Photon integrated interference imaging system based on front-end wave type microlens array

Abstract

The invention discloses a photon integrated interference imaging system based on a front-end wave-shaped microlens array, and the system comprises a microlens array which is of a wave-shaped structure and is formed by arranging a plurality of same interference arms according to a certain rule, the lenses on each interference arm and the lenses on the adjacent different interference arms can be paired to realize acquisition of optical signals; and the photon integrated chip and the signal processing system are positioned below the micro-lens array, and are used for transmitting the optical signal and performing interference processing to obtain target space frequency spectrum information, and then performing inverse Fourier transform to obtain a restored image of the target. According to the invention, the wave-shaped micro-lens array is designed, the one-dimensional to two-dimensional frequency spectrum coverage of the system is realized, and better imaging quality is realized by using fewer lenses.

Description

Technical Field

[0001] The invention belongs to the field of interference imaging, and in particular relates to a photon integrated interference imaging system based on a front-end wave-shaped microlens array. Background Art

[0002] Traditional optical telescopes use the principles of light refraction and reflection to form images. In order to improve the spatial resolution of the optical system, it is necessary to increase the aperture of the optical system, but at the same time the size, mass, power consumption and cost of the telescope also increase. Traditional imaging technology is approaching its capacity limit. In order to break through the limitations of the aperture of traditional telescopes, researchers have proposed a new imaging technology based on the Vansit Zernike theorem, which is called photon integrated interferometric imaging technology. Compared with traditional optical imaging technology, the imaging resolution of photon integrated interferometric imaging technology is not limited by the aperture. It collects target light information through a microlens array, transmits and interferes light signals in a photon integrated chip, and collects, processes and reconstructs interference signals through a back-end signal processing system. The system can greatly reduce the size of the imaging system and can be flexibly carried on space-based and ground-based equipment for imaging.

[0003] However, photon integrated interferometric imaging technology is still in its early stages of development, and its maturity and commercial application require further research and development. The arrangement of the microlens array and the baseline pairing method directly affect the UV spectrum coverage of the system, which in turn affects the imaging quality. The lens arrangement is mainly polar coordinate arrangement, but there are problems of radial spectrum redundancy and sparse tangential spectrum sampling, which makes the restored image obtained by the direct inverse Fourier transform of the system have more artifacts and poor imaging quality. Summary of the invention

[0004] The purpose of the present invention is to solve the problems of radial spectrum redundancy and sparse tangential spectrum sampling in the prior art, which cause poor system imaging quality. A photon integrated interference imaging system based on a front-end wave-shaped microlens array is proposed to achieve spectrum coverage from one dimension to two dimensions, and achieve better imaging quality with fewer lenses.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A photon integrated interference imaging system based on a front-end wave-shaped microlens array, comprising:

[0007] A microlens array, wherein the microlens array has a wavy structure and is composed of a plurality of identical interference arms arranged in a certain pattern, wherein the lenses on each interference arm and the lenses on adjacent different interference arms can be paired in pairs to realize the collection of optical signals;

[0008] The photonic integrated chip and signal processing system are located below the microlens array. They transmit the optical signal and perform interference processing to obtain the target spatial spectrum information, and then perform inverse Fourier transform to obtain the restored image of the target.

[0009] Compared with the prior art, the present invention has the following beneficial effects:

[0010] 1. The present invention optimizes the arrangement of the microlens array, and can achieve higher quality imaging effects with fewer lenses; the lenses on each interferometer arm are no longer arranged in a single straight line, so that the relationship between adjacent interferometer arms is closer, and the lenses of adjacent interferometer arms can be paired in pairs to form a baseline, and the directions of forming the baseline are more abundant, and the spectrum coverage range that can be obtained is wider, so that the imaging quality of the entire system is higher;

[0011] 2. The present invention has the advantages of small size, light weight, and can be flexibly mounted on space-based, ground-based and other imaging systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The above and other aspects, features and advantages of the present invention will be more clearly understood through the following detailed description in conjunction with the accompanying drawings, in which:

[0013] Figure 1 This is a diagram showing the internal structure of the photon integrated interference imaging system based on the front-end wavy microlens array of the present invention.

[0014] Figure 2 It is a schematic diagram of parameter design of the arrangement of the wave-shaped microlens array of the present invention.

[0015] Figure 3 Schematic diagram of the baseline pairing method of the wave-shaped microlens array arrangement of the present invention, wherein (a) is the horizontal pairing method, and (b) is the vertical pairing method.

[0016] Figure 4 The UV spectrum coverage diagram of the wavy microlens array of the present invention arranged in two baseline pairing modes.

[0017] Figure 5 This is the direct restoration image of the USAF1951 resolution plate of the present invention. Among them, (a) is the initial image; (b) is the system restoration image of the designed wavy microlens array arrangement.

[0018] Figure 6 This is the direct restoration image of the photographer by the present invention. Among them, (a) is the initial image; (b) is the system restoration image of the designed wave-shaped microlens array arrangement. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0020] The specific implementation of the present invention is described in detail below in conjunction with specific embodiments.

[0021] Figure 1 FIG. 1 is an internal structure diagram of the photon integrated interference imaging system based on the front-end wavy microlens array of the present invention. Figure 1 As shown, the system includes:

[0022] A microlens array, wherein the microlens array has a wavy structure and is composed of a plurality of identical interference arms arranged in a certain pattern, wherein the lenses on each interference arm and the lenses on adjacent different interference arms can be paired in pairs to realize the collection of optical signals;

[0023] The photonic integrated chip and signal processing system are located below the microlens array. They transmit the optical signal and perform interference processing to obtain the target spatial spectrum information, and then perform inverse Fourier transform to obtain the restored image of the target.

[0024] As a preferred embodiment of the present invention, the steps of establishing the microlens array unit are as follows:

[0025] S1. Calculate the angle between the innermost lenses of adjacent interference arms according to the following formula The innermost lens of the interferometer arm is arranged to form a closed circle, and the angle is determined by the straight line formed by connecting the center point of the circle with the origin of the photon integrated interferometric imaging system. size:

[0026] ,

[0027] Wherein, p represents the number of interference arms. The number of interference arms is generally set to be greater than 10 to ensure that the number of lenses in the system is not too low, so as not to affect the imaging quality. In the specific implementation of the present invention, the number of interference arms is set to 26;

[0028] Set an initial interferometer arm, and record the phase of the innermost lens of the initial interferometer arm as 0. Then the phase of the innermost lens of the jth interferometer arm is .

[0029] S2. Calculate the distance from the center of the innermost lens to the origin of the photon integrated interference imaging system according to the following formula: :

[0030] ,

[0031] Wherein, d represents the diameter of the lens, and its size depends on the processing technology and the manufacturing requirements of the system. In the specific implementation of the present invention, d is selected as 1 mm; Represents the angle between the innermost lenses of adjacent interference arms.

[0032] like Figure 2 As shown, in order to ensure that two adjacent lenses do not interfere with each other, the distance between the two lenses should be greater than d; the spatial distance between the two lenses is named baseline length, represented by B; B can be calculated by the coordinates of the center points of the two lenses, as shown in the following formula:

[0033] ,

[0034] in, , are the coordinates of the two lenses respectively.

[0035] S3. Calculate the distance between the center point of the i-th lens on each interferometer arm and the origin of the photon integrated interferometric imaging system according to the following formula: :

[0036] ,

[0037] in, It represents the distance from the center of the innermost lens of each interferometer arm to the origin of the photon integrated interferometric imaging system. The above formula can ensure that the distance between two lenses is greater than d and there is no overlap between the lenses.

[0038] S4. Calculate the phase of the center point of the i-th lens on the j-th interference arm relative to the phase of the innermost lens according to the following formula: :

[0039] ,

[0040] in, represents the phase of the innermost lens of the j-th interferometer arm, express Round down, It means that the direction of the lenses on the same interferometer arm changes every q lenses. represents an arbitrary phase change, through which the wave-like arrangement of lenses can be realized; Figure 2 As shown, in the specific implementation of the present invention, q is 3, that is, the extension direction of every three lens interference arms is changed once, Pick .

[0041] S5. Calculate the center point coordinates of all lenses in the microlens array according to the following formula:

[0042] ,

[0043] in, represents the distance between the center point of the i-th lens on each interferometer arm and the origin of the photon integrated interferometer imaging system, i represents the i-th lens on each interferometer arm, j represents the j-th interferometer arm starting from the set initial interferometer arm, and the initial interferometer arm j is 1. is the phase value of the center point of the i-th lens on the j-th interferometer arm relative to the phase of the innermost lens.

[0044] The spatial distance vector between any two lenses forms an interference baseline. Assume that the coordinates of the two lenses are , , then the spatial frequency f corresponding to the interference baseline formed by the pairing of these two lenses can be expressed as follows:

[0045] ,

[0046] in, represents the wavelength of light in the photon integrated interference imaging system, and z represents the distance from the plane where the target is located to the plane of the microlens array. Different spectral information of the target can be obtained according to different pairing methods of two lenses.

[0047] After different microlenses are paired in pairs to obtain enough spatial frequencies, the target image can be restored by performing an inverse Fourier transform on the spatial frequency coverage.

[0048] like Figure 3 (a) and (b) show the lateral and radial pairing methods adopted by the present invention, and as much spectrum information as possible is collected by combining the two pairing methods. Figure 4 The UV spectrum coverage diagram of the wave-shaped microlens array of the present invention under two baseline pairing modes. As a preferred embodiment of the present invention, the specific method of pairing the microlens arrays is as follows:

[0049] The optical signal collected by each lens is divided into two parts in a 1:1 ratio using optical fiber, one for lateral pairing and the other for radial pairing. The specific lateral pairing method is that the i-th lens on one interference arm is paired with the i-th lens on the adjacent interference arm; the specific radial pairing method is that the i-th lens on one interference arm is paired with the n-i+1-th lens on the adjacent interference arm (n is the total number of lenses on each interference arm).

[0050] As a preferred embodiment of the present invention, the wavy microlens array is connected to a photon integrated chip, and an optical waveguide, an arrayed waveguide grating (AWG), a phase modulator, and a balanced orthogonal detector are integrated on the photon integrated chip to transmit and interfere with the optical signal. The specific structure is as follows Figure 1As shown. The optical waveguide transmits the optical signal, and the array waveguide grating performs splitting multiplexing on the optical signal to obtain narrow-band light waves of different wavelengths; the phase modulator performs phase modulation on the optical signal transmitted by the optical waveguide and the narrow-band light wave transmitted by the array waveguide grating, so that the two light waves meet the interference conditions and are transmitted to the balanced orthogonal detector; the balanced detector performs interference and signal measurement on the two light waves to obtain the in-phase current I and the orthogonal current Q; the amplitude and phase of the interference fringes are extracted from I and Q, and the complex coherence factor of the target is obtained through the digital signal processing system; the light intensity distribution of the target is obtained by performing inverse Fourier transform on the complex coherence factor, so as to realize the imaging and reconstruction of the target.

[0051] The process of obtaining the complex coherence factor of the target by the digital signal processing system through the amplitude and phase of the interference fringes is as follows: the amplitude k and phase of the photon integrated interference imaging system can be obtained by the in-phase current I and the orthogonal current Q. :

[0052] ,

[0053] Then the negative coherence factor is obtained through the amplitude and phase:

[0054] .

[0055] This is the main function of the signal processing system in the photonic integrated interferometric imaging system.

[0056] As a preferred embodiment of the present invention, the specific imaging process of the photon integrated interference imaging system based on the wave-shaped microlens array is as follows:

[0057] The wave-shaped microlens array receives the optical signal of the distant space target and couples the signal to the photonic integrated chip. The optical signal is transmitted through the optical waveguide on the photonic integrated chip, and the waveguide array grating is used for multiplexing to obtain narrow spectrum light waves of different wavelengths. The phase modulator phase modulates the optical signal transmitted by the optical waveguide and the narrow spectrum light wave transmitted by the array waveguide grating, so that they meet the interference conditions and are transmitted to the balanced orthogonal detector. The balanced detector interferes with the two light waves and measures the signal to obtain the in-phase current I and the orthogonal current Q. The amplitude and phase of the interference fringes are extracted from I and Q, and the complex coherence factor of the target is obtained through the digital signal processing system. The light intensity distribution of the target is obtained by inverse Fourier transforming the complex coherence factor, and the imaging and reconstruction of the target are realized. The imaging effect of the final system is as follows: Figure 5 and Figure 6 As shown, it can be seen that the imaging quality of the system is high and some detailed information of the object can be distinguished.

[0058] The above are only preferred embodiments of the present invention. It should be pointed out that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention. These should also be regarded as the protection scope of the present invention, and these will not affect the effect and practicality of the implementation of the present invention.

Claims

1. A photon integrated interference imaging system based on a front-end wave-shaped microlens array, characterized in that: include: A microlens array, wherein the microlens array has a wavy structure and is composed of a plurality of identical interference arms arranged in a certain pattern, wherein the lenses on each interference arm and the lenses on adjacent different interference arms can be paired in pairs to realize the collection of optical signals; The photonic integrated chip and signal processing system are located below the microlens array. They transmit the optical signal and perform interference processing to obtain the target spatial spectrum information, and then perform inverse Fourier transform to obtain the restored image of the target.

2. The photon integrated interference imaging system based on the front-end wavy microlens array according to claim 1 is characterized in that: The steps of establishing the microlens array arrangement are as follows: Step S1: Calculate the angle between the innermost lenses of adjacent interference arms according to the following formula: The innermost lens of the interferometer arm is arranged to form a closed circle, and the angle is determined by the straight line formed by connecting the center point of the circle with the origin of the photon integrated interferometric imaging system. size: ， Where p represents the number of interference arms; Set an initial interferometer arm, and record the phase of the innermost lens of the initial interferometer arm as 0. Then the phase of the innermost lens of the jth interferometer arm is ; Step S2: Calculate the distance from the center of the innermost lens to the origin of the system according to the following formula: : ， Where d is the diameter of the lens, represents the angle between the innermost lenses of adjacent interference arms; Step S3: Calculate the distance between the center point of the i-th lens on each interferometer arm and the origin of the photon integrated interferometric imaging system according to the following formula: : ， in, Indicates the distance from the center of the innermost lens of each interferometer arm to the origin of the photon integrated interferometric imaging system; Step S4: Calculate the phase value of the center point of the i-th lens on the j-th interference arm relative to the phase value of the innermost lens according to the following formula: : ， in, represents the phase of the innermost lens of the j-th interferometer arm, express Round down, It means that the direction of the lenses on the same interferometer arm changes every q lenses. represents an arbitrary phase change, and the wave-like arrangement of the lenses is realized by the above phase change; Step S5, calculating the center point coordinates of all lenses in the microlens array according to the following formula: ， in, represents the distance between the center point of the i-th lens on each interferometer arm and the origin of the photon integrated interferometer imaging system, i represents the i-th lens on each interferometer arm, j represents the j-th interferometer arm starting from the set initial interferometer arm, and the initial interferometer arm j is 1. is the phase value of the center point of the i-th lens on the j-th interferometer arm relative to the phase of the innermost lens.

3. The photon integrated interference imaging system based on the front-end wavy microlens array according to claim 1 is characterized in that: The spatial distance vector between any two lenses forms an interference baseline. Assume that the coordinates of the two lenses are , , then the spatial frequency f corresponding to the interference baseline formed by the pairing of these two lenses is expressed by the following formula: ， in, represents the light wavelength of the photon integrated interference imaging system, and z represents the distance from the target plane to the microlens array plane.

4. The photon integrated interference imaging system based on the front-end wavy microlens array according to claim 1 is characterized in that: After different microlenses are paired in pairs to obtain spatial frequency coverage, the spatial frequency coverage is inversely Fourier transformed through the signal processing system to restore the target image.

5. The photon integrated interference imaging system based on the front-end wavy microlens array according to claim 1 is characterized in that: The specific method of pairing the lenses in pairs is as follows: Optical fiber is used to divide the light signal collected by each lens into two parts in a 1:1 ratio, one part is used for lateral pairing and the other part is used for radial pairing. The lateral pairing method is: the i-th lens on one interference arm is paired with the i-th lens on the adjacent interference arm; the radial pairing method is: the i-th lens on one interference arm is paired with the n-i+1-th lens on the adjacent interference arm, where n is the total number of lenses on each interference arm.

6. The photon integrated interference imaging system based on the front-end wavy microlens array according to claim 1 is characterized in that: The wave-shaped microlens array is connected to a photon integrated chip, and an optical waveguide, an arrayed waveguide grating (AWG), a phase modulator, and a balanced orthogonal detector are integrated on the photon integrated chip, wherein the optical waveguide transmits an optical signal, and the arrayed waveguide grating performs light splitting and multiplexing on the optical signal to obtain narrow-spectrum light waves of different wavelengths; the phase modulator performs phase modulation on the optical signal transmitted by the optical waveguide and the narrow-spectrum light wave transmitted by the arrayed waveguide grating, so that the two light waves meet the interference condition and are transmitted to the balanced orthogonal detector; the balanced detector performs interference and signal measurement on the two light waves to obtain an in-phase current I and an orthogonal current Q; the amplitude and phase of the interference fringes are extracted from I and Q, and the complex coherence factor of the target is obtained through a digital signal processing system; the light intensity distribution of the target is obtained by performing inverse Fourier transform on the complex coherence factor, thereby realizing imaging and reconstruction of the target.

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