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CN-122017860-A - Real-time absolute distance measurement system and method based on hybrid electro-optic frequency comb

CN122017860ACN 122017860 ACN122017860 ACN 122017860ACN-122017860-A

Abstract

The invention discloses a real-time absolute distance measurement system and method based on a hybrid electro-optic frequency comb. The carrier comb module is used for modulating and sending out light beams of the carrier comb, the electro-optical frequency comb module is used for modulating and sending out light beams of the electro-optical frequency comb and light beams of the local electro-optical frequency comb respectively, the light beams of the electro-optical frequency comb and the carrier comb are combined into light beams of the hybrid electro-optical frequency comb, and the light beams of the hybrid electro-optical frequency comb and the local electro-optical frequency comb are input to the measuring light path module to generate multi-heterodyne interference and output the multi-heterodyne interference signals to the signal processing module for analysis and measurement. The invention can simultaneously construct a series of synthetic wavelengths from large to small, is simultaneously used for absolute distance measurement, and finally realizes large-range high-precision real-time absolute distance measurement.

Inventors

  • CHEN BENYONG
  • XIE JIANDONG
  • YAN LIPING

Assignees

  • 浙江理工大学

Dates

Publication Date
20260512
Application Date
20260408

Claims (10)

  1. 1. A real-time absolute distance measurement system based on a hybrid electro-optic frequency comb is characterized in that: The device comprises a carrier wave comb module, an electro-optical frequency comb module, a measuring light path module, an optical fiber combiner (8) and a signal processing module (22), wherein the output end of the carrier wave comb module and one output end of the electro-optical frequency comb module are both connected to two input ends of the optical fiber combiner (8), the output end of the optical fiber combiner (8) and the other output end of the electro-optical frequency comb module are respectively input to the measuring light path module after passing through two collimators, the output end of the measuring light path module is connected with the signal processing module (22), and a moving part in the measuring light path module is fixedly connected with an object/target to be measured; The carrier comb module is modulated to send out light beam signals of carrier combs with different frequencies in light intensity, the electro-optical frequency comb module is modulated to send out light beam signals of the electro-optical frequency comb and light beam signals of the local electro-optical frequency comb after frequency shifting respectively, the two light beam signals are input to the optical fiber combiner (8) together to be combined to form the light beam signals with the mixed electro-optical frequency comb, the light beam signals with the local electro-optical frequency comb and the light beam signals of the local electro-optical frequency comb are input to the measuring light path module to generate multi-heterodyne interference so that detection can obtain multi-heterodyne interference signals of objects/targets to be detected, and finally the multi-heterodyne interference signals are analyzed and measured by the signal processing module (22).
  2. 2. The real-time absolute distance measurement system based on the hybrid electro-optic frequency comb according to claim 1, wherein the carrier comb module comprises a plurality of signal sources, a radio frequency combiner (4), a low-pass filter (5), a laser driving circuit (6) and a carrier light source (7), wherein the output ends of the signal sources are connected with the input end of the radio frequency combiner (4), the output end of the radio frequency combiner (4) is connected with the control end of the carrier light source (7) after passing through the low-pass filter (5) and the laser driving circuit (6) in sequence, and the output end of the carrier light source (7) outputs light beam signals with different frequencies and provided with the carrier comb and is connected with one input end of an optical fiber combiner (8).
  3. 3. The real-time absolute distance measuring system based on the hybrid electro-optic frequency comb according to claim 1, wherein the electro-optic frequency comb module comprises a seed light source (11), an optical fiber beam splitter (12), an acousto-optic frequency shifter (13), a first electro-optic phase modulator (14) and a second electro-optic phase modulator (15), wherein an output end of the seed light source (11) is connected with an input end of the optical fiber beam splitter (12), one output end of the optical fiber beam splitter (12) is connected with the first electro-optic phase modulator (14), a light beam signal with the electro-optic frequency comb is output after being modulated by the first electro-optic phase modulator (14), and the other output end of the optical fiber beam splitter (12) is connected with the second electro-optic phase modulator (15), and a light beam signal with the local electro-optic frequency comb is output after being modulated by the second electro-optic phase modulator (15).
  4. 4. The real-time absolute distance measurement system based on the mixed electro-optic frequency comb, which is disclosed in claim 1, is characterized in that the measurement light path module comprises a target lens (17), a reference lens (18), two polarization beam splitters (16 and 19) and two photodetectors (20 and 21), the mixed electro-optic frequency comb light beam is incident on the first polarization beam splitter (16) to be reflected and transmitted, the reflected light beam is incident on the second polarization beam splitter (19) to be reflected, the transmitted light beam is reflected and reversely returned to the first polarization beam splitter (16) to be transmitted again through the target lens (17), the local electro-optic frequency comb light beam is incident on the second polarization beam splitter (19) to be reflected and transmitted, the light beam reflected by the second polarization beam splitter (19) is incident on the first polarization beam splitter (16) to be reflected, the two light beams reflected and reversely transmitted by the first polarization beam splitter (16) are incident on the first photodetector (20), the light beam transmitted by the second polarization beam splitter (19) is reflected and reversely returned to the second polarization beam splitter (19) to be transmitted again after the two light beams are reflected and reflected again by the second polarization beam splitter (21).
  5. 5. The system for measuring the real-time absolute distance based on the hybrid electro-optical frequency comb according to claim 4, wherein the reference mirror (18) is fixed in position, and the target mirror (17) is fixed on the object/target to be measured and moves along with the object/target to be measured.
  6. 6. A real-time absolute distance measuring method applied to the real-time absolute distance measuring system according to any one of claims 1 to 5, characterized in that the method specifically comprises: 1) Hybrid electro-optic frequency comb generation Generating seed laser and carrier laser respectively, splitting the seed laser to generate a beam signal with an electro-optic frequency comb and a beam signal with a local electro-optic frequency comb, generating a beam signal with a carrier comb by the carrier laser, and combining the beam signal with the electro-optic frequency comb and the beam signal with the carrier comb to form a beam signal with a mixed electro-optic frequency comb; 2) The method comprises the steps that a light beam signal with a mixed electro-optical frequency comb and a light beam signal with a local electro-optical frequency comb are subjected to multi-heterodyne interference in a measuring light path module, and two mixed signals S 1 (t) and S 2 (t) with multi-heterodyne interferometry signals and reference signals are obtained by a photoelectric detector; the light beam signal with the mixed electro-optic frequency comb propagates in a light path measuring module to form a large-to-small composite wavelength chain, wherein the large-to-small composite wavelength chain comprises a primary composite wavelength, a secondary composite wavelength and a millimeter-level composite wavelength; 3) The two mixed signals obtained in the step 2) are input into a signal processing module (22), and the absolute distance accurate value of the object to be detected/the target to be detected is obtained through analysis of the signal processing module (22).
  7. 7. The real-time absolute distance measurement method of claim 6, wherein: The step 1) comprises the steps of emitting two paths of seed lasers by a seed light source (11), carrying out high-frequency electro-optic phase modulation on one path of seed lasers to obtain a beam signal with an electro-optic frequency comb, carrying out frequency shift and high-frequency electro-optic phase modulation on the other path of seed lasers by an acousto-optic frequency shifter (13) and a second electro-optic phase modulator (15) to generate a beam signal with a local electro-optic frequency comb, generating sinusoidal signals by multiple paths of signal sources, adding the sinusoidal signals to obtain one path of multi-frequency signals, inputting the multi-frequency signals, carrying out current modulation on a carrier light source (7), enabling the carrier light source (7) to generate the beam signal with carrier combs with different frequencies, and combining the beam signal with the electro-optic frequency comb and the beam signal with the carrier comb to obtain the beam signal with the hybrid electro-optic frequency comb.
  8. 8. The real-time absolute distance measurement method of claim 6, wherein: The frequency distribution of the beam signal with the electro-optical frequency comb and the beam signal with the carrier comb is preset, so that the beam signal with the hybrid electro-optical frequency comb forms a composite wavelength chain from large to small which satisfies the following formula when multi-heterodyne interference occurs in optical path propagation in the measuring optical path module.
  9. 9. The real-time absolute distance measurement method of claim 6, wherein: In the step 2), the light beam signal with the mixed electro-optic frequency comb is divided into two paths of light after entering the measuring light path module, wherein one path of light is reflected by the target mirror (17) and returns to be combined with the local electro-optic frequency comb light beam signal to obtain a measuring mixed signal S 1 (t) of the multi-heterodyne interferometry signal through photoelectric conversion, the other path of light is reflected by the two polarizing spectroscopes (16, 19) and combined with the local electro-optic frequency comb light beam signal reflected by the reference mirror (18), and the reference mixed signal S 2 (t) of the multi-heterodyne interferometry reference signal is obtained through photoelectric conversion, and the two mixed signals are respectively expressed as follows: S 1 (t)=∑ 3 i=1 A m (i)sin[2πf p (i)t+ψ m (i)] + ∑ 5 j=1 B m (j)sin[2πf d (j)t+φ m (j)] S 2 (t)=∑ 3 i=1 A r (i)sin[2πf p (i)t+ψ r (i)] + ∑ 5 j=1 B r (j)sin[2πf d (j)t+φ r (j)] Wherein i and j represent the frequency carrier, the sequence number of the frequency comb, f p (i) represent the i carrier frequency in the carrier comb, f d (j) represent the j-th comb component frequency of the multi-heterodyne interference signal, A m (i) and A r (i) represent the i carrier frequency amplitude in the measurement and reference light intensity signal, B m (j) and B r (j) represent the j-th comb component amplitude in the multi-heterodyne interference measurement and reference signal, ψ m (i) and ψ r (i) represent the i-th carrier frequency phase in the measurement and reference light intensity signal, φ m (j) and φ r (j) represent the j-th comb component phase in the multi-heterodyne interference measurement and reference signal, and t represents time.
  10. 10. The real-time absolute distance measurement method of claim 6, wherein: The step 3) is specifically as follows: 31 Firstly, the decimal phase of each synthetic wavelength in the synthetic wavelength chain is demodulated in parallel through a signal processing module (22); 32 Combining each synthetic wavelength in the synthetic wavelength chain with the decimal phase obtained in step 31), solving according to an equation set to obtain a major phase of each synthetic wavelength in the synthetic wavelength chain: L=λ ss[i1,i2] [N SS (i1,i2) + ε SS (i1,i2)]/2, i1,i2=1,2,…M p L=λ s[i] [N S (i) + ε S (i)]/2, i=1,2,…M p L=Λ s[j] [N Λ (j) + ε Λ (j)]/2, j=1,2,…M E Wherein L is an unknown distance value to be measured, epsilon SS (i1,i2)、ε S (i)、ε Λ (j) respectively represents the fractional phases of the secondary synthesis wavelength, the primary synthesis wavelength and the millimeter synthesis wavelength, and N SS (i1,i2)、N S (i)、N Λ (j) respectively represents the large-number phases of the secondary synthesis wavelength, the primary synthesis wavelength and the millimeter synthesis wavelength; 33 According to the obtained maximum number phase of the maximum serial number M E in millimeter-level synthesized wavelength, the absolute distance accurate value of the object to be measured/the target to be measured is obtained according to the following formula: L ADM =Λ s[ME] [N Λ (M E ) + ε Λ (M E )]/2 Where L ADM represents the final absolute distance measurement, Λ s[ME] represents the millimeter-scale composite wavelength with number M E , M E represents the largest number of millimeter-scale composite wavelengths, N Λ (M E ) and epsilon Λ (M E ) represent the fractional and fractional phases, respectively, corresponding to the millimeter-scale composite wavelength with number M E .

Description

Real-time absolute distance measurement system and method based on hybrid electro-optic frequency comb Technical Field The invention belongs to the technical field of laser absolute distance measurement, and particularly relates to a hybrid electro-optical frequency comb absolute distance measurement system and method. Background The laser absolute distance measurement technology is widely applied to the fields of precise assembly, robot calibration and the like, and in the application scenes, besides higher requirements on measurement precision and measurement range, real-time performance and high-speed measurement capability are becoming a core requirement increasingly. How to realize real-time measurement with large length and high precision is a common problem of the existing absolute distance measurement method. For example, the frequency scanning interferometry needs to measure the phase change amount in the scanning process, the scanning is finished to obtain a measurement result, the method is suitable for the absolute distance measurement of a static target, the dispersion interferometry needs to distinguish interference fringes by a spectrometer, the non-fuzzy distance and the real-time performance of the dispersion interferometry are limited by the performance of the spectrometer, and the large-scale and high-speed real-time measurement is difficult to realize. The femtosecond pulse alignment flight time method needs to adjust the repetition frequency of an optical comb in measurement to expand the non-fuzzy distance, thereby limiting the measurement instantaneity. The multi-wavelength interferometry constructs meter-scale composite wavelength chains by locking multiple lasers to an optical frequency comb, with high accuracy but with non-ambiguous distances still limited by the optical frequency comb repetition frequency. The multi-heterodyne interferometry is limited by the modulation frequency, usually in the order of centimeters, and needs to be expanded through time-sharing measurement steps of adjusting the repetition frequency, so that the real-time performance is limited. In summary, the simultaneous construction of the synthesized wavelength chains from large to small and the simultaneous demodulation of the fractional phases of the synthesized wavelengths, and the real-time calculation of the absolute distance are key to realizing the real-time absolute distance measurement with large length and high precision. Disclosure of Invention In order to solve the problems in the background technology, the invention discloses a real-time absolute distance measurement system and method based on a hybrid electro-optic frequency comb. The carrier wave comb is mixed into the electro-optic frequency comb to generate the mixed electro-optic frequency comb, which is used for simultaneously constructing a large-to-small synthetic wavelength chain and combining the phase synchronous demodulation technology and the transition calculation of the synthetic wavelength chain to obtain the absolute distance in real time. The method mainly comprises the following steps: 1. Real-time absolute distance measurement system based on hybrid electro-optic frequency comb: The device comprises a carrier wave comb module, an electro-optical frequency comb module, a measuring light path module, an optical fiber combiner and a signal processing module; The output end of the carrier wave comb module and one output end of the electro-optical frequency comb module are connected to two input ends of the optical fiber beam combiner, the output end of the optical fiber beam combiner and the other output end of the electro-optical frequency comb module are respectively input to two input ends of the measuring light path module after passing through the first collimator and the second collimator, the two output ends of the measuring light path module are connected to the signal processing module, and the moving part in the measuring light path module is fixedly connected with an object to be measured/a target to be measured; the carrier wave comb module is modulated to emit light beam signals (laser) with carrier wave combs with different frequencies in light intensity, the electro-optical frequency comb module is modulated to emit light beam signals with electro-optical frequency combs and frequency-shifted light beam signals with local electro-optical frequency combs respectively, the light beam signals with the electro-optical frequency combs and the light beam signals with the carrier wave combs are input into the optical fiber beam combiner together to form the light beam signals with the mixed electro-optical frequency combs, the light beam signals with the mixed electro-optical frequency combs and the light beam signals with the local electro-optical frequency combs are input into the measuring light path module together to generate multi-heterodyne interference so as to obtain multi-heterodyne interference signals with mov