Parallax-free and time-difference-free multispectral imaging system and method

Abstract

The invention discloses a parallax-free and time-difference-free multispectral imaging system and a parallax-free and time-difference-free multispectral imaging method, and solves the problem that an existing multispectral imaging device cannot meet the requirements of large-view-field, multi-channel, time-difference-free and parallax-free high-precision multispectral detection. The system specifically comprises an incident window, a light splitting unit, first to eighth imaging mirrors, first to eighth optical filters and first to eighth detectors. The incident window is used for receiving target light; the light splitting unit is used for splitting the received target light into eight paths of emergent light; the first to eighth imaging mirrors, the first to eighth optical filters and the first to eighth detectors are sequentially arranged on light paths where eight paths of emergent light are located in the emergent direction of the emergent light according to the sequence of one imaging mirror, one optical filter and one detector; the peak transmission wavelengths of the first to eighth optical filters are eight preset and different wavelengths. According to the invention, eight-channel multispectral imaging can be realized, and the high-precision multispectral detection requirements of large field of view, multiple channels, no time difference and no parallax can be met.

Description

Technical Field

[0001] The present invention relates to an imaging system and method, and in particular to a multi-spectral imaging system and method without parallax and time difference. Background Art

[0002] Multispectral imaging optical systems can be used for long-term phenological observations of the growth and development of plants and animals. They can also be used to investigate the surface morphology, material composition, distribution and other characteristics of targets during geological surveys. By selecting the characteristic spectrum corresponding to the observed target, changes in physiological indicators of plants and animals, mineral composition and evolution can be detected, which can play an important role in scientific research, disaster warning, material detection and other aspects.

[0003] The design schemes generally adopted by multispectral imaging optical systems include the following:

[0004] 1) A filter wheel imaging device is used. By adding a rotating device in the imaging mirror to switch different narrow-band filters, spectra of different spectral bands can be acquired. The device can realize independent imaging of each spectral band, but the optical system contains moving parts, and the reliability is not high when working in the field. In addition, the filter wheel imaging method is a non-simultaneous imaging method. Each spectral band cannot image the same target at the same time, and the time threshold registration is difficult;

[0005] 2) An imaging device with multiple cameras placed side by side is used. The principle of this device is simple. Multiple cameras are placed side by side. Each imaging channel is relatively independent and the overall envelope is compact. However, the imaging areas of each channel in this device will be different, which will cause parallax and easily lead to errors in the later image registration.

[0006] 3) Filter array imaging device, which realizes multispectral imaging by adding a filter array at the rear end of the imaging mirror. It has a compact structure and shares a single camera and detector, but realizes multispectral imaging by dividing the field of view. The imaging field of view is small and spectral aliasing is prone to occur.

[0007] Therefore, the above devices cannot meet the requirements of high-precision multi-spectral detection with large field of view, multi-channel, no time difference and no parallax. Summary of the invention

[0008] In order to solve the technical problem that existing multispectral imaging devices cannot meet the requirements of high-precision multispectral detection with large field of view, multi-channel, no time difference and no parallax, the present invention provides a multispectral imaging system and method with no parallax and no time difference.

[0009] In order to achieve the above object, the present invention adopts the following technical solution:

[0010] A multi-spectral imaging system without parallax and time difference, which is special in that it includes an incident window, a light splitting unit, first to eighth imaging mirrors, first to eighth filters and first to eighth detectors;

[0011] The incident window is used to receive target light;

[0012] The light splitting unit is used to split the received target light into eight outgoing lights;

[0013] The first to eighth imaging mirrors, the first to eighth filters and the first to eighth detectors are respectively arranged in sequence on the optical paths of the eight outgoing lights along the outgoing direction of the outgoing light in the order of one imaging mirror, one filter and one detector;

[0014] The peak transmission wavelengths of the first to eighth filters are eight preset and different wavelengths.

[0015] Further, the light splitting unit includes a first dichroic mirror, a folding mirror, a first beam splitter, a second beam splitter, a second dichroic mirror, a third dichroic mirror, a fourth dichroic mirror and a fifth dichroic mirror;

[0016] The first dichroic mirror is arranged on the optical path of the target light received by the incident window, and is used to separate the target light into a first transmitted light and a first reflected light;

[0017] The folding mirror is arranged on the optical path of the first reflected light, and is used to reflect the first reflected light to form a second reflected light parallel to the first transmitted light;

[0018] The first beam splitter is arranged on the optical path of the first transmitted light, and is used to split the first transmitted light into a second transmitted light and a third reflected light;

[0019] The second beam splitter is arranged on the optical path of the second reflected light, and is used to split the second reflected light into a third transmitted light and a fourth reflected light;

[0020] The second dichroic mirror is arranged on the optical path of the second transmitted light, and is used to separate the second transmitted light into a fourth transmitted light and a fifth reflected light;

[0021] The third dichroic mirror is arranged on the optical path of the third reflected light, and is used to separate the third reflected light into a fifth transmitted light and a sixth reflected light;

[0022] The fourth dichroic mirror is arranged on the optical path of the third transmitted light, and is used to separate the third transmitted light into a sixth transmitted light and a seventh reflected light;

[0023] The fifth dichroic mirror is arranged on the optical path of the fourth reflected light, and is used to separate the fourth reflected light into a seventh transmitted light and an eighth reflected light;

[0024] The fourth transmitted light, the fifth reflected light, the fifth transmitted light, the sixth reflected light, the sixth transmitted light, the seventh reflected light, the seventh transmitted light and the eighth reflected light constitute eight paths of the outgoing light.

[0025] Furthermore, the structures of the first to eighth imaging lenses are the same, and respectively include a first biconvex glass lens A, a biconcave glass lens B, and a second biconvex glass lens C which are sequentially arranged along the exit direction of the exit light;

[0026] Definition: The direction close to the incident light is the front, and the direction far away from the incident light is the back;

[0027] The first biconvex glass lens A has a front surface curvature radius R1 of 7.945 mm, a rear surface curvature radius R2 of -29.16 mm, and a center distance between the front surface and the rear surface of 2.73 mm;

[0028] The front surface curvature radius R3 of the biconcave glass lens B is -8.785 mm, and the rear surface curvature radius R4 is 6.535 mm; the center distance between the front surface and the rear surface of the first biconvex glass lens A is 1.36 mm; the center distance between the rear surface and the front surface is 1.82 mm;

[0029] The front surface curvature radius R5 of the second biconvex glass lens C is 29.16mm, and the rear surface curvature radius R6 is -7.945mm; the center distance between its front surface and the rear surface of the biconcave glass lens B is 1.8mm, and the center distance between its rear surface and its front surface is 2.73mm; the center distance between its rear surface and the corresponding detector detection surface located on its rear side is 10.75mm.

[0030] Further, the refractive index of the first biconvex glass lens A is 1.7469, and the linear Abbe number is 51.0086;

[0031] The refractive index of the biconcave glass lens B is 1.7552, and the linear Abbe number is 27.5300;

[0032] The refractive index of the second biconvex glass lens C is 1.7469, and the linear Abbe number is 51.0086.

[0033] Further, the peak transmission wavelengths of the first to eighth filters are 415nm, 511nm, 553nm, 570nm, 670nm, 720nm, 754nm and 890nm, respectively, and the bandwidths of the eight filters are 20nm, 20nm, 15nm, 14nm, 13nm, 10nm, 10nm, 40nm, respectively, and the refractive index of the eight filters is 1.5168, the linear Abbe number of the eight filters is 64.1987, and the diameter of the eight filters is 17.5mm×1mm;

[0034] The peak transmittances of the first to second filters are greater than or equal to 90%, the peak transmittances of the third to fifth filters are greater than or equal to 85%, the peak transmittances of the sixth to seventh filters are greater than or equal to 80%, and the peak transmittance of the eighth filter is greater than or equal to 92%.

[0035] Furthermore, the transmission bandwidth of the incident window ranges from 400nm to 910nm;

[0036] The transmission bandwidth of the first dichroic mirror is in the range of 650nm-910nm, and the reflection bandwidth is in the range of 400nm-600nm;

[0037] The reflection bandwidth range of the folding mirror is 400nm-600nm;

[0038] The transmission bandwidth of the first beam splitter is in the range of 650nm-910nm, and the reflection bandwidth is in the range of 650nm-910nm;

[0039] The transmission bandwidth of the second beam splitter is in the range of 400nm-600nm, and the reflection bandwidth is in the range of 400nm-600nm;

[0040] The transmission bandwidth of the second dichroic mirror is in the range of 860nm-910nm, and the reflection bandwidth is in the range of 690-750nm;

[0041] The transmission bandwidth of the third dichroic mirror is in the range of 730nm-780nm, and the reflection bandwidth is in the range of 650nm-690nm;

[0042] The transmission bandwidth of the fourth dichroic mirror is in the range of 555nm-595nm, and the reflection bandwidth is in the range of 490nm-525nm;

[0043] The transmission bandwidth range of the fifth dichroic mirror is 520nm-580nm, and the reflection bandwidth range is 400nm-440nm.

[0044] Furthermore, the average transmittance of the incident window is greater than or equal to 90%;

[0045] The transmittance of the first dichroic mirror is greater than or equal to 93%, and the reflectivity thereof is greater than or equal to 90%;

[0046] The reflectivity of the folding mirror is greater than or equal to 90%;

[0047] The transmittance and reflectance ranges of the first beam splitter and the second beam splitter are both 50%±3%;

[0048] The transmittance and reflectance ranges of the second dichroic mirror, the third dichroic mirror, the fourth dichroic mirror and the fifth dichroic mirror are all greater than or equal to 90%.

[0049] Furthermore, the size of the incident window is 92 mm×73 mm×5 mm;

[0050] The size of the first dichroic mirror is 83mm×80mm×2mm;

[0051] The size of the folding mirror is 61mm×61mm×2mm;

[0052] The sizes of the first beam splitter and the second beam splitter are both 35mm×54mm×2mm;

[0053] The sizes of the second dichroic mirror, the third dichroic mirror, the fourth dichroic mirror and the fifth dichroic mirror are all 25 mm×38 mm×2 mm.

[0054] Furthermore, the refractive index of the incident window, the first dichroic mirror, the folding mirror, the first beam splitter, the second beam splitter, the second dichroic mirror, the third dichroic mirror, the fourth dichroic mirror and the fifth dichroic mirror are all 1.5168, and the linear Abbe number is all 64.1987.

[0055] A multispectral imaging method without parallax and time difference adopts the multispectral imaging system without parallax and time difference, and its special feature is that it includes the following steps:

[0056] Step 1, receiving target light through the incident window;

[0057] Step 2: Split the target light into eight outgoing lights through a light splitting unit;

[0058] Step 3, using the first to eighth imaging mirrors to converge the eight-way outgoing light respectively;

[0059] Step 4, using the first to eighth filters to filter the converged outgoing light into different spectral bands respectively;

[0060] Step 5, using the first to eighth detectors to detect the eight paths of filtered light respectively, to obtain eight sets of detection data;

[0061] Step 6: Imaging of the target light is achieved by aligning the eight sets of detection data.

[0062] Beneficial effects of the present invention:

[0063] 1. The multispectral imaging system and method with no parallax and no time difference provided by the present invention can realize eight-channel multispectral imaging, with a large number of spectral bands and a wide detectable spectral range, and can meet the needs of high-precision multispectral detection with large field of view, multi-channel, no time difference and no parallax.

[0064] 2. Compared with the multi-spectral imaging method of the filter wheel, the present invention eliminates moving parts, has high reliability, and meets the requirements of long-term field work. Each channel can image the same target in real time, avoiding observation errors caused by non-simultaneous imaging and improving imaging quality.

[0065] 3. Compared with the non-common optical path imaging method in which multiple cameras are placed side by side, the present invention adopts a color separation and common optical path structure to avoid the visual axis error between the spectral channels and improve the accuracy of image registration.

[0066] 4. Compared with the imaging method of the filter array, the imaging field of the present invention is larger, full-frame imaging can be achieved, and each spectral channel is independent without the risk of spectral aliasing.

[0067] 5. The present invention reflects the first emitted light into the second reflected light parallel to the first transmitted light through the folding mirror, so that the whole imaging system forms a double-layer optical structure, compresses the volume of the imaging system, and makes the optical path more compact. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 It is a structural schematic diagram of an embodiment of a multi-spectral imaging system without parallax and time difference of the present invention;

[0069] Figure 2 is a schematic structural diagram of the first to eighth imaging mirrors in an embodiment of the present invention;

[0070] Figure 3 415nm channel modulation transfer function MTF diagram of the multi-spectral imaging system without parallax and time difference in the embodiment of the present invention;

[0071] Figure 4 511nm channel modulation transfer function MTF diagram of the multi-spectral imaging system without parallax and time difference in the embodiment of the present invention;

[0072] Figure 5 553nm channel modulation transfer function MTF diagram of the multi-spectral imaging system without parallax and time difference in the embodiment of the present invention;

[0073] Figure 6 570nm channel modulation transfer function MTF diagram of the multi-spectral imaging system without parallax and time difference in the embodiment of the present invention;

[0074] Figure 7 670nm channel modulation transfer function MTF diagram of the multi-spectral imaging system without parallax and time difference in the embodiment of the present invention;

[0075] Figure 8 720nm channel modulation transfer function MTF diagram of the multi-spectral imaging system without parallax and time difference in the embodiment of the present invention;

[0076] Fig. 9 754nm channel modulation transfer function MTF diagram of the multi-spectral imaging system without parallax and time difference in the embodiment of the present invention;

[0077] Fig.10 It is a modulation transfer function MTF diagram of the 890nm channel of the multi-spectral imaging system without parallax and time difference in an embodiment of the present invention.

[0078] Figure Number:

[0079] 1-incident window, 2-first dichroic mirror, 3-folding mirror, 41-first beam splitter, 42-second beam splitter, 51-second dichroic mirror, 52-third dichroic mirror, 53-fourth dichroic mirror, 54-fifth dichroic mirror, 61-first imaging mirror, 62-second imaging mirror, 63-third imaging mirror, 64-fourth imaging mirror, 65-fifth imaging mirror, 66-sixth imaging mirror, 67-seventh imaging mirror, 68-eighth imaging mirror, 71-first filter, 72-second filter, 73-third filter, 74-fourth filter, 75-fifth filter, 76-sixth filter, 77-seventh filter, 78-eighth filter, S1-first detector, S2-second detector, S3-third detector, S4-fourth detector, S5-fifth detector, S6-sixth detector, S7-seventh detector, S8-eighth detector. DETAILED DESCRIPTION

[0080] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0081] An embodiment of the present invention provides a multispectral imaging system without parallax and time difference. In order to realize real-time frame-type observation of the scene, the scheme adopts a combination of color separation and beam splitting of a common optical path + a detector array. Color separation and beam splitting are realized by a color separation sheet and a 1:1 energy beam splitter. Each imaging mirror is equipped with a filter of a different band, ultimately realizing multispectral detection without time difference and parallax.

[0082] like Figure 1 As shown, the imaging system of this embodiment includes an incident window 1, a spectroscopic unit, first to eighth imaging mirrors (labeled 61 to 68 in the figure), first to eighth filters (labeled 71 to 78 in the figure) and first to eighth detectors (labeled S1 to S8 in the figure).

[0083] In order to facilitate the description of its structure, the direction close to the incident light is defined as the front, and the direction far from the incident light is defined as the back.

[0084] The incident window 1 is used to receive the target light; the transmission bandwidth range of the incident window 1 is 400nm-910nm; the average transmittance of the incident window 1 is greater than or equal to 90%; the size of the incident window 1 is 92mm×73mm×5mm; the refractive index of the incident window 1 is 1.5168, and the line Abbe number is 64.1987. The incident window 1 can transmit the entire spectrum of visible light (400nm-910nm), and plays a role in sealing the multi-spectral imaging optical system and preventing pollutants from entering the instrument.

[0085] The spectroscopic unit is used to divide the received target light into eight outgoing lights; the spectroscopic unit includes a first color splitter 2 with a wide spectrum, a folding mirror 3, a first spectroscopic mirror 41, a second spectroscopic mirror 42, a second spectroscopic mirror 51, a third spectroscopic mirror 52, a fourth spectroscopic mirror 53 and a fifth spectroscopic mirror 54; the first spectroscopic mirror 41 and the second spectroscopic mirror 42 are energy spectroscopic mirrors, and the second spectroscopic mirror 51, the third spectroscopic mirror 52, the fourth spectroscopic mirror 53 and the fifth spectroscopic mirror 54 are all color splitters with narrow spectrum.

[0086] The first dichroic mirror 2 is arranged on the optical path where the target light received by the incident window 1 is located, and is used to separate the target light into a first transmitted light and a first reflected light; the transmission bandwidth range of the first dichroic mirror 2 is 650nm-910nm, and the reflection bandwidth range is 400nm-600nm; the transmittance of the first dichroic mirror 2 is greater than or equal to 93%, and the reflectivity is greater than or equal to 90%; the size of the first dichroic mirror 2 is 83mm×80mm×2mm; the refractive index of the first dichroic mirror 2 is 1.5168, and the line Abbe number is 64.1987. The first dichroic mirror 2 can separate the 400nm-910nm spectrum, reflect the 400nm-600nm short-wave spectrum into the lower optical path of the multi-spectral imaging optical system, and transmit the 650nm-910nm long-wave spectrum into the upper optical path of the multi-spectral imaging optical system, thereby optimizing the overall structural layout and reducing the envelope size.

[0087] The folding mirror 3 is arranged on the optical path of the first reflected light, and is used to reflect the first reflected light to form a second reflected light parallel to the first transmitted light; the reflection bandwidth range of the folding mirror 3 is 400nm-600nm; the reflectivity of the folding mirror 3 is greater than or equal to 90%; the size of the folding mirror 3 is 61mm×61mm×2mm; the refractive index of the folding mirror 3 is 1.5168, and the line Abbe number is 64.1987. The folding mirror 3 is used in conjunction with the first wide-band dichroic mirror 2 to fold the light entering the lower optical path of the multi-spectral imaging optical system by 90°, so that it is parallel to the upper optical path, optimize the overall structural layout, and reduce the vertical length and volume.

[0088] The first beam splitter 41 is arranged on the optical path of the first transmitted light, and is used for splitting the first transmitted light into a second transmitted light and a third reflected light; the transmission bandwidth range of the first beam splitter 41 is 650nm-910nm, and its reflection bandwidth range is 650nm-910nm; the transmittance and reflectance range of the first beam splitter 41 is 50%±3%; the size of the first beam splitter 41 is 35mm×54mm×2mm; the refractive index of the first beam splitter 41 is 1.5168, and the linear Abbe number is 64.1987.

[0089] The second beam splitter 42 is arranged on the optical path of the second reflected light, and is used for splitting the second reflected light into a third transmitted light and a fourth reflected light; the transmission bandwidth range of the second beam splitter 42 is 400nm-600nm, and its reflection bandwidth range is 400nm-600nm; the transmittance and reflectance range of the second beam splitter 42 is 50%±3%; the size of the second beam splitter 42 is 35mm×54mm×2mm; the refractive index of the second beam splitter 42 is 1.5168, and the linear Abbe number is 64.1987.

[0090] The first beam splitter 41 can split the energy of the light in the 650nm-910nm spectrum range, and the second beam splitter 42 can split the energy of the light in the 400nm-600nm spectrum range, so that the transmitted energy accounts for 50% and the reflected energy accounts for 50%. The light entering the upper optical path and the lower optical path is divided into four parts respectively, and enters the subsequent dichroic mirrors respectively.

[0091] The second dichroic mirror 51 is arranged on the optical path of the second transmitted light, and is used to separate the second transmitted light into a fourth transmitted light and a fifth reflected light; the transmission bandwidth range of the second dichroic mirror 51 is 860nm-910nm, and the reflection bandwidth range is 690-750; the transmittance and reflectance ranges of the second dichroic mirror 51 are both greater than or equal to 90%. The size of the second dichroic mirror 51 is 25mm×38mm×2mm. The refractive index of the second dichroic mirror 51 is 1.5168, and the line Abbe number is 64.1987. The second dichroic mirror 51 can separate the long-wave spectrum of 650nm-910nm, and reflect the light in the spectral range of 690nm-750nm into the first imaging mirror 61, and is received by the target surface of the first detector S1; the second dichroic mirror 51 can also transmit the light in the spectral range of 860nm-910nm into the second imaging mirror 62, and is received by the target surface of the second detector S2.

[0092] The third dichroic mirror 52 is arranged on the optical path where the third reflected light is located, and is used to separate the third reflected light into the fifth transmitted light and the sixth reflected light; the transmission bandwidth range of the third dichroic mirror 52 is 730nm-780nm, and its reflection bandwidth range is 650nm-690nm; the transmittance and reflectance range of the third dichroic mirror 52 is greater than or equal to 90%. The size of the third dichroic mirror 52 is 25mm×38mm×2mm. The refractive index of the third dichroic mirror 52 is 1.5168, and the line Abbe number is 64.1987. The third dichroic mirror 52 can separate the long-wave spectrum of 650nm-910nm, and reflect the light in the 650nm-690nm spectrum range into the third imaging mirror 63, and is received by the target surface of the fourth detector S3; the third dichroic mirror 52 can also transmit the light in the 730nm-780nm spectrum range into the fourth imaging mirror 64, and is received by the target surface of the fourth detector S4.

[0093] The fourth dichroic mirror 53 is arranged on the optical path of the third transmitted light, and is used to separate the third transmitted light into the sixth transmitted light and the seventh reflected light; the transmission bandwidth range of the fourth dichroic mirror 53 is 555nm-595nm, and its reflection bandwidth range is 490nm-525nm; the transmittance and reflectance range of the fourth dichroic mirror 53 is greater than or equal to 90%. The size of the fourth dichroic mirror 53 is 25mm×38mm×2mm. The refractive index of the fourth dichroic mirror 53 is 1.5168, and the line Abbe number is 64.1987. The fourth dichroic mirror 53 can separate the short-wave spectrum of 400nm-600nm, and reflect the light in the spectral range of 490nm-525nm into the fifth imaging mirror 65, and is received by the target surface of the fifth detector S5; the fourth dichroic mirror 53 can also transmit the light in the spectral range of 555nm-595nm into the sixth imaging mirror 66, and is received by the target surface of the sixth detector S6.

[0094] The fifth dichroic mirror 54 is arranged on the optical path where the fourth reflected light is located, and is used to separate the fourth reflected light into the seventh transmitted light and the eighth reflected light; the transmission bandwidth range of the fifth dichroic mirror 54 is 520nm-580nm, and its reflection bandwidth range is 400nm-440nm. The transmittance and reflectance range of the fifth dichroic mirror 54 is greater than or equal to 90%. The size of the fifth dichroic mirror 54 is 25mm×38mm×2mm. The refractive index of the fifth dichroic mirror 54 is 1.5168, and the line Abbe number is 64.1987. The fifth dichroic mirror 54 can separate the short-wave spectrum of 400nm-600nm, and reflect the light in the spectral range of 400nm-450nm into the seventh imaging mirror 67, and is received by the target surface of the seventh detector S7; the fifth dichroic mirror 54 can also transmit the light in the spectral range of 520nm-580nm into the eighth imaging mirror 68, and is received by the target surface of the eighth detector S8.

[0095] The fourth transmitted light, the fifth reflected light, the fifth transmitted light, the sixth reflected light, the sixth transmitted light, the seventh reflected light, the seventh transmitted light and the eighth reflected light are the eight-path output light.

[0096] The above parameters are summarized in Table 1 below:

[0097] Table 1

[0098]

[0099] The first to eighth imaging mirrors, the first to eighth filters and the first to eighth detectors are respectively arranged in sequence on the optical paths of the eight outgoing lights along the outgoing direction of the outgoing light in the order of one imaging mirror, one filter and one detector;

[0100] like Figure 2 As shown, the structures of the first to eighth imaging mirrors are the same, and all adopt a three-piece transmission structure, which respectively include a first biconvex glass lens A, a biconcave glass lens B and a second biconvex glass lens C which are arranged in sequence along the emitting direction of the outgoing light.

[0101] As shown in Table 2 below, the focal power range of the first biconvex glass lens A is 0.08-0.14; the front surface curvature radius R1 of the first biconvex glass lens A is 7.945 mm, the rear surface curvature radius R2 is -29.16 mm, and the center distance between the front surface and the rear surface is 2.73 mm; the refractive index of the first biconvex glass lens A is 1.7469, and the linear Abbe number is 51.0086;

[0102] The focal power range of the double concave glass lens B is -0.18--0.24, the radius of curvature R3 of its front surface is -8.785mm, and the radius of curvature R4 of its rear surface is 6.535mm; the center distance between its front surface and the rear surface of the first double convex glass lens A is 1.36mm; the center distance between its rear surface and its front surface is 1.82mm; the refractive index of the double concave glass lens B is 1.7552, and the linear Abbe number is 27.5300.

[0103] The focal power range of the second biconvex glass lens C is 0.08-0.14, the radius of curvature R5 of its front surface is 29.16mm, and the radius of curvature R6 of its rear surface is -7.945mm; the center distance between its front surface and the rear surface of the biconcave glass lens B is 1.8mm, and the center distance between its rear surface and its front surface is 2.73mm; the center distance between its rear surface and the corresponding detector detection surface located at its rear side is 10.75mm. The refractive index of the second biconvex glass lens C is 1.7469, and the linear Abbe number is 51.0086.

[0104] Table 2

[0105]

[0106] As shown in Table 3 below, the peak transmission wavelengths of the first to eighth filters are 415nm, 511nm, 553nm, 570nm, 670nm, 720nm, 754nm and 890nm, respectively, and the bandwidths of the eight filters are 20nm, 20nm, 15nm, 14nm, 13nm, 10nm, 10nm, 40nm, respectively, and the refractive index of the eight filters is 1.5168, the line Abbe number of the eight filters is 64.1987, and the diameter of the eight filters is 17.5mm×1mm; the peak transmittance of the first to second filters is greater than or equal to 90%, the peak transmittance of the third to fifth filters is greater than or equal to 85%, the peak transmittance of the sixth to seventh filters is greater than or equal to 80%, and the peak transmittance of the eighth filter is greater than or equal to 92%. The first to eighth filters all use flat optical glass, and narrow-band filters with different transmission spectrum bands are plated on different optical glasses to achieve narrow-band multi-spectral imaging.

[0107] Table 3

[0108]

[0109]

[0110] The first to eighth detectors use CMOS detectors with a pixel number of 1292×964 and a pixel size of 3.75μm, which can receive light of different spectral bands and bandwidths and image the target.

[0111] like Figure 3-Figure 10 As shown, the modulation transfer function (MTF) of the imaging system in each spectral band reaches the diffraction limit in the entire field of view.

[0112] The imaging system is used to perform imaging, which specifically includes the following steps:

[0113] Step 1, receiving target light through incident window 1;

[0114] Step 2, the target light is divided into a first transmitted light and a first reflected light by the first dichroic mirror 2; the folding mirror 3 reflects the first reflected light to form a second reflected light parallel to the first transmitted light; the first dichroic mirror 41 divides the first transmitted light into a second transmitted light and a third reflected light; the second dichroic mirror 42 divides the second reflected light into a third transmitted light and a fourth reflected light; the second dichroic mirror 51 divides the second transmitted light into a fourth transmitted light and a fifth reflected light; the third dichroic mirror 52 divides the third reflected light into a fifth transmitted light and a sixth reflected light; the fourth dichroic mirror 53 divides the third transmitted light into a sixth transmitted light and a seventh reflected light; the fifth dichroic mirror 54 divides the fourth reflected light into a seventh transmitted light and an eighth reflected light; the fourth transmitted light, the fifth reflected light, the fifth transmitted light, the sixth reflected light, the sixth transmitted light, the seventh reflected light, the seventh transmitted light and the eighth reflected light are eight-way output light.

[0115] Step 3, using the first to eighth imaging mirrors to converge the eight-way outgoing light respectively;

[0116] Step 4, using the first to eighth filters to filter the converged outgoing light into different spectral bands respectively;

[0117] Step 5, using the first to eighth detectors to detect the eight paths of filtered light respectively, to obtain eight sets of detection data;

[0118] Step 6: Imaging of the target light is achieved by aligning the eight sets of detection data.

[0119] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A multispectral imaging system without parallax and time difference, characterized in that: It comprises an incident window (1), a light splitting unit, first to eighth imaging mirrors, first to eighth filters and first to eighth detectors; The incident window (1) is used to receive target light; The light splitting unit is used to split the received target light into eight outgoing lights; The first to eighth imaging mirrors, the first to eighth filters and the first to eighth detectors are respectively arranged in sequence on the optical paths of the eight outgoing lights along the outgoing direction of the outgoing light in the order of one imaging mirror, one filter and one detector; The peak transmission wavelengths of the first to eighth filters are eight preset and different wavelengths.

2. The multi-spectral imaging system without parallax and time difference according to claim 1, characterized in that: The light splitting unit comprises a first dichroic mirror (2), a folding mirror (3), a first beam splitter (41), a second beam splitter (42), a second dichroic mirror (51), a third dichroic mirror (52), a fourth dichroic mirror (53) and a fifth dichroic mirror (54); The first dichroic mirror (2) is arranged on the light path of the target light received by the incident window (1), and is used to separate the target light into a first transmitted light and a first reflected light; The folding mirror (3) is arranged on the optical path of the first reflected light and is used to reflect the first reflected light to form a second reflected light parallel to the first transmitted light; The first beam splitter (41) is arranged on the optical path of the first transmitted light, and is used to split the first transmitted light into a second transmitted light and a third reflected light; The second beam splitter (42) is arranged on the optical path of the second reflected light, and is used to split the second reflected light into a third transmitted light and a fourth reflected light; The second dichroic mirror (51) is arranged on the optical path of the second transmitted light and is used to separate the second transmitted light into a fourth transmitted light and a fifth reflected light; The third dichroic mirror (52) is arranged on the optical path of the third reflected light, and is used to separate the third reflected light into a fifth transmitted light and a sixth reflected light; The fourth dichroic mirror (53) is arranged on the optical path of the third transmitted light and is used to separate the third transmitted light into a sixth transmitted light and a seventh reflected light; The fifth dichroic mirror (54) is arranged on the optical path of the fourth reflected light, and is used to separate the fourth reflected light into a seventh transmitted light and an eighth reflected light; The fourth transmitted light, the fifth reflected light, the fifth transmitted light, the sixth reflected light, the sixth transmitted light, the seventh reflected light, the seventh transmitted light and the eighth reflected light constitute eight paths of the outgoing light.

3. The multi-spectral imaging system without parallax and time difference according to claim 2, characterized in that: The structures of the first to eighth imaging lenses are the same, and respectively include a first biconvex glass lens A, a biconcave glass lens B, and a second biconvex glass lens C which are sequentially arranged along the exit direction of the exit light; Definition: The direction close to the incident light is the front, and the direction far away from the incident light is the back; The first biconvex glass lens A has a front surface curvature radius R1 of 7.945 mm, a rear surface curvature radius R2 of -29.16 mm, and a center distance between the front surface and the rear surface of 2.73 mm; The front surface curvature radius R3 of the biconcave glass lens B is -8.785 mm, and the rear surface curvature radius R4 is 6.535 mm; the center distance between the front surface and the rear surface of the first biconvex glass lens A is 1.36 mm; the center distance between the rear surface and the front surface is 1.82 mm; The front surface curvature radius R5 of the second biconvex glass lens C is 29.16 mm, and the rear surface curvature radius R6 is -7.945 mm; The center distance between its front surface and the rear surface of the double concave glass lens B is 1.8 mm, the center distance between its rear surface and its front surface is 2.73 mm; the center distance between its rear surface and the corresponding detector detection surface located at its rear side is 10.75 mm.

4. The multi-spectral imaging system without parallax and time difference according to claim 3, characterized in that: The refractive index of the first biconvex glass lens A is 1.7469, and the linear Abbe number is 51.0086; The refractive index of the biconcave glass lens B is 1.7552, and the linear Abbe number is 27.5300; The refractive index of the second biconvex glass lens C is 1.7469, and the linear Abbe number is 51.0086.

5. The multi-spectral imaging system without parallax and time difference according to any one of claims 2 to 4, characterized in that: The peak transmission wavelengths of the first to eighth filters are 415nm, 511nm, 553nm, 570nm, 670nm, 720nm, 754nm and 890nm, respectively, and their bandwidths are 20nm, 20nm, 15nm, 14nm, 13nm, 10nm, 10nm, 40nm, respectively. The refractive index of the eight filters is 1.5168, the linear Abbe number of the eight filters is 64.1987, and the diameter of the eight filters is 17.5mm×1mm. The peak transmittances of the first to second filters are greater than or equal to 90%, the peak transmittances of the third to fifth filters are greater than or equal to 85%, the peak transmittances of the sixth to seventh filters are greater than or equal to 80%, and the peak transmittance of the eighth filter is greater than or equal to 92%.

6. The multi-spectral imaging system without parallax and time difference according to claim 5, characterized in that: The transmission bandwidth of the incident window (1) is in the range of 400nm-910nm; The transmission bandwidth of the first dichroic mirror (2) is in the range of 650nm-910nm, and the reflection bandwidth is in the range of 400nm-600nm; The reflection bandwidth range of the folding mirror (3) is 400nm-600nm; The transmission bandwidth of the first beam splitter (41) is in the range of 650nm-910nm, and the reflection bandwidth is in the range of 650nm-910nm; The transmission bandwidth of the second beam splitter (42) is in the range of 400nm-600nm, and the reflection bandwidth is in the range of 400nm-600nm; The transmission bandwidth of the second dichroic mirror (51) is in the range of 860nm-910nm, and the reflection bandwidth is in the range of 690-750nm; The transmission bandwidth of the third dichroic mirror (52) is in the range of 730nm-780nm, and the reflection bandwidth is in the range of 650nm-690nm; The transmission bandwidth of the fourth dichroic mirror (53) is in the range of 555nm-595nm, and the reflection bandwidth is in the range of 490nm-525nm; The transmission bandwidth of the fifth dichroic mirror (54) is in the range of 520nm-580nm, and the reflection bandwidth is in the range of 400nm-440nm.

7. The multi-spectral imaging system without parallax and time difference according to claim 6, characterized in that: The average transmittance of the incident window (1) is greater than or equal to 90%; The transmittance of the first dichroic mirror (2) is greater than or equal to 93%, and the reflectivity thereof is greater than or equal to 90%; The reflectivity of the folding mirror (3) is greater than or equal to 90%; The transmittance and reflectance ranges of the first beam splitter (41) and the second beam splitter (42) are both 50%±3%; The transmittance and reflectance ranges of the second dichroic mirror (51), the third dichroic mirror (52), the fourth dichroic mirror (53) and the fifth dichroic mirror (54) are all greater than or equal to 90%.

8. The multi-spectral imaging system without parallax and time difference according to claim 7, characterized in that: The size of the incident window (1) is 92 mm×73 mm×5 mm; The size of the first dichroic mirror (2) is 83 mm×80 mm×2 mm; The size of the folding mirror (3) is 61 mm×61 mm×2 mm; The sizes of the first beam splitter (41) and the second beam splitter (42) are both 35 mm×54 mm×2 mm; The sizes of the second dichroic mirror (51), the third dichroic mirror (52), the fourth dichroic mirror (53) and the fifth dichroic mirror (54) are all 25 mm×38 mm×2 mm.

9. The multi-spectral imaging system without parallax and time difference according to claim 8, characterized in that: The incident window (1), the first dichroic mirror (2), the folding mirror (3), the first beam splitter (41), the second beam splitter (42), the second dichroic mirror (51), the third dichroic mirror (52), the fourth dichroic mirror (53) and the fifth dichroic mirror (54) all have a refractive index of 1.5168 and a linear Abbe number of 64.1987.

10. A multispectral imaging method without parallax and time difference, using the multispectral imaging system without parallax and time difference according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1, receiving target light through the incident window (1); Step 2: Split the target light into eight outgoing lights through a light splitting unit; Step 3, using the first to eighth imaging mirrors to converge the eight-way outgoing light respectively; Step 4, using the first to eighth filters to filter the converged outgoing light into different spectral bands respectively; Step 5, using the first to eighth detectors to detect the eight paths of filtered light respectively, to obtain eight sets of detection data; Step 6: Imaging of the target light is achieved by aligning the eight sets of detection data.

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