CN109856784A - Medium-wave infrared optical system and design method based on PASSIVE OPTICAL without thermalization principle - Google Patents
Medium-wave infrared optical system and design method based on PASSIVE OPTICAL without thermalization principle Download PDFInfo
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- CN109856784A CN109856784A CN201910169997.6A CN201910169997A CN109856784A CN 109856784 A CN109856784 A CN 109856784A CN 201910169997 A CN201910169997 A CN 201910169997A CN 109856784 A CN109856784 A CN 109856784A
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- 230000003287 optical effect Effects 0.000 title claims abstract description 99
- 238000000034 method Methods 0.000 title claims abstract description 36
- 238000013461 design Methods 0.000 title claims abstract description 20
- 239000000463 material Substances 0.000 claims abstract description 48
- 230000004075 alteration Effects 0.000 claims abstract description 17
- 238000010606 normalization Methods 0.000 claims description 23
- 229910052732 germanium Inorganic materials 0.000 claims description 8
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 claims description 8
- 229910052710 silicon Inorganic materials 0.000 claims description 7
- 239000010703 silicon Substances 0.000 claims description 7
- 230000005499 meniscus Effects 0.000 claims description 3
- 238000012938 design process Methods 0.000 abstract description 2
- 238000012827 research and development Methods 0.000 abstract description 2
- 238000012546 transfer Methods 0.000 abstract description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 6
- 230000007246 mechanism Effects 0.000 description 3
- 206010010071 Coma Diseases 0.000 description 2
- 201000009310 astigmatism Diseases 0.000 description 2
- 238000006073 displacement reaction Methods 0.000 description 2
- 238000009738 saturating Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000005662 electromechanics Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 238000001931 thermography Methods 0.000 description 1
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Abstract
The invention discloses a kind of medium-wave infrared method of designing optical system based on PASSIVE OPTICAL without thermalization principle, only with two panels lens and it is a piece of it is aspherical be achieved that optical system within the scope of -40 DEG C~60 DEG C without thermalized design, with small in size, the advantages that light-weight high with transmitance, with biggish relative aperture and biggish field angle, image planes are stablized, image quality is good, full filed modulation transfer function is greater than 0.7 at nyquist frequency 16.7lp/mm, close to diffraction limit, therefore be conducive to reduce research and development cost while improving the reliability and stability of military infrared system；Medium-wave infrared method of designing optical system of the invention, from the principle of PASSIVE OPTICAL penalty method, it establishes using optical material heat differential and chromatic aberration coefficient as equation group coefficient, focal power is the non-secondly equation group of equation group unknown number, solution of equations determines the reasonably combined of optical material and further determines that the focal power that should be distributed per a piece of lens through discussion, can simplify the design process of optical system.
Description
Technical field
The invention belongs to infrared thermal imaging technique fields, and in particular to a kind of medium wave based on PASSIVE OPTICAL without thermalization principle
Infrared optical system design method.
Background technique
With the continuous development of infrared imagery technique, infrared system is applied to military field more and more widely and space is visited
Survey field, and the infrared system for working in these fields generally requires the baptism for being subjected to harsh environments.It is general military
The operating temperature range of infrared optical system is -40 DEG C~60 DEG C, and is used for the infrared optical system of space exploration, work temperature
Spending range can be bigger, and the variation of temperature will lead to optical element and mechanical configuration parameter changes, as lens radius of curvature,
Refractive Index of Material and lens thickness etc..If the performance of system can be with work temperature without optical system without thermalized design
The variation of degree and by serious influence, or even will cause entire infrared system and can not work normally, it is therefore necessary to take certain
Method eliminate optical system heat differential so that its Stability and dependability with higher.
Common optical system domestic at present is roughly divided into three classes without thermalization technology: mechanical compensation method, PASSIVE OPTICAL compensation
Method and ray machine mixed compensation method.The essence of mechanical compensation method is to move axially a piece of or several lens by certain mechanism to realize
The compensation of image planes drift.According to the difference for realizing displacement mechanism, mechanical compensation method is divided into mechanical passive compensating method and machinery again
Active penalty method.Mechanical passive compensating method relies primarily on the combination of the lens barrel material of the different coefficients of expansion to realize that image planes are floated
The compensation of shifting carries out the optical system without thermalized design using such method and needs using multilayer lens barrel structure, so that entire system
The volume and weight of system significantly increases, and is not suitable for military infrared system design；Mechanical active type penalty method relies primarily on electromechanics
Device drives eyeglass is displaced the stabilization to realize image planes, and structure is complex, and there are moving components, are not suitable for reliable
Property with volume weight have the system strictly limited design among.PASSIVE OPTICAL penalty method is also known as heat differential complementarity principle, utilizes light
Learn the difference of thermal characteristics between material and lens barrel material and rationally carry out the collocation of optical material with combine to eliminate heat differential, reality
Now without thermalized design.This method have many advantages, such as structure simple, high reliablity, it is small in size with it is light-weight, be usually used in all kinds of
Infrared optical system without thermalized design among.Ray machine mixed compensation method eliminates optical system using the reasonable combination of optical material
Most of heat differential, then remaining heat differential eliminated by relatively easy mechanical mechanism to realize whole system without thermalization, this method
Although having the advantages that mechanical compensation method and PASSIVE OPTICAL penalty method simultaneously, machinery can be made relative to traditional mechanical compensation method
Displacement reduces an order of magnitude, but system design difficulty is big and how stable optical axis is also more scabrous problem.
Based on PASSIVE OPTICAL penalty method structure simple, high reliablity, it is small in size and light-weight the advantages that, more and more
Person is unfolded to study to PASSIVE OPTICAL penalty method.But in research papers reported at present, optical system structure is adopted more
It is not high with three pieces or four separate structures, the transmitance of entire optical system.In certain Military Application field such as infrared seekers
Head design field, requirement of the system to transmitance are even higher than requirement to image quality, therefore designed in these documents
Infrared optical system not necessarily can be applied to the certain pairs of demanding military fields of transmitance.
The existing patent close with the present invention is " the long-focus LONG WAVE INFRARED object lens of passive athermal in conjunction with ray machine " at present
(application publication number: CN102778748A).Although two panels lens, which are used only, in optical system involved in the patent realizes no heat
Change design, but which introduce at least a piece of diffraction surfaces and a piece of aspherical, so that processing cost is more high.Additionally, due to it
Using LONG WAVE INFRARED optical material, design scheme can not be used among medium-wave infrared Optical System Design.
Summary of the invention
In view of this, the object of the present invention is to provide a kind of medium-wave infrared optical systems based on PASSIVE OPTICAL without thermalization principle
System and design method can reduce the volume and weight of system, improve system transmitance, meet the needs of military infrared system.
A kind of medium-wave infrared optical system, including the successively negative lens of arranged in co-axial alignment in order along the light direction of propagation
(1), positive lens (2) and reception image planes (3)；
The negative lens (1) be negative meniscus lens, convex surface towards object space to；The positive lens (2) falcate that is positive is saturating
Mirror, concave surface direction receive the direction of image planes (3)；
The service band of the medium-wave infrared optical system is 3.3 μm~4.7 μm, and operating temperature is -40 DEG C~60 DEG C.
Preferably, the optical material of negative lens (1) is monocrystalline germanium, the optical material of positive lens (2) is silicon.
Preferably, the front surface (1.1) of negative lens (1) is secondary aspherical, the rear surface (1.2) of negative lens (1) is ball
Face；The front surface (2.1) of positive lens (2) and rear surface (2.2) are spherical surface.
A kind of design method of medium-wave infrared optical system, includes the following steps:
Step 1, establish using optical material heat differential and chromatic aberration coefficient as equation group coefficient, focal power for unknown number it is non-next
Equation group:
In formula (1): k is the quantity of lens in lens group, takes 2；hiIt is the paraxial rays after normalization on each lens
Delivery altitude,For normalization after each optical lens focal power,For the total focal power of system after normalization, ωiFor
The normalization chromatic aberration coefficient of lens selected materials, θiFor the normalization thermal differential coefficient of lens selected materials, Δ fbTo be caused by color difference
Lens group focus offset amount,For the lens group focal length variations amount as caused by difference variation；
Step 2 carries out abbreviation to the equation group (1) of the step 1, enables:
Further abbreviation is carried out for double separate structures:
Wherein, a and b intermediate computations parameter in formula (2)；
Step 3 solves (3) formula, obtains the condition that equation group has solution are as follows:
Step 4 is directed to common medium-wave infrared optical material, obtains the chromatic aberration coefficient and thermal differential coefficient of each optical material
Curve bus；The chromatic aberration coefficient optical material for meeting (4) two kinds of equation approximate with thermal differential coefficient is found in the graph, thus
Determine the material of two lens in the medium-wave infrared optical system；
The optical material of step 5, two lens determined according to step 4, parameter is updated in equation (3), by asking
It solves equation, obtains the respective material of two lens and normalization light focal power.
The invention has the following beneficial effects:
(1) medium-wave infrared optical system of the invention only with two panels lens and a piece of aspherical is achieved that optical system
Within the scope of -40 DEG C~60 DEG C without thermalized design, have many advantages, such as small in size, light-weight high with transmitance, have biggish
Relative aperture and biggish field angle, image planes are stablized, and image quality is good, and full filed modulation transfer function is in Nyquist
It is greater than 0.7 at frequency 16.7lp/mm, close to diffraction limit, therefore is conducive in the reliability that improves military infrared system and steady
Research and development cost is reduced while qualitative.
(2) medium-wave infrared method of designing optical system of the invention, from the principle of PASSIVE OPTICAL penalty method, establish with
Optical material heat differential and chromatic aberration coefficient are equation group coefficient, and focal power is the non-secondly equation group of equation group unknown number, by begging for
The reasonably combined of optical material is determined by solution of equations and further determines that the focal power that should be distributed per a piece of lens, it can be with
Simplify the design process of optical system.
Detailed description of the invention
Fig. 1 is optical system structure schematic diagram of the present invention.
Fig. 2 (a) is MTF figure of the optical system of the present invention at 20 DEG C, and Fig. 2 (b) is optical system of the present invention at 20 DEG C
Point range figure.
Fig. 3 (a) is MTF figure of the optical system of the present invention at -40 DEG C, and Fig. 3 (b) is optical system of the present invention at -40 DEG C
Under point range figure.
Fig. 4 (a) is MTF figure of the optical system of the present invention at 60 DEG C, and Fig. 4 (b) is optical system of the present invention at 60 DEG C
Point range figure.
Fig. 5 is " T-C " figure used in the present invention, and abscissa is the normalization chromatic aberration coefficient of material in figure, and ordinate is
The normalization thermal differential coefficient of material.
Specific embodiment
The present invention will now be described in detail with reference to the accompanying drawings and examples.
The technical solution of the invention is as follows: from the principle of PASSIVE OPTICAL penalty method, establishing with optical material heat differential
It is equation group coefficient with chromatic aberration coefficient, lens group focal power is the non-secondly equation group of equation group unknown number, through discussion equation
The solution of group determines the reasonably combined of optical material and further determines that the focal power that should be distributed per a piece of lens.
By solving the non-secondly equation group, determine using negative lens in preceding, the posterior double separate type optics of positive lens
Structure, wherein negative lens material selection monocrystalline germanium (Ge), positive lens select silicon (Si).Refractive index due to monocrystalline germanium at 4 μm is
4.0247, normalization thermal differential coefficient is 130 × 10-6/ DEG C, silicon is 3.4253 in 4 μm of refractive index, and normalization thermal differential coefficient is 63
×10-6/ DEG C, therefore negative lens should distribute lesser focal power as far as possible, positive lens should distribute biggish focal power to guarantee two
Heat differential caused by piece lens can compensate mutually.After determining the initial structure parameter of optical system, before negative lens
A piece of secondary aspherical is added in surface, for correcting spherical aberration, coma and the astigmatism of system.It is appropriate by setting hereby to cut down your curvature of field
Lens spacing with increase positive lens center thickness corrected.
As shown in Figure 1, a kind of medium-wave infrared optical system based on PASSIVE OPTICAL without thermalization principle according to the present invention
It is made of negative lens 1, positive lens 2 with image planes 3 are received.
One embodiment of the invention are as follows: 3.3 μm~4.8 μm of optical system works wave band, -40 DEG C of operating temperature range
~60 DEG C, optical system relative aperture F#=2, field angle ω=± 3.7 °, system effective focal length f=24mm, detector target surface
Size is 320 × 256, and pixel dimension size is 30 μm.
Nonhomogeneous equation group (1) can be listed according to PASSIVE OPTICAL the principle of compensation:
In formula (1): k is the quantity of lens in lens group, takes 2；hiIt is the paraxial rays after normalization on each lens
Delivery altitude,For normalization after each optical lens focal power,For the total focal power of system after normalization, ωiIt is saturating
The normalization chromatic aberration coefficient of mirror selected materials, θiFor the normalization thermal differential coefficient of lens selected materials, Δ fbFor as caused by color difference
Lens group focus offset amount,For the lens group focal length variations amount as caused by difference variation.
From equation group (1) as can be seen that passing through reasonably combined optical material and distributing suitable focal power and can realize
Optical system without thermalized design.For solution formula (1), abbreviation is carried out to it, is enabled:
Further abbreviation can be carried out for double separate structures:
In formula (2), a and b are for intermediate computations parameter set by abbreviation formula (2), no concrete meaning, the same formula of other parameters
(1) identical.
(3) formula of solution can obtain, only meetOptical material can just equation group be made to have solution.Since medium wave is red
The optical material quantity of wave section is relatively limited, therefore can be by the chromatic aberration coefficient of common medium-wave infrared optical material and heat differential system
Number is labeled in composition " temperature difference coefficient-chromatic aberration coefficient " figure in cartesian coordinate system, intuitively carries out the selection of optical material, such as schemes
Shown in 5.
It is stringent as can be seen from Figure 5 to meetOptical material combine and be not present, approximation meets the light of the condition
Combination of materials is germanium (Ge) and silicon (Si), therefore selects germanium and optical material of the silicon as lens.In order to simplify initial configuration
Solution procedure, it is assumed that optical system is contiguity lens group, and bringing parameters into (3) formula and solving first lens should select
With germanium, normalization light focal power isSecond lens should select Si, and normalization light focal power is
Since the combination of germanium and silicon does not meet strictlyCan there are remaining color difference or heat differential.It considers simultaneously
The relative aperture of optical system and field angle are larger, negative lens front surface introduce it is a piece of it is aspherical with compensate remaining color difference or
Heat differential, while spherical aberration, coma and astigmatism for correcting system.Optical texture after optimizing repeatedly is as shown in Figure 1,20 DEG C
Under MTF and point range figure such as Fig. 2 (a) and 2 (b) shown in, shown in MTF point range figure such as Fig. 3 (a) at -40 DEG C and 2 (b), 60 DEG C
Under MTF point range figure such as Fig. 4 (a) and 2 (b) shown in.It can be seen from the figure that optical system picture within the scope of -40 DEG C~60 DEG C
Face is stablized, and image quality is good, is not acted upon by temperature changes substantially.
In conclusion the above is merely preferred embodiments of the present invention, being not intended to limit the scope of the present invention.
All within the spirits and principles of the present invention, any modification, equivalent replacement, improvement and so on should be included in of the invention
Within protection scope.
Claims (4)
1. a kind of medium-wave infrared optical system, which is characterized in that including the successively arranged in co-axial alignment in order along the light direction of propagation
Negative lens (1), positive lens (2) and receive image planes (3)；
The negative lens (1) be negative meniscus lens, convex surface towards object space to；The positive lens (2) is positive meniscus shaped lens, recessed
Facing towards the direction for receiving image planes (3)；
The service band of the medium-wave infrared optical system is 3.3 μm~4.7 μm, and operating temperature is -40 DEG C~60 DEG C.
2. requiring a kind of medium-wave infrared optical system according to right 1, which is characterized in that the optical material of negative lens (1)
For monocrystalline germanium, the optical material of positive lens (2) is silicon.
3. requiring a kind of medium-wave infrared optical system according to right 2, which is characterized in that the front surface of negative lens (1)
It (1.1) is secondary aspherical, the rear surface (1.2) of negative lens (1) is spherical surface；The front surface (2.1) and rear surface of positive lens (2)
It (2.2) is spherical surface.
4. the design method that a kind of right 1 requires the medium-wave infrared optical system, which comprises the steps of:
Step 1 is established using optical material heat differential and chromatic aberration coefficient as equation group coefficient, and focal power is its non-equation of n th order n of unknown number
Group:
In formula (1): k is the quantity of lens in lens group, takes 2；hiFor projection of the paraxial rays after normalization on each lens
Highly,For normalization after each optical lens focal power,For the total focal power of system after normalization, ωiFor selected by lens
The normalization chromatic aberration coefficient of material, θiFor the normalization thermal differential coefficient of lens selected materials, Δ fbFor the lens group as caused by color difference
Focus offset amount,For the lens group focal length variations amount as caused by difference variation；
Step 2 carries out abbreviation to the equation group (1) of the step 1, enables:
Further abbreviation is carried out for double separate structures:
Wherein, a and b intermediate computations parameter in formula (2)；
Step 3 solves (3) formula, obtains the condition that equation group has solution are as follows:
Step 4 is directed to common medium-wave infrared optical material, obtains the chromatic aberration coefficient and thermal differential coefficient curve of each optical material
Figure；The chromatic aberration coefficient optical material for meeting (4) two kinds of equation approximate with thermal differential coefficient is found in the graph, thereby determines that institute
State the material of two lens in medium-wave infrared optical system；
The optical material of step 5, two lens determined according to step 4, parameter is updated in equation (3), by solution side
Journey obtains the respective material of two lens and normalization light focal power.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20090052018A1 (en) * | 2007-08-23 | 2009-02-26 | Recon/Optical, Inc. | Compact two-element infrared objective lens and IR or thermal sight for weapon having viewing optics |
| CN102778747A (en) * | 2012-07-25 | 2012-11-14 | 中国科学院长春光学精密机械与物理研究所 | Light-machine-combined passivity thermal difference removing long-focus long-wave infrared objective lens |
| CN103207445A (en) * | 2012-01-13 | 2013-07-17 | 株式会社腾龙 | Infrared fixed-focus lens |
| CN104411649A (en) * | 2012-04-20 | 2015-03-11 | 肖特公司 | Glasses for correction of chromatic and thermal optical aberrations for lenses transmitting in the near, mid, and far-infrared sprectrums |
| CN207586516U (en) * | 2017-11-06 | 2018-07-06 | 河北汉光重工有限责任公司 | A kind of two-piece type LONG WAVE INFRARED tight shot |
-
2019
- 2019-03-07 CN CN201910169997.6A patent/CN109856784A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20090052018A1 (en) * | 2007-08-23 | 2009-02-26 | Recon/Optical, Inc. | Compact two-element infrared objective lens and IR or thermal sight for weapon having viewing optics |
| CN103207445A (en) * | 2012-01-13 | 2013-07-17 | 株式会社腾龙 | Infrared fixed-focus lens |
| CN104411649A (en) * | 2012-04-20 | 2015-03-11 | 肖特公司 | Glasses for correction of chromatic and thermal optical aberrations for lenses transmitting in the near, mid, and far-infrared sprectrums |
| CN102778747A (en) * | 2012-07-25 | 2012-11-14 | 中国科学院长春光学精密机械与物理研究所 | Light-machine-combined passivity thermal difference removing long-focus long-wave infrared objective lens |
| CN207586516U (en) * | 2017-11-06 | 2018-07-06 | 河北汉光重工有限责任公司 | A kind of two-piece type LONG WAVE INFRARED tight shot |
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