Plane interference photoelectric system for visible light wave band imaging

Abstract

The invention discloses a plane interference photoelectric system for visible light wave band imaging, which is characterized by comprising a microtube array, a microlens array, a photoelectric module group and a substrate, and is characterized in that the microtube array is used for shielding stray light; the micro lens array is used for collecting light; the photoelectric module group is used for completing baseline pairing, visible light wave narrow-band filtering, coupling interference and information processing; the substrate is used for fixing and supporting the whole plane interference photoelectric system. According to the planar interference photoelectric system, the micro-nano optical filter is adopted to replace an array waveguide grating to realize the tunable nano-scale ultra-narrow linewidth spectrum of the whole visible light wave band, and the planar interference photoelectric system can be used as a light remote sensing imaging system and a light visible light imaging system. The system is used for imaging visible light wave bands and has the advantages of being short in length, small in size, light in weight, large in imaging spectrum range and high in response speed.

Description

Technical Field

[0001] The present invention belongs to the field of interference imaging and micro-nano optical technology, and relates to a planar interference photoelectric system, and specifically to a visible light band planar interference photoelectric imaging system based on interference imaging and micro-nano optical technology. Background Art

[0002] In order to significantly reduce the length, volume and weight of the optical imaging system, the United States proposed a planar interferometric photoelectric imaging system in 2012. The system uses a microlens array to collect light, realizes interference pairing, phase adjustment, waveguide coupling, and coherent detection in photonic integrated circuits, and obtains spatial images through signal processing, which can reduce the length, volume and weight of the optical system by 10 to 100 times. In order to obtain a good interference effect, the system uses an arrayed waveguide grating to filter out a narrowband spectrum with a nanometer line width from the incident light band. However, the arrayed waveguide grating can only work in the near-infrared optical communication band (1540nm~1600nm). Since the optical energy loss of the arrayed waveguide grating is very large when working in the visible light band, the system is currently unable to image the visible light band. The wavelength of visible light is much smaller than the near-infrared wavelength, and the imaging resolution of the visible light band is much higher than that of the near-infrared band. Therefore, it is of great theoretical significance and practical value to study a planar interferometric photoelectric system for imaging in the visible light band. Summary of the invention

[0003] The present invention provides a planar interference photoelectric system for imaging in the visible light band, which adopts a micro-nano optical filter instead of an array waveguide grating to realize an ultra-narrow linewidth spectrum at the nanometer level that is tunable in the entire visible light band.

[0004] The objective of the present invention is achieved through the following technical solutions:

[0005] A planar interference photoelectric system for imaging in the visible light band is composed of a plurality of interference arms, each of which includes a microlens array and a photoelectric module group. A microtube array is arranged above each microlens array to block stray light. The photoelectric module group of each interference arm includes a group of micro-nano optical filters, a group of coupling modules, and an information processing module. Every two microlenses on each interference arm are paired to form an interference baseline. Light radiation is collected by the microlens array and irradiated to the surface of a group of micro-nano optical filters at a given angle. The micro-nano optical filter group converts the incident light into a nanometer-level ultra-narrowband spectrum in the visible light band. The ultra-narrowband spectrum of the same wavelength obtained by a pair of microlenses enters a coupling module to form interference fringes. The interference fringes are converted into electrical signals by a photoelectric detector in the coupling module. The incident angle of light to the micro-nano optical filter group is changed to obtain electrical signals converted by interference of different wavelengths. The coupling module group combines the electrical signals into spectrum data, and performs Fourier inverse transformation in the information processing module to form an image.

[0006] Compared with the prior art, the present invention has the following advantages:

[0007] The planar interference photoelectric system of the present invention can be used as a lightweight remote sensing imaging system and a lightweight visible light imaging system. The system performs imaging in the visible light band and has the advantages of short length, small size, light weight, large imaging spectral range and fast response speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 The structure diagram of a planar interferometric photoelectric system used for imaging in the visible light band and a local interferometric arm thereof;

[0009] Figure 2 This is a structural diagram of a micro-nano optical filter;

[0010] Figure 3 This is the output spectrum of a micro-nano optical filter;

[0011] Figure 4 It is a structural diagram of a coupling module;

[0012] Figure 5 A structural diagram of a liquid crystal phase retarder.

[0013] Figure 6 is the light distribution map of the observed scene instance;

[0014] Figure 7 This is an imaging image of the observed scene by a planar interferometric optoelectronic system used for imaging in the visible light band. DETAILED DESCRIPTION

[0015] The technical solution of the present invention is further described below in conjunction with the accompanying drawings, but is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be included in the protection scope of the present invention.

[0016] The present invention provides a planar interferometric photoelectric system for imaging in the visible light band, such as Figure 1 As shown, the planar interference optoelectronic system is composed of a microtube array, a microlens array, an optoelectronic module and a substrate, wherein: the microtube array is used to block stray light; the microlens array is used to collect light; the optoelectronic module group is used to complete baseline pairing, narrow-band filtering of visible light waves, coupled interference and information processing; the substrate is used to fix and support the entire planar interference optoelectronic system.

[0017] like Figure 1As shown, the planar interference optoelectronic system for imaging in the visible light band is composed of multiple interference arms, and the optoelectronic module group of each interference arm includes a group of micro-nano optical filters, a group of coupling modules, and an information processing module. Every two microlenses on each interference arm are paired to form an interference baseline. The light radiation is collected by the microlens array and irradiated to the surface of a group of micro-nano optical filters at a given angle. The micro-nano optical filter group converts the incident light into an ultra-narrow band spectrum of the nanometer order in the visible light band. The ultra-narrow band spectrum of the same wavelength obtained by each pair of microlenses enters a coupling module to form interference fringes. The interference fringes are converted into electrical signals by the photoelectric detector in the coupling module, and the incident angle of the light to the micro-nano optical filter group is changed to obtain electrical signals converted by interference of different wavelengths. The coupling module group combines the electrical signals into spectrum data, and performs Fourier inverse transform in the information processing module to form an image.

[0018] like Figure 2 As shown, the micro-nano optical filter in the optoelectronic module is composed of a one-dimensional sub-wavelength grating layer with a refractive index of 1.61, a first thin film layer with a refractive index of 2.06, a second thin film layer with a refractive index of 1.81, and a substrate with a refractive index of 1.51 from top to bottom. The thicknesses of the one-dimensional sub-wavelength grating layer, the first thin film layer, the second thin film layer, and the substrate are 92.9nm, 54.9nm, 60.8nm, and 2mm, respectively, and the period and grating line width of the one-dimensional sub-wavelength grating layer are 265nm and 132.5nm, respectively.

[0019] like Figure 3 As shown in the figure, when the light collected by the microlens array is irradiated to the micro-nano optical filter at different incident angles, the line width of the output spectrum does not exceed 2nm. By changing the incident angle, the narrowband spectrum can be tuned and the spectrum tuning range covers the entire visible light band. When the incident angle changes continuously from small to large, the peak wavelength of the spectrum continuously shifts from short wave to long wave within the visible light wavelength range according to a linear law.

[0020] like Figure 4 As shown, the coupling module includes a 2×2 multimode fiber waveguide structure, a liquid crystal phase retarder, and photodetectors A, B, C, and D. Figure 5As shown, a liquid crystal (LC) phase retarder with a response speed of milliseconds is used to improve the response speed of the coupling module. The processing principle of the LC phase retarder is to plate an indium tin oxide (ITO) film with a thickness of about 200nm on two transparent substrates, and then apply a polyimide (PI) film. The friction direction of the two PI films of the LC phase retarder is consistent. Finally, SiO2 microsphere particles with a diameter of 10 to 100μm are used to separate the two PI film layers, inject LC and seal. Applying voltage to the two ITO film layers can change the refractive index of the LC layer, thereby achieving fast phase delay. After combining the LC phase retarder with the optical fiber coupler, the interference fringes are debugged. The response speed of the PIC of this structure depends on the LC phase retarder. By improving the manufacturing process of the LC phase retarder, the response speed can be increased to the millisecond level.

[0021] The coupling module is used to collect the amplitude and phase information of the interference fringes, and the spectrum data is converted into images after photoelectric conversion. The complex visibility of the interference fringes can be expressed as:

[0022]

[0023] Where λ is the central wavelength of each spectral channel, z is the object distance, and B x , B y is the component of the interference baseline in the x and y coordinate axes, O(x, y, λ) is the two-dimensional light field distribution of the object corresponding to the wavelength λ. The cutoff frequency u of the plane interferometric imaging system on the object side max It can be expressed as:

[0024]

[0025] Where λ is the average wavelength, B max is the length of the longest interference baseline. The optical signals S and R pass through the two input ends of the 2×2 multimode fiber waveguide structure respectively, and then are evenly divided into two optical signals. The two signals evenly divided from the optical signal S are in phase, while one of the two signals evenly divided from the optical signal R has a 90° phase delay, so the two signals evenly divided from the optical signal R are in orthogonal phase. After coherent superposition, the photocurrents generated by the photodetectors A, B, C, and D are as follows:

[0026]

[0027] Among them, E1(t) is the amplitude of signal S, E2(t) is the amplitude of signal R, k1 and φ1 are the wave vector and phase of optical signal S, k2 and φ2 are the wave vector and phase of optical signal R, ω is the angular frequency of the light wave, φ1=αk1, φ2=αk2.

[0028] The output signals I(t) and Q(t) are:

[0029] I(t)=I A (t)-I B (t) = 4E1E2 cos(α·k) (7)

[0030] Q(t)=I C (t)-I D (t)=4E1E2 cos(α·k+π / 2) (8)

[0031] Among them, k = k1-k2. The amplitude E1, E2, phase φ = αk can be calculated by the following formula:

[0032]

[0033] The amplitude information and phase of the interference fringes can be obtained through formulas (3) to (10).

[0034] The imaging simulation of the planar interferometric optoelectronic system for imaging in the visible light band is carried out with the parameters shown in Table 1. Figure 6 Shown is a light distribution diagram of an observed scene example. Figure 7 Shown is an imaging image of the observed scene by a planar interferometric optoelectronic system used for imaging in the visible light band.

[0035] Table 1 Parameters of the planar interferometric optoelectronic system for imaging in the visible light band

[0036]

[0037]

Claims

1. A planar interferometric photoelectric system for imaging in the visible light band, characterized in that The system comprises a plurality of interference arms, each of which comprises a microlens array and a photoelectric module group. A microtube array is arranged above each microlens array for shielding stray light. The photoelectric module group of each interference arm comprises a group of micro-nano optical filters, a group of coupling modules, and an information processing module. Every two microlenses on each interference arm are paired to form an interference baseline. Light radiation is collected by the microlens array and irradiated to the surface of a group of micro-nano optical filters at a given angle. The micro-nano optical filter group converts the incident light into an ultra-narrow band spectrum of the nanometer order in the visible light band. The ultra-narrow band spectrum of the same wavelength obtained by a pair of microlenses enters a coupling module to form interference fringes. The interference fringes are converted into electrical signals by a photoelectric detector in the coupling module. The incident angle of light to the micro-nano optical filter group is changed to obtain electrical signals converted by interference of different wavelengths. The coupling module group combines the electrical signals into spectrum data, and performs Fourier inverse transformation in the information processing module to form an image.

2. The planar interferometric photoelectric system for imaging in the visible light band according to claim 1, characterized in that When the light collected by the microlens array is irradiated to the micro-nano optical filter at different incident angles, the line width of the output spectrum does not exceed 2nm. By changing the incident angle, the narrowband spectrum can be tuned and the spectrum tuning range covers the entire visible light band.

3. The planar interferometric photoelectric system for imaging in the visible light band according to claim 1 or 2, characterized in that The micro-nano optical filter is composed of a one-dimensional sub-wavelength grating layer with a refractive index of 1.61, a first thin film layer with a refractive index of 2.06, a second thin film layer with a refractive index of 1.81, and a substrate with a refractive index of 1.51 from top to bottom.

4. The planar interferometric photoelectric system for imaging in the visible light band according to claim 3, characterized in that The thicknesses of the one-dimensional sub-wavelength grating layer, the first thin film layer, the second thin film layer and the substrate are 92.9 nm, 54.9 nm, 60.8 nm and 2 mm respectively, and the period and grating line width of the one-dimensional sub-wavelength grating layer are 265 nm and 132.5 nm respectively.

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