Multi-stage fringe tracking method

Abstract

The present application relates to the technical field of optical interferometer, especially to a kind of multistage fringe tracking method, comprising the following steps: S1, using ABCD four-step phase shift method to the light beam received by two optical interferometers is interfered, and four-way interference light is formed;S2, one way carrying phase shift in four-way interference light is led out and interfered with the light beam received by the third optical interferometer, and fringe tracking result is obtained;S3, according to fringe tracking result, three interferometers are adjusted in optical path.The present application utilizes the light field information in the interference light of two optical interferometers and interferes with another optical interferometer, can realize the interference of at least three optical interferometers simultaneously, improves the adjustment efficiency of optical interferometer.

Description

Technical Field

[0001] This invention relates to the field of optical interferometer technology, and in particular to a multi-level fringe tracking method. Background Technology

[0002] Astronomical observations require telescopes to have sufficiently high resolution. The traditional method to increase telescope resolution is to increase the telescope aperture. However, large-aperture mirrors are very difficult to manufacture, and the manufacturing cost is proportional to the square of the aperture, increasing significantly with the increase in aperture. In addition, excessively large apertures make existing mechanical support structures inadequate and increase transportation difficulties.

[0003] Therefore, finding a way to improve imaging resolution without increasing the aperture of a single telescope has become an urgent need for astronomers. Among these methods, interferometric imaging is one of the main techniques for achieving high-resolution imaging, and optical interferometer arrays utilize interferometric imaging for high-resolution observations.

[0004] Existing optical interferometer arrays typically use any two optical interferometers to interfere, and adjust the optical path of the optical interferometers based on the interference results. However, this interference method suffers from low adjustment efficiency. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a multi-level fringe tracking method that utilizes the light field information in the interference light to perform interference again, enabling simultaneous interference from at least three optical interferometers and improving the adjustment efficiency of the optical interferometers.

[0006] The multi-level stripe tracking method provided by this invention includes the following steps:

[0007] S1. The ABCD four-step phase-shifting method is used to perform phase-shifting interference on the beams received by the two optical interferometers to form four interference beams;

[0008] S2. Extract one of the four interferometric beams carrying the phase shift and perform phase-shifted interference with the beam received by the third optical interferometer to obtain the fringe tracking result;

[0009] S3. Adjust the optical path of the three interferometers based on the fringe tracing results.

[0010] Preferably, step S1 specifically includes the following steps:

[0011] S11. Split the beams received by the two optical interferometers into sub-beams I1, I2, I3 and I4 respectively, and shift the phase of sub-beam I4 by π / 2.

[0012] S12, interference occurs between sub-beam I1 and sub-beam I3, and interference occurs between sub-beam I2 and the phase-shifted sub-beam I4, resulting in interference beam I. 13 Interference light I 13 Interference light I 24 Interference light I 24 `.

[0013] Preferably, step S2 specifically includes the following steps:

[0014] S21. Split the beam received by the third optical interferometer into sub-beams I5 and I6, and shift the phase of sub-beam I6 by π / 2.

[0015] S22, Interference light I 24 Interfering with sub-beam I5 to interfere with the interference light I 24 Interference with the phase-shifted sub-beam I6 yields fringe tracking results.

[0016] Preferably, when performing phase shifting on sub-beams I4 and I6, the optical fibers corresponding to sub-beams I4 and I6 are inserted into the same piezoelectric ceramic phase shifter.

[0017] Compared with the prior art, the present invention utilizes the light field information in the interference light of two optical interferometers to interfere with another optical interferometer, which can simultaneously achieve interference of at least three optical interferometers and improve the adjustment efficiency of optical interferometers. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating the multi-level stripe tracking method provided in an embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram illustrating the principle of the multi-level stripe tracking method provided in an embodiment of the present invention. Detailed Implementation

[0020] In the following description, embodiments of the invention will be described with reference to the accompanying drawings. In the description below, the same modules are denoted by the same reference numerals. Where the same reference numerals are used, their names and functions are also the same. Therefore, their detailed description will not be repeated.

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0022] After two optical interferometers interfere, the applicant discovered that the interfering light also has optical field information. This optical field information can be utilized by using residual heat to interfere the interfering light with another interferometer, thereby achieving interference from three interferometers. Based on the interference results of the three interferometers, the optical path length of the three optical interferometers can be adjusted simultaneously. Compared with adjusting two optical interferometers simultaneously, this can improve the adjustment efficiency of the optical interferometers.

[0023] Figure 1 and Figure 2 The flow and principle of the multi-level stripe tracking method provided according to embodiments of the present invention are shown respectively.

[0024] like Figure 1 and Figure 2 As shown, the multi-level stripe tracking method provided in this embodiment of the invention includes the following steps:

[0025] S1. The ABCD four-step phase-shifting method is used to perform phase-shifting interference on the beams received by the two optical interferometers to form four interference beams.

[0026] Step S1 specifically includes the following steps:

[0027] S11. The beam received by the first optical interferometer and the beam received by the second optical interferometer are split into beams respectively.

[0028] The beams split by the first optical interferometer are denoted as sub-beams I1 and I2, and the beams split by the second optical interferometer are denoted as sub-beams I3 and I4. Sub-beam I4 is phase-shifted by π / 2.

[0029] S12, interference occurs between sub-beam I1 and sub-beam I3, and interference occurs between sub-beam I2 and the phase-shifted sub-beam I4, resulting in interference beam I. 13 Interference light I 13 Interference light I 24 Interference light I 24 `.

[0030] S2. One of the four interferometric beams carrying a phase shift is extracted and subjected to phase-shifted interference with the beam received by the third optical interferometer to obtain fringe tracking results.

[0031] Step S2 specifically includes the following steps:

[0032] S21. Split the beam received by the third optical interferometer into sub-beams I5 and I6, and shift the phase of sub-beam I6 by π / 2.

[0033] S22, Interference light I 24 Interfering with sub-beam I5 to interfere with the interference light I 24Interference with the phase-shifted sub-beam I6 yields fringe tracking results.

[0034] S3. Adjust the optical path of the first, second, and third optical interferometers based on the fringe tracing results.

[0035] If the interference light after interference by the first, second, and third interferometers still has light field information, that is, clear interference fringes, then the interference light can be interfered with by the fourth interferometer, and so on, until the interference fringes are no longer clear.

[0036] This allows for simultaneous interference from multiple optical interferometers; the more optical interferometers involved, the higher the adjustment efficiency.

[0037] When performing phase shifting on sub-beams I4 and I6, the optical fibers corresponding to sub-beams I4 and I6 are inserted into the same piezoelectric ceramic phase shifter. The piezoelectric ceramic phase shifter uniformly generates phase shifts on sub-beams I4 and I6, ensuring that the phase shift amounts generated by sub-beams I4 and I6 are consistent.

[0038] Similarly, for the case of more sub-beams, the phase shift of each sub-beam can be uniformly generated by the piezoelectric ceramic phase shifter to ensure that the phase shift of each sub-beam is consistent.

[0039] Furthermore, in traditional interferometry, if the interference between the first and second optical interferometers is to be achieved between the second and third optical interferometers, the second optical interferometer needs to be split. The sub-beam split from the second optical interferometer then interferes with the third optical interferometer. Because the second optical interferometer is split, the energy is weakened, and the interference fringes between the second and first optical interferometers will be affected.

[0040] This invention eliminates the need for the second optical interferometer to split the light; instead, it uses the interference result of the first and second optical interferometers to interfere with the third optical interferometer, ensuring that no light energy is lost.

[0041] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0042] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A multi-level stripe tracking method, characterized in that, Includes the following steps: S1. The ABCD four-step phase-shifting method is used to perform phase-shifting interference on the beams received by the two optical interferometers to form four interference beams; step S1 specifically includes the following steps: S11. Split the beams received by the two optical interferometers into sub-beams I1, I2, I3 and I4 respectively, and shift the phase of sub-beam I4 by π / 2. S12, interference occurs between sub-beam I1 and sub-beam I3, and interference occurs between sub-beam I2 and the phase-shifted sub-beam I4, resulting in interference beam I. 13 Interference light I 13 Interference light I 24 Interference light I 24 `; S2. Extract one of the four interferometric beams carrying the phase shift and perform phase-shifted interference with the beam received by the third optical interferometer to obtain the fringe tracking result; Step S2 specifically includes the following steps: S21. Split the beam received by the third optical interferometer into sub-beams I5 and I6, and shift the phase of sub-beam I6 by π / 2. S22, Interference light I 24 Interfering with sub-beam I5 to interfere with the interference light I 24 Interference with the phase-shifted sub-beam I6 yields fringe tracking results; S3. Adjust the optical path of the three interferometers based on the fringe tracing results.

2. The multi-level stripe tracking method as described in claim 1, characterized in that, When performing phase shifting on sub-beams I4 and I6, the optical fibers corresponding to sub-beams I4 and I6 are inserted into the same piezoelectric ceramic phase shifter.

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