A two-dimensional spatial framing imaging system

Abstract

The present invention belongs to the field of imaging technology and discloses a two-dimensional spatial framing imaging system, comprising a first cylindrical mirror, a spatial dispersion unit, a reflector unit, a second cylindrical mirror, and an imaging lens. Light beams of different wavelengths pass through the first cylindrical mirror and are incident on the spatial dispersion unit, which spatially disperses the incident light beams to obtain a sub-pulse array arranged in m columns and n rows in a two-dimensional space. The reflector unit includes m reflectors arranged separately in space, and each column of light beams is reflected by a different reflector. After reflection, each column of light beams is incident on the second cylindrical mirror. After being focused by the second cylindrical mirror, each column of light beams is incident on the imaging lens. The present invention can effectively increase the number of frames of framing imaging, while making each column of images clearer, thereby improving the resolution of the two-dimensional spatial framing imaging system.

Description

Technical Field

[0001] The present invention belongs to the field of imaging technology, and more specifically, relates to a two-dimensional space framing imaging system. Background Art

[0002] Ultrafast imaging is an important tool for studying ultrafast phenomena in fundamental science and industry, such as laser-induced shock waves, plasma dynamics, photochemical reactions, and microfluidic dynamics. All-optical ultrafast imaging has broad application prospects. Its all-optical image separation is free from mechanical and electronic limitations and can achieve frame rates of approximately 100 fs.

[0003] However, in the prior art, for example, a solution of focusing multiple sub-beams distributed in a two-dimensional array using a microlens array, each small lens in the microlens array is used to focus on a sub-pulse for imaging. The diameter d of each small lens in such a microlens array must be very small, and the minimum resolvable angular distance obtained by the Rayleigh criterion is When d is smaller, the minimum resolvable angular distance The larger the distance, the blurrier the image. Furthermore, existing technologies typically use a single reflector to reflect the array-distributed pulse sequence, allowing the pulses to enter the imaging lens for imaging. However, because the multiple pulses returning from the grating are distributed separately, if only a single reflector is used to reflect them onto the imaging lens for imaging, the optical path length for each pulse sequence will inevitably differ. Consequently, when one image is adjusted to be clear, the images in the other images will become blurred. Ensuring that each image is clearer and improving the resolution of two-dimensional spatial framing imaging systems is a technical problem that needs to be addressed in this field. Summary of the Invention

[0004] The present invention solves the problem of low resolution of two-dimensional space framing imaging systems in the prior art by providing a two-dimensional space framing imaging system.

[0005] The present invention provides a two-dimensional spatial framing imaging system, comprising: a first cylindrical mirror, a spatial dispersion unit, a reflector unit, a second cylindrical mirror, and an imaging lens; light beams of different wavelengths pass through the first cylindrical mirror and are incident on the spatial dispersion unit, the spatial dispersion unit spatially disperses the incident light beams to obtain a sub-pulse array arranged in m columns and n rows in a two-dimensional space; the reflector unit comprises m reflectors separated in space, each column of light beams is reflected by a different reflector; each column of light beams after reflection is incident on the second cylindrical mirror, and each column of light beams focused by the second cylindrical mirror is incident on the imaging lens.

[0006] Preferably, the two-dimensional spatial framing imaging system further includes: an imaging processing unit; the imaging processing unit includes a camera and a computer, each column of light beams is focused onto the photosensitive surface of the camera through the imaging lens, and the computer connected to the camera processes and displays m×n imaging images.

[0007] Preferably, the spatial dispersion unit includes: a dispersive optical device, a focusing optical device and a two-dimensional shear mirror array; the dispersive optical device spatially disperses the incident light beam, the focusing optical device converges the spatially dispersed light beam to the two-dimensional shear mirror array, the two-dimensional shear mirror array reflects the light beam at different angles, and the reflected light beam is converged again by the focusing optical device, and after passing through the dispersive optical device, m×n sub-pulses separated in space are obtained.

[0008] Preferably, the two-dimensional shear mirror array includes m groups of reflective subunits, each group of reflective subunits has a different reflection angle in the horizontal direction; each group of reflective subunits includes n reflective mirror surfaces, each reflective mirror surface has a different reflection angle in the vertical direction.

[0009] Preferably, the reflective subunit located in the middle is recorded as the first group of reflective subunits, and the remaining groups of reflective subunits are arranged symmetrically about the first group of reflective subunits; for either left or right side, as the distance from the first group of reflective subunits increases, the reflection angle of the reflective subunit in the horizontal direction also increases accordingly.

[0010] Preferably, the dispersive optical device is a grating or a prism.

[0011] Preferably, the focusing optical device is a lens, a lens array or a cylindrical mirror.

[0012] Preferably, the two-dimensional spatial framing imaging system further includes: a first lens, and the light beam is incident on the first cylindrical mirror after passing through the first lens.

[0013] One or more technical solutions provided in the present invention have at least the following technical effects or advantages:

[0014] (1) Compared with the solution of focusing multiple sub-beams distributed in a two-dimensional array separately through a microlens array, the imaging lens used in the present invention can completely cover all incident light beams. Taking the imaging results of the same 25 frames as an example, the lens size required for the imaging lens used in the present invention to completely cover 25 sub-beams is D, and the size of each small lens in the microlens array is D / 5. Therefore, the minimum resolution of the present invention will be 1 / 5 of that of the microlens array, and the resolution can be increased by 5 times.

[0015] (2) Compared with the scheme of using a reflector to reflect the pulse sequence distributed in the array so that the pulse is incident on the imaging lens for imaging, the present invention sets a first cylindrical mirror before framing the light beam, and adjusts the optical path difference between the multiple columns of light beams through multiple reflectors after framing, and then adjusts the image through the second cylindrical mirror. Finally, when imaging is performed through the imaging lens, not only can the multiple columns of light beams be spatially separated on the camera, but each column of image can also be made clearer. The present invention can greatly improve the resolution of the two-dimensional spatial framing imaging system.

[0016] (3) The two-dimensional shear mirror array used in the present invention includes m groups of reflective subunits, each group of reflective subunits has a different reflection angle in the horizontal direction; each group of reflective subunits includes n reflective mirrors, each reflective mirror has a different reflection angle in the vertical direction. Based on the special structure of the two-dimensional shear mirror array, the present invention can divide the incident light into m columns of light beams in two-dimensional space according to the different spectral wavelengths, and each column of light beams contains n sub-beams. It can disperse the multi-spectrum in two-dimensional space into an array of m columns and n rows of sub-pulses, achieving a higher number of frames. When the present invention is applied to the fields of multi-spectral imaging and ultrafast imaging, the number of frames of multi-spectral imaging and ultrafast burst imaging can be increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of a two-dimensional spatial framing imaging system provided by an embodiment of the present invention;

[0018] Figure 2 A schematic structural diagram of a two-dimensional shear mirror array in a two-dimensional spatial framing imaging system provided by an embodiment of the present invention; wherein, Figure 2 (a) is a top view, Figure 2 (b) is the front view, Figure 2 (c) is the left view. DETAILED DESCRIPTION

[0019] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0020] This embodiment provides a two-dimensional spatial framing imaging system. Figure 1The optical system comprises a first lens 101, a first cylindrical mirror 102, a spatial dispersion unit, a reflector unit, a second cylindrical mirror 109, an imaging lens 110, and an imaging processing unit. Light beams of different wavelengths sequentially pass through the first lens 101 and the first cylindrical mirror 102 before entering the spatial dispersion unit. The spatial dispersion unit spatially disperses the incident light beams, generating a sub-pulse array arranged in m columns and n rows in a two-dimensional space. The reflector unit comprises m spatially separated reflectors, with each column of light beams reflected by a different reflector. After reflection, each column of light beams enters the second cylindrical mirror 109. After being focused by the second cylindrical mirror 109, each column of light beams enters the imaging lens 110. The imaging processing unit comprises a camera 111 and a computer. Each column of light beams is focused by the imaging lens 110 onto the photosensitive surface of the camera 111. The computer, connected to the camera 111, processes and displays m×n images.

[0021] The spatial dispersion unit includes: a dispersive optical device 103, a focusing optical device 104 and a two-dimensional shearing mirror array 105; the dispersive optical device 103 performs spatial dispersion on the incident light beam, the focusing optical device 104 converges the spatially dispersed light beam to the two-dimensional shearing mirror array 105, the two-dimensional shearing mirror array 105 reflects the light beam at different angles, and the reflected light beam is converged again by the focusing optical device 104, and after passing through the dispersive optical device 103, m×n sub-pulses separated in space are obtained.

[0022] The dispersive optical device 103 may be a grating, a prism, etc. The focusing optical device 104 may be a lens, a lens array, a cylindrical mirror, etc.

[0023] The two-dimensional shear mirror array 105 includes m groups of reflection subunits, each group of reflection subunits has a different reflection angle in the horizontal direction; each group of reflection subunits includes n reflection mirror surfaces, each reflection mirror surface has a different reflection angle in the vertical direction.

[0024] For example, the reflective subunit located in the middle is recorded as the first group of reflective subunits, and the remaining groups of reflective subunits are arranged symmetrically with respect to the first group of reflective subunits. For either left or right side, as the distance from the first group of reflective subunits increases, the reflection angle of the reflective subunit in the horizontal direction also increases.

[0025] The present invention will be further described below by taking as an example that the spatial dispersion unit is composed of a grating, a lens, and a two-dimensional shear mirror array, and the reflector unit includes three reflectors separated in space.

[0026] After passing through the first lens 101 and the vertically focused first cylindrical mirror 102, the image of the object hits the grating. After being dispersed by the grating, the light beam is converged by a lens onto the two-dimensional shearing mirror array 105. Different wavelengths will hit different reflective mirrors of the two-dimensional shearing mirror array 105. Different reflective mirrors have different reflection angles, reflecting each sub-pulse in different directions in two-dimensional space. After passing through the lens and the grating again, multiple sub-pulses will be arranged and returned in three columns in two-dimensional space. Three reflective mirrors (i.e., the first reflector 106, the second reflector 107, and the third reflector 108) respectively reflect these three columns of light beams and compensate for the optical path differences between them. The three reflected light beams all hit the vertically focused second cylindrical mirror 109. The second cylindrical mirror 109 focuses each column of light beams in the vertical direction, making them no longer parallel. At the same time, the second cylindrical mirror 109 and the first cylindrical mirror 102 form a 4f system. Therefore, the image information carried by each converged sub-pulse after passing through the second cylindrical mirror 109 remains unchanged. By adjusting the angles between the three reflectors simultaneously, the three beams can be made non-parallel, so that each sub-pulse passes through the imaging lens 110 and is imaged separately on the camera 111. Each lens and cylindrical mirror in the system is confocal on the grating, and the focal lengths of the first cylindrical mirror 102 and the second cylindrical mirror 109 are smaller than the focal lengths of the first lens 101 and the imaging lens 110.

[0027] The spatial dispersion unit in the present invention is further described below.

[0028] The present invention uses the dispersive optical device to expand the spectrum in the transverse dispersion, and then uses the focusing optical device to focus the light beam on different reflective mirror surfaces of the two-dimensional shearing mirror array, which is equivalent to performing a Fourier transform on the light beam. The two-dimensional shearing mirror array performs angular modulation on light beams of different wavelengths on the Fourier surface of the focusing optical device, and then returns through the focusing optical device and the dispersive optical device, which is equivalent to an inverse Fourier transform of the light beam. Light beams of different angles return to different positions in space, thereby achieving two-dimensional spatial spectroscopy of the light beam. The entire transformation process does not affect the image information carried by the light beam. Using it for multispectral imaging or burst ultrafast imaging can effectively increase the number of imaging frames.

[0029] Existing two-dimensional spatial spectrometry is usually achieved through diffraction optical elements, but the spectrum of each beam of light separated by this method is the same, and different spectra cannot be separated. Existing ultrafast imaging spectrometry systems based on wavelength time-domain stretching are mostly one-dimensional, and the size of each optical device severely limits the increase of sub-pulses in the one-dimensional spectrometry system. The present invention can divide the incident light into multiple sub-pulses according to the wavelength of the light source, and arrange them separately in two-dimensional space. For multi-spectral imaging, the more frames, the finer the spectrum is divided, which facilitates more detailed research on the absorption of different spectra by materials. The two-dimensional spatial framing imaging system provided by the present invention breaks through the limitations of one-dimensional spectroscopic imaging, and can disperse and arrange multiple spectra in two-dimensional space to achieve more frames, which is beneficial to research in the field of multi-spectral imaging.

[0030] Ultrafast burst imaging requires not only high temporal resolution but also high spatial resolution, and spatial spectrometry technology directly limits the number of imaging frames and imaging quality. Generally, ultrafast imaging involves expanding multiple sub-pulses into a column in one dimension, and recording the optical signals of this column of sub-pulses through a camera. Each sub-pulse is an image, so the sub-pulses are at a certain distance from each other. If the number of sub-pulses is large, the optical devices located on the rear optical path will be large, which is also detrimental to the performance of the entire system. In the prior art, the number of sub-pulses generally does not exceed 10, which will seriously limit the increase in the number of system frames. Although the number of frames of the entire system can be increased by designing multiple optical paths, this also increases the complexity of the system. The present invention can obtain m×n sub-pulses, each of which is an image, thereby achieving multi-frame imaging. The present invention can obtain more sub-pulses without affecting the imaging quality, which is beneficial to research in the field of ultrafast burst imaging.

[0031] The following describes the application of the present invention to multispectral imaging as an example.

[0032] After the incident light beam passes through the grating in the spatial dispersion unit, each spectrum will be dispersed laterally into a divergent line of light, which is then converged by the lens in the spatial dispersion unit. The grating and the two-dimensional shear mirror array are located at the focal points on both sides of the lens, so this divergent line of light will become a parallel line of light after passing through the lens, and the wavelengths of light at different positions are different. These different wavelengths of light are then incident on different reflective mirrors of the two-dimensional shear mirror array. Figure 2 , different reflecting mirror surfaces of the two-dimensional shear mirror array have different reflection angles, Figure 2 (a) is a top view of the two-dimensional shearing mirror array. For example, the two-dimensional shearing mirror array has 50 reflective mirror surfaces, which are divided into 5 groups of reflective subunits, and each group of reflective subunits includes 10 reflective mirror surfaces; Figure 2(b) is a front view of the two-dimensional shear mirror array, wherein the five groups of reflective subunits are tilted relative to each other, with the middle group being horizontal, and the two groups on the left and right being tilted a° and b° to the right, respectively, and the two groups on the right being tilted a° and b° to the left, respectively, with a symmetric left-right orientation. Figure 2 (c) is the left view. The 10 reflective mirrors in each group of reflective subunits have an inclination angle with each other and the inclination angle increases successively. The maximum inclination angle is c°. Therefore, each reflective mirror in the two-dimensional shearing mirror array has a different inclination angle, which allows light of different wavelengths to hit different reflective mirrors of the two-dimensional shearing mirror array respectively. The light beam will be divided into 50 sub-pulses and reflected back in the horizontal direction according to Figure 2 (b) shows that there are 5 reflections with different dip angles, which are divided into 5 groups; each group contains 10 sub-pulses in the vertical direction. Figure 2 As shown in (c), there are 10 reflections with different inclination angles; these reflected sub-pulses have different angles and are focused again by the lens. After passing through the grating, the sub-pulses will change from divergent to parallel in space, thus being arranged into a 5×10 sub-pulse array.

[0033] In summary, the present invention can improve the resolution of a two-dimensional spatial framing imaging system. When the present invention is applied to the fields of multispectral imaging and ultrafast imaging, the number of frames of multispectral imaging and ultrafast burst imaging can be increased.

[0034] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A two-dimensional spatial framing imaging system, characterized in that: include: A first cylindrical mirror, a spatial dispersion unit, a reflector unit, a second cylindrical mirror and an imaging lens; light beams with different wavelengths pass through the first cylindrical mirror and are incident on the spatial dispersion unit, the spatial dispersion unit spatially disperses the incident light beams to obtain a sub-pulse array arranged in m columns and n rows in a two-dimensional space, where m is greater than 1; the reflector unit includes m reflectors separated in space, and each column of light beams is reflected by a different reflector; each column of light beams after reflection is incident on the second cylindrical mirror, and each column of light beams focused by the second cylindrical mirror is incident on the imaging lens.

2. The two-dimensional spatial framing imaging system according to claim 1, characterized in that: Also includes: An imaging processing unit comprises a camera and a computer. Each column of light beams is focused onto the photosensitive surface of the camera through the imaging lens. The computer connected to the camera processes and displays m×n imaging images.

3. The two-dimensional spatial framing imaging system according to claim 1, wherein: The spatial dispersion unit includes: a dispersive optical device, a focusing optical device and a two-dimensional shear mirror array; the dispersive optical device spatially disperses the incident light beam, the focusing optical device converges the spatially dispersed light beam to the two-dimensional shear mirror array, the two-dimensional shear mirror array reflects the light beam at different angles, and the reflected light beam is converged again by the focusing optical device, and after passing through the dispersive optical device, m×n sub-pulses separated in space are obtained.

4. The two-dimensional spatial framing imaging system according to claim 3, characterized in that: The two-dimensional shear mirror array includes m groups of reflection subunits, each group of reflection subunits has a different reflection angle in the horizontal direction; each group of reflection subunits includes n reflection mirror surfaces, each reflection mirror surface has a different reflection angle in the vertical direction.

5. The two-dimensional spatial framing imaging system according to claim 4, characterized in that: The reflective subunit located in the middle is recorded as the first group of reflective subunits, and the remaining groups of reflective subunits are arranged symmetrically with respect to the first group of reflective subunits. For either left or right side, as the distance from the first group of reflective subunits increases, the reflection angle of the reflective subunit in the horizontal direction also increases.

6. The two-dimensional spatial framing imaging system according to claim 3, characterized in that: The dispersive optical component is a grating or a prism.

7. The two-dimensional spatial framing imaging system according to claim 3, wherein: The focusing optical device is a lens, a lens array or a cylindrical mirror.

8. The two-dimensional spatial framing imaging system according to claim 1, wherein: Also includes: The first lens is used for incident light beams onto the first cylindrical mirror after passing through the first lens.

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