Design method of Fermat spiral Greek ladder photon sieve and its imaging optical path

A design method and imaging optical path technology, applied in optics, diffraction gratings, optical elements, etc., to achieve the effect of improving beam imaging quality and increasing imaging contrast

Active Publication Date: 2021-09-07
SHANGHAI INST OF OPTICS & FINE MECHANICS CHINESE ACAD OF SCI
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Therefore, zone plates and photon sieves can only achieve one imaging result

Method used

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  • Design method of Fermat spiral Greek ladder photon sieve and its imaging optical path
  • Design method of Fermat spiral Greek ladder photon sieve and its imaging optical path
  • Design method of Fermat spiral Greek ladder photon sieve and its imaging optical path

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Embodiment 1

[0025] figure 1 A schematic diagram of the design process of a Fermat spiral Greek ladder photon sieve. In the picture:

[0026] (a) is a Fermat spiral diagram. The Fermat spiral conforms to the equation R=a×θ 1 / 2 , where R is the radius in polarized coordinates, a is the adjustment coefficient, and θ is the angle in polarized coordinates. When the radial phase of the Greek ladder photon sieve changes 2π, the Fermat helix rotates one circle.

[0027] (b) is a schematic diagram of the structure of the Greek ladder photonic sieve, which is obtained by modulating the pore distribution in the photonic sieve with the Greek ladder sequence code. Under monochromatic parallel wave illumination, a three-dimensional array focal point with equal intensity distribution can be generated to achieve coherent focusing and imaging. The overall radius and wavelength focal length of the Greek ladder photon sieve follow the following relationship: r n 2 =n×λ×f, where n represents the numbe...

Embodiment 2

[0043] According to the relationship between the overall radius of the Fermat spiral Greek ladder photon sieve and the wavelength focal length: r n 2 =n×λ×f, when the wavelength and the reference focal length are respectively set to 2.8nm and 2.8mm, a Greek ladder photon sieve working in the X-ray band is obtained. The Fermat spiral Greek ladder photon sieve can be obtained through the modulation of the Fermat spiral as mentioned above, which can produce axial three focal points. The focal lengths of the three focal points are: 3.3799mm, 2.8000mm, and 2.3899mm respectively. The processed base is the amplitude Type, making the amplitude type Fermat spiral Greek ladder photon sieve, the amplitude type Fermat spiral Greek ladder photon sieve uses diffraction to realize the modulation of the amplitude and phase of the light wavefront, and will not lose its effect due to the strong absorption characteristics of the material. Repeat the design process and imaging optical path in Ex...

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Abstract

The point spread function determines the imaging properties of the optical system, and different point spread functions can achieve different imaging results. By introducing the Fermat helix into the Greek ladder photon sieve, the Fermat helix modulates the distribution positions of the sieve holes in the Greek ladder photon sieve to obtain the Fermat helix Greek ladder photon sieve. Through the imaging optical path based on the Fermat spiral Greek ladder photon sieve to generate multiple focal points in the axial direction, the function of different point spread functions of the multi-focal plane of a single device is realized, including anisotropic Airy disk and vortex focus, which can be applied to coherence Focusing and imaging from X-ray to terahertz band in light field. The first and third focuses are anisotropic Airy disks, which can achieve different resolutions in different directions for the input object, which helps to improve the resolution of the object's interested direction; the second focus is the vortex focus, The vortex focus can be used for optical trapping. In addition, when used for imaging, the radial Hilbert transform can be realized based on the helical phase filter, and the edge enhancement of the amplitude and phase objects can be realized.

Description

technical field [0001] The invention relates to a diffractive optical element, in particular to a design method of a Fermat spiral Greek ladder photon sieve capable of realizing different point spread functions of multiple focal planes under a coherent light field and its imaging optical path. Background technique [0002] Due to its strong penetrating ability, X-rays are widely used in the non-destructive imaging and detection of internal structures in biomedical imaging, industrial production, material science and other fields. However, due to the strong absorption and weak refraction effect of the optical device material in the visible light band, the visible light band device cannot be used in the short wavelength band. As a diffractive optical element, the photon sieve can realize focusing and imaging in the X-ray band by modulating the amplitude and phase of the light wavefront. The photon sieve is developed on the basis of the Fresnel zone plate. In addition to the p...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G02B5/18G02B27/00G02B27/42
CPCG02B5/1876G02B27/0012G02B27/4205
Inventor 张军勇徐守英周申蕾朱健强张艳丽
Owner SHANGHAI INST OF OPTICS & FINE MECHANICS CHINESE ACAD OF SCI
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