CN-121994167-A - Large-range long-baseline interference fringe tracking method

CN121994167ACN 121994167 ACN121994167 ACN 121994167ACN-121994167-A

Abstract

The invention relates to a large-range long-baseline interference fringe tracking method, belongs to the technical field of optical measurement, and solves the problems that the existing fringe tracking method depends on single wavelength or limited wave bands and is difficult to realize high-precision and large-dynamic-range measurement in a wide spectrum. The method comprises the following steps of utilizing a built-in light source to project a light source in an interference direction, utilizing a voice coil motor carried by the rear end of a reflecting mirror to modulate, guaranteeing that the rear end has no non-common light path, utilizing an optical fiber beam combining device as a light source input, adopting three wavelengths to input, utilizing the three wavelengths to form a high-precision and large-dynamic-range test framework, connecting the test framework with a front-end light path, balancing and teaching by comparing the phase difference of the non-common light path at the rear end with the phase difference at the front end, moving a differential guide rail, and utilizing a plane reflecting mirror to select a corresponding light reflection light path to compensate a large range of geometric delay. The invention improves the performance and reliability of the long baseline interference array in a complex observation environment.

Inventors

AN QICHANG
LIU XINYUE
LI HONGWEN

Assignees

中国科学院长春光学精密机械与物理研究所

Dates

Publication Date: 20260508
Application Date: 20260212

Claims (2)

1. The large-range long-baseline interference fringe tracking method is characterized by comprising the following steps of: projecting a light source to the interference direction by using a built-in light source; modulating by using a voice coil motor pair carried by the rear end of the reflector, so as to ensure that the rear end has no non-common optical path; The optical fiber beam combining device is used as a light source for input, three wavelengths are used for input, and the three wavelengths are used for forming a high-precision and large-dynamic-range test framework; The testing structure is connected with the front-end light path, the balance adjustment is carried out by comparing the phase difference of the rear-end non-common light path with the phase difference of the front-end, meanwhile, the differential guide rail is moved, and the plane mirror is utilized to select the corresponding light reflection light path so as to compensate the large-range geometric delay.
2. The method of claim 1, further comprising, prior to the step of directing the light source to the interference using the built-in light source, a pupil alignment step of the planar mirror, the pupil alignment step comprising: reducing the base difference of the system by adjusting the secondary mirror; The method for actively controlling the balance position by adopting calibration and singular value decomposition concretely comprises the steps of obtaining the position and angle information of incident light through iterative measurement before and after focusing based on curvature sensing, constructing a control matrix and performing singular value decomposition to construct an orthogonal adjustment mode, and performing orthogonal pupil adjustment on the plane mirror according to the control matrix.

Description

Large-range long-baseline interference fringe tracking method Technical Field The invention relates to the technical field of optical measurement, in particular to a large-range long-baseline interference fringe tracking method. Background Long baseline interference arrays are a key technology to achieve astronomical high resolution imaging. Along with the increasingly weak observation targets and the continuously improved requirements on the fineness of the celestial structure, the requirements on the baseline length, the working spectrum width and the phase stability of the interference array are also becoming severe. The traditional interference fringe tracking method faces a series of challenges in coping with large-range geometric delay compensation, simultaneous operation of wide spectrum and high-precision optical path difference real-time correction. In particular, to achieve stable interference fringe detection, precise path matching and compensation must be performed for the paths from the different telescopes. The existing compensation method is mostly dependent on a mechanical delay line, the dynamic range and the moving precision of the compensation method are contradictory, and the positioning precision of the micrometer level or even the submicron level is difficult to maintain at the same time when the compensation method moves in a large range, so that the quick and accurate tracking capability of time-varying delay under a long base line is limited. In addition, the single wavelength phase detection method has a phase ambiguity problem in that the range of measurement is not generally limited to one wavelength, and it is difficult to directly cope with a large-amplitude optical path difference disturbance exceeding several wavelengths caused by an atmospheric disturbance, mechanical vibration, or a large-range baseline projection change. In interferometric arrays employing optical fibers for beam transport, while optical fibers increase the flexibility and stability of the system, new complexities are introduced. The dispersion characteristics of the optical fiber and the coupler, the influence of the environmental temperature drift on the length of the optical fiber, and the possible pointing errors and aberrations of the telescope at the front end of the system are converted into the wavefront errors and phase noise of the final composite beam, so that the co-phase maintenance in a wide spectrum section is particularly difficult. The existing fringe tracking method is difficult to synchronously calculate and compensate the complex error sources in a wide spectrum, so that the contrast of interference fringes is reduced, and the observation sensitivity and the imaging quality are affected. Therefore, a novel interference fringe tracking method needs to be developed, which has the following capabilities of (1) realizing high-precision residual optical path difference detection and locking under the background of large-scale geometric delay (corresponding to optical path differences of tens of centimeters or even meters), (2) solving the problem of single-wavelength measurement phase ambiguity by utilizing wide-spectrum information, expanding the phase disturbance range capable of capturing and tracking, and (3) effectively distinguishing and compensating aberration or error of a system common optical path and a non-common optical path part and improving overall phase stability and fringe visibility. Aiming at the above needs, the invention provides a stripe tracking method integrating a multi-wavelength phase measurement technology and a precise delay compensation mechanism, so as to improve the performance and reliability of a long baseline interference array in a complex observation environment. Disclosure of Invention In order to solve the problems, the invention provides a large-range long-baseline interference fringe tracking method. A large-range long baseline interference fringe tracking method comprises the following steps: A built-in light source is utilized to project a light source in the interference forming direction; Modulating the system engineering by using a voice coil motor carried by the rear end of the reflector, and ensuring that the rear wheel has no non-common optical path; The optical fiber beam combining device is used as a light source for input, three wavelengths are used for input, and the three wavelengths are used for forming a high-precision and large-dynamic-range test framework; The system is connected with the front-end light path, the balance adjustment is carried out by comparing the phase difference of the rear-end non-common light path with the phase difference of the front-end, meanwhile, the differential guide rail is moved, and the plane reflector is utilized to select the corresponding light reflection light path so as to compensate the large-scale geometric delay. The invention has the beneficial effects that the system deviation angle can be dete