter-wave pulse and a second spurious emission; filtering the second spurious emission from the first millimeter-wave signal to yield the first millimeter-wave pulse; exciting a sample with the first millimeter-wave pulse to produce a first sample emission; mixing the first sample emission with the second millimeter-wave pulse to produce a first downconverted sample emission; detecting the first downconverted sample emission to produce a first electronic signal; generating, with the free-running signal generator, a third microwave pulse and a fourth microwave pulse in response to a second trigger signal, the third microwave pulse and the fourth microwave pulse being phase-coherent with the first microwave pulse and the second microwave pulse; frequency-multiplying the third microwave pulse to form a third millimeter-wave signal, the third millimeter-wave signal including a third millimeter-wave pulse and a third spurious emission; filtering the third spurious emission from the third millimeter-wave signal to yield the third millimeter-wave pulse; frequency-multiplying the fourth microwave pulse to form a fourth millimeter-wave signal, the fourth millimeter-wave signal including a fourth millimeter-wave pulse and a fourth spurious emission; filtering the fourth spurious emission from the fourth millimeter-wave signal to yield the fourth millimeter-wave pulse; exciting the sample with the third millimeter-wave pulse to produce a second sample emission, the second sample emission being phase-coherent with the first sample emission; mixing the second sample emission with the fourth millimeter-wave pulse to produce a second downconverted sample emission; detecting the second downconverted sample emission to produce a second electronic signal; and averaging the first electronic signal and the second electronic signal. ### Claim 10 (depends on 9) The method of claim 9, wherein the frequency of first millimeter-wave pulse is offset from the frequency of the second millimeter-wave pulse by from about 720 MHz to about 1440 MHz.