CN102183304B - A kind of optical path structure of cylindrical anastigmatic grating dispersion type imaging spectrometer - Google Patents
A kind of optical path structure of cylindrical anastigmatic grating dispersion type imaging spectrometer Download PDFInfo
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Abstract
A kind of optical path structure of cylindrical anastigmatic grating dispersion type imaging spectrometer, including slit (1)；Collimator objective (2), by by the luminous reflectance of slit to grating (3)；Grating (3), carries out light splitting；Image-forming objective lens group is made up of spherical reflector (4) and cylindrical mirror (5), carries out spectral imaging by the photosurface of the photoimaging after light splitting to detector (6).Spectrogrph uses total-reflection type optical element, and all reflecting elements all plate high reflection film.This construction features is that introducing cylindrical mirror reduces the sagittal surface astigmatism of grating dispersion type imaging spectrometer, greatly improves Spectral resolution and the Imaging Resolution of spectrogrph.
Description
Technical field
The present invention relates to spectrogrph, particularly relate to the light channel structure of grating dispersion type imaging spectrometer.
Background technology
Imaging spectral technology originates from the multispectral romote sensing technology of phase at the beginning of the seventies in last century, and along with earth observation is applied
Needs and develop, be the emerging field combining imaging technique and spectral technique.Imager obtains the image information of target, chases after
Seek fine definition and study its spatial character；Spectrogrph is then separated into the radiation of target the spectral radiance of different wave length, pursues
High spectral resolution power, thus target is measured and analyzes.The crystallization imaging spectrometer of both technological incorporation can
Obtain the high spectrum image of target specific band to be measured, there is the advantage of collection of illustrative plates unification.
Color dispersion-type imaging spectrometer generally uses grating as beam splitter, the color dispersion-type imaging spectrometer light of total-reflection type
Line structure has the advantages such as Spectral resolution height, wavelength band width, good reliability.But the requirement of light path unshielding determines entirely
Reflective color dispersion-type spectrogrph belongs to off-axis optical system, is traditional Qie Erni-Tener type spectrum as depicted in figs. 1 and 2
Instrument light channel structure: include slit.The aberration of this class formation is bigger, it is impossible to realize higher Spectral resolution and Imaging Resolution.
Summary of the invention
The present invention relates to cylinder anastigmatic grating dispersion type imaging spectrometer, including slit, limit entrance spectrogrph and divide
The beam size of photosystem, its width determines the Spectral resolution of spectrogrph, and its height determines the imaging dimension angle of visual field of spectrogrph,
The i.e. areas imaging of single width spectrum picture；
Collimator objective, by by the luminous reflectance of slit to grating；
Grating, the parallel polychromatic light that collimation object lens reflect back is divided into the collimated light beam group of the corresponding angle of diffraction by wavelength；
Image-forming objective lens group, focuses to carry out at the photosurface of detector spectral imaging by the collimated light beam group after light splitting；
Detector, two-dimensional detector can receive simultaneously comprise one-dimensional spectral information and the spectrogram of one-dimensional space information
Picture.
Wherein, each optical element in optical system all uses total-reflection type optical element, all reflections in addition to slit
Element all plates high reflection film.
Wherein, spectrogrph clear aperature preferably 10～150mm；Spectrum Wei Shunshishichangjiao preferably 0.01 °～2.0 °；Scanning
The angle of visual field is in the range of 10 °～160 °.
Wherein, image-forming objective lens group is collectively constituted by spherical reflector and cylindrical mirror.
Wherein, introduce cylindrical mirror and eliminate imaging spectrometer astigmatism in sagittal surface.
The problem the highest in order to solve the color dispersion-type spectrogrph Imaging Resolution of tradition total-reflection type, the light path to spectrogrph
Structure carries out innovation at three:
Plane mirror between image-forming objective lens and detector, on the basis of not increasing optical element, is replaced by the first
For cylindrical mirror, the imaging characteristics of cylindrical surface type is utilized to eliminate the effects of the act the maximum astigmatism of imaging spectrometer image quality, and not
It it is the toroidal mirror utilizing difficulty of processing the biggest.
It two is the focal length making the spacing of collimator objective and slit be not equal to collimator objective, using this distance parameter as excellent
Changing parameter, i.e. the light beam after collimator objective collimates is not directional light, but non-with certain angle of divergence or convergent angle
Directional light, this design makes whole optical system have more optimized variable.
It three is the relation according to the imaging spectrometer aberration shown in formula 1 Yu optical texture, calculate that aberration is minimum one
Group structure, in formula 1, the meaning representated by symbol is as shown in Figure 1.Can be derived when the distance of collimator objective 2 to grating 3 is by formula 1
2 times of (l of collimator objective focal length1=2f '1), and grating 3 is to 2 times of (l that distance is image-forming objective lens group focal length of image-forming objective lens 42
=2f '2) time imaging spectrometer aberration coefficients minimum, so the aberration of imaging spectrometer is also the most minimum.
This light channel structure can be greatly improved Spectral resolution and the Imaging Resolution of spectrogrph, and difficulty of processing
Little, cost is relatively low.
Accompanying drawing explanation
Fig. 1 show Qie Erni-Tener type spectrogrph principle schematic；
Fig. 2 show the light channel structure schematic diagram of traditional imaging spectrometer；
Fig. 3 show the light channel structure schematic diagram of the traditional imaging spectrometer with plane mirror；
Fig. 4 show the light channel structure schematic diagram of the imaging spectrometer according to the present invention.
(in accompanying drawing each parts size and distance wait draw in strict accordance with ratio).
Detailed description of the invention
Below, describe in detail according to a preferred embodiment of the invention in conjunction with accompanying drawing.Fig. 4 show the enforcement according to the present invention
The scanning imagery light path of optical spectrometer structural representation of mode.The optical system of this spectrogrph includes a) slit 1, b) collimator objective 2,
C) plane grating 3, d) image-forming objective lens group 4,5, e) detector 6.
Being observed object and be placed at slit 1 or be observed the real image of object at slit 1, object or object real image are sent
Light carried out light splitting through slit 1 by collimator objective 2 collimated reflected to plane grating 3, then gathered by focusing objective len group 4,5
Burnt imaging on the photosurface of detector 6.
As seen from Figure 2, traditional Qie Erni-two pieces of spherical reflectors of Tener type optical routing are as collimator objective 2 He
Image-forming objective lens 4, beam splitter is plane grating 3, and spectrum picture is imaged on detector 5 by image-forming objective lens 4.Fig. 3 is also tradition
Qie Erni-Tener type light path.The installation of detector for convenience, generally installs one piece of plane anti-in the structure shown in Fig. 2
Penetrate mirror 5 and light deflection about 45 ° is reflexed to imaging on detector 6.This light channel structure has obtained in non-imaged spectrogrph
To extensively application, hinder its application in imaging spectrometer yet with the feature that this light path astigmatism is big.The present invention draws
Enter cylindrical mirror, and improve light channel structure to improve Imaging Resolution and the Spectral resolution of imaging spectrometer, design philosophy
As follows:
First pass through Aberration Theory analysis it can be calculated that be collimation objective focal length when collimator objective 2 arrives the distance of grating 3
2 times, and grating 3 to 2 times that distance is image-forming objective lens group focal length of image-forming objective lens group 4 time, the aberration of imaging spectrometer is minimum,
Now astigmatism is main residual aberration, and astigmatism hinders the raising of imaging spectrometer Imaging Resolution greatly.According to picture
The producing cause dissipated divides, and present invention employs two kinds of methods and eliminates astigmatisms:
1, the basic reason producing astigmatism is the off-axis angle of optical element in Qie Erni-Tener type light path, according to derivation
Astigmatism formula find the biggest astigmatism of off-axis angle the biggest, therefore reduce off-axis angle be reduce imaging spectrometer astigmatism important hands
Section.And invention increases grating to collimator objective and the distance of image-forming objective lens, this is collimator objective and image-forming objective lens off-axis angle
Adjustable extent provide bigger space, can be that off-axis angle is less, fundamentally reduce the generation of astigmatism.
2, the immediate cause producing astigmatism is meridian focal length and the sagitta of arc focal length of optical system, cause meridianal image surface with
Sagittal image surface is misaligned, the cylindrical mirror in replacing with Fig. 3 midplane reflecting mirror 5 such as Fig. 4 according to this feature of astigmatism
5, cylindrical mirror have in sagittal surface be not 0 curvature.So, the optimal of meridian plane can first be found when initial designs
Image planes position, now on slit, some the light spot shape in image planes should be the length elongated strip along sagitta of arc direction.Then change
Become cylindrical mirror curvature in sagittal surface, it is possible to be substantially reduced the length of hot spot in image planes, finally give the circle of minor radius
Hot spot.
It addition, can produce astigmatism when grating is placed under non-parallel light irradiates, therefore the position of slit is carried out by the present invention
Fine setting, makes the slit distance away from collimator objective be slightly less than the focal length of collimator objective, so that grating is at the less light beam of the angle of divergence
Irradiate the certain astigmatism of lower generation and offset the astigmatism of image planes, the final spectrum picture obtaining little aberration.
Reflecting mirror and grating in the present embodiment are reflection type optical element, and reflecting surface plates high reflection film, and
Mirror surface type is sphere or cylinder, does not uses secondary or more high-order curved surface mirror that difficulty of processing is bigger.
Below each optical element in the spectrogrph of present embodiment is described in detail.
A) slit 1
The effect of slit 1 is the beam size limiting and entering spectrogrph beam splitting system, and according to imaging spectrometer principle, it is wide
Degree determines the Spectral resolution of spectrogrph, and its height determines imaging the dimension angle of visual field, the i.e. imaging of single width spectrum picture of spectrogrph
Scope.
B) collimator objective 2
The Main Function of collimator objective 2 is the beam collimation being entered spectrogrph beam splitting system by entrance slit to be reflexed to
On plane grating 3.In present embodiment, collimator objective uses spherical surface type, and the light beam through collimator objective can be directional light
Or diverging light.
C) plane grating 3
Plane grating, as the beam splitter of color dispersion-type spectrogrph, is the core parts of whole spectrogrph.According to diffraction light
Grid light-dividing principle, parallelism of raster pair polychromatic light is divided into the collimated light beam group with different diffraction angle, every Shu Pinghang by wavelength difference
Light is monochromatic light, thus realizes the dispersion of spectrum.
D) focusing objective len group 4 and 5
The effect of focusing objective len 4 and 5 is the collimated light beam group of the object plane information that carries separated through grating 6 to be focused on
On the photosurface of detector, thus realize the spectral imaging to object.In present embodiment, its face type uses spherical reflector
And cylindrical mirror.
E) detector 6
Use 2-dimensional array detector to receive simultaneously and comprise one-dimensional spectral information and the spectrogram of one-dimensional space information
Picture, can be obtained the multispectral datacube of two-dimensional space, finally give through rebuilding spectrum and treat by the scanning tieing up spectrum
Survey the high spectrum image of target.
One embodiment of imaging spectrometer according to present embodiment is as follows, system population parameter:
1) wavelength band: 200nm～1000nm；
2) grating line number: 1200lp/mm；
3) Spectral resolution: be better than 1.0nm；
4) focal length: 192.85；
5) Imaging Resolution: 141p/mm；
In optical system, the concrete optical parametric of each optical element is as shown in table 1.In form, " face type " represents each face
Title；" radius of curvature " is the radius size of each optical surface；" to distance below " is that this optical surface is to next optics
The distance in face；" clear aperature " represents half caliber size of this optical element；Off-axis angle represents the rotation between this face and front one side
Corner.Length positive and negative with from left to right for just, on the contrary it is negative；Angle positive and negative with along imaging direction (i.e. sagitta of arc direction) up time
Pin just rotates to be, otherwise is negative.
Table 1 scanning imagery light path of optical spectrometer structural parameters
A kind of preferred embodiment of the simply present invention described in this specification, above example is only in order to illustrate this
Invention technical scheme rather than limitation of the present invention.All those skilled in the art under this invention's idea by logical analysis,
Reasoning or the available technical scheme of limited experiment, all should be within the scope of the present invention.
Claims (5)
1. cylinder anastigmatic grating dispersion type imaging spectrometer, including:
Slit, limits the beam size entering spectrogrph, and its width determines the Spectral resolution of spectrogrph, and its height determines spectrum
Imaging the dimension angle of visual field, the i.e. areas imaging of single width spectrum picture of instrument；
Collimator objective, will collimate and reflex to by the light of slit on reflective planar diffraction grating；
Reflective planar diffraction grating, the parallel polychromatic light that collimation object lens reflect back is divided into by wavelength difference and has difference and spread out
The collimated light beam group of firing angle, often group collimated light beam is monochromatic light；
Image-forming objective lens group, is made up of spherical reflector and cylindrical mirror, and the collimated light beam group after light splitting is focused to detector
Photosurface at carry out spectral imaging；
Detector, 2-dimensional array detector, gather spectral image data.
2. cylinder anastigmatic grating dispersion type imaging spectrometer, including:
Slit, limits the beam size entering spectrogrph, and its width determines the Spectral resolution of spectrogrph, and its height determines spectrum
Imaging the dimension angle of visual field, the i.e. areas imaging of single width spectrum picture of instrument；
Collimator objective, will collimate and reflex to by the light of slit on reflective planar diffraction grating；
Reflective planar diffraction grating, the polychromatic light that collimation object lens reflect back is divided into by wavelength difference and has different diffraction angle
Light beam group, often group light beam be monochromatic light；
Image-forming objective lens group, is made up of spherical reflector and cylindrical mirror, and the light beam group after light splitting focuses to the light of detector
Spectral imaging is carried out at quick；
Detector, 2-dimensional array detector, gather spectral image data；
Wherein, the light beam after collimator objective collimates is the divergent beams that the angle of divergence is less, irradiates reflective planar diffraction light
Certain astigmatism can be produced to offset the astigmatism of image planes, the final spectrum picture obtaining little aberration after grid.
Cylinder the most according to claim 1 and 2 anastigmatic grating dispersion type imaging spectrometer, it is characterised in that imaging
Each optical element in spectrometer all uses total-reflection type optical element, all reflection type optical elements in addition to slit and detector
All plate high reflection film.
Cylinder the most according to claim 1 and 2 anastigmatic grating dispersion type imaging spectrometer, it is characterised in that collimation object
Mirror to 2 times that distance is collimation objective focal length of reflective planar diffraction grating, and reflective planar diffraction grating is to imaging
The distance of objective lens is 2 times of image-forming objective lens group focal length.
Cylinder the most according to claim 1 and 2 anastigmatic grating dispersion type imaging spectrometer, it is characterised in that introducing
Cylindrical mirror can eliminate the astigmatism of imaging spectrometer.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201110023147.9A CN102183304B (en) | 2011-01-21 | A kind of optical path structure of cylindrical anastigmatic grating dispersion type imaging spectrometer |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201110023147.9A CN102183304B (en) | 2011-01-21 | A kind of optical path structure of cylindrical anastigmatic grating dispersion type imaging spectrometer |
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| CN102183304B true CN102183304B (en) | 2016-12-14 |
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Citations (4)
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|---|---|---|---|---|
| CN1415945A (en) * | 2002-10-17 | 2003-05-07 | 复旦大学 | Design of multiple grating spectrograph imaging device |
| CN1973233A (en) * | 2004-06-21 | 2007-05-30 | 皇家飞利浦电子股份有限公司 | Aberration correction for spectroscopic analysis |
| CN201464039U (en) * | 2009-03-24 | 2010-05-12 | 上海谱纳光电仪器有限公司 | Miniature cylindrical mirror multi-grating spectrum analysis instrument |
| CN201464040U (en) * | 2009-07-29 | 2010-05-12 | 北京卓立汉光仪器有限公司 | imaging grating spectrograph |
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1415945A (en) * | 2002-10-17 | 2003-05-07 | 复旦大学 | Design of multiple grating spectrograph imaging device |
| CN1973233A (en) * | 2004-06-21 | 2007-05-30 | 皇家飞利浦电子股份有限公司 | Aberration correction for spectroscopic analysis |
| CN201464039U (en) * | 2009-03-24 | 2010-05-12 | 上海谱纳光电仪器有限公司 | Miniature cylindrical mirror multi-grating spectrum analysis instrument |
| CN201464040U (en) * | 2009-07-29 | 2010-05-12 | 北京卓立汉光仪器有限公司 | imaging grating spectrograph |
Non-Patent Citations (3)
| Title |
|---|
| Broadband astigmatism-corrected Czerny-Turner spectrometer;Kye-Sung Lee等;《OPTICS EXPRESS》;20101025;第18卷(第22期);第23378-23384页 * |
| 宽光谱Czerny-Turner光谱仪中的彗差与分辨率;陈谭轩等;《光谱学与光谱分析》;20100630;第30卷(第6期);第1692-1696页 * |
| 星载车尔尼-特纳型成像光谱仪像差校正的研究;薛庆生等;《光学学报》;20090131;第29卷(第1期);第35-40页 * |
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