CN-122016250-A - System and method for generating and evaluating aberration suppression of middle infrared fixed light interference fringes based on 4F spatial filtering

CN122016250ACN 122016250 ACN122016250 ACN 122016250ACN-122016250-A

Abstract

The invention discloses a system and a method for generating and evaluating aberration suppression of middle infrared fixed star light interference fringes based on 4F system spatial filtering. The system is applied to coherent interferometry of middle-infrared band constant starlight in astronomical observation, and comprises a telescope collimation unit, an aberration equivalent unit, a 4F relay light path unit, an adjustable pinhole spatial filtering unit arranged on a 4F intermediate focal plane, a reference light generation and phase inclination modulation unit and a coherent superposition and interference pattern output unit. By arranging the pinholes, the high spatial frequency components of the wave fronts of the test arms are cut, so that the influence of atmospheric turbulence or high-order aberration on interference fringes is reduced, and the regularity of the fringes is improved. The system further provides a parameterization strategy for setting the pinhole size by taking the Airy spot radius as a scale, and can perform contrast analysis and wave front map PV value calculation on interference fringes under different pinhole multiplying power. The invention is suitable for the scenes such as mid-infrared coherent imaging, wave front shaping, spatial filtering teaching demonstration and the like.

Inventors

XU TENG
WANG ZHUYU
HOU YONGHUI
SUN YUE
WEI WEI

Assignees

中国科学院南京天文光学技术研究所

Dates

Publication Date: 20260512
Application Date: 20260211

Claims (7)

1. A system for generating and evaluating aberration suppression of mid-infrared sidereal light interference fringes based on 4F spatial filtering, comprising: A telescope collimation unit for coupling mid-infrared light from the stars to the system and forming a collimated beam; the aberration equivalent unit is arranged on the test light path and used for introducing controllable wavefront aberration to the test light to represent atmospheric turbulence or higher-order aberration; The 4F relay unit comprises a first lens and a second lens, the distance between the first lens and the second lens is the sum of the focal lengths of the two lenses, and the back focal plane of the first lens corresponds to the front focal plane of the second lens; The spatial filtering unit is arranged at the middle focal plane of the 4F relay unit and comprises a pinhole diaphragm with an adjustable aperture and is used for selectively transmitting the spatial frequency component of the test light; a reference light generation and modulation unit for generating reference light coherent with the test light and applying a controllable linear phase tilt to the reference light to set an interference fringe period and direction; and the coherent superposition and output unit is used for carrying out coherent superposition on the test light subjected to 4F spatial filtering and the reference light, outputting an interference intensity distribution map and carrying out contrast evaluation on interference fringes under different pinhole aperture conditions.
2. The system of claim 1, wherein the pinhole diaphragm has an aperture at an airy radius Setting a scale, wherein lambda is the working wavelength, F is the focal length of a 4F system lens, D is the diameter of an entrance pupil, and the radius of the pinhole is Wherein the pinhole radius magnification Taking 0.8-2.0.
3. The system of claim 2, wherein the pinhole radius magnification k comprises at least three steps 1.5, 1.2 and 1.0 for forming a plurality of contrast interferograms.
4. The system of claim 1, wherein the aberration introducing unit is a phase plane, and a plurality of higher order Zernike coefficients are arranged in the form of Zernike FRINGE PHASE to introduce high spatial frequency wavefront errors.
5. The system of claim 1, wherein the linear phase tilt parameter of the reference light is set according to a target stripe number N such that the stripe number in the caliber range satisfies Wherein Is a fringe period.
6. The system of claim 1, wherein the coherent addition and output unit performs coherent addition based on light field complex amplitude data to output interference intensity distribution and support uniform grid resampling of interferograms at different pinhole magnifications to ensure comparability.
7. A method for generating and evaluating aberration suppression of mid-infrared sidereal light interference fringes based on 4F spatial filtering, the method being based on the system of any one of claims 1 to 6, the method comprising: a) Acquiring fixed star mid-infrared light and collimating; b) Introducing a controllable wavefront aberration on the test light to characterize atmospheric turbulence or lens aberration; c) Inputting test light into a 4F relay light path, and setting a pinhole diaphragm at a 4F intermediate focal plane to spatially filter the test light; d) Generating reference light coherent with the test light, and applying a linear phase tilt to the reference light to generate interference fringes of a predetermined period; e) The test light and the reference light are coherently overlapped to obtain interference intensity distribution; f) Obtaining interference patterns under different pinhole multiplying powers by changing the pinhole aperture and repeating steps c) to e); g) And evaluating the fringe regularity of the interference pattern and testing the PV value of the wavefront chart to obtain the corresponding relation between the aberration suppression effect and the pinhole parameters.

Description

System and method for generating and evaluating aberration suppression of middle infrared fixed light interference fringes based on 4F spatial filtering Technical Field The invention relates to the field of coherent optics and spatial filtering, in particular to a method for eliminating wavefront distortion by using a spatial filtering technology under a middle-far infrared band so as to improve astronomical interference measurement fringes. Background In astronomical observation, the mid-infrared band (N band 8-13 um is commonly used in astronomical observation) has the advantages of sensitivity to dust radiation, small influence of interstellar extinction and the like, and is widely applied to the fields of star formation areas, planetary discs and astronomical observation with high angular resolution. Because the astronomical interferometry technology can break through the limitation of the caliber of a single telescope on the angular resolution, the angular resolution capability is greatly improved, and the technology is also widely applied to astronomical observation. In practical systems, high-order aberration and scattering cause wave front to have high spatial frequency phase fluctuation, which can cause the phenomena of bending, fracture and the like of fringes, seriously affect the regularity of interference fringes, and in particular in mid-infrared (such as 10 μm wave band) systems, the high-order aberration is often introduced into a laser beam-expanding collimation system due to the processing precision and refractive index non-uniformity of infrared materials (such as germanium and zinc selenide). The interference fringe damage caused by the higher-order aberration cannot be suppressed by changing the optical path difference or the inclination angle of the light. The 4F spatial filtering technology can realize space frequency selective transmission on a Fourier plane, and a pinhole can inhibit high space frequency components and improve the smoothness of an output wave front. However, existing spatial filters typically only act as simple "denoising" tools, lacking implementation paths in combination with streak generation, parameterized pinholes. Disclosure of Invention The invention aims to provide a system and a method for combining 4F spatial filtering and coherent superposition, which realize 'step-by-step improvement' of interference fringes by adjusting a Fourier surface pinhole and provide indexes such as fringe contrast and the like for quantitative evaluation. In order to achieve the above purpose, the present invention provides the following technical solutions: The invention provides a system for generating and evaluating aberration suppression of middle infrared star light interference fringes based on 4F spatial filtering, which comprises the following components: A telescope collimation unit for coupling mid-infrared light from the stars to the system and forming a collimated beam; the aberration introducing unit is arranged on the test light path and used for introducing controllable wave front aberration to the test light; The 4F relay unit comprises a first lens and a second lens, the distance between the first lens and the second lens is the sum of the focal lengths of the two lenses, and the back focal plane of the first lens corresponds to the front focal plane of the second lens; The spatial filtering unit is arranged at the middle focal plane of the 4F relay unit and comprises a pinhole diaphragm with an adjustable aperture and is used for selectively transmitting the spatial frequency component of the test light; a reference light generation and modulation unit for generating reference light coherent with the test light and applying a controllable linear phase tilt to the reference light to set an interference fringe period and direction; and the coherent superposition and output unit is used for carrying out coherent superposition on the test light subjected to 4F spatial filtering and the reference light, outputting an interference intensity distribution map and carrying out contrast evaluation on interference fringes under different pinhole aperture conditions. Further, the aperture of the pinhole diaphragm is in terms of an Airy spot radiusSetting a scale, wherein lambda is the working wavelength, F is the focal length of a 4F system lens, D is the diameter of an entrance pupil, and the radius of the pinhole isWherein the pinhole radius magnificationTaking 0.8-2.0. Further, the pinhole radius multiplying power k at least comprises three gears of 1.5, 1.2 and 1.0 and is used for forming a plurality of contrast interference patterns. Further, the aberration introducing unit is a phase plane, and a plurality of higher-order Zernike coefficients are set in a form of Zernike FRINGE PHASE to introduce a wavefront error with high spatial frequency. Further, the linear phase tilt parameter of the reference light is set according to the target stripe number N, so that the st