CN113759530B - Double-slit long-wave infrared spectrometer, optical system thereof and optical system design method - Google Patents
Double-slit long-wave infrared spectrometer, optical system thereof and optical system design method Download PDFInfo
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Abstract
The invention discloses a double-slit long-wave infrared spectrometer, an optical system thereof and a design method of the optical system, wherein the optical system comprises a first inclined slit, a second inclined slit, a primary mirror, a secondary mirror and a tertiary mirror; the primary mirror and the third mirror are spherical reflectors, the secondary mirror is a curved prism with a concave surface plated with a reflecting film, and the primary mirror, the secondary mirror and the third mirror form an offner structure; at the temperature of T1, the image surfaces of the first inclined slit, the primary mirror, the secondary mirror, the tertiary mirror and the long-wave infrared spectrometer are all positioned in a first light path; at the temperature of T2, the image planes of the first inclined slit, the primary mirror, the secondary mirror, the tertiary mirror and the long-wave infrared spectrometer are all positioned in a second light path; t1 > T2. The invention meets the requirements of normal temperature installation and adjustment, low temperature use, good stability, small volume, small mass and low processing and manufacturing difficulty in one system under the conditions of not sacrificing system image quality and large temperature difference application environment.
Description
Technical Field
The invention belongs to the technical field of long-wave infrared spectrometers, and particularly relates to a double-slit long-wave infrared spectrometer, an optical system thereof and a design method of the optical system.
Background
The fine light splitting capability of the spectrometer can detect the tiny difference of substances, and the long-wave infrared spectrum section is used as one of main transmission windows of the atmosphere and is also an important coverage area of the spectral characteristics of the ground objects, so that the long-wave infrared spectrometer has important application value in the military and civil fields of mineral exploration and geological mapping, chemical gas detection and classification, military camouflage identification, underwater target detection and the like.
The long-wave infrared spectrometer has serious background radiation, the identification of the spectrometer on a target can be seriously influenced, and the inhibition level of background stray light directly determines the performance of the spectrometer. Therefore, to increase the detection sensitivity of a long wave infrared spectrometer, the background radiation of the long wave infrared spectrometer must be reduced.
Background radiation suppression by adopting a full-optical-path or partial-optical-path refrigeration mode is the most important method at present, a spectrometer is required to work at an extremely low temperature, and a long-wave infrared spectrometer is required to be designed and installed at normal temperature and used at a low temperature. A large temperature change exists from normal temperature to low temperature, so that the refractive index, the curvature radius, the thickness, the interval, the mirror surface shape and the refractive index of a medium of the optical element are changed, the position of a focal plane is shifted relative to the normal temperature state, defocusing is formed, and the imaging quality of an instrument is reduced.
At present, various solutions for defocusing of an optical system of a low-temperature spectrometer exist, and typical technical methods include the following steps:
first, as shown in fig. 1, a focusing device is used, a temperature sensor is used to automatically detect temperature, the detected temperature information is transmitted to a processor, the processor calculates the image plane displacement caused by temperature change in real time, and after receiving the displacement information, a control system moves elements or a receiving surface of the system through a motor and a transmission mechanism to compensate the influence of temperature on an optical system.
With this approach, the entire system requires an additional set of electronics, which increases the size and weight of the system, making the system more complex and less reliable. In addition, when the temperature of the system is lower than 100K, the temperature adaptability of the focusing mechanism needs to be additionally considered.
Second, as shown in fig. 2, the material matching is used to eliminate the effect of temperature variation in the optical system by reasonable combination of different materials with different characteristics by using the difference between the thermal characteristics of the optical material and the mechanical material.
In the design process of a low-temperature spectrometer system, for a transmission structure, the compensation amount caused by material matching is far insufficient for defocusing caused by large temperature difference (293K to 100K); in order to ensure uniform expansion and contraction of the optical element and the mechanical structure, the optical element and the mechanical structure are generally made of the same material. Both of the above two methods are very strict in material selection, and the optical material of the low-temperature optical system also needs to consider permeability, high temperature resistance and corrosion resistance, which results in less available materials.
Thirdly, as shown in fig. 3, the focal plane is preset, the position of the focal plane at low temperature is obtained by theoretical calculation, and after the system is installed and adjusted at normal temperature, the detector is moved to be located at the position of the focal plane at low temperature. Since each cooling and heating process and vacuuming of the thermostat take a long time, and the setting result at room temperature varies during low-temperature operation, and it is difficult to adjust at low temperature. The system needs to be heated up to the normal temperature again for modification, so that the design period is increased, and data feedback is not timely. Although fine adjustment at low temperature can be performed by some piezoelectric actuators, it is difficult to ensure reliability thereof.
In conclusion, the low-temperature long-wave infrared spectrometer designed by the existing method has the problems of rapid increase of system complexity and volume, few optional materials, long design period and the like, and is not an optimal method.
Disclosure of Invention
The invention aims to provide a double-slit long-wave infrared spectrometer, an optical system thereof and an optical system design method aiming at the defects of the prior art. Aiming at the low-temperature design of the long-wave infrared spectrometer, the optical system is ensured to be well imaged at normal temperature (such as 20 ℃) and low temperature (such as-173 ℃), and the design index is met on the basis that no moving element exists in the system.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
an optical system of a double-slit long-wave infrared spectrometer is characterized by comprising a first inclined slit, a second inclined slit, a primary mirror, a secondary mirror and a third mirror; the primary mirror and the tertiary mirror are both spherical reflectors, the secondary mirror is a curved prism with a concave surface plated with a reflecting film, and the primary mirror, the secondary mirror and the tertiary mirror form an offner structure;
at the temperature of T1, the image planes of the first inclined slit, the primary mirror, the secondary mirror, the tertiary mirror and the long-wave infrared spectrometer are all positioned in a first light path; at the temperature of T2, the image planes of the first inclined slit, the primary mirror, the secondary mirror, the tertiary mirror and the long-wave infrared spectrometer are all positioned in a second light path; t1 > T2.
By means of the structure, the invention creatively provides that the inclined double-slit structure is introduced into a long-wave infrared spectrometer system for realizing low-temperature background radiation suppression design. The offner structure is selected as the main structure of the optical system of the long-wave infrared spectrometer, the main mirror and the three mirrors of the system use spherical reflectors, the secondary mirror uses a curved prism with a concave surface plated with a reflective film to replace the curved prism as a dispersion element, and the front surface and the rear surface of the curved prism are spherical surfaces. One of the tilted double slits is used for adjusting the spectrometer at a normal temperature T1 (such as 20 ℃) and the other is used for a low temperature T2 (such as-173 ℃). There is a space between the two slits that is much larger than the width of the slits. Therefore, according to the use requirement of the spectrometer, the second inclined slit is selected as the entrance slit at low temperature, and the system can keep good imaging quality at low temperature. The invention does not introduce special surface type and special structure, has good stability, small volume and small mass, and has low processing and manufacturing difficulty.
Further, the device also comprises at least one third inclined slit arranged between the first inclined slit and the second inclined slit.
And a proper amount of slits are additionally etched between the two slits, so that the imaging quality of the spectrometer system can be monitored in real time in the cooling process. In addition, according to the use requirement of the spectrometer, a proper inclined slit is selected as an incident slit, and good imaging quality can be achieved under different temperature conditions.
In a preferred embodiment, T1 is 20 ℃ and T2 is-173 ℃.
In a preferred embodiment, the first inclined slits and/or the second inclined slits have an inclination angle of 4 ° to 5 °.
Preferably, the size of the first inclined slit and/or the second inclined slit is 60mm × 60 um.
Based on the same inventive concept, the invention also provides a double-slit long-wave infrared spectrometer which is characterized by comprising the optical system.
As a preferred mode, the spectrum range of the spectrometer is 8 um-12 um.
Based on the same inventive concept, the invention also provides a design method of the optical system, which is characterized by comprising the following steps:
step one, determining the positions of the image surfaces of a first inclined slit, a primary mirror, a secondary mirror, a tertiary mirror and a long-wave infrared spectrometer at a temperature of T1;
and step two, reducing the temperature to T2, and determining the position of the second inclined slit by adopting a back light path tracking method.
According to the reversibility of the light, the detector is used as a virtual object plane, and the light path tracing is carried out in the direction opposite to the actual light propagation direction, so that the position of the slit in the low-temperature state can be obtained. The method for tracking the inverse light path is not only suitable for determining the position of the inclined slit when the position of the image plane of the spectrometer detector is not changed, but also can be used for determining the position of the image plane of the spectrometer detector when the position of the inclined slit is not changed.
Further, the method also comprises a third step of arranging at least one third inclined slit between the first inclined slit and the second inclined slit.
Further, the step one and/or the step two further comprises: the specifications and/or positions of the elements in the optical system are adjusted so that the optical system obtains the desired performance parameters.
After the position determination, the optical system can also be fine-tuned, so that the operating state of the optical system is optimized.
Compared with the prior art, the invention simultaneously meets the requirements of normal-temperature installation and adjustment, low-temperature use, good stability, small volume, small mass and low processing and manufacturing difficulty in one system under the conditions of not sacrificing system image quality and large temperature difference application environment.
Drawings
Fig. 1 is a schematic diagram of a conventional focusing method.
Fig. 2 is a schematic diagram of a conventional material matching method.
FIG. 3 is a schematic diagram of a conventional method for presetting a focal plane.
Fig. 4(a) is a meridional optical structure diagram of an optical system.
Fig. 4(b) is a sagittal optical structure diagram of the optical system.
FIG. 5 is a 3D model diagram according to the present invention.
FIG. 6 is a functional diagram of a tilted double slit.
Fig. 7 is an image quality evaluation effect diagram of the present invention, in which fig. 7(a) shows the scattered speckles of the system at 20 ℃ at normal temperature, fig. 7(b) shows the scattered speckles of the system at-173 ℃ at low temperature, fig. 7(c) shows the MTF of the system at 20 ℃ at normal temperature, and fig. 7(d) shows the MTF of the system at-173 ℃ at low temperature.
Fig. 8(a) is a schematic diagram of positive optical path tracking.
Fig. 8(b) is a schematic diagram of the back light path tracking.
FIG. 9 is a flowchart of an embodiment of a method for designing an optical system.
Wherein, 1 is a first inclined slit, 2 is a second inclined slit, 3 is a primary mirror, 4 is a secondary mirror, 5 is a tertiary mirror, and 6 is an image surface.
Detailed Description
The invention relates to the following explanation of the related terms:
background radiation: when the infrared detection system observes an object, the object radiation enters the image plane 6 together with other radiation, and the radiation except the object is defined as background radiation.
Spectrometer: the device for measuring the intensities of different wavelength positions of a spectral line by using the optical detector generally comprises a slit, a collimation system, a dispersion system, a convergence system and the optical detector.
A cryogenic optical system: a special optical system that works well over a wide temperature range and maintains diffraction limited imaging.
The invention applies the inclined double slits to the design of the optical system of the long-wave infrared spectrometer in the low-temperature environment, designs a novel spectrometer, and in one embodiment of the invention, the long-wave infrared spectrometer is ensured to be installed and adjusted at the normal temperature of 20 ℃ and used at the low temperature of-173 ℃ on the premise of not introducing an additional device.
As shown in fig. 4 and 5, the optical system of the double-slit long-wave infrared spectrometer comprises a first inclined slit 1, a second inclined slit 2, a primary mirror 3, a secondary mirror 4 and a tertiary mirror 5; the primary mirror 3 and the tertiary mirror 5 are both spherical reflectors, the secondary mirror 4 is a curved prism with a concave surface plated with a reflecting film, and the primary mirror 3, the secondary mirror 4 and the tertiary mirror 5 form an offner structure.
At the normal temperature of 20 ℃, the first inclined slit 1, the primary mirror 3, the secondary mirror 4, the tertiary mirror 5 and the image surface 6 of the long-wave infrared spectrometer are all positioned in a first light path; at the low temperature of-173 ℃, the second inclined slit 2, the primary mirror 3, the secondary mirror 4, the tertiary mirror 5 and the image plane 6 of the long-wave infrared spectrometer are all positioned in a second light path.
All optical elements of an optical system of the long-wave infrared spectrometer only have five parts, namely an inclined double slit based on an Offner structure, two reflectors, a curved prism and an image surface 6 of an infrared detector. The position of the curved prism at the position of the Offner secondary mirror 4 not only plays a role of dispersion in the system, but also plays a role of reflection of the Offner secondary mirror 4 due to the fact that the concave surface of the curved prism is coated with a reflection film.
The optical system has fewer elements, all surfaces of the whole system are spherical surfaces, no special surface is provided, the processing and detection difficulty is reduced, and meanwhile, the system has no special moving mechanism except for expansion with heat and contraction with cold caused by temperature change, so that the reliability of the system is improved. Under the condition of not sacrificing system image quality and large temperature difference application environment, the system simultaneously meets the requirements of normal-temperature installation and debugging and low-temperature use in one system. The novel long-wave infrared spectrometer adopting the inclined double-slit design has important significance for researching a low-temperature optical system.
The tilted double slit bears the serious low-temperature defocusing of the system due to temperature change, and is the most important part in the whole design. When the system is adjusted at the normal temperature of 20 ℃, light rays enter the optical system through the first inclined slit 1, the primary mirror 3 reflects the light rays onto the curved surface prism, the same light beam is dispersed into different wavelengths after the dispersion of the curved surface prism, and the three mirrors 5 reflect the dispersed light rays onto the image plane 6 of the long-wave infrared spectrometer.
After the optical system is installed and adjusted at the normal temperature of 20 ℃, the temperature of the system is reduced to-173 ℃ by using a thermostat, the second inclined slit 2 starts to work, the working path is similar to that of the first inclined slit 1, and the image is imaged on an image surface 6 of the long-wave infrared spectrometer through the main mirror 3, the curved surface prism and the three mirrors 5 in sequence. Through the arrangement of the two inclined slits, the focal plane position of the system is not changed after the system experiences thermal expansion and cold contraction due to temperature change, and the imaging quality of the system is ensured. A schematic diagram of the slanted double slit is shown in fig. 6.
In this embodiment, a spectrometer with a spectral range of 8um to 12um, a numerical aperture of 0.11, a slit length of 60mm, and a dispersion width of 1.2mm was designed, the set-up temperature was 20 ℃, and the operating temperature was-173 ℃.
The meridian and sagittal structures of the system in Zemax are shown in figure 4, a slit is used as an object plane of the whole system to emit a beam of light, the light is reflected by a primary mirror 3 firstly to realize the first turning of a light path, the light reaches a curved prism, and a reflecting film is plated on the concave surface of the curved prism, so that the light not only realizes the light dispersion through the curved prism but also changes the direction of the light, the second turning of the light path is realized, the light emitted from the curved prism passes the curved prism again to carry out the second dispersion, and the dispersed light passes through a three-mirror 5 to realize the third turning of the light path and finally converges on an image plane 6 of a long-wave infrared spectrometer.
The optical system structure parameters and the tilted double slit parameters are shown in tables 1 and 2 below.
TABLE 1 System architecture parameters
TABLE 2 Tilt Dual slit parameters
| Technical index | Parameter(s) |
| Single size | 60mm× |
| Slit | |
| 1 eccentric (Y) | - |
| Slit | |
| 2 eccentric (Y) | -30mm |
| Spacing (Y) | 1.356923mm |
| Spacing (Z) | 10mm |
| Inclination angle | 4.782940° |
As shown in fig. 6, the system image quality evaluation means that a better image quality can be obtained depending on the adjustment capability of the tilted double slit because of a serious defocus caused by a temperature change at the focal plane, which is a meaning of the tilted double slit. A modulation transfer function curve (MTF) and a standard point sequence chart (SPT) at 20 ℃ and 173 ℃ are respectively selected, so that the MTF of the whole system is close to a diffraction limit, the RMS diffuse spot radius is within one Airy spot radius, and the system has better image quality.
The first inclined slit 1 and the second inclined slit 2 have a space which is far larger than the width of the slits, and at least one third inclined slit can be arranged between the first inclined slit 1 and the second inclined slit 2, so that the imaging quality of the system can be measured when the temperature is adjusted and used, and the real-time monitoring of the quality of the system can be realized.
The third slanted slit is not shown in the drawings, but does not affect the understanding and implementation of the present invention by those skilled in the art.
The double-slit long-wave infrared spectrometer comprises the optical system.
In order to complete the design of the spectrometer, the invention provides a method for designing the system, namely a 'back light path tracking' method, which comprises the following steps:
step one, determining the positions of a first inclined slit 1, a main mirror 3, a secondary mirror 4, a three-mirror 5 and an image plane 6 of a long-wave infrared spectrometer at a temperature of T1.
And step two, reducing the temperature to T2, and determining the position of the second inclined slit 2 by adopting a back light path tracking method.
Preferably, step three is further included, at least one third inclined slit is provided between the first inclined slit 1 and the second inclined slit 2.
Preferably, the step one and/or the step two further comprises: the specifications and/or positions of components in the optical system are adjusted so that the optical system obtains desired performance parameters.
By the method and the influence of temperature on the system, the position of the corresponding new slit for keeping the position of the detector image surface 6 unchanged after the system is subjected to low temperature is solved, and then the new slit is optimized in optical software, so that a result meeting the requirements can be obtained.
Back light path tracking:
the optical path tracing is to sequentially pass through all the optical elements along the actual propagation direction of the light, and the position and the information of the light finally imaged on the image surface 6 of the detector of the long-wave infrared spectrometer are usually obtained through the optical path tracing. After the system is optimized at normal temperature T1, the temperature of the system is controlled, and the temperature change can affect the refractive index, curvature radius, thickness, interval, surface profile of the element and the refractive index of the medium in which the element is located, so that the imaging quality of the system is reduced. The inverse light path tracing means that according to the reversibility of light rays, an image surface 6 of a detector of the long-wave infrared spectrometer is used as a virtual object surface, the light path tracing is carried out in the direction opposite to the propagation direction of actual light rays, and the position of the second inclined slit 2 in a low-temperature state can be obtained.
The effect of temperature on the optical system is illustrated as follows:
refractive index of element: n'abs＝nabs+Δnabs
Curvature radius of element: r ═ R0(1+αgΔT)
③ thickness of element: d ═ d0(1+αgΔT)
Element spacing: d ═ L + z'1(h)-z'2(h)
L＝L0(1+αmΔT)
h＝h0(1+αgΔT)
Surface type of element:
medium refractive index: in order to achieve the low temperature effect, the constant temperature chamber is generally vacuumized, and the refractive index is 1
Wherein:
n′abs-refractive index of material at low temperature
nabsAbsolute refractive index of material
Δnabs-the amount of change in refractive index when the temperature changes by Δ T from the standard temperature
Delta T is the temperature variation difference relative to a standard temperature of 20 DEG C
R-radius of curvature of apex of element after temperature change Δ T
R0-at standard temperature, the apex radius of curvature of the element
αg-coefficient of thermal expansion of the element
d-thickness of the element after temperature change Δ T
d0-inThickness of the element at standard temperature
D-center spacing of two elements after temperature change Δ T
L-edge separation of two elements after temperature change Δ T
z1' -edge point rise of element after temperature change Δ T
z2' -edge point rise of element after temperature change Δ T
h-half aperture of element after temperature change Δ T
h0-at standard temperature, half-bore of the element
L0At standard temperature, the edge spacing of the two elements
αm-coefficient of thermal expansion of mechanical structure
z1-surface rise of the element
c1-the curvature of the apex of the element is equal to 1/R0
r1The distance of the surface from the axis of symmetry
k-cone coefficient
a′i-high-order aspheric coefficients, i ═ 1, 2, 3, 4, … …
Fig. 8(a) shows a principle diagram of forward optical path tracking, and fig. 8(b) shows a principle diagram of backward optical path tracking.
Known incident ray incident point E0(x0,y0,z0) And the direction of incidence
Radius of curvature R of the element1,R2Interval d, refractive index n, n', angle of inclination θ, and finding the spot E1(x1,y1,z1) And the direction of emergence
After the back light path sequentially traces the position of the light ray at each point one by one, the meridional and sagittal image distances are finally calculated by using the Coodington Function:
wherein:
D＝l-t
l＝-α0(d+x0)-β0y0-γ0z0
M＝(x0+lα0+d,y0+lβ0,z0+lγ0)
Γ＝n′cosI′-ncosI
cosI＝α0(cosθ-ρx1)-β0(sinθ+ρy1)-γ0ρz1
d-an intermediate parameter, meaningless, representing only 1-t
Gamma-deflection constant
I-incident angle of light ray on element surface
I' -angle of refraction of light at surface of element
t-meridian object distance
s-object distance in sagittal direction
t' -image distance in meridian direction
s' -sagittal image distance
RsRadius of curvature in sagittal direction
RtRadius of curvature in the meridian direction
n' — image side refractive index
n-refractive index of matter
Rho-equal to 1/R, as the curvature of the element surface
l-projection of distance between two refracting spherical vertexes in light propagation direction
t-an intermediate parameter, without any meaning, introduced only for calculation
Mx-vectors
Component in x direction
My-vectors
Component in the y direction
The general flow chart of the design of the above method is shown in fig. 9.
Specifically, in a low-temperature long-wave infrared spectrometer, the design of an inclined double-slit optical system is realized by the following design method:
evaluating background radiation;
determining the low-temperature working temperature of the optical system;
optimizing the normal temperature state of the optical system;
analyzing the normal temperature performance of the spectrometer;
calculating low-temperature parameters of the optical system;
optimizing the low-temperature state of the optical system;
analyzing the low-temperature performance of the spectrometer;
evaluating the ability to tilt the double slit;
and outputting the designed system when the performance meets the requirement.
While the present invention has been described with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, which are illustrative and not restrictive, and it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (9)
1. An optical system of a double-slit long-wave infrared spectrometer is characterized by comprising a first inclined slit (1), a second inclined slit (2), a primary mirror (3), a secondary mirror (4) and a three-mirror (5); the primary mirror (3) and the tertiary mirror (5) are both spherical reflectors, the secondary mirror (4) is a curved prism with a concave surface plated with a reflecting film, and the primary mirror (3), the secondary mirror (4) and the tertiary mirror (5) form an offner structure;
at the temperature of T1, the first inclined slit (1), the primary mirror (3), the secondary mirror (4), the tertiary mirror (5) and the image plane (6) of the long-wave infrared spectrometer are all positioned in a first light path; at the temperature of T2, the second inclined slit (2), the primary mirror (3), the secondary mirror (4), the tertiary mirror (5) and the image plane (6) of the long-wave infrared spectrometer are all positioned in a second light path;
the temperature T1 is 20 ℃, and the temperature T2 is-173 ℃;
the two inclined slits are respectively arranged corresponding to different temperatures, so that the focal plane position of the optical system is not changed after the optical system undergoes thermal expansion and cold contraction after the optical system undergoes temperature change.
2. The optical system of a double-slit long-wave infrared spectrometer of claim 1, further comprising at least one third tilted slit disposed between the first tilted slit (1) and the second tilted slit (2).
3. The optical system of a double-slit long-wave infrared spectrometer as claimed in any of claims 1-2, characterized in that the first tilted slit (1) and/or the second tilted slit (2) is tilted at an angle of 4 ° to 5 °.
4. The optical system of a double-slit long-wave infrared spectrometer according to any one of claims 1-2, characterized in that the size of the first inclined slit (1) and/or the second inclined slit (2) is 60mm x 60 um.
5. A double slit long wave infrared spectrometer comprising an optical system as claimed in any one of claims 1 to 4.
6. The dual slit long wave infrared spectrometer of claim 5, wherein the spectrometer has a spectral range of 8um to 12 um.
7. A method for designing an optical system as set forth in any one of claims 1 to 4, comprising:
step one, determining the positions of a first inclined slit (1), a main mirror (3), a secondary mirror (4), a three-mirror (5) and an image plane (6) of a long-wave infrared spectrometer at a temperature of T1;
and step two, reducing the temperature to T2, and determining the position of the second inclined slit (2) by adopting a back light path tracking method.
8. The design method of claim 7, further comprising:
and thirdly, arranging at least one third inclined slit between the first inclined slit (1) and the second inclined slit (2).
9. The design method of claim 7, wherein the step one and/or the step two further comprises: the specifications and/or positions of components in the optical system are adjusted so that the optical system obtains desired performance parameters.
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| CN110579277A (en) * | 2019-09-19 | 2019-12-17 | 中国科学院长春光学精密机械与物理研究所 | optical system design method and optical system of large-field free-form surface spectrometer |
| CN110672206A (en) * | 2019-09-30 | 2020-01-10 | 中国海洋大学 | Double-slit curved prism chromatic dispersion ultra-large field of view spectrometer optical system |
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| CN110579277A (en) * | 2019-09-19 | 2019-12-17 | 中国科学院长春光学精密机械与物理研究所 | optical system design method and optical system of large-field free-form surface spectrometer |
| CN110672206A (en) * | 2019-09-30 | 2020-01-10 | 中国海洋大学 | Double-slit curved prism chromatic dispersion ultra-large field of view spectrometer optical system |
Non-Patent Citations (1)
| Title |
|---|
| 双狭缝高分辨率紫外成像光谱仪光学系统设计;朱雨霁;《半导体光电》;20180831;全文 * |
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