CN115166957B - Dual-band spectrum imaging method - Google Patents
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- CN115166957B CN115166957B CN202210689360.1A CN202210689360A CN115166957B CN 115166957 B CN115166957 B CN 115166957B CN 202210689360 A CN202210689360 A CN 202210689360A CN 115166957 B CN115166957 B CN 115166957B
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- G—PHYSICS
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- G02B17/00—Systems with reflecting surfaces, with or without refracting elements
- G02B17/08—Catadioptric systems
- G02B17/082—Catadioptric systems using three curved mirrors
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B17/00—Systems with reflecting surfaces, with or without refracting elements
- G02B17/08—Catadioptric systems
- G02B17/0856—Catadioptric systems comprising a refractive element with a reflective surface, the reflection taking place inside the element, e.g. Mangin mirrors
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/0025—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for optical correction, e.g. distorsion, aberration
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/10—Beam splitting or combining systems
- G02B27/1006—Beam splitting or combining systems for splitting or combining different wavelengths
- G02B27/1013—Beam splitting or combining systems for splitting or combining different wavelengths for colour or multispectral image sensors, e.g. splitting an image into monochromatic image components on respective sensors
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/10—Beam splitting or combining systems
- G02B27/1086—Beam splitting or combining systems operating by diffraction only
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
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Abstract
The invention relates to a dual-band spectrum imaging method. An optical system is constructed, an immersed structure is adopted for bonding a main prism with a secondary prism with a free-form surface, and a filter plate is arranged at the bonding position of the two prisms; during spectral imaging, object light enters through a slit arranged on a free-form surface main prism, is reflected to a reflective grating through a main reflecting surface, and the split light is reflected by a secondary reflecting surface to reach a filter; light rays in the visible near infrared band are transmitted through the filter, and are imaged on a visible near infrared detection surface on the secondary prism; light rays in a short wave infrared band are reflected by the filter and imaged on a short wave infrared detection surface on the free-form surface main prism; the main reflecting surface, the reflective grating and the secondary reflecting surface are 6 th order polynomial free curved surfaces. The dual-band spectrum imaging method provided by the invention effectively controls the full-band full-view field aberration, and remarkably improves the imaging quality and resolution; the optical system has the characteristics of compact structure, small volume and easy adjustment.
Description
Technical Field
The invention belongs to the technical field of spectral imaging, and particularly relates to an imaging method of a dual-band imaging spectrometer based on a free-form surface prism.
Background
The hyperspectral imaging technique can acquire image information and spectrum information of a target scene at the same time.
The free-form surface has non-rotational symmetry, can bring higher design freedom in optical design, is favorable for improving image quality and reducing system volume simultaneously, and is increasingly widely applied to various imaging systems along with continuous progress of advanced manufacturing technology in recent years.
According to the immersion type optical path imaging method, air can be replaced by a material with a high refractive index, elements are integrated into a whole, the size is further reduced, and the problem of difficult system adjustment is solved. The immersion type design is introduced into the free-form surface to realize spectrum imaging, so that the volume can be further reduced, and the imaging spectrometer with a more compact structure and higher system parameters is obtained, thereby having very important significance.
In the prior art, the document Design of a compact wide-satellite double-channel prism imaging spectrometer with freeform surface (Applied Optics, volume 57, issue 31) proposesThe dual-band spectrum imaging method based on the offner structure is characterized by that it uses a prism as light-dividing element, its F number is 3, its visual field is 30 deg., two working bands are respectively 400nm to 1000nm and 1000nm to 2500nm, maximum spectral resolution is respectively 13.2nm and 13.5nm, volume is 5040 cm 3 Its spectral resolution and volume are yet to be optimized.
Disclosure of Invention
Aiming at the defects existing in the prior art, the invention provides a dual-band spectrum imaging method, which realizes high-image-quality imaging and has a simple and compact imaging optical system structure.
The technical scheme for realizing the purpose of the invention is to provide a dual-band spectrum imaging method, the working band is 400-2500 nm, comprising the following steps:
(1) Adopting an immersed structure of bonding a free-form surface main prism and a secondary prism, and arranging a filter at the bonding surface of the free-form surface main prism and the secondary prism to construct a dual-band spectrum imaging optical system; a slit, a main reflecting surface, a reflective grating, a secondary reflecting surface and a short wave infrared spectrum imaging surface are arranged on the main prism of the free curved surface; a visible near infrared spectrum imaging surface is arranged on the secondary prism; the aperture diaphragm of the system is arranged on the reflective grating; the main prism and the secondary prism of the free curved surface are made of barium fluoride;
the relative positions of the optical elements in the dual-band spectral imaging optical system are as follows:
the space where the slit is located is defined as a first three-dimensional rectangular coordinate system (x 1 ，y 1 ，z 1 ) A first three-dimensional rectangular coordinate system (x 1 ，y 1 ，z 1 ) Is at the center of the slit, the incident direction of the light is z 1 Positive axis direction, y 1 Upward in the positive direction of axis, x 1 The axial direction is vertical to the paper surface and inwards;
the space where the main reflecting surface is located is defined as a second three-dimensional rectangular coordinate system (x 2 ，y 2 ，z 2 ) A second three-dimensional rectangular coordinate system (x 2 ，y 2 ，z 2 ) Is located at the origin of the first three-dimensional rectangular coordinate system (x 1 ，y 1 ，z 1 ) Origin directionz 1 Forward translation 118-119 mm, z 2 The positive axis direction is relative to the first three-dimensional rectangular coordinate system (x 1 ，y 1 ，z 1 ) Z of (2) 1 The shaft rotates clockwise by 13-14 degrees in the positive direction;
the space where the reflective grating is located is defined as a third three-dimensional rectangular coordinate system (x 3 ，y 3 ，z 3 ) A third three-dimensional rectangular coordinate system (x 3 ，y 3 ，z 3 ) Is located at the origin of the second three-dimensional rectangular coordinate system (x 2 ，y 2 ，z 2 ) Origin direction y 2 Forward translation of 21-22 mm, z 2 Negative direction translation 114-115 mm, z 3 The positive axis direction is relative to a second three-dimensional rectangular coordinate system (x 2 ，y 2 ，z 2 ) Z of (2) 2 The shaft rotates clockwise by 23-24 degrees in the positive direction;
the space where the secondary reflecting surface is located is defined as a fourth three-dimensional rectangular coordinate system (x 4 ，y 4 ，z 4 ) Fourth three-dimensional rectangular coordinate system (x 4 ，y 4 ，z 4 ) Is located at the origin of the third three-dimensional rectangular coordinate system (x 3 ，y 3 ，z 3 ) Origin direction y 3 Negative direction translation of 14-15 mm, z 3 Negative direction translation 111-112 mm, z 4 The positive axis direction is relative to a third three-dimensional rectangular coordinate system (x 3 ，y 3 ，z 3 ) Z of (2) 3 The shaft rotates clockwise by 19-20 degrees in the positive direction;
the space where the filter is located is defined as a fifth three-dimensional rectangular coordinate system (x 5 ，y 5 ，z 5 ) A fifth three-dimensional rectangular coordinate system (x 5 ，y 5 ，z 5 ) Is located at the origin of the fourth three-dimensional rectangular coordinate system (x 4 ，y 4 ，z 4 ) Origin z 4 Negative direction translation 103-104 mm, z 5 The positive axis direction is relative to the fourth three-dimensional rectangular coordinate system (x 4 ，y 4 ，z 4 ) Z of (2) 4 The shaft rotates 30 degrees anticlockwise in the positive direction;
the space where the short-wave infrared spectrum imaging surface is located is defined as a sixth three-dimensional rectangular coordinate system(x 6 ，y 6 ，z 6 ) A sixth three-dimensional rectangular coordinate system (x 6 ，y 6 ，z 6 ) Is located at the origin of the fifth three-dimensional rectangular coordinate system (x 5 ，y 5 ，z 5 ) Origin direction y 5 Negative direction translation of 8-9 mm, z 5 Forward translation 40mm, z 6 The positive axis direction is relative to the fifth three-dimensional rectangular coordinate system (x 5 ，y 5 ，z 5 ) Z of (2) 5 The shaft rotates clockwise by 16-17 degrees in the positive direction;
the space where the visible near infrared spectrum imaging surface is located is defined as a seventh three-dimensional rectangular coordinate system (x 7 ，y 7 ，z 7 ) Seventh three-dimensional rectangular coordinate system (x 7 ，y 7 ，z 7 ) Is located at the origin of the fifth three-dimensional rectangular coordinate system (x 5 ，y 5 ，z 5 ) Origin direction y 5 Forward translation of 8-9 mm to z 5 Forward translation 40mm, z 7 The positive axis direction is relative to the fifth three-dimensional rectangular coordinate system (x 5 ，y 5 ，z 5 ) Z of (2) 5 The shaft rotates anticlockwise by 16-17 degrees in the positive direction;
the main reflecting surface, the reflective grating and the secondary reflecting surface arranged on the free-form surface main prism are respectively corresponding to the two surfaces in a second three-dimensional rectangular coordinate system (x 2 ，y 2 ，z 2 ) Third three-dimensional rectangular coordinate system (x 3 ，y 3 ，z 3 ) Fourth three-dimensional rectangular coordinate System (x 4 ，y 4 ，z 4 ) The free-form surface of the XY polynomial of degree 6; the surface expression z of the free-form surface is:
wherein c is the curvature; k is a quadric coefficient;A 1 ～A 27 coefficients of each item respectively;
the line direction of the reflection grating is parallel to x 3 The direction, the density of the scribing lines is 150 strips/mm, and the diffraction order is 1 order;
the working face of the filter and x in a fifth three-dimensional rectangular coordinate system 5 y 5 The plane is parallel, and the center of the working surface coincides with the origin of the fifth coordinate system;
x in the short wave infrared spectrum imaging surface and the sixth three-dimensional rectangular coordinate system 6 y 6 The plane is parallel, and the center of the detection surface coincides with the origin of the sixth coordinate system;
x in the visible near infrared spectrum imaging surface and the seventh three-dimensional rectangular coordinate system 7 y 7 The plane is parallel, and the center of the detection surface coincides with the origin of the seventh coordinate system;
(2) The object side light is incident through a slit arranged on the free-form surface main prism and is reflected to the reflective grating through the main reflecting surface;
(3) The light split by the reflective grating is reflected to the secondary reflecting surface, and then reaches the filter after being reflected by the secondary reflecting surface;
(4) Light rays in the visible near infrared band are transmitted through the filter, and are imaged on a visible near infrared spectrum imaging surface on the secondary prism; light rays in the short wave infrared band are reflected by the filter and imaged on a short wave infrared spectrum imaging surface on the free-form surface main prism.
The invention provides a dual-band spectrum imaging method, which is characterized in that the curvature c= -0.01862 of a 6-degree XY polynomial free-form surface of a main reflecting surface; quadric coefficients k= -0.98477; polynomial coefficient A 1 ～A 27 The method comprises the following steps of: -1X 10 -3 ≤A 2 ≤0,0≤A 3 ≤1×10 -2 ,0≤A 5 ≤1×10 -2 , -1×10 -7 ≤A 7 ≤0,0≤A 9 ≤1×10 -6 , -1×10 -9 ≤A 10 ≤0, -1×10 -9 ≤A 12 ≤0, -1×10 -9 ≤A 14 ≤0, -1×10 -11 ≤A 16 ≤0, -1×10 -11 ≤A 18 ≤0,0≤A 20 ≤1×10 -10 ，-1×10 -13 ≤A 21 ≤0，-1×10 -13 ≤A 23 ≤0，-1×10 -12 ≤A 25 ≤0，-1×10 -13 ≤A 27 Less than or equal to 0, and the rest is 0.
The curvature c= 1.27693E-153 of the 6 th order XY polynomial free-form surface of the reflective grating; quadric coefficient k=0; polynomial coefficient A 1 ～A 27 The method comprises the following steps of: -1X 10 -7 ≤A 2 ≤0, -1×10 -4 ≤A 3 ≤0, -1×10 -4 ≤A 5 ≤0, -1×10 -6 ≤A 7 ≤0,0≤A 9 ≤1×10 -4 , -1×10 -8 ≤A 10 ≤0, -1×10 -8 ≤A 12 ≤0, -1×10 -8 ≤A 14 ≤0, -1×10 -19 ≤A 16 ≤0, 0≤A 18 ≤1×10 -8 ,0≤A 20 ≤1×10 -8 ，-1×10 -12 ≤A 21 ≤0，-1×10 -11 ≤A 23 ≤0，0≤A 25 ≤1×10 -8 ，-1×10 -9 ≤A 27 Less than or equal to 0, and the rest is 0.
A 6 th order XY polynomial free-form surface of the secondary reflecting surface, the curvature c= -0.04548; quadric coefficients k= -0.99951; polynomial coefficient A 1 ～A 27 The method comprises the following steps of: -1X 10 -3 ≤A 2 ≤0,0≤A 3 ≤1×10 -1 ,0≤A 5 ≤1×10 -1 , -1×10 -7 ≤A 7 ≤0,0≤A 9 ≤1×10 -6 , -1×10 -9 ≤A 10 ≤0, -1×10 -9 ≤A 12 ≤0, -1×10 -10 ≤A 14 ≤0, -1×10 -13 ≤A 16 ≤0, -1×10 -11 ≤A 18 ≤0, -1×10 -11 ≤A 20 ≤0，-1×10 -14 ≤A 21 ≤0，-1×10 -13 ≤A 23 ≤0，0≤A 25 ≤1×10 -11 ，0≤A 27 ≤1×10 -11 The balance being 0.
The invention provides a dual-band imaging spectrum method, which has the following working principle: the light rays of the incident slit are reflected by the main reflecting surface to form first reflected light; the reflection type grating is arranged on a reflection light path of the main reflection surface, and the incident light is dispersed and used for splitting the first reflection light and secondarily reflecting the first reflection light to form second reflection light; the split light rays are reflected again by a secondary reflecting surface arranged on a reflecting grating reflecting light path to form third reflecting light, and the light path of the first reflecting light, the light path of the second reflecting light and the light path of the third reflecting light are overlapped in a free-form surface main prism; the filter is used for receiving the third reflected light and splitting light, light with the wave band of 400nm to 1000nm passes through the filter, reaches the visible near infrared spectrum imaging surface and images, and light with the wave band of 1000nm to 2500nm is reflected by the filter, reaches the short wave infrared spectrum imaging surface and images.
The invention adopts the spectrum imaging method of the off-axis three-reflector structure of the free curved surface, utilizes the free curved surface to correct the aberration generated by the off-axis and reduce the volume of the system, and simultaneously adopts the immersion type element which can be integrated in the prism to further reduce the volume of the system so as to realize the light miniaturization, the simple and compact structure and the high-image quality imaging of the imaging spectrum system.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention integrates the elements into the prism in an immersed design, and adopts the filter structure to realize the dual-band spectrum imaging.
2. The invention adopts the light splitting method of the reflective grating, and the surface shape of the grating is a free curved surface, so that the aberration can be corrected while the better spectral resolution is obtained.
3. The invention adopts the off-axis three-reflection structure method, and the surfaces of the three reflecting optical elements are free curved surfaces, and simultaneously adopts immersion type, thereby greatly reducing the volume of the system, having longer slits and wide working wave bands and being suitable for unmanned aerial vehicle high-altitude hyperspectral imaging.
Drawings
FIG. 1 is a schematic plan view of a structure of an optical system of a dual-band imaging spectrometer according to an embodiment of the present invention;
in the figure, 1, a free-form surface main prism; 11. an entrance slit; 12. a main reflecting surface; 13. a reflective grating; 14. a secondary reflecting surface; 15. a short-wave infrared spectrum imaging surface; 2. a secondary prism; 21. a visible near infrared spectrum imaging surface; 3. a filter;
FIG. 2 is a schematic diagram of a light path and a coordinate system of each element in an optical system of a dual-band spectral imaging method according to an embodiment of the present invention;
FIG. 3 is a graph of a full field of view full band transfer function curve MTF obtained by a dual band spectral imaging method according to an embodiment of the present invention;
FIG. 4 is a graph of RMS spot radius for a full field of view full operating band obtained by a dual band spectral imaging method according to an embodiment of the invention.
Detailed Description
The technical scheme of the invention is further described below with reference to the accompanying drawings and examples.
Example 1
The embodiment provides a dual-band spectral imaging method with an operating band of 400nm to 2500 nm.
Referring to fig. 1, which is a schematic structural plan view of an optical system of a dual-band imaging spectrometer provided in this embodiment, elements of the optical system mainly include a main prism 1 with a free-form surface and a secondary prism 2, the two prisms are glued, and a filter 3 is arranged at the glued surface; the free-form surface main prism is provided with an incident slit 11, a main reflecting surface 12, a reflective grating 13, a secondary reflecting surface 14 and a short-wave infrared spectrum imaging surface 15; the visible near infrared spectrum imaging surface 21 is provided on the secondary prism.
Referring to fig. 2, a schematic diagram of an optical path and a coordinate system where each element in an optical system of a dual-band spectral imaging method is located is provided in this embodiment; during spectral imaging, object light passes through the entrance slit, sequentially passes through the main reflection surface, the reflection type grating and the secondary reflection surface, and then is reflected to the filter, wherein light is split when passing through the reflection type grating, finally, the part of the light with the wave band of 400nm to 1000nm penetrates through the filter to reach the visible near infrared spectrum imaging surface for imaging, and the part of the light with the wave band of 1000nm to 2500nm is reflected by the filter to reach the short wave infrared spectrum imaging surface for imaging.
As can be seen from fig. 2, in the dual-band imaging spectrum method provided in the present embodiment, the coordinate systems of the elements in the optical system are respectively: with the centre of the entrance slit as the originEstablishing a first three-dimensional rectangular coordinate system (x 1 ，y 1 ，z 1 ) A straight line passing through the center of the entrance slit in the horizontal direction is z 1 The axis is negative to the left and positive to the right (the incident direction of the light is z 1 Positive axis direction), y 1 The axis being perpendicular to z 1 Positive in axial direction and negative in axial direction, x 1 The axis being perpendicular to y 1 z 1 Plane, vertical y 1 z 1 The plane is positive inwards and negative outwards; in space relative to a first three-dimensional rectangular coordinate system (x 1 ，y 1 ，z 1 ) Defining a second three-dimensional rectangular coordinate system (x 2 ，y 2 ，z 2 ) A third three-dimensional rectangular coordinate system (x) is defined by the space of the reflective grating 3 ，y 3 ，z 3 ) A fourth three-dimensional rectangular coordinate system (x) is defined by the space in which the secondary reflection surface is located 4 ，y 4 ，z 4 ) A fifth three-dimensional rectangular coordinate system (x 5 ，y 5 ，z 5 ) A sixth three-dimensional rectangular coordinate system (x) is defined by the space of the visible near infrared spectrum imaging surface 6 ，y 6 ，z 6 ) A seventh three-dimensional rectangular coordinate system (x) is defined by the space of the short-wave infrared spectrum imaging surface 7 ，y 7 ，z 7 )。
In this embodiment, the positional relationship of each three-dimensional rectangular coordinate system is as follows:
second three-dimensional rectangular coordinate system (x 2 ，y 2 ，z 2 ) Is arranged at the origin of the first three-dimensional rectangular coordinate system (x 1 ，y 1 ，z 1 ) (0,0,118.65194) position (unit: mm), z 2 The positive axis direction is relative to the first three-dimensional rectangular coordinate system (x 1 ，y 1 ，z 1 ) Z of (2) 1 The shaft is rotated 13.80746 deg. clockwise.
Third three-dimensional rectangular coordinate system (x 3 ，y 3 ，z 3 ) Is arranged at the origin of the second three-dimensional rectangular coordinate system (x 2 ，y 2 ，z 2 ) Positions (0,21.29270, -114.47325) (unit: mm), z 3 The positive axis direction is relative to a second three-dimensional rectangular coordinate system(x 2 ，y 2 ，z 2 ) Z of (2) 2 The shaft is rotated 23.92956 deg. clockwise.
Fourth three-dimensional rectangular coordinate system (x 4 ，y 4 ，z 4 ) Is arranged in a third three-dimensional rectangular coordinate system (x 3 ，y 3 ，z 3 ) (0, -14.61372,111.92814) position (unit: mm), z 4 The positive axis direction is relative to a third three-dimensional rectangular coordinate system (x 3 ，y 3 ，z 3 ) Z of (2) 3 The shaft is rotated 19.55533 deg. clockwise.
Fifth three-dimensional rectangular coordinate system (x 5 ，y 5 ，z 5 ) Is arranged in a fourth three-dimensional rectangular coordinate system (x 4 ，y 4 ，z 4 ) (0, -103.55807) (unit: mm), z 5 The positive axis direction is relative to the fourth three-dimensional rectangular coordinate system (x 4 ，y 4 ，z 4 ) Z of (2) 4 The shaft is rotated 30 deg. counter clockwise.
Sixth three-dimensional rectangular coordinate system (x 6 ，y 6 ，z 6 ) Is arranged in a fifth three-dimensional rectangular coordinate system (x 5 ，y 5 ，z 5 ) (0, -8.65,40) position (unit: mm), z 6 The positive axis direction is relative to the fifth three-dimensional rectangular coordinate system (x 5 ，y 5 ，z 5 ) Z of (2) 5 The shaft is rotated 16.57013 deg. clockwise.
Seventh three-dimensional rectangular coordinate system (x 7 ，y 7 ，z 7 ) Is arranged in a fifth three-dimensional rectangular coordinate system (x 5 ，y 5 ，z 5 ) (0,8.65,40) position (unit: mm), z 7 The positive axis direction is relative to the fifth three-dimensional rectangular coordinate system (x 5 ，y 5 ，z 5 ) Z of (2) 5 The shaft rotates 16.57013 counter-clockwise.
The mathematical descriptions of the primary reflecting surface, the reflective grating and the secondary reflecting surface of the optical system are respectively expressed in a second three-dimensional rectangular coordinate system (x 2 ，y 2 ，z 2 ) Third three-dimensional rectangular coordinate system (x 3 ，y 3 ，z 3 ) Fourth three-dimensional rectangular coordinate System (x 4 ，y 4 ，z 4 ) The surface expression z of the free-form surface is:
wherein, the curvature c, the quadric surface coefficient k and each coefficient of each curved surfaceA i See table 1 for values of (c).
TABLE 1
| Main reflecting surface | Reflection type grating | Secondary reflecting surface | |
| c | -0.01862 | 1.27693E-153 | -0.04548 |
| k | -0.98477 | 0 | -0.99951 |
|
|
0 | 0 | 0 |
| A 2 | -0.02855 | -8.70887E-06 | -0.06669 |
| A 3 | 5.99089E-03 | -2.82971E-03 | 0.02066 |
|
|
0 | 0 | 0 |
| A 5 | 5.81844E-03 | -5.68415E-03 | 0.02020 |
|
|
0 | 0 | 0 |
| A 7 | -3.08427E-06 | -5.80109E-05 | -1.64509 |
| A | |||
| 8 | 0 | 0 | 0 |
| A 9 | 9.15345E-07 | 3.38679E-05 | 2.30573E-07 |
| A 10 | -2.75419E-08 | -4.07969E-07 | -1.97595 |
| A | |||
| 11 | 0 | 0 | 0 |
| A 12 | -7.85000E-08 | -8.10764E-07 | -1.30246 |
| A | |||
| 13 | 0 | 0 | 0 |
| A 14 | -2.72602E-08 | -2.32277E-07 | -9.68101 |
| A | |||
| 15 | 0 | 0 | 0 |
| A 16 | -1.24718E-10 | -1.61505E-08 | -1.30679 |
| A | |||
| 17 | 0 | 0 | 0 |
| A 18 | -1.56336E-10 | 1.54569E-09 | -1.25840 |
| A | |||
| 19 | 0 | 0 | 0 |
| A 20 | 4.98823E-11 | 9.89587E-09 | -2.96839E-10 |
| A 21 | -1.01149E-12 | -8.19456E-11 | -2.56367 |
| A | |||
| 22 | 0 | 0 | 0 |
| A 23 | -2.52556E-12 | -6.39162E-10 | -2.21304 |
| A | |||
| 24 | 0 | 0 | 0 |
| A 25 | -1.05965E-11 | 2.48611E-09 | 5.56526 |
| A | |||
| 26 | 0 | 0 | 0 |
| A 27 | -7.97297E-12 | -1.04253E-08 | 5.46710E-12 |
In this embodiment, the scribe line direction of the reflective grating is parallel to x 3 The direction, the density of the scribing lines is 150 strips/mm, and the diffraction order is 1 order; working face of filter plate and fifth three-dimensional rectangular coordinate systemX of (2) 5 y 5 The plane is parallel, and the center of the working surface coincides with the origin of the fifth coordinate system; visible near infrared spectrum imaging surface and x in sixth three-dimensional rectangular coordinate system 6 y 6 The plane is parallel, and the center of the spectrum imaging surface coincides with the origin of the sixth coordinate system; x in short wave infrared spectrum imaging surface and seventh three-dimensional rectangular coordinate system 7 y 7 The plane is parallel, and the center of the spectrum imaging plane coincides with the origin of the seventh coordinate system.
The optical system of the dual-band spectrum imaging method provided by the embodiment adopts prism integration, and the material of the prism is barium fluoride (BAF) 2 ）。
The spectral imaging system provided in this embodiment has performance parameters satisfying the conditions of table 2.
TABLE 2
| Spectral range | 400nm～2500nm |
| Object space numerical aperture | 0.14 |
| Working F number | 3.57 |
| Image plane dispersion width | 6mm/14mm |
| Slit length | 10mm |
| Score line density | 150 strips/mm |
| Spectral resolution | 3.5nm |
| Volume of | 405 cm 3 |
| Visible near infrared spectrum imaging surface pixel | 14µm×14µm |
| Short wave infrared spectrum imaging surface pixel | 18µm×18µm |
Referring to fig. 3, a full-band transfer function MTF graph obtained by an optical imaging system based on a freeform prism is used in the dual-spectrum imaging method according to the present embodiment; in the figures, (a) diagram, (b) diagram, (c) diagram, (d) diagram, (e) diagram and (f) diagram are all view field transfer function MTF curves of the optical system on corresponding image planes with wavelengths of 400nm, 700nm, 1000nm, 1500nm, 2000nm and 2500nm respectively. As can be seen from FIG. 3, the optical transfer functions of the full view field of the working wave bands from 400nm to 1000nm at 36lp/mm are all larger than 0.5, the optical transfer functions of the full view field of the working wave bands from 1000nm to 2500nm at 28lp/mm are all larger than 0.3, the diffraction limit is approached, the curve is smooth and compact, the imaging of the system is clear and uniform, and the system has better imaging quality in the full wave band and the full view field.
Referring to fig. 4, a graph of RMS spot radius in a full field of view and full operating band is obtained using a free-form prism-based optical imaging system according to the dual spectral imaging method provided in this embodiment. Curve (a) is the RMS radius of the full field of view full operating band and curve (b) is the RMS radius of the full operating band at the diffraction limit. As can be seen from fig. 4, in the full-view full-working band, the RMS root mean square spot radius of the system is smaller than 4.5 μm, and smaller than the diffraction limit RMS radius, and the energy is concentrated, so as to meet the use requirement.
The results prove that the optical imaging system based on the freeform prism is adopted in the dual-band spectrum imaging method provided by the invention, the working F number can reach 3.57, the slit length can reach 10mm, the working band is 400nm to 2500nm, the optical transfer functions of the full working band and the full field of view are close to diffraction limit in the sampling frequency, the imaging quality is better, and the volume is only 405 cm 3 The requirements of wide wave band, wide view field, miniaturization and high resolution of the unmanned aerial vehicle spectral imaging system are met.
Claims (4)
1. The dual-band spectrum imaging method is characterized by comprising the following steps of:
the method comprises the steps of (1) adopting an immersed structure formed by gluing a free-form surface main prism (1) and a secondary prism (2), and arranging a filter (3) at the gluing surface of the free-form surface main prism and the secondary prism to construct a dual-band spectrum imaging optical system; a slit (11), a main reflecting surface (12), a reflective grating (13), a secondary reflecting surface (14) and a short-wave infrared spectrum imaging surface (15) are arranged on the free-form surface main prism; a visible near infrared spectrum imaging surface (21) is arranged on the secondary prism; the aperture diaphragm of the system is arranged on the reflective grating; the main prism and the secondary prism of the free curved surface are made of barium fluoride;
the relative positions of the optical elements in the dual-band spectral imaging optical system are as follows:
the space where the slit is located is defined as a first three-dimensional rectangular coordinate system (x 1 ，y 1 ，z 1 ) A first three-dimensional rectangular coordinate system (x 1 ，y 1 ，z 1 ) Is at the center of the slit, the incident direction of the light is z 1 Positive axis direction, y 1 Upward in the positive direction of axis, x 1 The axial direction is vertical to the paper surface and inwards;
the space where the main reflecting surface is located is defined as a second three-dimensional rectangular coordinate system (x 2 ，y 2 ，z 2 ) A second three-dimensional rectangular coordinate system (x 2 ，y 2 ，z 2 ) Is located at the origin of the first three-dimensional rectangular coordinate system (x 1 ，y 1 ，z 1 ) Origin z 1 Forward translation 118-119 mm, z 2 The positive axis direction is relative to the first three-dimensional rectangular coordinate system (x 1 ，y 1 ，z 1 ) Z of (2) 1 The shaft rotates clockwise by 13-14 degrees in the positive direction;
the space where the reflective grating is located is defined as a third three-dimensional rectangular coordinate system (x 3 ，y 3 ，z 3 ) A third three-dimensional rectangular coordinate system (x 3 ，y 3 ，z 3 ) Is located at the origin of the second three-dimensional rectangular coordinate system (x 2 ，y 2 ，z 2 ) Origin direction y 2 Forward translation of 21-22 mm, z 2 Negative direction translation 114-115 mm, z 3 The positive axis direction is relative to a second three-dimensional rectangular coordinate system (x 2 ，y 2 ，z 2 ) Z of (2) 2 The shaft rotates clockwise by 23-24 degrees in the positive direction;
the space where the secondary reflecting surface is located is defined as a fourth three-dimensional rectangular coordinate system (x 4 ，y 4 ，z 4 ) Fourth three-dimensional rectangular coordinate system (x 4 ，y 4 ，z 4 ) Is located at the origin of the third three-dimensional rectangular coordinate system (x 3 ，y 3 ，z 3 ) Origin direction y 3 Negative direction translation of 14-15 mm, z 3 Negative direction translation 111-112 mm, z 4 The positive axis direction is relative to a third three-dimensional rectangular coordinate system (x 3 ，y 3 ，z 3 ) Z of (2) 3 The shaft rotates clockwise by 19-20 degrees in the positive direction;
the space where the filter is located is defined as a fifth three-dimensional rectangular coordinate system (x 5 ，y 5 ，z 5 ) A fifth three-dimensional rectangular coordinate system (x 5 ，y 5 ，z 5 ) Is located at the origin of the fourth three-dimensional rectangular coordinate system (x 4 ，y 4 ，z 4 ) Origin z 4 Negative direction translation 103-104 mm, z 5 The positive axis direction is relative to the fourth three-dimensional rectangular coordinate system (x 4 ，y 4 ，z 4 ) Z of (2) 4 The shaft rotates 30 degrees anticlockwise in the positive direction;
defining the space where the short-wave infrared spectrum imaging surface is located as a sixth three-dimensionalRectangular coordinate system (x) 6 ，y 6 ，z 6 ) A sixth three-dimensional rectangular coordinate system (x 6 ，y 6 ，z 6 ) Is located at the origin of the fifth three-dimensional rectangular coordinate system (x 5 ，y 5 ，z 5 ) Origin direction y 5 Negative direction translation of 8-9 mm, z 5 Forward translation 40mm, z 6 The positive axis direction is relative to the fifth three-dimensional rectangular coordinate system (x 5 ，y 5 ，z 5 ) Z of (2) 5 The shaft rotates clockwise by 16-17 degrees in the positive direction;
the space where the visible near infrared spectrum imaging surface is located is defined as a seventh three-dimensional rectangular coordinate system (x 7 ，y 7 ，z 7 ) Seventh three-dimensional rectangular coordinate system (x 7 ，y 7 ，z 7 ) Is located at the origin of the fifth three-dimensional rectangular coordinate system (x 5 ，y 5 ，z 5 ) Origin direction y 5 Forward translation of 8-9 mm to z 5 Forward translation 40mm, z 7 The positive axis direction is relative to the fifth three-dimensional rectangular coordinate system (x 5 ，y 5 ，z 5 ) Z of (2) 5 The shaft rotates anticlockwise by 16-17 degrees in the positive direction;
the main reflecting surface, the reflective grating and the secondary reflecting surface arranged on the free-form surface main prism are respectively corresponding to the two surfaces in a second three-dimensional rectangular coordinate system (x 2 ，y 2 ，z 2 ) Third three-dimensional rectangular coordinate system (x 3 ，y 3 ，z 3 ) Fourth three-dimensional rectangular coordinate System (x 4 ，y 4 ，z 4 ) The free-form surface of the XY polynomial of degree 6; the surface expression z of the free-form surface is:
wherein c is the curvature; k is a quadric coefficient;A i the coefficients are respectively that i is more than or equal to 1 and less than or equal to 27, and i is an integer;
the line direction of the reflection grating is parallel to x 3 The direction, the density of the scribing lines is 150 strips/mm, and the diffraction order is 1 order;
the working face of the filter and x in a fifth three-dimensional rectangular coordinate system 5 y 5 The plane is parallel, and the center of the working surface coincides with the origin of the fifth coordinate system;
x in the short wave infrared spectrum imaging surface and the sixth three-dimensional rectangular coordinate system 6 y 6 The plane is parallel, and the center of the detection surface coincides with the origin of the sixth coordinate system;
x in the visible near infrared spectrum imaging surface and the seventh three-dimensional rectangular coordinate system 7 y 7 The plane is parallel, and the center of the detection surface coincides with the origin of the seventh coordinate system;
(2) The object side light is incident through a slit arranged on the free-form surface main prism and is reflected to the reflective grating through the main reflecting surface;
(3) The light split by the reflective grating is reflected to the secondary reflecting surface, and then reaches the filter after being reflected by the secondary reflecting surface;
(4) Light rays in the visible near infrared band are transmitted through the filter, and are imaged on a visible near infrared spectrum imaging surface on the secondary prism; light rays in the short wave infrared band are reflected by the filter and imaged on a short wave infrared spectrum imaging surface on the free-form surface main prism.
2. A dual band spectral imaging method according to claim 1, wherein: a 6 th order XY polynomial free-form surface of the main reflecting surface, the curvature c= -0.01862; quadric coefficients k= -0.98477; polynomial coefficient A i The method comprises the following steps of: -1X 10 -3 ≤A 2 ≤0,0≤A 3 ≤1×10 -2 ,0≤A 5 ≤1×10 -2 , -1×10 -7 ≤A 7 ≤0,0≤A 9 ≤1×10 -6 , -1×10 -9 ≤A 10 ≤0, -1×10 -9 ≤A 12 ≤0, -1×10 -9 ≤A 14 ≤0, -1×10 -11 ≤A 16 ≤0, -1×10 -11 ≤A 18 ≤0,0≤A 20 ≤1×10 -10 ，-1×10 -13 ≤A 21 ≤0，-1×10 -13 ≤A 23 ≤0，-1×10 -12 ≤A 25 ≤0，-1×10 -13 ≤A 27 Less than or equal to 0, and the rest is 0.
3. A dual band spectral imaging method according to claim 1, wherein: the curvature c= 1.27693E-153 of the 6 th order XY polynomial free-form surface of the reflective grating; quadric coefficient k=0; polynomial coefficient A i The method comprises the following steps of: -1X 10 -7 ≤A 2 ≤0, -1×10 -4 ≤A 3 ≤0, -1×10 -4 ≤A 5 ≤0, -1×10 -6 ≤A 7 ≤0,0≤A 9 ≤1×10 -4 , -1×10 -8 ≤A 10 ≤0, -1×10 -8 ≤A 12 ≤0, -1×10 -8 ≤A 14 ≤0, -1×10 -19 ≤A 16 ≤0, 0≤A 18 ≤1×10 -8 ,0≤A 20 ≤1×10 -8 ，-1×10 -12 ≤A 21 ≤0，-1×10 -11 ≤A 23 ≤0，0≤A 25 ≤1×10 -8 ，-1×10 -9 ≤A 27 Less than or equal to 0, and the rest is 0.
4. A dual band spectral imaging method according to claim 1, wherein: a 6 th order XY polynomial free-form surface of the secondary reflecting surface, the curvature c= -0.04548; quadric coefficients k= -0.99951; polynomial coefficient A i The method comprises the following steps of: -1X 10 -3 ≤A 2 ≤0,0≤A 3 ≤1×10 -1 ,0≤A 5 ≤1×10 -1 , -1×10 -7 ≤A 7 ≤0,0≤A 9 ≤1×10 -6 , -1×10 -9 ≤A 10 ≤0, -1×10 -9 ≤A 12 ≤0, -1×10 -10 ≤A 14 ≤0, -1×10 -13 ≤A 16 ≤0, -1×10 -11 ≤A 18 ≤0, -1×10 -11 ≤A 20 ≤0，-1×10 -14 ≤A 21 ≤0，-1×10 -13 ≤A 23 ≤0，0≤A 25 ≤1×10 -11 ，0≤A 27 ≤1×10 -11 The balance being 0.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB849347A (en) * | 1957-05-27 | 1960-09-28 | Richard Fiske Jarrell | Improvements in spectrometers |
| CN103017900A (en) * | 2012-11-26 | 2013-04-03 | 中国科学院长春光学精密机械与物理研究所 | Dual-channel common-path prism dispersion broadband imaging spectrometer optical system |
| CN106289524A (en) * | 2016-07-14 | 2017-01-04 | 中国科学院光电研究院 | Spectrum imaging system based on free form surface |
| CN111751915A (en) * | 2020-06-27 | 2020-10-09 | 同济大学 | Compact infrared viewfinder optical system based on free-form surface prism |
| CN111751914A (en) * | 2020-06-27 | 2020-10-09 | 同济大学 | Common-caliber infrared free-form surface prism optical system with double wave bands and double view fields |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB849347A (en) * | 1957-05-27 | 1960-09-28 | Richard Fiske Jarrell | Improvements in spectrometers |
| CN103017900A (en) * | 2012-11-26 | 2013-04-03 | 中国科学院长春光学精密机械与物理研究所 | Dual-channel common-path prism dispersion broadband imaging spectrometer optical system |
| CN106289524A (en) * | 2016-07-14 | 2017-01-04 | 中国科学院光电研究院 | Spectrum imaging system based on free form surface |
| CN111751915A (en) * | 2020-06-27 | 2020-10-09 | 同济大学 | Compact infrared viewfinder optical system based on free-form surface prism |
| CN111751914A (en) * | 2020-06-27 | 2020-10-09 | 同济大学 | Common-caliber infrared free-form surface prism optical system with double wave bands and double view fields |
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