CN111965802A - Long-rear working distance optical athermal long-wave infrared lens - Google Patents
Long-rear working distance optical athermal long-wave infrared lens Download PDFInfo
- Publication number
- CN111965802A CN111965802A CN202010973834.6A CN202010973834A CN111965802A CN 111965802 A CN111965802 A CN 111965802A CN 202010973834 A CN202010973834 A CN 202010973834A CN 111965802 A CN111965802 A CN 111965802A
- Authority
- CN
- China
- Prior art keywords
- lens
- focal lens
- optical
- optical focal
- positive
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 230000003287 optical effect Effects 0.000 title claims abstract description 157
- 235000012149 noodles Nutrition 0.000 claims abstract description 8
- 238000003825 pressing Methods 0.000 claims description 18
- 239000011521 glass Substances 0.000 claims description 12
- 238000007789 sealing Methods 0.000 claims description 9
- 125000006850 spacer group Chemical group 0.000 claims description 6
- 229910052732 germanium Inorganic materials 0.000 claims description 4
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 claims description 4
- 230000001681 protective effect Effects 0.000 claims description 3
- 230000008859 change Effects 0.000 abstract description 17
- 230000000694 effects Effects 0.000 abstract description 14
- 238000013461 design Methods 0.000 abstract description 12
- 238000003384 imaging method Methods 0.000 abstract description 12
- 210000001747 pupil Anatomy 0.000 abstract description 12
- 230000004075 alteration Effects 0.000 abstract description 11
- 239000000463 material Substances 0.000 description 16
- 238000001228 spectrum Methods 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 5
- 238000000034 method Methods 0.000 description 5
- 238000004458 analytical method Methods 0.000 description 4
- 238000001914 filtration Methods 0.000 description 4
- 238000000701 chemical imaging Methods 0.000 description 3
- 238000001514 detection method Methods 0.000 description 3
- PFNQVRZLDWYSCW-UHFFFAOYSA-N (fluoren-9-ylideneamino) n-naphthalen-1-ylcarbamate Chemical compound C12=CC=CC=C2C2=CC=CC=C2C1=NOC(=O)NC1=CC=CC2=CC=CC=C12 PFNQVRZLDWYSCW-UHFFFAOYSA-N 0.000 description 2
- 239000005387 chalcogenide glass Substances 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 230000017525 heat dissipation Effects 0.000 description 2
- 238000002329 infrared spectrum Methods 0.000 description 2
- 230000013011 mating Effects 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000003595 spectral effect Effects 0.000 description 2
- 230000002277 temperature effect Effects 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 230000008602 contraction Effects 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000013016 damping Methods 0.000 description 1
- 238000012938 design process Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000007888 film coating Substances 0.000 description 1
- 238000009501 film coating Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 229910052752 metalloid Inorganic materials 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 238000005057 refrigeration Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 238000012306 spectroscopic technique Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 229910052714 tellurium Inorganic materials 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/14—Optical objectives specially designed for the purposes specified below for use with infrared or ultraviolet radiation
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/18—Optical objectives specially designed for the purposes specified below with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
- G02B7/02—Mountings, adjusting means, or light-tight connections, for optical elements for lenses
- G02B7/021—Mountings, adjusting means, or light-tight connections, for optical elements for lenses for more than one lens
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
- G02B7/02—Mountings, adjusting means, or light-tight connections, for optical elements for lenses
- G02B7/026—Mountings, adjusting means, or light-tight connections, for optical elements for lenses using retaining rings or springs
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Health & Medical Sciences (AREA)
- Toxicology (AREA)
- Lenses (AREA)
Abstract
The invention provides a long-rear working distance optical athermalization long-wave infrared lens, which comprises a first positive optical focal lens, a negative optical focal lens, a second positive optical focal lens, an optical filter and a detector for receiving pictures, wherein the first positive optical focal lens, the negative optical focal lens, the second positive optical focal lens, the optical filter and the detector are sequentially arranged along the light incidence direction, a diaphragm space ring is arranged between the negative optical focal lens and the second positive optical focal lens, the surfaces of the lenses are sequentially numbered from S1 to S6 in the light incidence direction, the S2 surface is an even aspheric surface, and the S5 surface is a binary diffraction surface; the rest of the noodles are standard noodles. The invention has the advantages that: the imaging surface is moved backwards through the matching of the negative optical focal lens and the second positive optical focal lens, so that the rear working distance is increased, and the aberration can be well eliminated by adding the aspheric surface; through adding the diffraction face, can reduce the influence of big focal power to hot refracting index, through adding the diaphragm space ring between negative light focal lens and the positive light focal lens of second, can change the entrance pupil position through the diaphragm effect, reduce the entrance pupil size, realize the miniaturized design of lens.
Description
Technical Field
The invention relates to the technical field of infrared spectrum imaging, in particular to a long-back working distance optical athermal long-wave infrared lens.
Background
The infrared spectrum imaging detection technology is a novel detection technology rapidly developed in recent years, has remarkable remote detection capability, large detectable spectrum range, multiple detectable gas types, relatively simple structure and no need of background reflection and radiation source of a system, and is used for dividing incident full-wave band or wide-wave band optical signals into a plurality of narrow-wave band light beams to obtain images of different spectrum wave bands. The current spectroscopic techniques used in imaging spectrometers are mainly dispersive, interferometric, binary, and filtering.
There are many common implementations of filter-type imaging spectrometers, such as: the multispectral camera of the multi-lens type, it has multiple lenses, each lens have a color filter, let a narrower spectrum pass through separately, multiple lenses shoot the same scenery at the same time, record the image information of different spectra at the same time with a film; the multi-spectrum camera of the multiphase type, it is made up of several cameras, the lens of every camera is equipped with different light filters separately, receive the information on different spectral bands of the scenery separately, shoot the same scenery in order to obtain the image information of a set of specific spectral bands at the same time; a multi-spectrum camera of beam separation type is composed of a lens for taking the scene, a plurality of triple prism light splitters for separating the light from the scene into several light beams in different wave bands, and multiple image systems for recording the optical information in different wave bands.
In the process of researching the filtering type multispectral imaging technology, the optical lens at the front end and the detector at the rear end need to be ensured to be strictly coaxial, so that a mechanical device for auxiliary fixation needs to be arranged between the optical lens and the detector, meanwhile, in order to conveniently research the influence of different optical filters on an imaging result, an optical filter switching device is arranged between the lens and the detector, and the rear working distance from an imaging surface to the last lens of the traditional optical lens is short, the infrared optical lens disclosed in the invention patent application with publication number CN109521542A has a rear working distance of only 4mm, in addition, most of the prior arts in the field tend to reduce the rear working distance of the optical lens to achieve miniaturization of the image pickup apparatus, so that the existing optical lens has no more mechanical devices spatially arranged, and research and development of the filtering type multispectral imaging technology are limited.
In addition, since the refractive index of the optical lens is very sensitive to temperature change, and the lens barrel material also expands with heat and contracts with cold, the influence of the temperature change on the imaging quality is very large, and the influence of the temperature effect is generally eliminated by a passive athermalization design at present. The athermal design is to eliminate the influence of temperature by reasonable combination of different materials with different characteristics by utilizing the difference between the thermal characteristics of the optical materials. Compared with other ways of eliminating the temperature effect, the method has the advantages of relatively simple mechanism, small size, light weight, no need of power supply and good system reliability. Because infrared light energy is weak, the relative aperture of infrared camera lens is big, and longer back working distance makes the athermal design degree of difficulty increase, this also is one of the important reason that prior art generally selected short back working distance, and the working distance is all less than 20mm behind the infrared camera lens of the vast majority on the market at present.
Disclosure of Invention
The present invention provides a athermal long-wavelength infrared lens with a long rear working distance, which is aimed at solving the technical problem of short rear working distance of the existing optical lens, so as to overcome the limitation of the existing lens on the filtering type multispectral imaging technology.
The invention solves the technical problems through the following technical scheme: a long-rear working distance optical athermalization long-wave infrared lens comprises a first positive optical focal lens, a negative optical focal lens, a second positive optical focal lens, an optical filter and a detector for receiving pictures, wherein the first positive optical focal lens, the negative optical focal lens, the second positive optical focal lens, the optical filter and the detector are sequentially arranged along the incident direction of light rays; a diaphragm space ring is arranged between the negative optical focal lens and the second positive optical focal lens, the air space between the first positive optical focal lens and the negative optical focal lens is 10mm, the air space between the negative optical focal lens and the diaphragms in the diaphragm space ring is 2mm, the air space between the diaphragm and the second positive optical focal lens is 2mm, the pixel size of the detector is 17 mu m, a protective window with the thickness of 1mm is arranged at the position 1mm in front of the detector, the air space between the second positive optical focal lens and the detector is 40.53mm, and the optical filter is positioned at any position between the second positive optical focal lens and the detector;
the surfaces of the lenses are sequentially numbered from S1 to S6 in the light incidence direction, wherein the S2 surface is an even aspheric surface, and the S5 surface is a binary diffraction surface; the rest of the noodles are standard noodles.
According to the invention, the imaging surface is moved backwards through the matching of the negative optical focal lens and the second positive optical focal lens, so that the back working distance is increased, the aberration can be well eliminated by adding the aspheric surface, the number of the lenses can be reduced, the structure is lighter and simpler, the cost is reduced, and the energy loss of infrared rays passing through the lenses is reduced; through adding the diffraction face, can reduce the influence of big focal power to hot refracting index, combine suitable camera lens material, can realize the no thermalization design of long back working distance, through adding the diaphragm space circle between negative light focal lens and the positive light focal lens of second, can change the position of going into the pupil through the diaphragm effect, reduce and go into the pupil size, realize the miniaturized design of lens.
Preferably, the diaphragm space ring is an annular space ring, and a circle of convex parts playing the role of the diaphragm are arranged on the annular surface inside the diaphragm space ring.
Preferably, the detector is an uncooled detector with a resolution of 640 x 512.
Preferably, the material of the protection window is germanium glass.
Preferably, the optical lens further comprises a lens barrel, and a front pressing ring, a first positive optical focal lens, a negative optical focal lens, a diaphragm spacing ring, a second positive optical focal lens and a rear pressing ring are sequentially fixed in the lens barrel along the light incidence direction; a first sealing ring is arranged between the front pressing ring and the first positive focusing lens.
Preferably, the inside of the lens barrel sequentially comprises a first matching surface, a second matching surface, a limiting step, a third matching surface and a fourth matching surface along the incident direction, the diameter of the first matching surface is larger than that of the second matching surface, the diameter of the second matching surface is smaller than that of the third matching surface, and the diameter of the fourth matching surface is larger than that of the third matching surface; the limiting step protrudes inwards relative to the second matching surface and the third matching surface; the first positive optical focal lens is matched with the second matching surface, the front pressing ring is matched with the first matching surface and tightly presses the S1 surface of the first positive optical focal lens, and the first sealing ring is limited in an interval enclosed by the front pressing ring, the S1 surface and the first matching surface; the S2 surface of the first positive focal lens abuts against the step surface of one side of the limiting step facing the second matching surface; the S3 face of the negative optical focal lens is abutted against the step face of the limiting step facing the third matching face, the negative optical focal lens, the diaphragm spacer ring and the second positive optical focal lens are arranged on the third matching face, and the rear pressing ring is fixedly matched with the fourth matching face and is abutted against the S6 face of the second positive optical focal lens.
Preferably, one end of the lens barrel, which faces the optical filter, is the rear end of the lens barrel, the outer surface of the rear end can be connected with the multispectral camera, and a second sealing ring is further arranged on the outer surface of the rear end.
The long-back working distance optical athermalization long-wave infrared lens provided by the invention has the advantages that: the imaging surface is moved backwards through the matching of the negative optical focal lens and the second positive optical focal lens, so that the back working distance is increased, the aberration can be well eliminated by adding the aspheric surface, the number of the lenses can be reduced, the structure is lighter and simpler, the cost is reduced, and the energy loss of infrared rays passing through the lenses is reduced; through adding the diffraction face, can reduce the influence of big focal power to hot refracting index, combine suitable camera lens material, can realize the no thermalization design of long back working distance, through adding the diaphragm space circle between negative light focal lens and the positive light focal lens of second, can change the position of going into the pupil through the diaphragm effect, reduce and go into the pupil size, realize the miniaturized design of lens.
Drawings
Fig. 1 is a schematic diagram of an infrared lens provided in an embodiment of the present invention;
FIG. 2 illustrates MTF curves at 20 ℃ for an IR lens provided by an embodiment of the present invention;
FIG. 3 is a MTF curve at-60 ℃ for an IR lens provided by an embodiment of the present invention;
FIG. 4 is an MTF curve at 80 ℃ for an IR lens provided by an embodiment of the present invention;
Detailed Description
In order that the objects, technical solutions and advantages of the present invention will become more apparent, the present invention will be further described in detail with reference to the accompanying drawings in conjunction with the following specific embodiments.
As shown in fig. 1, the present embodiment provides a long back working distance optical athermalization long-wave infrared lens, the thermal effect of the optical lens includes two parts, namely, the thermal expansion and cooling of mechanical members such as glass and lens barrel and the thermal refractive index effect of glass, the size change of the mechanical members is very fixed, and the mechanical members expand with the increase of temperature and shrink with the decrease of temperature. However, the refractive index change of the glass is related to the thermal refractive index (thermal optical coefficient) dn/dt and the power value phi of the glass, and the thermal refractive index and the power value have positive and negative values. Therefore, the athermalization of the optical system is to compensate the thermal expansion and contraction of the glass and the mechanical part by using the thermal refractive index effect of the glass.
The formula of the thermal difference of the optical lens pin is
Wherein h is1Is the height, phi, of the first paraxial ray in the lens group iiIs the focal power of the lens group i, phi is the total focal power of the optical system, chiiIs the coefficient of photothermal expansion of the glass, ahIs linear expansion of mechanical partsThe coefficient, L, is the length of the mechanical piece.
The following conclusions can be drawn according to the formula of the heat dissipation difference: (1) the larger the focal power is, the larger the thermal effect change of the lens is, so that the lens with the small focal power is selected as much as possible; (2) the mechanical part is designed to be as short as possible, and is made of a material with a small linear expansion coefficient.
According to the definition of the focal length in geometric optics, the focal length is the distance from the focal point to the image side principal point, and then the definition of the working distance is the distance from the vertex of the last surface in the optical system to the focal length. With the increasing of the back working distance, the position of the image side main surface is continuously close to the position of the last lens, and when the back working distance is larger than the focal length, the image side main surface is closer to the focal plane than the back surface of the optical system, so that the common inverse-distance type light group is formed. With the backward movement of the image side main surface, according to a graphical method of geometric optics, the light incidence height of the last lens is increased, the size of the lens is increased, the focal power is increased, the large spherical aberration is generated and is difficult to correct, and according to the analysis, the larger the focal power is, the larger the thermal effect change is.
In addition, increasing the back working distance increases the length of the external mechanical components in the optical system, i.e. the right half of the equation has a larger value change, and the left half of the equation has a larger value to be compensated, which causes difficulty in selecting optical materials and distributing optical power.
Based on the above conclusion, increasing the rear working distance brings great difficulty to athermal design.
Based on the above analysis, the long-rear working distance optical athermalization long-wave infrared lens provided in this embodiment is as shown in fig. 1, and includes a first positive optical focal lens 2, a negative optical focal lens 3, a second positive optical focal lens 5, an optical filter 7, and a detector 9 for receiving a picture, which are sequentially arranged along a light incidence direction, where the first positive optical focal lens 2 and the second positive optical focal lens 5 are both formed by chalcogenide glass, and the negative optical focal lens 3 is formed by zinc selenide glass; a diaphragm space ring 4 is arranged between the negative optical focal lens 3 and the second positive optical focal lens 5, the air space between the first positive optical focal lens 2 and the negative optical focal lens 3 is 10mm, the air space between the negative optical focal lens 3 and the diaphragms in the diaphragm space ring 4 is 2mm, the air space between the diaphragms and the second positive optical focal lens 5 is 2mm, an optical filter 7 for splitting is added between the second positive optical focal lens 5 and the detector 9, and the position and the thickness of the optical filter 7 can be randomly selected according to specific requirements because no focal power of the optical filter 7 participates in correcting aberration. A protective window 8 with the thickness of 1mm is arranged at the position 1mm in front of the detector 9; the surfaces of the lenses are sequentially numbered from S1 to S6 in the light incidence direction, wherein the S2 surface is an even aspheric surface, and the S5 surface is a binary diffraction surface; the rest of the noodles are standard noodles, which are as follows:
in the embodiment, the negative optical focal lens 3 and the second positive optical focal lens 5 are matched to move the imaging surface backwards, so that the back working distance is increased, the aspheric surface is added, the aberration can be well eliminated, the number of the lenses can be reduced, the structure is lighter and simpler, the cost is reduced, and the energy loss of infrared rays passing through the lenses is reduced; through adding binary diffraction face, can reduce the influence of big focal power to hot refracting index, combine suitable camera lens material, can realize the no heat design of long back working distance, through adding diaphragm space circle 4 between negative light focal lens 3 and second positive light focal lens 5, can change the position of entrance pupil through the diaphragm effect, reduce the size of entrance pupil, realize the miniaturized design of lens. The chalcogenide glass is a glass mainly composed of S, Se and Te of group VIA of the periodic table and containing a certain amount of other metalloid elements. The infrared material has good transmission performance in a wave band of 1-14 mu m, has refractive index dispersion characteristics equivalent to those of zinc selenide in a long wave band, has good temperature characteristics which are far smaller than those of germanium, and is a good infrared material with achromatic color and thermal aberration.
The specific design process is as follows:
in order to protect the front end of the first positive focal lens 2 and the rear end of the second positive focal lens 5 during use and facilitate film coating, the front end of the first positive focal lens 2 and the rear end of the second positive focal lens 5 are convex;
according to the definition of the focal length in geometric optics, the focal length is the distance from the focal point to the image side principal point, and then the definition of the working distance is the distance from the vertex of the last surface in the optical system to the focal length. With the increasing of the back working distance, the position of the image side main surface is continuously close to the position of the last lens, and when the back working distance is larger than the focal length, the image side main surface is closer to the focal plane than the back surface of the optical system, so that the common inverse-distance type light group is formed. With the backward movement of the image side main surface, the light incidence height of the last lens is increased according to a graphical method of geometric optics, and the size of the lens is increased. And too large a size will lead to a heavy instrument, high cost, large aberration and large thermal effect.
Based on the above analysis, the present embodiment reduces the size of the last lens by changing the position of the stop, placing the stop between the negative focal lens 3 and the second positive focal lens 5, and changing the entrance pupil position. Meanwhile, the size of the entrance pupil should be reduced, theoretically, the smaller the entrance pupil can be, but considering the weak infrared ray energy, the relative aperture D (entrance pupil size)/f (system focal length) value is strictly ensured to be less than 2. And a diffraction surface is arranged on the front surface of the second optical focal lens 5 with the largest focal power, so that the heat effect brought by the large focal power is reduced.
Specifically, the diaphragm spacer 4 in this embodiment is an annular spacer, and a ring of protruding portions 11 protruding inward inside the annular surface function as a diaphragm.
An optical system consists of a plurality of lenses, which are called light groups. Each optical group can be viewed as an ideal optical system having a focal length, a focal point, and a principal point. The distance between each light group and the size parameter also have some relation limits, and the relation of one calculated light ray between two adjacent light groups is as follows:
hi＝hi-1-di-1tanU′I-1
wherein i is the number of light group, U'IIs the angle between the emergent ray and the optical axis, called the aperture angle, hiIs the incident height of the incident ray on the i-th main surface, diIs the mutual position of the two light groups.
For the combined system of three light groups of this example, let h be1Let tan U 10, i.e. parallel light incidence, UiIs the angle between the incident ray and the optical axis. Then there are:
h2＝h1-d1tanU′1
h3＝h2-d2tanU′2
f′iis the focal length of each optical group and represents the focal power because the focal power in air
The change in optical power is the main contributing factor to the change in optical system parameters.
The rear working distance of the present example is 40.53mm, but not limited to 40.53mm, and the rear working distance of more than 40mm, the ratio of the rear working distance to the focal length, can be easily optimized for the optical system with large focal length by the combination of three lenses and the application of the aspheric surface and the diffractive surface
In time, only three lens are used for penetration due to overlarge spherical aberration of the systemThe mirror cannot correct both aberrations and thermal differentials, thereby affecting imaging.
The principle of the athermal difference of the diffraction surface is as follows:
the temperature characteristic of an optical element is characterized by the optical thermal expansion coefficient χ, which is defined as the relative change in power per unit change in temperature;
diffraction element:
a refractive element:
tg is the linear expansion coefficient of the optical element, n0Is the refractive index of the ambient medium and n is the refractive index of the optical element.
It can be seen from the formula that the temperature characteristic of the diffraction element is determined only by the expansion coefficient of the material and is independent of the refractive index characteristic of the material, and the temperature characteristic of the refraction element is determined not only by the expansion coefficient of the material but also by the temperature coefficient of the refractive index of the material. The effect of the refractive index change on the thermal effect is the largest, so that the diffraction element has better thermal stability compared with the refraction element, and can be used for eliminating the thermal effect change brought by a lens with large focal power. Therefore, in the present embodiment, a diffraction surface is added to the surface S5 to reduce the influence of large optical power on the thermal refractive index.
The formula for the athermal design is:
power distribution:
equation of heat dissipation difference:
achromatic squareThe process:
wherein the content of the first and second substances,
is the dispersion coefficient. n lambda1，nλ2，nλ0Which respectively refer to the refractive index of the lens material corresponding to the two edge wavelengths and the center wavelength of the operating band.
Aspheric equation:
z is the rise of the aspheric surface, where r2＝x2+y2X and y are the position coordinates of points on the aspherical surface,
c is the vertex curvature, R is the vertex curvature radius, k is the conic coefficient, k is-e2And e is the Euler number;
binary optical surface phase retardation function:
wherein M is the diffraction order of the diffraction surface, and N is the maximum number of terms of the diffraction surface. A. theiIs the coefficient of the diffraction surface, p2iThe order of the diffraction coefficient.
According to the aspheric equation and the binary diffraction surface equation, corresponding parameters are set in zemax software as variables, and corresponding specific parameters are optimized through optimization simulation of a program and according to a damping minimum quadratic fitting algorithm carried by the program.
Based on the above analysis, the parameters of the optical lens provided in this embodiment are as follows:
the working wave band is as follows: 8-14 μm;
focal length: f ═ 50 mm;
a detector: the long-wave infrared non-refrigeration type is 640 multiplied by 512, and the pixel size is 17 mu m;
cutoff frequency: 29lp/mm
The field angle: 12.4 ° × 9.9 °;
relative pore diameter D/f': 1/1.4;
rear working distance: 40.53mm
RMS radius: 0.707 field of view <8.5mm, 1 field of view <10 mm.
The dimensions of the specific optical lens provided by the embodiment are as follows: the air interval between first positive light focal lens piece and the negative light focal lens piece is 10mm, the air interval of the diaphragm in negative light focal lens piece and the diaphragm space ring is 2mm, the air interval between diaphragm and the second positive light focal lens piece is 2mm, the air interval between the second positive light focal lens piece and the light filter piece is 18mm, the thickness of the light filter piece is 3mm, the pixel size of the detector is 17 mu m, a protection window with the thickness of 1mm is arranged at the position 1mm in front of the detector, and the air interval between the protection window and the light filter piece is 17.53 mm.
The detector 9 is an uncooled detector, and the resolution is 640 x 512; the protection window 8 is made of germanium glass.
Referring to fig. 1 again, the optical lens barrel further includes a lens barrel 13 for fixing lenses, and a front pressing ring 1, a first positive optical focal lens 2, a negative optical focal lens 3, a diaphragm spacer 4, a second positive optical focal lens 5 and a rear pressing ring 6 are sequentially fixed in the lens barrel 13 along the light incidence direction; a first sealing ring 10 is arranged between the front pressing ring 1 and the first positive focusing lens 2. The inside of the lens barrel 13 sequentially comprises a first matching surface 131, a second matching surface 132, a limiting step 133, a third matching surface 134 and a fourth matching surface 135 along the incident direction, wherein the diameter of the first matching surface 131 is larger than that of the second matching surface 132, the diameter of the second matching surface 132 is smaller than that of the third matching surface 134, and the diameter of the fourth matching surface 135 is larger than that of the third matching surface 134; the limit step 133 protrudes inward relative to the second mating face 132 and the third mating face 133; the first positive focal lens 2 is matched with the second matching surface 132, the front pressing ring 1 is matched with the first matching surface 131 and is pressed against the surface S1 of the first positive focal lens 2, and the first sealing ring 10 is limited in an interval enclosed by the front pressing ring 1, the surface S1 and the first matching surface 131; the surface S2 of the first positive focal lens 2 abuts against the step surface of the limit step 133 on the side facing the second matching surface 132; the surface S3 of the negative optical focal lens 3 abuts against the step surface of the limit step facing the third matching surface 134, the negative optical focal lens 3, the diaphragm spacer ring 4 and the second positive optical focal lens 5 are arranged on the third matching surface 134, and the rear pressing ring 6 is fixedly matched with the fourth matching surface 135 and abuts against the surface S6 of the second positive optical focal lens 5.
One end of the lens cone 13 facing the optical filter is a rear end of the lens cone, the outer surface of the rear end can be connected with the multispectral camera, an accommodating groove (not shown) with an opening along the axial direction is arranged on the outer side of the rear end, and a second sealing ring 12 is arranged in the accommodating groove; thereby maintaining a hermetic seal when the multispectral camera is connected.
Fig. 2 to 4 respectively show MTF (Modulation Transfer Function) curves of the lens provided in this embodiment at 20 ℃, -60 ℃, and 80 ℃, and it can be found that, in a wide range of-60 ℃ to 80 ℃, MTF curves in different fields are close to diffraction limit, so that aberration and thermal difference are well corrected, and requirements of the optical multi-spectral camera for working at various temperatures are met. And the long working distance reserves space for adding various mechanical devices in the middle.
Claims (7)
1. A long-back working distance optical athermal long-wave infrared lens is characterized in that: the optical filter comprises a first positive optical focal lens, a negative optical focal lens, a second positive optical focal lens, an optical filter and a detector for receiving pictures, wherein the first positive optical focal lens, the negative optical focal lens and the detector are sequentially arranged along the incident direction of light rays; a diaphragm space ring is arranged between the negative optical focal lens and the second positive optical focal lens, the air space between the first positive optical focal lens and the negative optical focal lens is 10mm, the air space between the negative optical focal lens and the diaphragms in the diaphragm space ring is 2mm, the air space between the diaphragm and the second positive optical focal lens is 2mm, the pixel size of the detector is 17 mu m, a protective window with the thickness of 1mm is arranged at the position 1mm in front of the detector, the air space between the second positive optical focal lens and the detector is 40.53mm, and the optical filter is positioned at any position between the second positive optical focal lens and the detector;
the surfaces of the lenses are sequentially numbered from S1 to S6 in the light incidence direction, wherein the S2 surface is an even aspheric surface, and the S5 surface is a binary diffraction surface; the rest of the noodles are standard noodles.
2. The long back working distance optical athermal long wave infrared lens of claim 1, wherein: the diaphragm space ring is an annular space ring, and a circle of convex parts playing the role of a diaphragm are arranged on the annular surface inside the diaphragm space ring.
3. The long back working distance optical athermal long wave infrared lens of claim 1, wherein: the detector is an uncooled detector, and the resolution is 640 x 512.
4. The long back working distance optical athermal long wave infrared lens of claim 1, wherein: the protection window is made of germanium glass.
5. The long back working distance optical athermal long wave infrared lens of claim 1, wherein: the lens barrel is internally and sequentially fixed with a front pressing ring, a first positive optical focal lens, a negative optical focal lens, a diaphragm space ring, a second positive optical focal lens and a rear pressing ring along the incident direction of light; a first sealing ring is arranged between the front pressing ring and the first positive focusing lens.
6. The long back working distance optical athermal long wave infrared lens of claim 6, wherein: the lens barrel comprises a first matching surface, a second matching surface, a limiting step, a third matching surface and a fourth matching surface in sequence along the incident direction, wherein the diameter of the first matching surface is larger than that of the second matching surface, the diameter of the second matching surface is smaller than that of the third matching surface, and the diameter of the fourth matching surface is larger than that of the third matching surface; the limiting step protrudes inwards relative to the second matching surface and the third matching surface; the first positive optical focal lens is matched with the second matching surface, the front pressing ring is matched with the first matching surface and tightly presses the S1 surface of the first positive optical focal lens, and the first sealing ring is limited in an interval enclosed by the front pressing ring, the S1 surface and the first matching surface; the S2 surface of the first positive focal lens abuts against the step surface of one side of the limiting step facing the second matching surface; the S3 face of the negative optical focal lens is abutted against the step face of the limiting step facing the third matching face, the negative optical focal lens, the diaphragm spacer ring and the second positive optical focal lens are arranged on the third matching face, and the rear pressing ring is fixedly matched with the fourth matching face and is abutted against the S6 face of the second positive optical focal lens.
7. The long back working distance optical athermal long wave infrared lens of claim 7, wherein: one end of the lens cone facing the optical filter is the rear end of the lens cone, the outer surface of the rear end can be connected with the multispectral camera, and a second sealing ring is further arranged on the outer surface of the rear end.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010973834.6A CN111965802A (en) | 2020-09-16 | 2020-09-16 | Long-rear working distance optical athermal long-wave infrared lens |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010973834.6A CN111965802A (en) | 2020-09-16 | 2020-09-16 | Long-rear working distance optical athermal long-wave infrared lens |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN111965802A true CN111965802A (en) | 2020-11-20 |
Family
ID=73393381
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010973834.6A Pending CN111965802A (en) | 2020-09-16 | 2020-09-16 | Long-rear working distance optical athermal long-wave infrared lens |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111965802A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112684597A (en) * | 2020-12-28 | 2021-04-20 | 中国科学院福建物质结构研究所 | Laser lens camera lens and laser projector |
| CN114199382A (en) * | 2021-12-15 | 2022-03-18 | 武汉高德智感科技有限公司 | Infrared temperature measurement lens and temperature measurement method |
-
2020
- 2020-09-16 CN CN202010973834.6A patent/CN111965802A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112684597A (en) * | 2020-12-28 | 2021-04-20 | 中国科学院福建物质结构研究所 | Laser lens camera lens and laser projector |
| CN114199382A (en) * | 2021-12-15 | 2022-03-18 | 武汉高德智感科技有限公司 | Infrared temperature measurement lens and temperature measurement method |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA2696775C (en) | Compact two-element infrared objective lens and ir or thermal sight for weapon having viewing optics | |
| US8101918B1 (en) | Re-imaging infrared lenses | |
| EP3669226B1 (en) | Two-color very wide field of view refractive eyepiece-type optical form | |
| US5737120A (en) | Low weight, achromatic, athermal, long wave infrared objective lens | |
| EP1405119A2 (en) | Fixed focus, optically athermalized, diffractive infrared zoom objective lens | |
| US6018414A (en) | Dual band infrared lens assembly using diffractive optics | |
| Bigwood et al. | Two-element lenses for military applications | |
| CN111965802A (en) | Long-rear working distance optical athermal long-wave infrared lens | |
| CN106772959B (en) | Short-wave and long-wave infrared dual-waveband confocal-surface large-relative-aperture optical system | |
| IL270713A (en) | Two-color inverse telephoto refractive optical form with external pupil for cold shielding | |
| CN206282023U (en) | Short-wave and long-wave infrared dual-waveband confocal-surface large-relative-aperture optical system | |
| CN212569267U (en) | Long-rear working distance optical athermal long-wave infrared lens | |
| EP3015902B1 (en) | Compact multispectral wide angle refractive optical system | |
| CN114137699B (en) | Small high-resolution athermalized medium-wave infrared optical system | |
| IL98514A (en) | Ultra-wideband achromatic lens | |
| KR102209218B1 (en) | Short Wave Infrared Camera Optical System for The Long Range Image Monitoring | |
| EP2573604B1 (en) | Ultra compact inverse telephoto optical system for use in the IR spectrum | |
| CN112882210B (en) | Non-refrigeration medium-long wave broadband confocal infrared optical system | |
| Akram | A design study of dual-field-of-view imaging systems for the 3–5 µm waveband utilizing focal-plane arrays | |
| US6856468B2 (en) | Zoom lens | |
| Greisukh et al. | Passive mechanical athermalization of thermal imaging zoom lenses coupled to an uncooled infrared matrix detector | |
| CN114690379B (en) | Small-sized infrared optical lens | |
| US20230179842A1 (en) | Optical system, imaging device, and imaging system | |
| CN110850566B (en) | Ultrashort 20-time medium wave continuous zoom lens without diffraction surface | |
| Morrison et al. | Dual-Band Imaging System Based on a Compact Coaxial Folded Optic Architecture |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |