Method and system for eliminating double-optical-comb frequency spectrum aliasing

Abstract

The invention relates to a laser ranging method and system for eliminating double-optical-comb frequency spectrum aliasing, and the system comprises a first optical comb, a signal optical pulse emitted by the first optical comb passes through a first spectroscope, one beam of light enters a reference mirror, the other beam of light enters a measurement mirror, and the reference mirror and the light reflected by the measurement mirror are emitted to a second spectroscope through the first spectroscope; a second optical comb which emits a local oscillation light pulse to enter the second spectroscope and interferes with the light emitted by the first spectroscope; a first band-pass filter which is used for acquiring a frequency component of a part of light emitted by the second spectroscopein a certain frequency range; a second band-pass filter which is used for acquiring a frequency component of the other part of light emitted by the second spectroscope in another frequency range; anda signal processor which is used for processing the acquired frequency component signal to complete distance measurement.

Description

technical field [0001] The invention relates to a method and system for eliminating double-comb spectrum aliasing, and relates to the technical field of optical precision measurement. Background technique [0002] Absolute distance measurement has important applications in the fields of large-scale precision machinery manufacturing and aerospace. Traditional pulsed laser ranging or interferometric ranging techniques are not suitable for absolute distance measurement with large range, high precision and high speed. The new type of laser light source born in this century - femtosecond laser frequency comb, referred to as optical frequency comb or optical comb, has the characteristics of wide spectrum, multiple longitudinal modes, high coherence, narrow linewidth and so on. The emergence of optical frequency combs has promoted the rapid development of precision measurement technology. As a precision optical ruler in the time domain and frequency domain, the optical frequency ...

AI Technical Summary

Problems solved by technology

When it changes such that the spectral range of the sub-comb contains 0 or f r2 / 2, two sets of radio spectrum lines with different phase rules will appear in some frequency intervals, and aliasing will occur between these two sets of spectral lines, so that the phase-frequency slope cannot be calculated correctly, resulting in the inability to obtain usable ranging result

It should be noted that the repetition frequency term in the longitudinal mode frequency is due to the coefficient n 1 Amplification, which has a greater effect relative to a change in offset frequency

Susceptibility to spectral aliasing is the main reason why free-running dual-comb systems are unusable in industrial sites

In addition, for the dual optical comb system that only locks the repetition frequency but not the offset frequency, the aliasing phenomenon makes the system unable to measure stably for a long time in an industrial field environment; for the dual optical comb system that locks the repetition frequency and offset frequency Generally speaking, this aliasing phenomenon limits the adjustable range of repetition frequency and offset frequency, so that the dual optical comb system cannot adjust the repetition frequency and offset frequency of the optical comb arbitrarily according to needs.

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